EPRSQ EPIRUS Biopharmaceuticals Inc (CE)

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Filed Pursuant to Rule 424(b)(5)
Registration No. 333- 205420

PROSPECTUS SUPPLEMENT
(To prospectus dated July 17, 2015)

$30,000,000 of Shares
Common Stock

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        This prospectus supplement and accompanying prospectus relate to the issuance and sale of up to $30,000,000 of shares of our common stock, par value $0.001 per share, from time to time through our sales agent, BTIG, LLC, or BTIG. These sales, if any, will be made under an at-the-market sales agreement, dated February 29, 2016, between us and BTIG, which we refer to as the sales agreement.

        Sales of our common stock, if any, under this prospectus supplement and the accompanying prospectus may be made by any method permitted by law deemed to be an "at-the-market offering" as defined in Rule 415 under the Securities Act of 1933, as amended, which we refer to as the Securities Act, including sales made directly on The NASDAQ Capital Market, on any other existing trading market for our common stock or to or through a market maker or through an electronic communications network. If expressly authorized by us, BTIG may also sell our common stock in privately negotiated transactions. BTIG will act as sales agent on a commercially reasonable efforts basis, consistent with its normal trading and sales practices and applicable state and federal laws, rules and regulations and the rules of The NASDAQ Capital Market. There is no specific date on which the offering will end, there are no minimum sale requirements and there are no arrangements to place any of the proceeds of this offering in an escrow, trust or similar account.

        BTIG will be entitled to compensation at a fixed commission rate of 3.0% of the gross proceeds from the sale of our common stock pursuant to the sales agreement. In connection with the sale of the common stock on our behalf, BTIG may, and will with respect to sales effected in an "at-the-market offering," be deemed to be an "underwriter" within the meaning of the Securities Act, and the compensation of BTIG may be deemed to be underwriting commissions or discounts. We have also agreed to provide indemnification and contribution to BTIG against certain civil liabilities, including liabilities under the Securities Act.

        Our common stock is listed on The NASDAQ Capital Market under the symbol "EPRS". The last reported sale price of our common stock on The NASDAQ Capital Market on February 26, 2016 was $2.80 per share.

        Investing in our common stock involves a high degree of risk. See "Risk Factors" beginning on page S-7 of this prospectus supplement and page 5 of the accompanying prospectus.

        Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

   

The date of this prospectus supplement is March 1, 2016.

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TABLE OF CONTENTS

PROSPECTUS SUPPLEMENT

PROSPECTUS

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ABOUT THIS PROSPECTUS SUPPLEMENT

        This document is in two parts. The first part is the prospectus supplement, including the documents incorporated by reference, which describes the specific terms of this offering. The second part, the accompanying prospectus, including the documents incorporated by reference, provides more general information. Generally, when we refer to this prospectus, we are referring to both parts of this document combined. Before you invest, you should carefully read this prospectus supplement, the accompanying prospectus, all information incorporated by reference herein and therein, as well as the additional information described under "Where You Can Find Additional Information" on page S-52 of this prospectus supplement. These documents contain information you should consider when making your investment decision. This prospectus supplement may add, update or change information contained in the accompanying prospectus. To the extent that any statement that we make in this prospectus supplement is inconsistent with statements made in the accompanying prospectus or any documents incorporated by reference therein, the statements made in this prospectus supplement will be deemed to modify or supersede those made in the accompanying prospectus and such documents incorporated by reference therein.

        You should rely only on the information contained in or incorporated by reference in this prospectus supplement, the accompanying prospectus and any free writing prospectus that we have authorized for use in connection with this offering. We have not, and BTIG has not, authorized anyone to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. We are not, and BTIG is not, making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted or in which the person making that offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer or solicitation. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus, the documents incorporated by reference in this prospectus supplement and the accompanying prospectus, and any free writing prospectus that we have authorized for use in connection with this offering, is accurate only as of the date of those respective documents. Our business, financial condition, results of operations and prospects may have changed since those dates. You should read this prospectus supplement, the accompanying prospectus, the documents incorporated by reference in this prospectus supplement and the accompanying prospectus, and any free writing prospectus that we have authorized for use in connection with this offering, in their entirety before making an investment decision. You should also read and consider the information in the documents to which we have referred you in the sections of this prospectus supplement entitled "Where You Can Find More Information" and "Incorporation of Certain Information by Reference."

        We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference into the accompanying prospectus were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreement, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties or covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

        "EPIRUS Biopharmaceuticals", "In Market, For Market" and "SCALE" are registered trademarks of EPIRUS Biopharmaceuticals, Inc. Our logos and trademarks are the property of EPIRUS Biopharmaceuticals, Inc. All other brand names or trademarks appearing in this prospectus are the property of their respective holders. Use or display by us of other parties' trademarks, trade dress, or products in this prospectus supplement is not intended to, and does not, imply a relationship with, or endorsements or sponsorship of, us by the trademark or trade dress owners.

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RISK FACTORS

        Investing in our common stock involves a high degree of risk. You should consider carefully the risks and uncertainties described below, together with all of the other information in this prospectus supplement, the accompanying prospectus, and the documents incorporated by reference herein before deciding whether to invest in our common stock. The risks described below are not the only ones we face. If any of the following risks actually occurs, our business, financial condition, results of operations and future prospects would likely be materially and adversely affected. In that event, the market price of our common stock could decline and you could lose all or part of your investment. Our actual results could differ materially from those anticipated in the forward-looking statements made throughout this prospectus supplement, the accompanying prospectus and the documents incorporated by reference, as a result of different factors, including the risks we face described below.

        In the following discussion of risk factors, references to "Zalicus" refer to the business of Zalicus Inc. as it existed prior to the merger on July 15, 2014, and references to "Private Epirus" refer to the business of EPIRUS Biopharmaceuticals, Inc. prior to the merger on July 15, 2014. References to "we," "us," "our," and similar terms refer to the combined business of EPIRUS Biopharmaceuticals, Inc. after the merger on July 15, 2014.

Risks Related to Financial Results, Need for Additional Financing and Debt Arrangements

We have a history of operating losses. We expect to incur significant operating losses and may never be profitable. Our common stock is a highly speculative investment.

        Private Epirus incurred operating losses since its inception, and was never cash-positive. Similarly, following the Merger described elsewhere in this prospectus supplement, Public Epirus has continued to incur net losses and has not been cash-positive. As of September 30, 2015, we had an accumulated deficit of $123.4 million. We have spent, and expect to continue to spend, significant resources to fund research and development of our product candidates and to enhance our drug development technologies. We expect to incur substantial operating losses over the next several years due to our ongoing research, development, pre-clinical testing, and clinical trial activities. As a result, our accumulated deficit will continue to increase.

        Except for BOW015, our product candidates are in the early stages of development and may never result in any revenue. We will not be able to generate product revenue unless we or our partners successfully commercialize BOW015 or our early stage product candidates. We may seek to obtain revenue from collaboration or licensing agreements with third parties. Our current collaboration and license agreements may not provide us with material, sustainable ongoing future revenue, and we may not be able to enter into additional collaboration agreements. Even if we eventually generate product revenues, we may never be profitable, and if we ever achieve profitability, we may not be able to sustain it.

We will require substantial additional funds to obtain regulatory approval for and commercialize our biosimilar product candidates and any future pipeline product candidates and, if additional capital is not available, we may need to limit, scale back or cease our operations.

        Since our inception, we have devoted substantial resources to the nonclinical and clinical development of our most advanced biosimilar product candidate, BOW015, a proposed biosimilar of Remicade® (infliximab). We will incur substantial costs for our global clinical program for BOW015, which we initiated in February 2016. We believe that we will continue to expend substantial resources for the foreseeable future for the clinical development of our current pipeline of biosimilar product candidates, including for development of any other indications and product candidates we may choose to pursue. These expenditures will include costs associated with research and development, conducting nonclinical studies and clinical trials, and manufacturing and supply as well as marketing and selling

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any products approved for sale. In addition, other unanticipated costs may arise. Because the outcome of any clinical trial is highly uncertain, we cannot reasonably estimate the actual amounts necessary to successfully complete the development and commercialization of BOW015 in all of the markets in which we plan to commercialize the product and our pipeline of other product candidates.

        We believe that our existing cash and cash equivalents will be sufficient to fund our operations through the second quarter of 2016. As a result, we believe that it is likely that the report of our independent registered public accounting firm to be included in our Annual Report on Form 10-K for the year ending December 31, 2015 will include an explanatory paragraph relating to our ability to continue as a going concern. As of September 30, 2015, our total cash and cash equivalents, including restricted cash, and marketable securities were $46.2 million. We may seek additional capital due to favorable market conditions or strategic considerations, even if we believe we have sufficient funds for our current or future operating plans. We may also seek to raise additional funds before that time if our research and development expenses exceed current expectations, our collaboration funding is less than current assumptions or expectations, or we encounter obstacles to our development and commercialization of our product candidates that were not anticipated. This could occur for many reasons, including:

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our product candidates require more extensive clinical or pre-clinical testing, our research and development programs for our product candidates do not proceed as expected, our clinical trials take longer to complete than we currently expect or our clinical trials are not successful;



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we advance more of our product candidates than expected into costly later stage clinical trials;



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we advance more of our pre-clinical product candidates than expected into early stage clinical trials;



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our revenue-generating collaboration agreements are terminated;



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the time and costs involved in obtaining regulatory approvals are higher than anticipated in one or more jurisdictions where we are seeking to manufacture and/or market our products;



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some or all of our product candidates fail in clinical or pre-clinical studies or prove to be less commercially promising than we expect or we are forced to seek additional product candidates;



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we are required, or consider it advisable, to acquire or license rights from one or more third parties;



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we determine to enter into additional business combinations or acquire or license rights to additional product candidates or new technologies;



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the cost of regulatory, manufacturing and commercialization activities, if any, relating to our product candidates, are higher, or take longer to establish than anticipated; or



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we are subject to litigation in relation to our activities with respect to our product candidates, including potential patent litigation with innovator companies or others who may hold patents.

        While we expect to seek additional funding through public or private financings, we may not be able to obtain financing on acceptable terms, or at all. In addition, the terms of any financings may be dilutive to, or otherwise adversely affect, holders of our common stock. We may also seek additional funds through arrangements with collaborators or others. These arrangements would generally require us to relinquish rights to some of our technologies, product candidates or products, and we may not be able to enter into such agreements on acceptable terms, if at all. The arrangements also may include issuances of equity, which may also be dilutive to, or otherwise adversely affect, holders of our common stock. There can be no assurance that we will be able to access equity or credit markets in order to finance our operations or expand development programs for any of our product candidates, or that there will not be a deterioration in financial markets and confidence in economies that could make it

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difficult or impossible to access these markets. We may also have to scale back or further restructure our operations. If we are unable to obtain additional funding on a timely basis, we may be required to curtail or terminate some or all of our research or development programs.

Our term loans include certain covenants and other events of default. Should we not comply with these covenants or incur an event of default, we may be required to repay our obligation in cash, which could have an adverse effect on our liquidity.

        Our term loans from Hercules Technology Growth Capital, Inc. include certain customary covenants, including limitations on other indebtedness, liens, acquisitions, investments and dividends.

        If we fail to stay in compliance with our covenants or suffer some other event of default under the term loans, we may be required to repay the outstanding principal. Should this occur, our liquidity would be adversely impacted.

The requirements of being a public company have required and will continue to require significant resources, increase our costs and occupy our management's time and efforts, and we may be unable to continue to comply with these requirements in a timely or cost-effective manner.

        Our merger with Zalicus was determined to constitute a reverse acquisition and Private Epirus, a privately held company, was determined to be the acquirer for accounting purposes. Although Zalicus was an operating company, its operations were deemphasized following the consummation of the merger with the post-merger entity, which focuses on Private Epirus' biosimilar business. Because the financial statements and information relating to Private Epirus now constitute our financial statements and information, we are in a position similar to a newly public company.

        As a company with public reporting responsibilities, we have incurred and will continue to incur significant legal, accounting, and other expenses that Private Epirus did not incur as a private company. Complying with rules, regulations and requirements applicable to public companies has required substantial effort and has increased and may continue to increase our costs and expenses. We have been required to:

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institute a more formalized function of internal control over financial reporting;



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prepare, file and distribute periodic and current reports under the Securities Exchange Act of 1934, or the Exchange Act, and comply with other Exchange Act requirements applicable to public companies;



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formalize old and establish new internal policies, such as those relating to insider trading and disclosure controls and procedures;



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involve and retain to a greater degree outside counsel and accountants in the above activities; and



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establish and maintain an investor relations function, including the provision of certain information on our website.

        Compliance with these rules and regulations has increased, and will continue to increase, our legal and financial compliance costs and will make some activities more time-consuming and costly. For example, these rules and regulations have made it more expensive for us to obtain director and officer liability insurance and we have been required to incur substantial costs to maintain the same or similar coverage.

        In connection with our merger, the Securities and Exchange Commission, or the SEC, granted us a waiver of the requirements of Section 404 of the Sarbanes-Oxley Act of 2002, or the Sarbanes-Oxley Act, for a period of one year, and therefore we are not required to make a formal assessment of the

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effectiveness of our internal controls over financial reporting for that purpose until the filing of our annual report on Form 10-K for the fiscal year ending December 31, 2015. In anticipation of this formal assessment, we have been required to comply with Section 404 since January 1, 2015. In connection with the preparation of certain of our 2014 interim financial statements, our management team and independent registered public accounting firm identified certain weaknesses in our internal controls that were considered to be a material weakness. As of September 30, 2015, our management, including our Chief Executive Officer and Chief Financial Officer, evaluated our internal controls and procedures, including the existence of the material weakness in our internal control over financial reporting, and concluded that our disclosure controls and procedures were not effective to provide reasonable assurance that information required to be disclosed by us in reports that we file or submit under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the SEC's rules and forms, or that such information is accumulated and communicated to our management, including the CEO and CFO, as appropriate to allow timely decisions regarding required disclosure. Additionally, in connection with our acquisition of Bioceros and the preparation of audited 2014 financial statements for that entity, Bioceros' independent registered public accounting firm identified certain material weaknesses with regards to converting the Bioceros financial statements from accounting principles generally accepted in the Netherlands, or Dutch GAAP, to accounting principles generally accepted in the United States, or U.S. GAAP.

        We may subsequently identify additional errors or deficiencies in our internal control over financial reporting, including any such errors or deficiencies in connection with the Bioceros financial statements that are deemed to be material weaknesses, such as the material weakness discussed in the other risk factors described in this section. Additionally, in complying with Section 404, we have incurred, and expect to continue to incur, significant expenses and devote substantial management effort toward ensuring compliance with these requirements. If we are not able to comply with these requirements in a timely manner, or if we identify deficiencies in our internal control over financial reporting that are deemed to be material weaknesses, the market price of our common stock could decline and we could be subject to sanctions or investigations by the SEC or other regulatory authorities, which would entail expenditure of additional financial and management resources. See "Risks Related to an Investment in Our Common Stock—Our management and independent auditors have identified material weaknesses in our internal controls, and we may be unable to develop, implement and maintain appropriate internal and disclosure controls in future periods, which may lead to errors or omissions in our financial statements."

Our international operations subject us to potentially adverse tax consequences.

        We generally conduct our international operations through wholly-owned subsidiaries and report our taxable income in various jurisdictions worldwide based upon our business operations in those jurisdictions. Our intercompany relationships are subject to complex transfer pricing regulations administered by taxing authorities in various jurisdictions. The relevant taxing authorities may disagree with our determinations as to the income and expenses attributable to specific jurisdictions. If such a disagreement were to occur, and our position were not sustained, we could be required to pay additional taxes, interest and penalties, which could result in one-time tax charges, higher effective tax rates, reduced cash flows and lower overall profitability of our operations.

Risks Relating to the Development, Manufacturing and Commercialization of Our Products

We are largely dependent on the success of BOW015. All of our other product candidates are still in pre-clinical development. If we are unable to obtain regulatory approval in additional jurisdictions for, or successfully commercialize, BOW015, our business will be materially harmed.

        Our business prospects and potential product revenues are largely dependent upon our ability to obtain regulatory approval of, and successfully commercialize, BOW015. We have reported positive

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bioequivalence and efficacy data in the clinical development program for BOW015, including a Phase 1 clinical trial in the United Kingdom and a Phase 3 clinical trial in India, in each case showing equivalence with Remicade as the reference product. We also announced positive 58 week follow up data from the Phase 3 trial. In this open label phase, we demonstrated that patients can be initiated and maintained on BOW015 for 58 weeks, and that patients can be switched from Remicade to BOW015 and maintained out to 58 weeks, with a favorable safety and efficacy profile. In March 2014, our manufacturing partner, Reliance Life Sciences Pvt Ltd, or RLS, obtained marketing approval on our behalf in India for BOW015 for rheumatoid arthritis on the basis of our Phase 3 trial, and in September 2014, RLS received final manufacturing and market approval on our behalf from the Drug Controller General of India, or the DCGI. We currently have an agreement to commercialize BOW015 in India with our partner Sun Pharmaceutical Industries Ltd., or Sun, and in November 2014, we launched BOW015 in India with Sun. As discussed in the other risk factors described in this section, we settled a dispute with RLS that may adversely affect our ability to rely on the approvals that have been obtained by RLS for our benefit and that we currently rely upon for selling BOW015 in India. In the event that the DCGI does not approve the transfer of the marketing approval to us or our designee, pursuant to the terms of our Settlement Agreement with RLS (as described below) and it becomes necessary to obtain new manufacturing and marketing approvals from the DCGI, no assurance can be given as to whether we or our partners will be able to obtain the required approvals or that any such approvals will be obtained in a timely manner. If Sun encounters delays or difficulties in commercializing BOW015 pursuant to our agreement, it may adversely affect our ability to successfully commercialize BOW015 in India. Additionally, in conjunction with other potential partners with whom we may form alliances, we intend to file for regulatory approval in additional markets where our current data are expected to be sufficient for approval. In February 2016, we initiated this global clinical program, which we refer to as the UNIFORM Study. The UNIFORM Study is a 58-week, double-blind, one-to-one randomized, comparator-controlled multi-center global study to compare safety, efficacy and immunogenicity and demonstrate clinical equivalence of BOW015 with Remicade. As discussed in the other risk factors described in this section, obtaining regulatory approval is costly and uncertain. Even if we obtain regulatory approval for BOW015 in a jurisdiction, we may not be successful in commercializing it in the jurisdiction. If we fail to successfully commercialize BOW015, or encounter significant delays in doing so, we may be required to curtail or terminate some or all of our research or development programs and our business prospects, financial condition and results of operations would be materially harmed. To date, we have not yet commercialized BOW015 in any of our target markets other than India.

        Our other product candidates, BOW050, BOW070, BOW080, BOW090 and BOW100 are in pre-clinical development. Before we can commercialize these product candidates we need to:

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conduct substantial research and development;



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undertake nonclinical and clinical testing, for the purpose of demonstrating bioequivalence with the applicable reference products, and engage in sampling activity and other costly and time consuming measures;



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scale-up manufacturing processes; and



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pursue and obtain marketing and manufacturing approvals and, in some jurisdictions, pricing and reimbursement approvals.

        This process involves a high degree of risk and takes many years, and success is never guaranteed. Our product development efforts with respect to these product candidates may fail for many reasons, including:

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failure of the product candidate in nonclinical studies, including those required to demonstrate bioequivalence with the reference product;

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inability to obtain on a timely basis supplies of the applicable reference products to which our product candidates must be compared;



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delays or difficulty enrolling patients in clinical trials, particularly for disease indications with small patient populations;



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patients exhibiting adverse reactions to the product candidate or indications of other safety concerns;



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insufficient clinical trial data to support the bioequivalence of one or more of our product candidates with the applicable reference product;



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inability to manufacture sufficient quantities of the product candidate for development or commercialization activities in a timely and cost-efficient manner, if at all;



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potential patent litigation with innovator companies or others who may hold patents;



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failure to obtain, or delays in obtaining, the required regulatory approvals for the product candidate, the facilities or the processes used to manufacture the product candidate; or



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changes in the regulatory environment, including pricing and reimbursement that make development of our biosimilar product candidates or development of such product candidates for a new indication no longer desirable.

        If our product development efforts fail for any of these or other reasons, or we decide to abandon development of a product candidate at any time, we would never realize revenue from those programs and our business could be materially harmed.

If an improved version of a reference product, such as Remicade, is developed, or if the market for a reference product significantly declines, sales or potential sales of our biosimilar product candidates may suffer.

        We are developing and commercializing follow-on versions of approved, reference biological products. Such follow-on products are known as biosimilars. Innovator companies may develop improved versions of a reference product as part of a life cycle extension strategy, and may obtain regulatory approval of the improved version under a new or supplemental application filed with the applicable regulatory authority. Should the innovator company succeed in obtaining an approval of an improved biologic product, it may capture a significant share of the collective reference product market in the applicable jurisdiction and significantly reduce the market for the reference product and thereby the potential size of the market for our product candidates. In addition, the improved product may be protected by additional patent rights and thereby subject our follow-on biosimilar to claims of infringement.

        Additionally, competition in the biotechnology industry is intense. Reference biologic products face competition on numerous fronts as technological advances are made that may offer patients a more convenient form of administration or increased efficacy, or as new products are introduced. As new products are approved that compete with the reference products to our biosimilar product candidates, such as Remicade, or our pipeline products, such as Humira and others, sales of the reference biologic products may be significantly and adversely impacted and may render the reference products obsolete. If the market for the reference product is impacted, we in turn may lose significant market share or market potential for our biosimilar products and product candidates, and the value for our product pipeline could be negatively impacted. As a result of the above factors, our business, prospects and financial condition could suffer.

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Our biosimilar product candidates, if approved, will face significant competition from the reference products and from other biosimilars approved for the same indication as the reference biologic products. Our failure to effectively compete may prevent us from achieving significant market penetration and expansion.

        Our business involves highly competitive pharmaceutical and biotechnology markets. Successful competitors in the pharmaceutical market have the ability to effectively discover, obtain patents, develop, test and obtain regulatory approvals for products, as well as the ability to effectively commercialize, market and promote approved products, including communicating the effectiveness, safety and value of products to actual and prospective customers and medical staff. Numerous companies, universities, and other research institutions are engaged in developing, patenting, manufacturing and marketing of products competitive with those that we are developing. Many of these potential competitors, such as Celltrion, Inc. and Hospira, Inc. (acquired by Pfizer, Inc.), are large, experienced companies that enjoy significant competitive advantages, such as substantially greater financial, research and development, manufacturing, personnel and marketing resources, greater brand recognition and more experience and expertise in undertaking nonclinical testing and clinical trials of product candidates, and obtaining regulatory approvals of products. If we do not effectively compete with these potential competitors, the value of our product pipeline could be negatively impacted and our business, prospects and financial condition could suffer.

Use of our product candidates could be associated with side effects or adverse events.

        As with most pharmaceutical and biological drug products, use of our product candidates could be associated with side effects or adverse events, which can vary in severity (from minor reactions to death) and frequency. Side effects or adverse events associated with the use of our product candidates or those of our collaborators may be observed at any time, including in clinical trials or later when a product is commercialized, and any such side effects or adverse events may negatively affect our ability to obtain regulatory approvals or market our product candidates. Side effects such as toxicity or other safety issues associated with the use of our product candidates could require us or our collaborators to halt development or sale of these product candidates or expose us to product liability lawsuits that would harm our business. We may also be required by regulatory agencies to conduct additional nonclinical studies or clinical trials that we have not planned or anticipated. There can be no assurance that we will resolve any issues related to any product-related adverse events to the satisfaction of any regulatory agency in a jurisdiction where we are seeking to commercialize our products or obtain approval in a timely manner or ever, which could harm our business, prospects and financial condition.

        In addition, if we are successful in commercializing the most advanced biosimilar in our pipeline, BOW015, or any other of our pipeline product candidates, then laws and regulations may require that we report certain information about adverse medical events according to timelines that may vary from jurisdiction to jurisdiction. The timing of our obligation to report may be triggered by the date we become aware of the adverse event as well as the nature of the event. We may fail to report adverse events we become aware of within the prescribed timeframe. We may also fail to appreciate that we have become aware of a reportable adverse event, especially if it is not reported to us as an adverse event or if it is an adverse event that is unexpected or removed in time from the use of our products. If we fail to comply with our reporting obligations, regulatory agencies could take action including, without limitation, criminal prosecution, the imposition of civil monetary penalties, seizure of our products, or delay in approval of future products. Any of the foregoing scenarios could materially harm the commercial prospects for our product candidates.

We may have significant product liability exposure that may harm our business and our reputation.

        Although our product candidates are biosimilar products, and are designed to be equivalent against reference products that have an established safety record in the indications in which they are marketed and used, we face a risk of product liability as a result of the clinical testing of our product

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candidates and will face an even greater risk as we commercialize our products. For example, we may incur liability if any product we develop allegedly causes injury or is found to be otherwise unsuitable during product testing, manufacturing, marketing or sale. Any such product liability claims may include allegations of defects in manufacturing, defects in design, a failure to warn of dangers inherent in the product, negligence, strict liability and a breach of warranties. Claims could also be asserted under state consumer protection acts or comparable statutes abroad. If we cannot successfully defend ourselves against product liability claims, we may incur substantial liabilities or be required to limit commercialization of our products. Regardless of the merits or eventual outcome, liability claims may result in:

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decreased demand for BOW015, or any future product candidates that may obtain regulatory approval;



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injury to our reputation and significant negative media attention;



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withdrawal of clinical trial participants or cancellation of clinical trials;



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costs to defend the related litigation;



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a diversion of management's time and our resources;



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substantial monetary awards to trial participants or patients;



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regulatory investigations, product recalls, withdrawals or labeling, marketing or promotional restrictions;



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loss of revenue; and



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the inability to commercialize any products we develop.

        Our inability to obtain and maintain sufficient product liability insurance at an acceptable cost and scope of coverage to protect against potential product liability claims could impact the commercialization of BOW015, and any of our other product candidates. We currently carry product liability insurance covering our clinical trials in the amount of $5 million in the aggregate. Although we maintain such insurance, any claim that may be brought against us could result in a court judgment or settlement in an amount that is not covered, in whole or in part, by our insurance or that is in excess of the limits of our insurance coverage. Our insurance policies also have various exclusions and deductibles, and we may be subject to a product liability claim for which we have no coverage. We will have to pay any amounts awarded by a court or negotiated in a settlement that exceed our coverage limitations or that are not covered by our insurance, and we may not have, or be able to obtain, sufficient capital to pay such amounts. Moreover, in the future, we may not be able to maintain insurance coverage at a reasonable cost or in sufficient amounts to protect us against losses in all the jurisdictions in which we seek to market and sell our products. As we obtain approvals for marketing BOW015 and any other product candidates in more jurisdictions, we intend to expand our insurance coverage to include the sale of such products; however, we may be unable to obtain this liability insurance on commercially reasonable terms.

If we fail to attract and keep senior management and key scientific personnel, we may be unable to successfully develop our pipeline product candidates, conduct our clinical trials and commercialize BOW015, or any future pipeline product candidates we develop.

        Our success depends in large part on our continued ability to attract, retain and motivate highly qualified management, clinical and scientific personnel. We believe that our future success is highly dependent upon the contributions of our senior management, particularly our chief executive officer, chief financial officer, chief technical officer, vice president of program management, and vice president of manufacturing and quality, as well as our senior scientists and other members of our senior

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management team. The loss of services of any of these individuals could delay or prevent the successful development of our product pipeline, completion of our planned clinical trials or the commercialization of BOW015, or any future products we develop.

        Although we have not historically experienced significant difficulties attracting and retaining qualified employees, we could experience such problems in the future. For example, competition for qualified personnel in the biotechnology and pharmaceuticals field is intense due to the limited number of individuals who possess the skills and experience required by our industry. We will need to hire additional personnel as we expand our process and clinical development and commercial activities. We may not be able to attract and retain quality personnel on acceptable terms, or at all, which may cause our business and operating results to suffer.

We expect to enter into alliances with other companies that can provide capabilities and funds for the development and commercialization of our product candidates, as well as local market access in jurisdictions where we intend to pursue our In Market, For Market commercialization strategy. If we are unsuccessful in forming or maintaining these alliances on favorable terms, or if such alliances do not prove to be as successful as we anticipate, our business could be adversely affected.

        Our In Market, For Market strategy for development and commercialization of our biosimilar product candidates in key emerging markets is based on the assumption that we will enter into collaborative relationships with local entities to facilitate our access to and penetration into such markets. We also have limited or no capabilities for independent manufacturing, sales, marketing and distribution. In September 2014, we entered into a collaboration agreement with Livzon MabPharm Inc., or Livzon, for the development and commercialization of BOW015 and other pipeline biosimilar products to be agreed with Livzon in China, using our In Market, For Market strategy, and in September 2015, added BOW070 as a product candidate to be developed pursuant to the terms of this collaboration agreement. We retain global rights to commercialize BOW015, BOW070 and the other pipeline biosimilar products outside of China, subject to our other agreements with third parties.

        In the future, we expect to form additional alliances with other companies that are based in our target markets and that have expertise in development, manufacture and commercialization of biologics and biosimilar products in our target markets to enable us to expand the commercialization opportunities for our product candidates. In such alliances, we would expect our partners to provide substantial capabilities in clinical development, manufacturing, regulatory affairs, sales and marketing. We may not be successful in entering into any such alliances. Even if we do succeed in securing such alliances, we may not be able to maintain them if, for example, development or approval of a product candidate is delayed or sales of an approved product are disappointing. If we are unable to secure or maintain such alliances we may not have the capabilities necessary to continue or complete development of our product candidates and bring them to market, which may have an adverse effect on our business.

        In addition to product development and commercialization capabilities, we may depend on our alliances with other companies, such as our current alliances with Livzon, Polpharma, and Mabxience, among others, to provide substantial additional funding for development and potential commercialization of our product candidates. We may not be able to obtain funding on favorable terms from these alliances, and if we are not successful in doing so, we may not have sufficient funds to develop a particular product candidate internally, or to bring product candidates to market. Failure to bring our product candidates to market would prevent us from generating sales revenue, and this would substantially harm our business. Furthermore, any delay in entering into these alliances could delay the development and commercialization of our product candidates and reduce their competitiveness even if they reach the market. As a result, our business may be adversely affected.

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Failure to obtain or maintain adequate coverage and reimbursement for our product candidates could limit our ability to market those products and decrease our ability to generate revenue.

        Sales of our product candidates will depend substantially, both domestically and abroad, on the extent to which our product candidates will be covered by third party payors such as private health insurers, managed care organizations, and government healthcare programs such as Medicare and Medicaid and the adequacy of the payments for those products. If coverage and reimbursement are not available, or are available only to limited levels, we may not be able to successfully commercialize our product candidates. Because there are not many approved biosimilars available, many countries and payors have not yet established policies for the coverage and payment for those types of drugs, even if the reference biologic is covered. Moreover, even if coverage is provided, the approved reimbursement amount may not be high enough to allow us to establish or maintain pricing sufficient to realize a return on our investment.

        There is significant uncertainty related to the insurance coverage and reimbursement of newly approved products. In the United States, third-party payors, including private and governmental payors, such as the Medicare and Medicaid programs, play an important role in determining the extent to which new drugs and biologics will be covered and reimbursed. The Medicare program covers most individuals aged 65 or older, individuals suffering from end-stage renal disease and certain disabled individuals. The Medicaid program, which varies from state-to-state, covers individuals and families who have limited financial means or meet other eligibility requirements. Medicare is often used as a model for how private payors and other governmental payors develop their coverage and reimbursement policies for drugs and biologics. It is difficult to predict at this time what third-party payors will decide with respect to the coverage and reimbursement for our product candidates.

        Outside the United States, international operations are generally subject to extensive governmental price controls and other market regulations, and we believe the increasing emphasis on cost-containment initiatives in Europe, Canada, and other countries has and will continue to put pressure on the pricing and usage of our product candidates. In many countries, the prices of medical products are subject to varying price control mechanisms as part of national health systems. In general, the prices of medicines under such systems are substantially lower than in the United States. Other countries allow companies to fix their own prices for medical products, but monitor and control company profits. Additional foreign price controls or other changes in pricing regulation could restrict the amount that we are able to charge for our product candidates. Accordingly, in markets outside the United States, the reimbursement for our products may be reduced compared with the United States and may be insufficient to generate commercially reasonable revenues and profits.

        Moreover, increasing efforts by governmental and third-party payors in the United States and abroad to cap or reduce healthcare costs may cause such organizations to limit both coverage and the level of reimbursement for new products approved and, as a result, they may not cover or provide adequate payment for our product candidates. We expect to experience pricing pressures in connection with the sale of any of our product candidates due to the trend toward managed healthcare, the increasing influence of health maintenance organizations and additional legislative changes. The downward pressure on healthcare costs in general, particularly prescription drugs and surgical procedures and other treatments, has become very intense. As a result, increasingly high barriers are being erected to the entry of new products.

Healthcare legislative reform measures may have a material adverse effect on our business and results of operations.

        In the United States, there have been and continue to be a number of legislative initiatives to contain healthcare costs. For example, in March 2010, the Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act, or the Affordable Care Act, was

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passed, which substantially changes the way health care is financed by both governmental and private insurers, and significantly impacts the U.S. pharmaceutical industry. The Affordable Care Act, among other things, subjects biologic products to potential competition by lower-cost biosimilars, and introduced a new methodology for determining the payment amount for a biosimilar product under Medicare Part B. In October 2015, the Center for Medicare & Medicaid Services, or CMS, finalized the rule for reimbursement of biosimilars. Under the rule, all biosimilars relying on a common reference product will be grouped into the same payment calculation for determining the single average sales price, or ASP, payment limit. Until such time as there are additional sales data for subsequent biosimilars to determine an ASP, a newly approved biosimilar price will be determined by local contractors using available pricing information. As with newly approved drugs and biologicals, Medicare Part B payment will generally be available once the product is approved by the FDA provided the claim is reasonable and necessary and meets applicable coverage and claims submission criteria. CMS has not yet issued guidance for interchangeable biologics since there are currently no interchangeable biologics being marketed.

        We expect that additional state and federal healthcare reform measures will be adopted in the future, any of which could limit the amounts that federal and state governments will pay for healthcare products and services, which could result in reduced demand for our product candidates or additional pricing pressures.

We may be subject, directly or indirectly, to federal and state healthcare fraud and abuse laws, false claims laws, and health information privacy and security laws. If we are unable to comply, or have not fully complied, with such laws, we could face substantial penalties.

        If we obtain approval from the U.S. Food and Drug Administration, or FDA, for any of our product candidates and begin commercializing those products in the United States, our operations may be directly, or indirectly through our customers, subject to various federal and state fraud and abuse laws, including, without limitation, the federal Anti-Kickback Statute, the federal False Claims Act, and physician sunshine laws and regulations. These laws may impact, among other things, our proposed sales, marketing, and education programs. In addition, we may be subject to patient privacy regulation by both the federal government and the states in which we conduct our business. The laws that may affect our ability to operate include:

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the federal Anti-Kickback Statute, which prohibits, among other things, persons from knowingly and willfully soliciting, receiving, offering or paying remuneration, directly or indirectly, to induce, or in return for, the purchase or recommendation of an item or service reimbursable under a federal healthcare program, such as the Medicare and Medicaid programs;



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federal, civil and criminal false claims laws and civil monetary penalty laws, which prohibit, among other things, individuals or entities from knowingly presenting, or causing to be presented, claims for payment from Medicare, Medicaid, or other third-party payors that are false or fraudulent;



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the federal Health Insurance Portability and Accountability Act of 1996, or HIPAA, which created new federal criminal statutes that prohibit executing a scheme to defraud any healthcare benefit program and making false statements relating to healthcare matters;



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HIPAA, as amended by the Health Information Technology and Clinical Health Act, or HITECH, and its implementing regulations, which imposes certain requirements relating to the privacy, security, and transmission of individually identifiable health information;



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the federal physician sunshine requirements under the Affordable Care Act, which require manufacturers of drugs, devices, biologics, and medical supplies to report annually to the U.S. Department of Health and Human Services information related to payments and other transfers of value to physicians, other healthcare providers, and teaching hospitals, and ownership and investment interests held by physicians and other healthcare providers and their immediate family members and applicable group purchasing organizations; and

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state law equivalents of each of the above federal laws, such as anti-kickback and false claims laws that may apply to items or services reimbursed by any third-party payor, including commercial insurers, state laws that require pharmaceutical companies to comply with the pharmaceutical industry's voluntary compliance guidelines and the relevant compliance guidance promulgated by the federal government, or otherwise restrict payments that may be made to healthcare providers and other potential referral sources; state laws that require drug manufacturers to report information related to payments and other transfers of value to physicians and other healthcare providers or marketing expenditures; and state laws governing the privacy and security of health information in certain circumstances, many of which differ from each other in significant ways and may not have the same effect, thus complicating compliance efforts.

        Because of the breadth of these laws and the narrowness of the statutory exceptions and safe harbors available, it is possible that some of our current or future business activities could be subject to challenge under one or more of such laws. In addition, recent health care reform legislation has strengthened these laws. For example, the Affordable Care Act, among other things, amends the intent requirement of the federal anti-kickback and criminal healthcare fraud statutes. A person or entity no longer needs to have actual knowledge of this statute or specific intent to violate it. Moreover, the Affordable Care Act provides that the government may assert that a claim including items or services resulting from a violation of the federal anti-kickback statute constitutes a false or fraudulent claim for purposes of the False Claims Act.

        If our operations are found to be in violation of any of the laws described above or any other governmental regulations that apply to us, we may be subject to penalties, including civil and criminal penalties, damages, fines, exclusion from participation in government health care programs, such as Medicare and Medicaid, imprisonment of our employees, and the curtailment or restructuring of our operations, any of which could adversely affect our ability to operate our business and our results of operations.

Failure to comply with the Foreign Corrupt Practices Act, or FCPA, and other similar anti-corruption laws and anti-money laundering laws, as well as export control laws, customs laws, sanctions laws and other laws governing our operations could subject us to significant penalties and damage our reputation.

        We are subject to the FCPA, which generally prohibits U.S. companies and intermediaries acting on their behalf from offering or making corrupt payments to "foreign officials" for the purpose of obtaining or retaining business or securing an improper business advantage. The FCPA also requires companies whose securities are publicly listed in the United States to maintain accurate books and records and to maintain adequate internal accounting controls. We are also subject to other similar anti-corruption laws and anti-money laundering laws, as well as export control laws, customs laws, sanctions laws and other laws that apply to our activities in the countries where we operate. Certain of the jurisdictions in which we conduct or expect to conduct business have heightened risks for public corruption, extortion, bribery, pay-offs, theft and other fraudulent practices. In addition, our international business is heavily regulated and therefore involves significant interactions with "foreign officials." We are also subject to other federal statutes and regulations, including those established by the Office of Foreign Assets Control, or OFAC. In many countries, health care professionals who serve as investigators in our clinical studies, or prescribe or purchase our commercialized products, are employed by a government or an entity owned or controlled by a government. Dealings with these investigators, prescribers and purchasers are subject to regulation under the FCPA. Under these laws and regulations, as well as other anti-corruption laws, anti-money-laundering laws, export control laws, customs laws, sanctions laws and other laws governing our operations, various government agencies may require export licenses, may seek to impose modifications to business practices, including cessation of business activities in sanctioned countries or with sanctioned persons or entities and modifications to

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compliance programs, which may increase compliance costs, and may subject us to fines, penalties and other sanctions.

        Recent events in Ukraine and Crimea have resulted in the European Union and the United States imposing and escalating sanctions on Russia and certain businesses, sectors and individuals in Russia. The European Union and the United States have also suspended the granting of certain types of export licenses to Russia. Russia has imposed its own sanctions on certain individuals in the United States and may impose other sanctions on the United States and the European Union and/or certain businesses or individuals from these regions. Although our products are not currently subject to such sanctions, we cannot assure you that the current sanctions or any further sanctions imposed by the European Union, the United States or other international interests will not materially adversely affect our operations. We rely on local and strategic business partners and collaborators to produce and commercialize our products in certain markets outside of the United States, and we rely on distributors and other intermediaries to sell and distribute our products internationally.

        We maintain policies, procedures and internal controls designed to promote compliance with the FCPA, OFAC restrictions and other anti-corruption laws and anti-money laundering laws, as well as export control laws, customs laws, sanctions laws and other laws. However, if we, our business partners, collaborators or intermediaries fail to comply with the requirements of the FCPA, OFAC restrictions or similar laws of other countries, or our controls and procedures fail to detect such noncompliance, governmental authorities in the United States or elsewhere, as applicable, could seek to impose civil penalties, criminal fines, and other collateral consequences. As we continue to expand internationally, there continues to be risk that the policies, procedures and internal controls on which we currently rely to promote compliance with these laws, regulations and restrictions will fail to be sufficiently effective and we will need to continue to develop those policies. A violation of these laws or regulations could damage our reputation and have a material adverse effect on our business, financial condition, and results of operations.

Our employees, independent contractors, principal investigators, contract research organizations, or CROs, consultants and collaborators may engage in misconduct or other improper activities, including noncompliance with regulatory standards and requirements and insider trading.

        We are exposed to the risk that our employees, independent contractors, principal investigators, CROs, consultants and collaborators may engage in fraudulent conduct or other illegal activity. Misconduct by these parties could include intentional, reckless and/or negligent conduct or unauthorized activities that violate: (1) regulations of regulatory authorities in jurisdictions where we are performing activities in relation to our product candidates, including those laws requiring the reporting of true, complete and accurate information to such authorities; (2) manufacturing regulations and standards; (3) applicable regulatory laws prohibiting the promotion of a medical product for a use that has not been cleared or approved by the applicable regulator; (4) fraud and abuse, anti-corruption laws and anti-money laundering laws, as well as similar laws and regulations and other laws; or (5) laws that require the reporting of true and accurate financial information and data. In particular, sales, marketing and business arrangements in the healthcare industry are subject to extensive laws and regulations, as well as various corruption investigations, intended to prevent fraud, bias, misconduct, kickbacks, self-dealing and other abusive practices, and these laws may differ substantially from country to country. These laws and regulations may restrict or prohibit a wide range of pricing, discounting, marketing and promotion, sales commission, customer incentive programs and other business arrangements. Misconduct by these parties could also include the improper use of information obtained in the course of clinical trials, which could result in regulatory sanctions and serious harm to our reputation. While we have in place a Code of Business Conduct and Ethics, it is not always possible to identify and deter misconduct by employees and other third parties. Moreover, the precautions we take to detect and prevent this activity may not be effective in controlling misconduct or preventing

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governmental investigations or proceedings or lawsuits stemming from a failure to be in compliance with such laws or regulations. If any such actions are instituted against us, and we are not successful in defending ourselves or asserting our rights, those actions could have a significant impact on our business including the imposition of significant civil, criminal and administrative penalties, damages, monetary fines, possible exclusion from participation in subsidized healthcare programs in a given country, contractual damages, reputational harm, diminished profits and future earnings, and curtailment of our operations, any of which could adversely affect our ability to operate our business and our results of operations.

Risks Related to Regulatory Approvals

The regulatory approval process is costly and lengthy and, for biosimilar products, still evolving. We may not be able to successfully obtain all required regulatory approvals or may be delayed in commercializing our products even after regulatory approvals are obtained.

        The pre-clinical development, clinical trials, manufacturing, marketing, testing, approval, and labeling of pharmaceutical and biological products, including biosimilars, are all subject to extensive regulation by numerous regulatory authorities throughout the world. We or our collaborators must obtain regulatory approval for product candidates before marketing or selling any of them. The approval process is typically lengthy and expensive, and approval is never certain. Moreover, only one biosimilar has been approved in the United States to date, and few biosimilars have been approved in other countries. It is not possible to predict with any specificity how long the approval processes of the applicable regulatory authorities for any of our products will take or whether any such approvals ultimately will be granted on a timely basis or at all. Moreover, we expect to seek regulatory approvals in jurisdictions in which we have limited experience navigating the regulatory frameworks, or where the regulatory frameworks for the approval of biosimilars are not well-developed and are constantly evolving. In particular, the regulatory standards applicable to establish biosimilarity vary by jurisdiction. The last ten years have seen the establishment in many jurisdictions of a formal regulatory process for review and approval of biosimilar products, but these procedures are at differing stages of development, with limited harmonization among major jurisdictions. We plan to continue to analyze and incorporate into our biosimilar development plans any new laws, regulations, or policies promulgated or established by relevant authorities. The costs of development and approval, along with the probability of success for our biosimilar product candidates, will be dependent upon application of any laws and regulations issued by the relevant regulatory authorities.

        Regulatory agencies generally have substantial discretion in the biologic and biosimilar approval processes, and positive results in pre-clinical testing or early phases of clinical trials offer no assurance of success in later phases of such tests or trials. Generally, pre-clinical and clinical testing of products can take many years and require the expenditure of substantial resources, and the data obtained from these tests and trials can be susceptible to varying interpretations that could delay, limit or prevent regulatory approval. Any delay in obtaining, or failure to obtain, approvals could prevent or adversely affect the marketing of our products or our collaborator's products and our ability to generate product revenue. The risks associated with the approval process include delays or rejections in the regulatory approval process based on the failure of clinical or other data to meet expectations, or the failure of the product or candidate to meet a regulatory agency's requirements for safety, efficacy and quality.

        Clinical trials can be delayed for a variety of reasons, including delays related to:

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ongoing discussions with the regulatory authorities regarding the scope or design of clinical trials;



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delays or the inability to obtain required approvals from institutional review committees or ethics committees at clinical sites selected for participation in our clinical trials;

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delays in enrolling patients and volunteers into clinical trials;



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lower than anticipated retention rates of patients and volunteers in clinical trials;



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the need to repeat clinical trials as a result of inconclusive or negative results or poorly executed testing;



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lack of sufficient funds for further clinical development;



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insufficient supply or deficient quality of product candidate materials or other materials necessary to conduct clinical trials;



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unsatisfactory regulatory inspection of a manufacturing, testing, labeling or packaging facility;



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unsatisfactory regulatory inspection of a clinical trial site or the records generated or maintained by such site;



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serious and unexpected drug-related side effects or serious adverse safety events experienced by participants in clinical trials or by patients following commercialization; or



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the placement of a clinical hold on a product candidate in a proposed or an ongoing clinical trial.

        We may not be able to conduct clinical trials at preferred sites, enlist clinical investigators, enroll sufficient numbers of patients, or demonstrate equivalence of our product candidates with the applicable reference products, or begin or successfully complete clinical trials in a timely fashion, if at all. Any failure to perform may delay or terminate the trials. Our current clinical trials may be insufficient to demonstrate that our potential products are equivalent to the applicable reference products, or sufficiently active, safe, or effective and as a result we may decide to abandon further development of such product candidates. Additional clinical trials may be required if clinical trial results are negative or inconclusive, or insufficient to obtain regulatory approval in one or more countries under applicable laws regulating biosimilar products, which will require us to incur additional costs and significant delays. If we do not receive the necessary regulatory approvals, we will not be able to generate product revenues and will not become profitable. We may encounter significant delays in the regulatory process that could result in excessive costs that may prevent us from continuing to develop our product candidates. In addition, the failure to comply with applicable regulatory requirements may result in criminal prosecution, civil penalties, product recalls, withdrawal of product approval, mandatory restrictions or other actions that could impair our ability to conduct our business.

The development, manufacture and commercialization of biosimilar products in the United States poses unique risks, and our failure to successfully introduce biosimilar products in the United States could have a negative impact on our business and future operating results.

        We intend to pursue market authorization for our biosimilar product candidates in numerous jurisdictions, including the United States. In the United States, an abbreviated pathway for approval of biosimilar products was established by the Biologics Price Competition and Innovation Act of 2009, or BPCIA, enacted on March 23, 2010, as part of the Patient Protection and Affordable Care Act. Subsequent to the enactment of the BPCIA, the FDA has released several final and draft guidance documents and a proposed rule regarding implementation of the BPCIA and other issues that will affect biosimilars.

        These guidance documents and proposed rule focus on scientific considerations, quality considerations and clinical pharmacology data related to demonstrating biosimilarity; meetings between the FDA and biosimilar product sponsors; requests for reference product exclusivity; common questions and answers regarding implementation of the BPCIA; the standards for interchangeability; and naming of biological products.

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        The FDA approved the first biosimilar drug, Zarxio®, Sandoz's biosimilar version of Amgen's Neupogen® (filgrastim) for all of the reference product's approved indications on March 6, 2015.

        Moreover, market acceptance of biosimilar products in the United States is unclear. Numerous states are considering or have already enacted laws that regulate or restrict the substitution by state pharmacies of biosimilars for biological products already licensed by the FDA pursuant to biologic license applications, or "reference products." Market success of biosimilar products will depend on demonstrating to patients, physicians, payors, and relevant authorities that such products are safe and efficacious compared to other existing products.

        We plan to continue to analyze and incorporate into our biosimilar development plans any final regulations issued by the FDA, pharmacy substitution policies enacted by state governments, and other applicable requirements established by relevant authorities. The costs of development and approval, along with the probability of success for our biosimilar product candidates, will be dependent upon application of any laws and regulations issued by the relevant regulatory authorities.

        Biosimilar products may also be subject to extensive patent clearances and patent infringement litigation, which will likely delay and could prevent the commercial launch of a product. Moreover, the BPCIA prohibits the FDA from accepting an application for a biosimilar candidate to a reference product within four years of the reference product's licensure by the FDA. In addition, the BPCIA provides innovative biologics with twelve years of exclusivity from the date of their licensure, during which time the FDA cannot approve any application for a biosimilar candidate to the reference product. However, in his proposed budget for fiscal year 2015, President Obama proposed to cut this twelve-year period of exclusivity down to seven years. He also proposed to prohibit additional periods of exclusivity due to minor changes in product formulations, a practice often referred to as "evergreening." It is possible that Congress may take these or other measures to reduce or eliminate periods of exclusivity.

        In July 2015, the U.S. Court of Appeals for the Federal Circuit interpreted the BPCIA as requiring biosimilar manufacturers to send a required pre-launch notice to the manufacturer of the reference biologic only after the FDA has approved the biosimilar for licensure. This ruling potentially provides the reference product manufacturer with an additional 180 days of marketing exclusivity for the innovator biologic, depending on whether the product's 12-year exclusivity has expired at the time that the pre-launch notice is received from the biosimilar manufacturer.

        The BPCIA is complex and only beginning to be interpreted and implemented by the FDA. As a result, its ultimate impact, implementation, and meaning is subject to significant uncertainty. Future implementation decisions by the FDA could result in delays in the development or commercialization of our product candidates or increased costs to assure regulatory compliance, and could adversely affect our operating results by restricting or significantly delaying our ability to market new biosimilar products in the United States.

Even if we receive regulatory approvals for our product candidates, we will be subject to ongoing obligations and continued regulatory review, which may result in significant additional expense. If we fail to comply with continuing regulatory requirements, we could lose regulatory approvals, and our business would be adversely affected.

        Even if we obtain regulatory approvals for our product candidates, we will be subject to extensive and continued regulatory review regarding manufacturing, labeling, packaging, distribution, adverse event reporting, storage, import, export, advertising, promotion and recordkeeping, among other activities. These requirements include submissions of safety and other post-marketing information and reports, manufacturing facility registration and inspection, as well as continued compliance with current Good Manufacturing Practices, or cGMPs and Good Clinical Practice, or GCPs for any clinical trials that we conduct post-approval. Any regulatory approvals that we receive for our product candidates

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may also be subject to limitations on the approved indicated uses for which the product may be marketed or to the conditions of approval, or contain requirements for potentially costly post-marketing testing and surveillance to monitor the safety and efficacy of the product candidate. Later discovery of previously unknown problems with a product, including adverse events of unanticipated severity or frequency, or with our third-party manufacturers or manufacturing processes, or failure to comply with regulatory requirements, may result in, among other things:

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restrictions on the marketing or manufacturing of the product, withdrawal of the product from the market, or voluntary or mandatory product recalls;



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fines, warning letters or holds on clinical trials;



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refusal by regulatory authorities to approve pending applications or supplements to approved applications filed by us, or suspension or revocation of product approvals;



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product seizure or detention, recalls, or refusal to permit the import or export of products; and



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injunctions or the imposition of civil or criminal penalties.

        The laws, regulations, and policies of the regulatory authorities may change and additional laws, regulations, and policies may be enacted or established that could prevent, limit or delay regulatory approval of our product candidates. If we are slow or unable to adapt to changes in existing requirements or the adoption of new requirements or policies, or if we are not able to maintain regulatory compliance, we may lose any marketing approval that we may have obtained, which would adversely affect our business, prospects and ability to achieve or sustain profitability. See "Risks Relating to our Reliance on Third Parties—We rely on third parties to conduct and oversee our clinical trials for our biosimilar product candidates, and expect to continue to do so as we progress the development of our pipeline product candidates. If these third parties do not successfully carry out their contractual duties, meet expected deadlines, or otherwise conduct the trials as required or comply with regulatory requirements, we may not be able to obtain regulatory approval for or commercialize our product candidates when expected or at all, and our business could be substantially harmed."

If we are not able to demonstrate biosimilarity of our biosimilar product candidates to the satisfaction of regulatory authorities, we will not obtain regulatory approval for commercial sale of our biosimilar product candidates and our future results of operations would be adversely affected.

        Our future results of operations depend, to a significant degree, on our ability to obtain regulatory approval for and to commercialize our proposed biosimilar products. To obtain regulatory approval for the commercial sale of these product candidates, we will be required to demonstrate to the satisfaction of regulatory authorities, among other things, that our proposed biosimilar products are highly similar to biological reference products already licensed by the regulatory authority pursuant to marketing applications, notwithstanding minor differences in clinically inactive components, and that they have no clinically meaningful differences as compared to the marketed biological products in terms of the safety, purity and potency of the products. Each individual jurisdiction may apply different criteria to assess biosimilarity, based on a preponderance of the data that can be interpreted subjectively in some cases. In the European Union, the similar nature of a biosimilar and a reference product is demonstrated by comprehensive comparability studies covering quality, biological activity, safety and efficacy.

        It is uncertain if regulatory authorities will grant the full originator label to biosimilar product candidates when they are approved. For example, Hospira's INFLECTRA™, an infliximab biosimilar molecule, was approved in Europe for the full originator label but did not receive the full originator label when approved in Canada. A similar outcome could occur with respect to one or more of our product candidates.

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        In the event that regulatory authorities require us to conduct additional clinical trials or other lengthy processes, the commercialization of our proposed biosimilar products could be delayed or prevented. Delays in the commercialization of or the inability to obtain regulatory approval for these products could adversely affect our operating results by restricting or significantly delaying our introduction of new biosimilars.

The structure of complex proteins used in protein-based therapeutics is inherently variable and highly dependent on the processes and conditions used to manufacture them. If we are unable to develop manufacturing processes that achieve a requisite degree of biosimilarity to the originator drug, and within a range of variability considered acceptable by regulatory authorities, we may not be able to obtain regulatory approval for our products.

        Protein-based therapeutics are inherently heterogeneous and their structures are highly dependent on the production process and conditions. Products from one production facility can differ within an acceptable range from those produced in another facility. Similarly, physicochemical differences can also exist among different lots produced within a single facility. The physicochemical complexity and size of biologic therapeutics create significant technical and scientific challenges in the context of their replication as biosimilar products.

        The inherent variability in protein structure from one production lot to another is a fundamental consideration with respect to establishing biosimilarity to an originator product to support regulatory approval requirements. For example, the glycosylation of the protein, meaning the manner in which sugar molecules are attached to the protein backbone of a therapeutic protein when it is produced in a living cell, is critical to half-life (how long the drug stays in the body), efficacy and even safety of the therapeutic and is therefore a key consideration for biosimilarity. Defining and understanding the variability of an originator molecule in order to match its glycosylation profile requires significant skill in cell biology, protein purification and analytical protein chemistry. Furthermore, manufacturing proteins with reliable and consistent glycosylation profiles at scale is challenging and highly dependent on the skill of the cell biologist and process scientist.

        There are extraordinary technical challenges in developing complex protein-based therapeutics that not only must achieve an acceptable degree of similarity to the originator molecule in terms of characteristics such as the unique glycosylation pattern (attachment of sugars to the protein) critical to therapeutic efficacy, but also the ability to develop manufacturing processes that can replicate the necessary structural characteristics within an acceptable range of variability sufficient to satisfy regulatory authorities.

        Given the challenges caused by the inherent variability in protein production, we may not be successful in developing our products if regulators conclude that we have not achieved a sufficient level of biosimilarity to the originator product, or that the processes we use to manufacture our products are unable to produce our products within an acceptable range of variability.

Risks Relating to our Reliance on Third Parties

We rely on third parties to conduct and oversee our clinical trials for our biosimilar product candidates, and expect to continue to do so as we progress the development of our pipeline product candidates. If these third parties do not successfully carry out their contractual duties, meet expected deadlines, or otherwise conduct the trials as required or comply with regulatory requirements, we may not be able to obtain regulatory approval for or commercialize our product candidates when expected or at all, and our business could be substantially harmed.

        We rely upon third-party CROs to monitor and manage the clinical sites and investigators for our ongoing clinical programs, and to audit and verify the data produced by these parties. We also rely upon medical institutions, clinical investigators and contract laboratories to conduct our trials in

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accordance with our clinical protocols and in accordance with applicable legal and regulatory requirements. These third parties play a significant role in the conduct of these trials and the subsequent collection and analysis of data from the clinical trials. These third parties are not our employees, and except for remedies available to us under our agreements with such third parties, there is no guarantee that any such third party will devote adequate time and resources to our clinical trial. If any CROs engaged by us or any other third parties upon which we rely for administration and conduct of our clinical trials do not successfully carry out their contractual duties or obligations or meet expected deadlines, if they need to be replaced or if the quality or accuracy of the clinical data they obtain is compromised due to the failure to adhere to our clinical protocols, regulatory requirements, or for other reasons, or if they otherwise perform in a substandard manner, our clinical trials may be extended, delayed, suspended or terminated, and we may not be able to complete development of, obtain regulatory approval for, or successfully commercialize our product candidates. We plan to rely heavily on these third parties for the execution of our planned global clinical program for BOW015 and for other clinical trials for products we are developing or may develop in the future, and will control only certain aspects of their activities. Nevertheless, we are responsible for ensuring that each of our clinical trials is conducted in accordance with the applicable protocol, legal, regulatory and scientific standards, and our reliance on our CROs does not relieve us of our regulatory responsibilities.

        We and any CROs that we engage are required to comply with GCP requirements, which are regulations and guidelines enforced by regulatory authorities around the world for products in clinical development. Regulatory authorities enforce these GCP regulations through periodic inspections of clinical trial sponsors, principal investigators and clinical trial sites. If we or any of our CROs fail to comply with applicable GCP regulations, the clinical data generated in our clinical trials may be deemed unreliable and our submission of marketing applications may be delayed or the regulatory authorities may require us to perform additional clinical trials before approving our marketing applications. We cannot provide any assurance that, upon inspection, a regulatory authority will determine that any of our clinical trials comply or complied with applicable GCP regulations. In addition, our clinical trials must be conducted with product produced under cGMP regulations. Our failure to comply with these regulations may require us to repeat clinical trials, which would delay the regulatory approval process.

        Clinical trials require a substantial number of patients that can allow statistically significant results. Delays in site initiation or unexpectedly low patient recruitment rates may delay the results of the clinical trial. CROs may also generate higher costs than anticipated. As a result, our results of operations and the commercial prospects for our product candidates would be harmed, our costs could increase, and our ability to generate revenue could be delayed. Further, if our relationship with any CRO that we engage to perform services on our behalf is terminated, we may be unable to enter into arrangements with an alternative CRO on commercially reasonable terms, or at all. Switching or adding CROs can involve substantial cost and require extensive management time and focus. In addition, there is a natural transition period when a new CRO commences work. As a result, delays may occur, which can materially impact our ability to meet our desired clinical development timelines. Though we carefully manage our relationships with our CROs, there can be no assurance that we will not encounter challenges or delays in the future or that these delays or challenges will not have a material adverse impact on our business, prospects, financial condition or results of operations.

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We rely on third parties, and in some cases a single third party, to manufacture nonclinical and clinical supplies of our product candidates, to store critical components of our product candidates for us, and also to commercialize our product candidates. Our business could be harmed if those third parties fail to provide us with sufficient quantities of product candidates at acceptable quality levels and on commercially reasonable terms, or fail to commercialize our products in accordance with the terms of our agreements with them.

        We do not have the infrastructure or capability internally to manufacture supplies of our biosimilar product candidates for use in the conduct of our nonclinical and clinical studies or on a commercial scale. We rely on third-party manufacturers, including our India-based contract manufacturer RLS, to manufacture and supply us with BOW015 in India. As discussed in the other risk factors described in this section, we may need to seek additional third-party manufacturers following RLS' completion of its manufacture obligations pursuant to the Settlement Agreement (as described below). In May 2015, we entered into a development and future distribution agreement with mAbxience, S.A., or Mabxience, a wholly owned subsidiary of CHEMO Group, for BOW015 in Latin American markets, including Argentina, Chile, Ecuador, Paraguay, Uruguay and Venezuela. We have an established partnership with Livzon for the production of biosimilars for China and associated markets. In July 2015, we also entered into an agreement with Swiss Pharma International AG, an affiliate of Pharmaceutical Works Polpharma S.A., or, together with Swiss Pharma International AG, Polpharma, for the development and commercialization of BOW015, BOW050 and BOW070 in certain designated territories, including most of the European Union, certain countries in the Middle East, Turkey, Russia, and other countries comprising the CIS. Further, we are currently party to an agreement with Sun, pursuant to which we granted to Sun exclusive rights under our intellectual property and regulatory materials relating to BOW015 to develop and commercialize BOW015 in India and certain other countries in Asia and North Africa. Pursuant to this agreement, Sun has agreed to distribute and sell BOW015 in India under the marketing authorization granted to RLS for BOW015. We also have an agreement with Fujifilm Diosynth Biotechnologies U.S.A., Inc., or Fujifilm, for BOW015 process development with a view toward establishing Fujifilm as a source of future clinical and commercial supply of BOW015. Developing successful scale up techniques for manufacture of our biosimilar product candidates for commercial quantities will be time consuming and may not yield the quantities of product that we anticipate, which may have a material impact on our ability to successfully commercialize our product candidates. Moreover, the market for contract manufacturing services for protein therapeutics is highly cyclical, with periods of relatively abundant capacity alternating with periods in which there is little available capacity. If any need we have for contract manufacturing services increases during a period of industry-wide production capacity constraints, we may not be able to produce our product candidates on a timely basis or on commercially viable terms. Although we generally do not begin a clinical study unless we believe we have a sufficient supply of a product candidate to complete such study, any significant delay or discontinuity in the supply of a product candidate for an ongoing clinical study due to the need to replace a third-party manufacturer could considerably delay completion of our clinical studies, product testing, and potential regulatory approval of our product candidates, which could harm our business and results of operations.

        Any failure or refusal to supply the components for product candidates that we may develop could delay, prevent or impair our clinical development or commercialization efforts. Although we endeavor, and will continue to do so in the future, to establish alternative sources of supply for BOW015 and our other product candidates in order to protect against any disruption in product supply, we cannot assure you that we will be able to find a suitable alternative manufacturer who is permitted to supply product under applicable regulatory laws, or to enter into appropriate agreements with such third parties on commercially reasonable terms, or at all. If our contract manufacturers were to breach or terminate their manufacturing arrangements with us, the development or commercialization of the affected products or product candidates could be delayed, which could have an adverse effect on our business. Any change in our manufacturers could be costly because the commercial terms of any new arrangement could be less favorable and the expenses relating to the transfer of necessary technology and processes could be significant.

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        If any of our product candidates are approved for any given jurisdiction, in order to produce the quantities necessary to meet anticipated market demand, any contract manufacturer that we engage may need to increase manufacturing capacity. If we are unable to produce our product candidates in sufficient quantities to meet the requirements for the launch of these products or to meet future demand, our revenue and gross margins could be adversely affected. Although we believe that we will not have any material supply issues, we cannot be certain that we will be able to obtain long-term supply arrangements for our product candidates or materials used to produce them on acceptable terms, if at all. If we are unable to arrange for third-party manufacturing, or to do so on commercially reasonable terms, we may not be able to complete development of our products or market them.

        We also rely on third parties to store the BOW015 master and working cell bank, and those of our pipeline product candidates. We have one master cell bank and one working cell bank and believe we would have adequate backup should any cell bank be lost in a catastrophic event. However, it is possible that we could lose multiple cell banks and have our manufacturing severely impacted by the need to replace the cell banks, which could materially and adversely affect our business, financial condition and results of operations.

        If we encounter delays or difficulties in executing our agreements with Mabxience, Polpharma or Sun to commercialize our product candidates in the various territories covered by our agreements, we may be required to seek alternative commercialization partners and/or develop a plan to commercialize our product candidates through direct sales into the various markets, either of which may adversely affect our ability to successfully commercialize our product candidates. We have no direct sales experience in these territories. Therefore, if we decide to commercialize our product candidates through direct sales, we cannot assure you that we would be successful.

Disputes under key agreements with third parties could adversely affect, delay or prevent development or commercialization of our product candidates.

        Any agreements we have or may enter into with third parties, such as collaboration, license, formulation supplier, manufacturing, testing, clinical research organization or clinical trial agreements, may give rise to disputes regarding the rights and obligations of the parties to such agreements. Disagreements may occur relating to the parties' rights and obligations under these agreements, such as the scope of development or commercialization rights, ownership or use of intellectual property, the approach to obtaining regulatory approvals or commercialization strategy. Any disputes or commercial conflicts could lead to the termination of these agreements, delay progress of our product development programs, compromise our ability to renew agreements or obtain future agreements, lead to the loss of suppliers of our products, harm our intellectual property rights or result in costly litigation.

        In December 2014, RLS exercised its three-year termination for-convenience right with respect to our manufacturing and supply agreement with RLS, which we refer to as the RLS Agreement, which would have caused the RLS Agreement to terminate in December 2017. In addition, in March 2015, RLS initiated an arbitration proceeding under the RLS Agreement alleging that the RLS Agreement grants RLS exclusive global supply rights to BOW015, that the terms of our collaboration agreements with Fujifilm and Livzon (described above) violate the RLS Agreement, and sought to terminate the RLS Agreement. On April 22, 2015, we entered into a Settlement Agreement with RLS. Pursuant to the Settlement Agreement, on May 4, 2015, RLS withdrew the arbitration proceeding it initiated, and the parties have agreed to release each other from all causes of actions or claims, present and future, arising under the RLS Agreement. Additionally, in late 2015 the parties finalized the remaining BOW015 batch production schedule with RLS agreeing to manufacture 12 final batches of BOW015 on or before June 30, 2017. RLS has also agreed to use reasonable commercial efforts to transfer the existing Indian marketing authorization for BOW015 granted by the DCGI to us or our designee, with all costs of the transfer to be borne by us and subject to the DCGI's approval of such transfer. We have agreed to pay to RLS a fee of $2,250,000, payable in four installments over the course of the final

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batch manufacture, with the final installment to be paid no later than ten days after June 30, 2016. Following the satisfaction by both parties of all of the terms of the Settlement Agreement, the RLS Agreement and related agreements between the parties shall be terminated and neither party shall have any further rights or obligations thereunder.

        While we believe that, based on forecasts from our Indian commercial partner, Sun, the current inventory, and future inventory as agreed to under the Settlement Agreement, of BOW015 is sufficient to fulfill anticipated demand there through the middle of 2017, it is possible that demand will increase in excess of our current inventory and that we will not be able to meet these demands if the agreed-upon batches to be manufactured by RLS pursuant to the Settlement Agreement are not sufficient to meet such increased needs. We intend to continue to build up additional BOW015 inventory via the agreed upon production runs by RLS, as necessary to establish sufficient product for the Indian territory, but we cannot be certain that this additional supply will be adequate. It is possible that RLS could stop providing us with BOW015 entirely, despite the terms of the Settlement Agreement and regardless of whether this causes RLS to breach the RLS Agreement or the Settlement Agreement. We and Sun intend to transfer BOW015 manufacturing for Indian territory to an alternate contract manufacturer, but there can be no assurances that we will be successful in making such a transfer on a timely basis, or at all. This, in turn, could materially and adversely affect our ability to manufacture or supply BOW015 for use in commercial sales in India and other markets currently contemplated to be served by Sun.

Where we apply our In Market, For Market strategy for commercialization of our product candidates in emerging markets, where approved, we expect to transfer our cell lines and certain proprietary manufacturing technology to our third-party partners in order to permit locally-based manufacture of our biosimilar products by our partners. If our alliances with these partners terminate, our business could be harmed if such former partners continue to use our technology in such countries following termination, in breach of our agreements with them.

        Under our collaboration with Livzon, and under future In Market, For Market collaborations, we expect to transfer the manufacture and certain development and commercialization responsibilities for BOW015 and certain of our pipeline product candidates to Livzon and other future collaborators, along with certain of our SCALE manufacturing technology, and to provide technical assistance in such territories to assist our partners in establishing manufacturing capacity or modifying their existing manufacturing capacity for the production of our biosimilar product candidates. If our alliances with Livzon and any future partners are not successful, or our agreements with such partners are terminated, our agreements will include terms that require the partners to immediately cease any use of our technology, and to return to us any tangible embodiments of such technology, including our cell lines. However, our former partners may fail to comply with these terms, and may continue to use our technology to manufacture and sell biosimilar products in such countries, in breach of our agreements with them. In such case, we may be forced to enforce our contractual and intellectual property rights in the applicable countries, which would be time-consuming and costly, and would divert substantial management time and resources from other aspects of our business. Further, although we endeavor to include dispute resolution provisions in our agreements that we believe are fully enforceable irrespective of the jurisdiction, including by the use of arbitration, countries outside the United States where we have In Market, For Market collaborations may not provide the same level of protection for our contractual and intellectual property rights, and there is no guarantee that we would be successful in preventing a party to whom we have transferred our technology from continuing to use our cell lines and technology to manufacture biosimilar products, in which case our business in those countries could be adversely affected.

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In certain countries where we expect to commercialize our product candidates, under applicable laws, it is necessary for us to rely on locally established third parties to act as the holder of marketing approvals or authorizations for our product candidates in such countries. Our business could be harmed if those third parties fail to comply with the terms of such marketing authorizations or approvals, or fail to act in accordance with our instructions in relation to the marketing and sale of our product candidates covered by such authorizations or approvals.

        In some circumstances, it may be necessary as a matter of applicable local law, for the marketing and manufacturing approvals for our biosimilar products to be held by a third party that is not one of our affiliates. For example, our marketing approval in India for BOW015 is currently held in the name of our manufacturing partner, RLS, which also holds the manufacturing approval for BOW015. Pursuant to the Settlement Agreement described above, RLS has agreed to use reasonable commercial efforts to transfer such authorization to us or our designee, subject to approval by the DCGI. The marketing approval held by RLS for manufacture and sale of infliximab in India is based on and is specific to the data arising from our clinical trials conducted with respect to BOW015, which data is owned solely by us, and RLS therefore has no right to commercialize BOW015 in India or in any other country independently of us on the basis of such marketing authorization. We have a manufacturing and supply agreement in place with RLS that includes provisions that permit us to have oversight over RLS's activities in order to protect against breach by RLS of the terms of such marketing approval, and we will seek to include equivalent contractual protections in future agreements with third parties that hold regulatory approvals on our behalf. However, there is no guarantee that RLS or any other such third party will comply with the terms of the marketing authorization for the applicable biosimilars or with applicable laws. Where permissible under applicable laws, we also seek to provide for transfer of rights in any regulatory approval to an alternative holder on termination of our agreements with such third parties, and we also endeavor, and will continue to do so in the future, to establish alternative sources of supply for BOW015 and our future product candidates in order to protect against any disruption in product supply. However, we cannot assure you that we will be able to find an alternative holder for any such regulatory approvals in a timely fashion, or to enter into appropriate agreements with such third parties on commercially reasonable terms, or at all. Any non-compliance with applicable laws or the terms of regulatory approvals by such third parties could result in the permission to market and sell the applicable product candidate being revoked in one or more countries, which would materially jeopardize our right to commercialize BOW015 in India and such other countries.

We expect to partner with third parties in connection with the development of certain of our product candidates. Even if we enter into such collaborations, and we believe that the development of our technology and product candidates is promising, our partners may choose not to proceed with such development.

        Our agreements with potential partners may include the right for our partner to terminate the agreement on short notice upon the occurrence of certain circumstances. Accordingly, even if we enter into agreements with third-party partners in all of the territories where we intend to pursue commercialization of our product candidates, and we believe that the development of such product candidates are worth pursuing, our partners may choose not to continue with such development. If any of our partnerships are terminated, we may be required to devote additional resources to the development of our product candidates or seek a new partner on short notice, and the terms of any additional partnerships or other arrangements that we establish may not be favorable to us, if an alternative partner is even available.

        We are also at risk that our partnerships or other arrangements may not be successful. Factors that may affect the success of our partnerships include the following:

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our partners may incur financial and cash-flow difficulties that force them to limit or reduce their participation in our joint projects;

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our partners may be pursuing alternative technologies or developing alternative products that are competitive to our technology and products, either on their own or in partnership with others;



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our partners may terminate their partnerships with us, which could make it difficult for us to attract new partners or adversely affect perception of us in the business and financial communities; and



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our partners may pursue higher priority programs or change the focus of their development programs, which could affect their commitment to us.

        We have entered into agreements with Mabxience, for the development and future distribution of BOW015 in certain Latin American countries, Polpharma, for the development and commercialization of BOW015, BOW050 and BOW070 in certain European and Middle Eastern countries, and Livzon, for development and commercialization of BOW015, BOW070 and up to three other biosimilar pipeline products in China and related territories. If our collaborations are not successful or if we or our partners terminate our agreements, we may not be able to progress our plans to develop and commercialize our product candidates in the related territories. Although we believe that there are appropriate alternative partners in each territory, there is no guarantee that we could identify and negotiate satisfactory terms with any such alternative partner, or that we could do so in a timeframe that would not compromise our ability to commercialize our product candidates in a timely manner or at all.

        If we cannot maintain successful partnerships, our business, financial condition and operating results may be adversely affected.

International expansion of our business exposes us to business, regulatory, political, operational, financial, and economic risks associated with doing business outside of the United States.

        Our business strategy incorporates significant international expansion, with a primary focus on developed markets, such as Europe, as well as local production markets, such as China and Brazil and accessible markets such as India and Latin America. We plan to engage in manufacturing, maintain sales representatives and conduct clinical trials outside of the United States. Doing business internationally involves a number of risks, including but not limited to:

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multiple, conflicting, and changing laws and regulations such as privacy regulations, tax laws, export and import restrictions, employment laws, intellectual property laws, regulatory requirements, and other governmental approvals, permits, and licenses;



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foreign laws favoring businesses that are owned by nationals of those countries as opposed to foreign-owned businesses operating locally;



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failure by us to obtain and maintain regulatory approvals for the use of our products in various countries;



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additional potentially relevant third-party patent or other rights;



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complexities and difficulties in obtaining protection and enforcing our intellectual property;



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difficulties in staffing and managing foreign operations;



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limits in our ability to penetrate and compete in international markets;



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financial risks, such as longer payment cycles, difficulty collecting accounts receivable, difficulty obtaining insurance coverage, the impact of local and regional financial crises on demand and payment for our products, and exposure to foreign currency exchange rate fluctuations and controls;

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•

natural disasters, political and economic instability, including wars, terrorism, and political unrest, outbreak of disease, boycotts, curtailment of trade, and other business restrictions;



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certain expenses including, among others, expenses for travel, translation, and insurance; and



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regulatory and compliance risks that relate to maintaining accurate information and control over sales and activities that may fall within the purview of the FCPA, its books and records provisions, or its anti-bribery provisions, OFAC restrictions, anti-money laundering laws, export control laws, customs laws, sanctions laws and other laws governing our operations.

        Any of these factors could significantly harm any future international expansion and operations and, consequently, could adversely affect our business prospects.

Our business could be harmed as a result of the risks associated with our acquisitions.

        As part of our business strategy, we may from time to time seek to acquire businesses or assets that provide us with additional intellectual property, product candidates, customer relationships or geographic coverage. We can provide no assurances that we will be able to find and identify desirable acquisition targets or that we will be successful in entering into a definitive agreement with any one target. In addition, even if we reach a definitive agreement with a target, there is no assurance that we will complete any future acquisition.

        Any acquisitions we undertake or have recently completed, including the acquisition of Bioceros Holding B.V., will likely be accompanied by business risks which may include, among other things:

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the effect of the acquisition on our financial and strategic position and reputation;



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the failure of an acquisition to result in expected benefits, which may include benefits relating to enhanced revenues, technology, human resources, costs savings, operating efficiencies, goodwill and other synergies;



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the difficulty, cost and management effort required to integrate the acquired businesses, including costs and delays in implementing common systems and procedures and costs and delays caused by communication difficulties;



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the assumption of certain known or unknown liabilities of the acquired business, including litigation-related liabilities;



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the reduction of our cash available for operations and other uses, the increase in amortization expense related to identifiable assets acquired, potentially dilutive issuances of equity securities or the incurrence of debt;



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a lack of experience in new markets, new business culture, products or technologies or an initial dependence on unfamiliar distribution partners;



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the possibility that we will pay more than the value we derive from the acquisition;



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the impairment of relationships with our customers, partners or suppliers or those of the acquired business; and



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the potential loss of key employees of the acquired business.

        These factors could harm our business, results of operations or financial condition.

        In addition to the risks commonly encountered in the acquisition of a business or assets as described above, we may also experience risks relating to the challenges and costs of closing a transaction. The risks described above may be exacerbated as a result of managing multiple acquisitions at once.

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Industry Related Risks

If efforts by manufacturers of reference products to delay or limit the use of biosimilars are successful, our sales of biosimilar products may suffer.

        Many manufacturers of reference products have increasingly used legislative, regulatory and other means in attempts to delay regulatory approval of and competition from biosimilars. These efforts have included sponsoring legislation to prevent pharmacists from substituting biosimilars for prescribed reference products or to make such substitutions more difficult by establishing notification, recordkeeping, and/or other requirements, as well as seeking to prevent manufacturers of biosimilars from referencing the brands of the innovator products in biosimilar product labels and marketing materials. If these or other efforts to delay or block competition are successful, we may be unable to sell our biosimilar product candidates, which could have a material adverse effect on our sales and profitability.

Foreign governments tend to impose strict price controls on pharmaceutical products, which may adversely affect our revenue, if any.

        In some foreign countries, the pricing of prescription pharmaceuticals is subject to governmental control. This is likely also to apply to pricing of biosimilar products. In these countries, pricing negotiations with governmental authorities can take considerable time after the receipt of marketing approval for a product. To obtain reimbursement or pricing approval in some countries, we may be required to conduct a clinical trial that compares the cost-effectiveness of our product candidate to other available therapies. If reimbursement of our products is unavailable or limited in scope or amount, or if pricing is set at unsatisfactory levels, our business could be adversely affected.

We use and generate materials that may expose us to expensive and time-consuming legal claims.

        Our development programs involve the use of hazardous materials, chemicals, and biological materials. We are subject to foreign, federal, state and local laws and regulations governing the use, manufacture, storage, and disposal of materials and waste products. We believe that our safety procedures for handling these materials comply with the standards prescribed by laws and regulations. However, we may incur significant costs to comply with current or future environmental laws and regulations. In addition, we cannot completely eliminate the risk of contamination or injury from hazardous materials. In the event of an accident, an injured party may seek to hold us liable for any damages that result. Any liability could exceed the limits or fall outside the coverage of our insurance, and we may not be able to maintain insurance on acceptable terms, if at all.

Risks Related to Intellectual Property

We may not be able to develop or commercialize our product candidates due to intellectual property rights held by third parties.

        Although we aim to launch our biosimilar product candidates in markets where there is no valid third party patent protection covering the reference biologic product, or in some cases where the fundamental patent protection for the reference product has expired, if a third party holds a patent to a formulation technology related to our planned formulation of a product candidate, we may not be able to develop or commercialize such product candidates without first obtaining a license to such patent, or waiting for such patent to expire. In addition, in the United States, under certain limited circumstances, patents known as "submarine" patents may issue without the corresponding application being previously published. If such a submarine patent were to issue and cover aspects of any one or more of our product candidates, it is possible that such patents could affect our ability to commercialize the affected product candidate(s). Our business will be harmed if we are unable to use the optimal formulation of our product candidates, which may occur because the formulations or

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methods of use are covered by one or more third-party patents, and a license to such patents is unavailable or is only available on terms that are unacceptable to us. In the case of our biosimilar product candidates, this may prevent us from establishing the equivalence to the reference biologic product required to gain regulatory approval for sale of such biosimilar product within a time frame that would make the commercialization of the affected biosimilar product candidate commercially viable.

We may not have identified all the relevant patents covering our product candidates, or the scope or term of identified patents may differ from our assessment, which may affect our ability to commercialize our product candidates.

        Although we have conducted searches in commercially available patent databases directed to patents that would cover reference products in our pipeline, we may not have identified all of the relevant patents. Patent filings can be complicated and involve many progeny cases in different jurisdictions around the world. Patents and patent applications are published weekly and if the databases that we use are not up to date when the search is conducted, then we may not identify relevant patents that may cover our product patents. If we fail to identify relevant patent filings in the jurisdictions in which we plan to commercialize, or if we incorrectly interpret the claims or scope of coverage afforded by any patent identified in our searches in any jurisdiction, such that our product candidates in fact infringe such patents, then our ability to commercialize our products in the applicable countries could be prevented or delayed. Further, the patents covering the reference products may be subject to adjustments or extensions under applicable law that may prolong the life of such patents. While we strive to avoid litigation by launching our product candidates in markets where the reference product is no longer subject to patent protection, if we incorrectly assess the applicable term of the patent, or if such term is extended in any jurisdiction via an appeal or otherwise, our ability to commercialize in that such jurisdiction could be adversely affected.

If we are unable to protect the confidentiality of our trade secrets, the value of our technology could be materially adversely affected and our business would be harmed.

        We do not currently own any patents or have any patent filings with any patent offices in the world. We rely solely on trade secret protection and confidentiality agreements to protect proprietary know-how that may not be patentable, processes for which patents may be difficult to obtain or enforce and any other elements of our product development processes that involve proprietary know-how, information or technology that is not covered by patents. This includes our rights in our proprietary SCALE technology, which is critical to the success of our In Market, For Market strategy for commercialization of our product candidates in emerging markets. Trade secret protection and confidentiality agreements may afford only limited protection and may not: prevent our competitors from duplicating our products; prevent our competitors from gaining access to our proprietary information and technology; or permit us to gain or maintain a competitive advantage.

        As part of our efforts to protect our trade secrets and other confidential information, we require our employees, consultants, collaborators and advisors to execute confidentiality agreements upon the commencement of their relationships with us, and we include equivalent provisions in all of our material collaboration and license agreements. These agreements require that all confidential information developed by the individual or made known to the individual by us during the course of the individual's relationship with us be kept confidential and not be disclosed to third parties. These agreements, however, may not provide us with adequate protection against improper use or disclosure of confidential information, and/or these agreements may be breached. Adequate remedies may not exist in the event of unauthorized use or disclosure of our confidential information. A breach of confidentiality could significantly affect our competitive position. Also, third parties, including our competitors, may independently develop substantially equivalent proprietary information and

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technologies or otherwise lawfully gain access to our trade secrets and other confidential information. In such a case, we would have no right to prevent such third parties from using such proprietary information or technologies to compete with us, which could harm our competitive position.

        In addition, where we enter into In Market, For Market collaborations to develop and commercialize our product candidates in emerging markets, these collaborations are expected to involve the establishment in such countries of independent manufacturing capacity for the applicable product candidates. Establishing such manufacturing capacity is expected to involve certain technology transfer by us to our strategic partners, and the provision by us of technical assistance in connection with such transfer. If our agreements with our collaborators are terminated, although these agreements provide that our former partners have no further rights in the transferred technology, such third parties could use the technology and know-how they received from us to continue to develop and commercialize the applicable products, in breach of our agreements with them, and which would materially impact our revenues from commercialization of our product candidates. In such case, it may be necessary for us to become involved in litigation or arbitration to retain and defend our rights in such technology, and to prevent such commercialization. Any such proceedings, which would be likely to be conducted in a country outside the United States, would be costly and time consuming, and would divert significant management time and resources, with no guarantee of a successful outcome.

If our trademarks and trade names are not adequately protected, then we may not be able to build name recognition in our markets of interest and our business may be adversely affected.

        We rely on trademark protection to protect our business and our products. Our registered or unregistered trademarks or trade names may be challenged, infringed, circumvented or declared generic or determined to be infringing on other marks. We may not be able to protect our rights to these trademarks and trade names, which we need to build brand name recognition by potential customers or partners in our markets of interest. Over the long term, if we are unable to establish name recognition based on our trademarks and trade names, then we may not be able to compete effectively and our business may be adversely affected.

We may be subject to damages resulting from claims that we or our employees have wrongfully used or disclosed alleged trade secrets of our employees' former employers.

        Some of our employees, consultants, collaborators, and advisors were previously employed at other biotechnology companies, including our competitors or potential competitors. Although no claims against us are currently pending, we may be subject to claims that these individuals or we have inadvertently or otherwise used or disclosed trade secrets or other proprietary information of our employees' former employers. Litigation may be necessary to defend against these claims. Even if we are successful in defending against these claims, litigation could result in substantial costs and be a distraction to management. If we fail in defending such claims, in addition to paying money damages, we may lose valuable intellectual property rights or personnel. A loss of key personnel or their work product could hamper or prevent our ability to commercialize certain product candidates, which would adversely affect our commercial development efforts.

We are dependent on proprietary technology licensed from others. If we lose our licenses, we may not be able to continue developing our products.

        We have obtained licenses that give us rights to third party intellectual property that is necessary or useful to our business. These license agreements covering our product candidates impose various royalty and other obligations on us. One or more of our licensors may allege that we have breached our license agreement with them, and accordingly seek to terminate our license. If we materially breach the obligations in our license agreements, the licensor typically has the right to terminate the license and we may not be able to market products that were covered by the license, which could adversely

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affect our competitive business position and harm our business prospects. In addition, any claims brought against us by our licensors could be costly and time-consuming and would divert the attention of our management and key personnel from our business operations.

We may not be able to protect against third-party copying of our product candidates.

        We may need to resort to litigation to enforce or defend our intellectual property rights, including any misappropriation of our trade secrets or know how. As noted above, we currently rely upon trade secrets to protect our product candidates. Our product candidates utilize the same formulations and ingredients as others used in the marketplace and, as such, may not be eligible for any patent protection. In addition, there may be third-party patents and patent applications directed to formulations, processes of manufacture or other processes that could cover our product candidates. If these third-party patent applications covering our product candidates are approved, our business, prospects and financial condition would be materially adversely affected.

Litigation or third-party claims of intellectual property infringement could require substantial time and money to resolve. Unfavorable outcomes in these proceedings could limit our activities.

        Our commercial success will depend in part on not infringing or violating the intellectual property rights of others. The manufacture, use and sale of new biosimilars that are the subject of conflicting patent rights have been the subject of substantial litigation in the biosimilars industry. These lawsuits relate to the validity and infringement of patents or proprietary rights of third parties. We may have to defend against charges that we violated patents or proprietary rights of third parties. This is especially true in the case of generic products on which the patent covering the reference product is expiring, an area where infringement litigation is prevalent, and in the case of new reference products where a competitor has obtained patents for similar products. We cannot guarantee that our product candidates will be free from claims by third parties alleging that we have infringed their intellectual property rights. Our competitors, some of which have substantially greater resources than we do and have made substantial intellectual property investments in competing technologies, may have applied for or obtained, or may in the future apply for and obtain, patent rights and other intellectual property that will prevent, limit or otherwise interfere with our ability to make, use and sell our products. Third parties may assert that we are employing their proprietary technologies without authorization and they may resort to litigation to attempt to enforce their rights. We may not be aware of whether our products do or will infringe existing or future patents or the intellectual property rights of others. Third parties may have or obtain patents in the future and claim that the use of our technology or any of our product candidates infringes their patents. Any lawsuits resulting from allegations that the operation of our business infringes the intellectual property rights of third parties could subject us to significant liability for damages and invalidate our proprietary rights, even if the lawsuits lack merit. We may not be able to develop or commercialize product candidates because of patent protection others have. Our business will be harmed if we cannot obtain a necessary or desirable license, can obtain such a license only on terms we consider to be unattractive or unacceptable, or if we are unable to redesign our product candidates or processes to avoid actual or potential patent or other intellectual property infringement.

        Our efforts to register, protect and defend our intellectual property rights, whether we are successful or not, may require us to incur substantial costs, including the diversion of management and technical personnel. An unfavorable ruling in intellectual property litigation could subject us to significant liabilities to third parties, require us to cease developing, manufacturing or selling the affected products or using the affected processes, require us to license the disputed rights from third parties, or result in awards of substantial damages against us. In addition, intellectual property litigation, whether we are successful or not, can be very expensive and may require us to incur substantial costs, including the diversion of management and technical personnel. During the course of

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any litigation, there may be public announcements of the results of hearings, motions, and other interim proceedings or developments in the litigation. If securities analysts or investors regard these announcements as negative, the market price of our common stock may decline. Any potential intellectual property litigation also could force us to do one or more of the following:

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stop making, selling or using products or technologies that allegedly infringe the asserted intellectual property;



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lose the opportunity to license our technology to others or to collect royalty payments based upon successful protection and assertion of our intellectual property rights against others;



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pay substantial damages or royalties to the party whose intellectual property rights we may be found to be infringing;



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pay the attorney fees and costs of litigation to the party whose intellectual property rights we may be found to be infringing;



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redesign or rename, in the case of trademark claims, those products that contain the allegedly infringing intellectual property, which could be costly, disruptive and/or infeasible; or



•

attempt to obtain a license to the relevant intellectual property from third parties, which may not be available on reasonable terms or at all.

        If we fail to obtain any required licenses or make any necessary changes to our products or technologies, we may have to withdraw existing products from the market or may be unable to commercialize one or more of our products, all of which could have a material adverse effect on our business, results of operations and financial condition. There can be no assurance that we would prevail in any intellectual property infringement action, will be able to obtain a license to any third-party intellectual property on commercially reasonable terms, successfully develop non-infringing alternatives on a timely basis, or license non-infringing alternatives, if any exist, on commercially reasonable terms. Any significant intellectual property impediment to our ability to develop and commercialize our products could seriously harm our business and prospects.

Risks Related to this Offering

Management will have broad discretion as to the use of the proceeds from this offering, and we may not use the proceeds effectively.

        Because we have not designated the amount of net proceeds from this offering to be used for any particular purpose, our management will have broad discretion as to the application of the net proceeds from this offering and could use them for purposes other than those contemplated at the time of the offering. Our management may use the net proceeds for corporate purposes that may not improve our financial condition or market value.

You may experience immediate and substantial dilution in the book value per share of the common stock you purchase in the offering.

        The offering price per share in this offering may exceed the net tangible book value per share of our common stock outstanding prior to this offering. Assuming that an aggregate of 10,714,286 shares of our common stock are sold at a price of $2.80 per share, the last reported sale price of our common stock on The NASDAQ Capital Market on February 26, 2016, for aggregate gross proceeds of approximately $30 million, and after deducting commissions and estimated aggregate offering expenses payable by us, you will experience immediate dilution of $1.49 per share, representing the difference between our net tangible book value per share as of September 30, 2015 and our as adjusted net tangible book value per share as of September 30, 2015 after giving effect to this offering at the assumed size and offering price. The exercise of outstanding stock options will result in further dilution

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of your investment. See the section below entitled "Dilution" for a more detailed illustration of the dilution you would incur if you participate in this offering.

Sales of a significant number of shares of our common stock in the public markets, or the perception that such sales could occur, could depress the market price of our common stock.

        Sales of a substantial number of shares of our common stock or other equity-related securities in the public markets could depress the market price of our common stock and impair our ability to raise capital through the sale of additional equity securities, including sales hereunder through BTIG. We cannot predict the effect that future sales of our common stock or other equity-related securities would have on the market price of our common stock.

Risks Related to an Investment in Our Common Stock

Our management and independent auditors have identified material weaknesses in our internal controls, and we may be unable to develop, implement and maintain appropriate internal and disclosure controls in future periods, which may lead to errors or omissions in our financial statements.

        In connection with the preparation of certain of our 2014 interim financial statements, our management team and independent registered public accounting firm identified certain weaknesses in our internal controls that were considered to be a material weakness. Specifically, our independent auditors identified errors in the draft financial statements of Private Epirus for the three and six-month periods ending June 30, 2014 that, in the aggregate, represented a material weakness in our financial statement close process. This material weakness has not been fully remediated. Prior to the complete remediation of this material weakness, there remains risk that the transitional controls on which we currently rely will fail to be sufficiently effective, which could result in a material misstatement of our financial position or results of operations and require a restatement of our financial statements.

        Additionally, in connection with our acquisition of Bioceros and the preparation of audited 2014 financial statements for that entity, Bioceros' independent registered public accounting firm identified certain material weaknesses with regards to converting Bioceros financial statements from Dutch GAAP to U.S. GAAP.

        As of September 30, 2015, our management, including our Chief Executive Officer and Chief Financial Officer, evaluated our internal controls and procedures, including the existence of the material weakness in our internal control over financial reporting, and concluded that our disclosure controls and procedures were not effective to provide reasonable assurance that information required to be disclosed by us in reports that we file or submit under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in the SEC's rules and forms, or that such information is accumulated and communicated to our management, including the CEO and CFO, as appropriate to allow timely decisions regarding required disclosure. We are currently designing and implementing new procedures and controls intended to address the material weakness described above over the financial statement close process. While this design and implementation phase is underway, we are relying significantly on outside accounting professionals until permanent employees can be hired to fill these roles and on manual procedures to assist us with meeting the objectives otherwise fulfilled by an effective control environment. The implementation of new procedures and controls could be costly and distract management from other activities.

        We note that a system of procedures and controls, no matter how well conceived and operated, can provide only reasonable, not absolute, assurance that the objectives of the control system are met. Because of the inherent limitations in all systems of procedures and controls, no evaluation can provide absolute assurance that all control issues, including instances of fraud, if any, have been detected. These inherent limitations include the realities that judgments in decision-making can be faulty, and breakdowns can occur because of simple error or mistake. Additionally, procedures and controls can be

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circumvented by the individual acts of some persons, by collusion of two or more people, or by management override. The design of any system of procedures and controls also is based in part upon certain assumptions about the likelihood of future events, and there can be no assurance that any design will succeed in achieving its stated goals under all potential future conditions. Over time, our systems of procedures and controls, as we further develop and enhance them, may become inadequate because of changes in conditions, or the degree of compliance with the policies or procedures may deteriorate. Because of the inherent limitations in a cost-effective system of procedures and controls, misstatements due to error or fraud may occur and not be detected and could be material and require a restatement of our financial statements.

        Following the expiration of the SEC waiver granted to us in connection with the Merger, we will be required to make a formal assessment of the effectiveness of our internal controls over financial reporting pursuant to Section 404 of the Sarbanes-Oxley Act, beginning with our annual report on Form 10-K for the fiscal year ending December 31, 2015. If we are unable to establish appropriate internal controls, we may not have adequate, accurate or timely financial information, and we may be unable to meet our reporting obligations or comply with the requirements of the SEC or the Sarbanes-Oxley Act, which could result in the imposition of sanctions, including the inability of registered broker dealers to make a market in our common shares, or investigation by regulatory authorities. Any such action or other negative results caused by our inability to meet our reporting requirements or comply with legal and regulatory requirements or by disclosure of an accounting, reporting or control issue could adversely affect the trading price of our securities. Further and continued determinations that there are significant deficiencies or material weaknesses in the effectiveness of our internal controls could also reduce our ability to obtain financing or could increase the cost of any financing we obtain and require additional expenditures to comply with applicable requirements.

Our failure to meet the continued listing requirements of The NASDAQ Capital Market could result in a delisting of our common stock.

        In connection with the Merger, we effected a reverse split of our common stock to enable us to comply with The NASDAQ Capital Market's minimum bid price listing requirement. Notwithstanding the reverse stock split and compliance with The NASDAQ Capital Market's minimum bid price listing requirement, we may not be able to maintain a price per share of our common stock in excess of $1.00 per share or the additional criteria for continued listing of our common stock set forth by The NASDAQ Capital Market. The occurrence of any future non-compliance with The NASDAQ Capital Market's minimum bid price or other listing requirements may have a material adverse effect on our stock price, our business and our prospects.

Our stock price is expected to continue to be volatile and you may not be able to resell your shares.

        We cannot assure you that an active trading market for shares of our common stock will develop or be sustained. If an active market for our common stock does not develop, or is not sustained, it may be difficult to sell shares without depressing the market price for the shares or to sell your shares at all.

        The market price for our common stock has been volatile, and market prices for securities of companies comparable to us have been highly volatile. In addition, the stock market as a whole and biotechnology and other life science stocks in particular have experienced significant price volatility. Like our common stock, these stocks have experienced significant price and volume fluctuations for reasons unrelated to the operating performance of the individual companies. Factors giving rise to this volatility may include:

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regulatory and other developments in both the United States and abroad;



•

developments concerning proprietary rights, including patents and litigation matters;

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disclosure of new collaborations or other strategic transactions;



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public concern about the safety or efficacy of our product candidates or technology, their components, or related technology or new technologies generally;



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public announcements by our competitors or others regarding new products or new product candidates;



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general market conditions and comments by securities analysts and investors; and



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developments relating to our key partners.

        In the past, securities class action litigation has often been brought against companies that experience volatility in the market price of their securities. Whether or not meritorious, litigation brought against us could result in substantial costs and a diversion of management's attention and resources, which could adversely affect our business, operating results and financial condition.

Fluctuations in our operating losses could adversely affect the price of our common stock.

        Our operating losses may fluctuate significantly on a quarterly basis. Some of the factors that may cause our operating losses to fluctuate on a period-to-period basis include the status of our clinical and pre-clinical development programs, level of expenses incurred in connection with our clinical and pre-clinical development programs, restructuring costs, implementation or termination of collaboration, licensing, manufacturing or other material agreements with third parties, non-recurring revenue or expenses under any such agreement, and compliance with regulatory requirements. Period-to-period comparisons of our historical and future financial results may not be meaningful, and investors should not rely on them as an indication of future performance. Our fluctuating losses may fail to meet the expectations of securities analysts or investors. Our failure to meet these expectations may cause the price of our common stock to decline.

Anti-takeover provisions in our charter documents and provisions of Delaware law may make an acquisition more difficult and could result in the entrenchment of management.

        We are incorporated in Delaware. Anti-takeover provisions of Delaware law and our charter documents may make a change in control or efforts to remove management more difficult. Also, under Delaware law, our board of directors may adopt additional anti-takeover measures. The existence of the following provisions of Delaware law and our sixth amended and restated charter, as amended, or our amended and restated bylaws could limit the price that investors might be willing to pay in the future for shares of our common stock.

        Our charter authorizes our board of directors to issue up to 5,000,000 shares of preferred stock and to determine the terms of those shares of stock without any further action by our stockholders. If the board of directors exercises this power to issue preferred stock, it could be more difficult for a third party to acquire a majority of our outstanding voting stock and vote the stock they acquire to remove management or directors.

        Our charter also provides staggered terms for the members of our board of directors. Under Section 141 of the General Corporation Law of the State of Delaware, or the DGCL, and our charter, our directors may be removed by stockholders only for cause and only by vote of the holders of 75% of voting shares then outstanding. These provisions may prevent stockholders from replacing the entire board in a single proxy contest, making it more difficult for a third party to acquire control without the consent of our board of directors. These provisions could also delay the removal of management by the board of directors with or without cause. In addition, our amended and restated bylaws limit the ability our stockholders to call special meetings of stockholders.

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        Our equity incentive plans generally permit our board of directors to provide for acceleration of vesting of options granted under these plans in the event of certain transactions that result in a change of control. If our board of directors uses its authority to accelerate vesting of options, this action could make an acquisition more costly, and it could prevent an acquisition from going forward.

        Under Section 203 of the DGCL, a corporation may not engage in a business combination with any holder of 15% or more of its capital stock until the holder has held the stock for three years unless, among other possibilities, the board of directors approves the transaction in advance. These provisions may have the effect of entrenching our management team and may deprive you of the opportunity to sell your shares to potential acquirers at a premium over prevailing prices. The potential inability to obtain a control premium could reduce the price of our common stock.

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FORWARD-LOOKING STATEMENTS

        Various statements throughout this prospectus supplement and the documents incorporated by reference herein are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements may appear throughout this prospectus supplement and the documents incorporated by reference herein. Words such as "believe," "anticipate," "expect," "estimate," "intend," "plan," "project," "will be," "will continue," "will result," "seek," "could," "may," "might," or the negative of these terms and similar expressions or words, identify forward-looking statements. Forward-looking statements are based upon current expectations that involve risks, changes in circumstances, assumptions and uncertainties. Important factors that could cause actual results to differ materially from those reflected in our forward-looking statements include, among others:

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our inability to obtain regulatory approval for, or successfully commercialize, our leading product candidate, BOW015, or our other product candidates, BOW050, BOW070, BOW080, BOW090 and BOW100;



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our inability to secure and maintain relationships with collaborators and single-source contract manufacturers;



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our history of operating losses and inability to ever become profitable;



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our limited history of complying with public company reporting requirements;



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our limited sales and marketing infrastructure;



•

uncertainty and volatility in the price of our common stock;



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our inability to develop, implement and maintain appropriate internal controls;



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our inability to remediate the material weaknesses in our internal control over financial reporting;



•

uncertainty as to our employees', independent contractors' and other collaborators' compliance with regulatory standards and requirements and insider trading rules;



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uncertainty as to the relationship between the benefits of our product candidates and the risks of their side-effect profiles;



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our inability to effectively compete with the reference biologic products for our biosimilar product candidates and from other pharmaceuticals approved for the same indication as the reference biologic products;



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our inability to complete our in-house cell line and process development activities;



•

dependence on the efforts of third-parties to conduct and oversee our clinical trials for our product candidates, to manufacture nonclinical and clinical supplies of our product candidates, to store critical components of our product candidates, and to commercialize our product candidates;



•

uncertainty relating to U.S. regulatory and legal landscapes and a fragmented payer market;



•

the extent of government regulations;



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uncertainty of clinical trial results;



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a loss of any of our key management personnel;



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our inability to develop or commercialize our product candidates due to intellectual property rights held by third parties and our inability to protect the confidentiality of our trade secrets;

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•

the cost and effects of potential litigation; and



•

our limited financial resources and inability to access capital to fund proposed operations.

        All written and verbal forward-looking statements attributable to us or any person acting on our behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. We caution investors not to rely too heavily on the forward-looking statements we make or that are made on our behalf. We undertake no obligation, and specifically decline any obligation, to update or revise publicly any forward-looking statements, whether as a result of new information, future events or otherwise. You are advised, however, to consult any further disclosures we make on related subjects in any annual, quarterly or current reports that we may file with the SEC.

        In addition, you should refer to the section of this prospectus supplement entitled "Risk Factors" as well as the documents we have incorporated by reference for a discussion of other important factors that may cause our actual results to differ materially from those expressed or implied by our forward-looking statements. As a result of these factors, we cannot assure you that the forward-looking statements in this prospectus supplement will prove to be accurate. Furthermore, if our forward-looking statements prove to be inaccurate, the inaccuracy may be material. In light of the significant uncertainties in these forward-looking statements, you should not regard these statements as a representation or warranty by us or any other person that we will achieve our objectives and plans in any specified time frame, or at all.

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USE OF PROCEEDS

        The amount of proceeds from this offering will depend upon the number of shares of our common stock sold and the market price at which they are sold. There can be no assurance that we will be able to sell any shares under or fully utilize the sales agreement with BTIG as a source of financing. We intend to use the net proceeds of this offering for general corporate purposes, which may include research and development expenditures, clinical trial expenditures, commercialization activities and working capital.

        The amounts and timing of our actual expenditures for each purpose may vary significantly depending upon numerous factors, including the timing and success of any ongoing clinical trials or clinical trials we may commence in the future, the timing of regulatory submissions, any unforeseen delays or problems in the development of our manufacturing capabilities and supply chain relationships, and the timing and amount of our future revenue, our future expenses as well as any collaborations or licensing that we may enter into with third parties for our product candidates, and any unforeseen cash needs. We reserve the right to change the use of proceeds as a result of certain contingencies such as competitive developments, opportunities to acquire technologies or products and other factors. Pending application of the proceeds of sales of the securities, we intend to invest the net proceeds of the sales in short-term, investment-grade, interest-bearing instruments.

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DESCRIPTION OF COMMON STOCK

        The following summary of certain provisions of our common stock does not purport to be complete. You should refer to our sixth amended and restated certificate of incorporation, as amended, and our amended and restated by-laws, both of which are included as exhibits to the registration statement of which this prospectus supplement forms a part. The summary below is also qualified by provisions of applicable law.

General Terms

        Our authorized capital stock currently consists of 70,000,000 shares of common stock, par value $0.001 per share. On February 26, 2016, we had 24,377,573 shares of common stock outstanding and approximately 53 stockholders of record. Except as otherwise provided in any resolution providing for the issue of any series of preferred stock, holders of our common stock have exclusive voting rights for the election of directors and for all other purposes. Holders of our common stock are entitled to one vote per share on all matters to be voted upon by our stockholders. Neither our sixth amended and restated certificate of incorporation, as amended, nor our amended and restated by-laws authorize cumulative voting. The holders of our common stock are entitled to receive dividends, if any, as may be declared from time to time by our board of directors out of funds legally available for the payment of dividends, subject to the rights of any series of preferred stock. In the event of a liquidation, dissolution or winding up of Epirus, the holders of our common stock are entitled to share ratably in all assets remaining after payment of the preferential amounts, if any, to which the holders of our preferred stock, if any, are entitled. Our common stock has no preemptive, conversion or other subscription rights. There are no redemption or sinking fund provisions applicable to our common stock. All of our outstanding shares of common stock are fully paid and non-assessable.

Our Board of Directors

        Our board of directors currently has eight (8) members. Our sixth amended and restated certificate of incorporation, as amended, and our amended and restated by-laws provide that the number of directors shall be fixed from time to time by resolution adopted by the vote of a majority of the directors then in office, but shall in no event be less than three. Our sixth amended and restated certificate of incorporation, as amended, provides that the board of directors shall be divided into three nearly equal classes, with each class's term expiring on a staggered basis. Vacancies and newly created directorships may be filled by a majority of the directors then in office, though less than a quorum. Directors may be removed only for cause by the affirmative vote of at least seventy-five percent (75%) of the outstanding shares of capital stock entitled to vote generally in the election of directors, voting together as a single class, cast at a meeting of the stockholders called for that purpose.

Transfer Agent and Registrar

        The transfer agent and registrar for our common stock is Computershare Trust Company, N.A.

NASDAQ Capital Market

        Our common stock is listed for quotation on the NASDAQ Capital Market under the symbol "EPRS."

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CERTAIN PROVISIONS OF DELAWARE LAW AND OF OUR SIXTH AMENDED AND RESTATED CERTIFICATE OF INCORPORATION, AS AMENDED, AND OUR AMENDED AND RESTATED BY-LAWS

Anti-Takeover Provisions of our Delaware Certificate of Incorporation and By-laws

        In addition to the board of directors' ability to issue shares of preferred stock, our sixth amended and restated certificate of incorporation, as amended, and our amended and restated by-laws contain other provisions that are intended to enhance the likelihood of continuity and stability in the composition of the board of directors and which may have the effect of delaying, deferring or preventing a future takeover or change in control of our company unless such takeover or change in control is approved by our board of directors. These provisions include a classified board of directors as discussed above, elimination of stockholder action by written consents, elimination of the ability of stockholders to call special meetings, advance notice procedures for stockholder proposals and supermajority vote requirements for amendments to our certificate of incorporation and by-laws.

        Classified Board.    Under the Delaware General Corporation Law, unless the certificate of incorporation otherwise provides, directors serving on a classified board can only be removed by the stockholders for cause. The provision for a classified board could prevent a party who acquires control of a majority of our outstanding common stock from obtaining control of the board until our second annual stockholders meeting following the date the acquirer obtains the controlling stock interest. The classified board provision could have the effect of discouraging a potential acquirer from making a tender offer or otherwise attempting to obtain control of us and could increase the likelihood that incumbent directors will retain their positions.

        Elimination of Stockholder Action Through Written Consent.    Our amended and restated by-laws provide that stockholder action can be taken only at an annual or special meeting of stockholders and cannot be taken by written consent in lieu of a meeting.

        Elimination of the Ability to Call Special Meetings.    Our sixth amended and restated certificate of incorporation, as amended and our amended and restated by-laws provide that, except as otherwise required by law, special meetings of our stockholders can only be called pursuant to a resolution adopted by a majority of our board of directors or by our chief executive officer or the chairman of our board of directors. Stockholders are not permitted to call a special meeting or to require our board to call a special meeting.

        Advanced Notice Procedures for Stockholder Proposals.    Our amended and restated by-laws establish an advance notice procedure for stockholder proposals to be brought before an annual meeting of our stockholders, including proposed nominations of persons for election to our board. Stockholders at our annual meeting may only consider proposals or nominations specified in the notice of meeting or brought before the meeting by or at the direction of our board or by a stockholder who was a stockholder of record on the record date for the meeting, who is entitled to vote at the meeting and who has given to our secretary timely written notice, in proper form, of the stockholder's intention to bring that business before the meeting. Although our amended and restated by-laws do not give our board the power to approve or disapprove stockholder nominations of candidates or proposals regarding other business to be conducted at a special or annual meeting, our amended and restated by-laws may have the effect of precluding the conduct of some business at a meeting if the proper procedures are not followed or may discourage or defer a potential acquirer from conducting a solicitation of proxies to elect its own slate of directors or otherwise attempting to obtain control of us.

        Amendments to the Certificate of Incorporation or By-laws.    Our sixth amended and restated certificate of incorporation, as amended, and our amended and restated by-laws provide that the affirmative vote of holders of at least 75% of the total votes eligible to be cast in the election of directors is required to amend, alter, change or repeal some of their provisions, unless such amendment

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or change has been approved by either a majority of those directors who are not affiliated or associated with any person or entity holding 10% or more of the voting power of our outstanding capital stock. This requirement of a super-majority vote to approve amendments to the certificate and by-laws could enable a minority of our stockholders to exercise veto power over any such amendments.

Provisions of Delaware Law Governing Business Combinations

        We are subject to the "business combination" provisions of Section 203 of the Delaware General Corporation Law. In general, such provisions prohibit a publicly held Delaware corporation from engaging in any "business combination" transactions with any "interested stockholder" for a period of three years after the date on which the person became an "interested stockholder," unless:

•

prior to such date, the board of directors approved either the "business combination" or the transaction which resulted in the "interested stockholder" obtaining such status;



•

upon consummation of the transaction which resulted in the stockholder becoming an "interested stockholder," the "interested stockholder" owned at least 85% of the voting stock of the corporation outstanding at the time the transaction commenced, excluding for purposes of determining the voting stock outstanding (but not the outstanding voting stock owned by the "interested stockholder") those shares owned by (a) persons who are directors and also officers and (b) employee stock plans in which employee participants do not have the right to determine confidentially whether shares held subject to the plan will be tendered in a tender or exchange offer; or



•

at or subsequent to such time the "business combination" is approved by the board of directors and authorized at an annual or special meeting of stockholders, and not by written consent, by the affirmative vote of at least 66²/3% of the outstanding voting stock which is not owned by the "interested stockholder."

        A "business combination" is defined to include mergers, asset sales and other transactions resulting in financial benefit to a stockholder. In general, an "interested stockholder" is a person who, together with affiliates and associates, owns 15% or more of a corporation's voting stock or within three years did own 15% or more of a corporation's voting stock. The statute could prohibit or delay mergers or other takeover or change in control attempts with respect to us and, accordingly, may discourage attempts to acquire us.

Limitations on Liability and Indemnification of Officers and Directors

        Our sixth amended and restated certificate of incorporation, as amended, limits the liability of our directors and executive officers to the fullest extent permitted by the Delaware General Corporation Law and provides that we will indemnify them to the fullest extent permitted by such law. We have entered into indemnification agreements with all of our current directors and executive officers and expect to enter into a similar agreement with any new directors and executive officers.

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DIVIDEND POLICY

        We have never declared or paid any cash dividends on our capital stock. We intend to retain future earnings, if any, to finance the operation and expansion of our business and do not anticipate paying any cash dividends in the foreseeable future. Any future determination related to dividend policy will be made at the discretion of our board of directors after considering our financial condition, results of operations, capital requirements, business prospects and other factors the board of directors deems relevant, and subject to the restrictions contained in our current or future financing instruments.

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DILUTION

        Purchasers of common stock offered by this prospectus supplement and the accompanying prospectus will suffer immediate and substantial dilution in the net tangible book value per share of common stock. Our net tangible book value as of September 30, 2015 was approximately $17.4 million, or approximately $0.72 per share of common stock. Net tangible book value per share represents the amount of total tangible assets less total liabilities, divided by the number of shares of our common stock outstanding as of September 30, 2015.

        Dilution in net tangible book value per share represents the difference between the amount per share paid by purchasers of shares in this offering and the net tangible book value per share of our common stock immediately after this offering. After giving effect to the sale of 10,714,286 shares of common stock in this offering at an assumed public offering price of $2.80 per share, which was the last reported sale price of our common stock on The NASDAQ Capital Market on February 26, 2016, and after deduction of the estimated offering commissions and expenses payable by us, our adjusted net tangible book value as of September 30, 2015 would have been approximately $46.1 million, or $1.31 per share of common stock. This represents an immediate increase in net tangible book value of $0.59 per share of common stock to our existing shareholders and an immediate dilution in net tangible book value of $1.49 per share of common stock to investors participating in this offering. The following table illustrates this per share dilution:

        The table above assumes, for illustrative purposes, that an aggregate of 10,714,286 shares of our common stock are sold at a price of $2.80 per share, the last reported sale price of our common stock on The NASDAQ Capital Market on February 26, 2016, for aggregate gross proceeds of approximately $30 million. The shares sold in this offering, if any, will be sold from time to time at various prices. An increase of $0.10 per share in the price at which the shares are sold from the assumed offering price of $2.80 per share shown in the table above, assuming all of our common stock in the aggregate amount of $30,000,000 is sold at that price, would increase our as adjusted net tangible book value per share after the offering to $1.33 per share and would increase the dilution in net tangible book value per share to new investors to $1.57 per share, after deducting commissions and estimated aggregate offering expenses payable by us. A decrease of $0.10 per share in the price at which the shares are sold from the assumed offering price of $2.80 per share shown in the table above, assuming all of our common stock in the aggregate amount of $30,000,000 is sold at that price, would result in our as adjusted net tangible book value per share after the offering being $1.30 per share and would decrease the dilution in net tangible book value per share to new investors to $1.40 per share, after deducting commissions and estimated aggregate offering expenses payable by us. This information is supplied for illustrative purposes only.

        The number of shares of our common stock to be outstanding immediately after this offering as shown above is based on 24,383,264 shares outstanding as of September 30, 2015. This number of shares excludes the following:

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2,607,164 shares issuable upon exercise of stock options outstanding as of September 30, 2015 at a weighted average exercise price of $10.20 per share;



•

92,892 shares issuable upon exercise of warrants outstanding as of September 30, 2015 at a weighted average exercise price of $12.98 per share;

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•

125,257 shares of unvested restricted stock units (of which 815 were cancelled subsequent to September 30, 2015);



•

352,722 shares available for future issuance under our 2015 Employee Stock Purchase Plan; and



•

1,446,782 shares available for future issuance under our 2015 Equity Incentive Plan (of which 1,029,818 shares issuable upon exercise of stock options were granted, net of cancellations, subsequent to September 30, 2015).

        To the extent that any options or warrants are exercised, new options are issued under our equity incentive plans, or we otherwise issue additional shares of common stock in the future, there will be further dilution to new investors.

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PLAN OF DISTRIBUTION

        We have entered into the sales agreement with BTIG, under which we may issue and sell our common stock having an aggregate offering price of up to $30,000,000 from time to time through BTIG, acting as our sales agent. The actual dollar amount and number of shares of common stock we sell pursuant to this prospectus supplement will be dependent, among other things, on market conditions and our capital raising requirements. The sales of our common stock, if any, under the sales agreement may be made by any method permitted by law deemed to be an "at-the-market offering" as defined in Rule 415 under the Securities Act, including sales made directly on The NASDAQ Capital Market, on any other existing trading market for our common stock or to or through a market maker or through an electronic communications network. If expressly authorized by us, BTIG may also sell our common stock in privately negotiated transactions.

        Each time that we wish to issue and sell shares of our common stock under the sales agreement, we will provide BTIG with a placement notice describing the amount of shares to be sold or the gross proceeds to be raised in a given time period, the time period during which sales are requested to be made, any limitation on the amount of shares of common stock that may be sold in any single day, any minimum price below which sales may not be made or any minimum price requested for sales in a given time period and any other instructions relevant to such requested sales. Upon receipt of a placement notice, BTIG, as our sales agent, will use commercially reasonable efforts, consistent with its normal trading and sales practices and applicable state and federal laws, rules and regulations and the rules of The NASDAQ Capital Market, to sell shares of our common stock under the terms and subject to the conditions of the placement notice and the sales agreement. We or BTIG may suspend the offering of common stock pursuant to a placement notice upon proper notice and subject to other conditions. BTIG, in its sole discretion, may decline to accept any placement notice. During the term of the sales agreement, BTIG will not engage in any market making, bidding, stabilization or other trading activity with regard to our common stock if such activity would be prohibited under Regulation M or other anti-manipulation rules under the Securities Act.

        BTIG will provide written confirmation to us no later than the opening of the trading day on The NASDAQ Capital Market following the trading day on which shares of our common stock are sold through BTIG under the sales agreement. Each confirmation will include the number of shares sold on the preceding day, the net proceeds to us and the commissions payable by us to BTIG in connection with the sales.

        We will pay BTIG commissions for its services in acting as agent in the sale of our common stock pursuant to the sales agreement. BTIG will be entitled to compensation at a fixed commission rate of 3.0% of the gross proceeds from the sale of our common stock pursuant to the sales agreement. Because there are no minimum sale requirements as a condition to this offering, the actual total public offering price, commissions and net proceeds to us, if any, are not determinable at this time. We estimate that the total expenses for this offering, excluding compensation payable to BTIG and certain expenses reimbursable to BTIG under the terms of the sales agreement, will be approximately $450,000.

        Settlement for sales of common stock will occur on the third trading day following the date on which any sales are made (or on such other date as is industry practice for regular-way trading), unless otherwise specified in the applicable placement notice, in return for payment of the net proceeds to us. There are no arrangements to place any of the proceeds of this offering in an escrow, trust or similar account. Sales of our common stock as contemplated in this prospectus supplement will be settled through the facilities of The Depository Trust Company or by such other means as we and BTIG may agree upon.

        In connection with the sale of the common stock on our behalf, BTIG may, and will with respect to sales effected in an "at-the-market offering," be deemed to be an "underwriter" within the meaning

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of the Securities Act, and the compensation of BTIG may be deemed to be underwriting commissions or discounts. We have agreed to provide indemnification and contribution to BTIG against certain civil liabilities, including liabilities under the Securities Act. We also have agreed to reimburse BTIG for its reasonable out-of-pocket expenses, including the fees and disbursements of counsel to BTIG, incurred in connection with the offering, up to a maximum amount of $75,000 during the first year of the sales agreement term, and up to $40,000 per year thereafter.

        The offering pursuant to the sales agreement will terminate upon the earlier of (i) the sale of all shares of common stock subject to the agreement and (ii) termination of the sales agreement as permitted therein. We may terminate the sales agreement in our sole discretion at any time by giving five days' prior notice to BTIG. BTIG may terminate the sales agreement under the circumstances specified in the sales agreement and in its sole discretion at any time by giving five days' prior notice to us.

        BTIG and its affiliates may in the future provide various investment banking and other financial services for us and our affiliates, for which services they may in the future receive customary fees.

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LEGAL MATTERS

        The validity of the shares of common stock offered hereby will be passed upon by Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., Boston, Massachusetts. BTIG is being represented in connection with this offering by Greenberg Traurig, LLP, New York, New York.

EXPERTS

        The consolidated financial statements of EPIRUS Biopharmaceuticals, Inc. appearing in EPIRUS Biopharmaceuticals, Inc.'s Annual Report on Form 10-K for the year ended December 31, 2014 have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their report thereon, included therein, and incorporated herein by reference. Such financial statements have been incorporated herein by reference in reliance upon such report given on the authority of such firm as experts in accounting and auditing.

        The consolidated financial statements of Bioceros Holding B.V., Inc. appearing in the Company's current report on Form 8-K/A for the year ended December 31, 2014, have been audited by Ernst & Young Accountants LLP, independent registered public accounting firm, as set forth in their report thereon, included therein, and incorporated herein by reference. Such financial statements are incorporated herein by reference in reliance upon such report given on the authority of such firm as experts in accounting and auditing.

WHERE YOU CAN FIND ADDITIONAL INFORMATION

        We file annual, quarterly and other reports, proxy statements and other information with the SEC. Our SEC filings are available to the public over the Internet at the SEC's website at http://www.sec.gov. You may also read and copy any document we file at the SEC's Public Reference Room at 100 F Street, NE, Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the Public Reference Room. Our annual reports on Form 10-K, quarterly reports on Form 10-Q, and current reports on Form 8-K, including any amendments to those reports, and other information that we file with or furnish to the SEC pursuant to Section 13(a) or 15(d) of the Exchange Act can also be accessed free of charge on our website at http://www.epirusbiopharma.com under the "Investors—Financials & Filings—SEC Filings" caption. These filings will be available as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC. Information contained on our website is not part of this prospectus supplement.

        You should rely only on the information provided in, and incorporated by reference in, this prospectus supplement and the accompanying prospectus and the registration statement to which this prospectus supplement and accompanying prospectus form a part. We have not authorized anyone else to provide you with different information. Our securities are not being offered in any jurisdiction where the offer is not permitted. The information contained in documents that are incorporated by reference in this prospectus supplement is accurate only as of the dates of those documents. Our business, financial condition, results of operations and prospects may have changed since those dates.

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INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

        The SEC allows us to incorporate by reference the information we file with it, which means that we can disclose important information to you by referring you to another document that we have filed separately with the SEC. You should read the information incorporated by reference because it is an important part of this prospectus supplement and the accompanying prospectus. We incorporate by reference the following information or documents that we have filed with the SEC:

•

our annual report on Form 10-K for the year ended December 31, 2014 filed with the SEC on March 31, 2015;



•

our quarterly reports on Form 10-Q for the quarters ended March 31, 2015, June 30, 2015 and September 30, 2015 filed with the SEC on May 13, 2015, August 12, 2015 and November 16, 2015, respectively;



•

our current reports on Form 8-K filed with the SEC on January 26, 2015, January 30, 2015, March 13, 2015, April 24, 2015, June 9, 2015, July 14, 2015, September 9, 2015, September 28, 2015, October 7, 2015, November 10, 2015, November 16, 2015 (solely with respect to Item 8.01), February 9, 2016 and February 29, 2016;



•

the portions of our definitive proxy statement on Schedule 14A filed with the SEC on April 24, 2015 that are deemed "filed" with the SEC under the Exchange Act; and



•

the description of our common stock contained in our registration statement on Form 8-A, which was filed with the SEC on February 18, 2005, including any amendment or report filed for the purpose of updating such description.

        Unless otherwise noted, the SEC file number for each of the documents listed above is 000-51171.

        All reports and other documents we subsequently file pursuant to Section 13(a), 13(c), 14 or 15(d) of the Exchange Act prior to the termination of this offering, but excluding any information furnished to, rather than filed with, the SEC, will also be incorporated by reference into this prospectus supplement and accompanying prospectus and deemed to be part of this prospectus supplement and accompanying prospectus from the date of the filing of such reports and documents.

        Any statement contained in any document incorporated by reference herein shall be deemed to be modified or superseded for purposes of this prospectus supplement and accompanying prospectus to the extent that a statement contained in this prospectus supplement or accompanying prospectus modifies or supersedes such statement. Any statement so modified or superseded shall not be deemed, except as so modified or superseded, to constitute a part of this prospectus supplement and accompanying prospectus.

        We will provide without charge to each person, including any beneficial owner, to whom this prospectus supplement and accompanying prospectus is delivered, upon written or oral request, a copy of any or all documents that are incorporated by reference into this prospectus supplement and accompanying prospectus, but not delivered with the prospectus supplement and accompanying prospectus, other than exhibits to such documents unless such exhibits are specifically incorporated by reference into the documents that this prospectus supplement and accompanying prospectus incorporates. You should direct written requests to:

EPIRUS Biopharmaceuticals, Inc.
699 Boylston Street
Eighth Floor
Boston, MA 02116
(617) 600-3497

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Prospectus

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$125,000,000
Debt Securities
Preferred Stock
Common Stock
Warrants
Units

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        This prospectus provides you with a general description of debt and equity securities that EPIRUS Biopharmaceuticals, Inc. may offer and sell, from time to time, either individually or in units in a maximum aggregate offering amount of up to $125,000,000. Each time we sell securities we will provide a prospectus supplement that will contain specific information about the terms of any debt or equity securities we offer and the specific manner in which we will offer the debt or equity securities. The prospectus supplement will also contain information, where appropriate, about material United States federal income tax consequences relating to, and any listing on a securities exchange of, the debt or equity securities covered by the prospectus supplement. The prospectus supplement may also add, update or change information contained in this prospectus. You should read this prospectus and the applicable prospectus supplement carefully before you invest in our securities.

        We may offer these securities in amounts, at prices and on terms determined at the time of offering. We may sell the securities directly to you, through agents we select, or through underwriters and dealers we select. For additional information on the methods of sale, you should refer to the section entitled "Plan of Distribution" in this prospectus and in the applicable prospectus supplement. If we use agents, underwriters or dealers to sell the securities, we will name them and describe their compensation in a prospectus supplement.

        Our common stock is listed on the NASDAQ Capital Market under the symbol "EPRS." On June 29, 2015, the closing price for our common stock, as reported on the NASDAQ Capital Market, was $5.78 per share. Our principal executive offices are located at 699 Boylston Street, Eighth Floor, Boston, Massachusetts 02116.

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        Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties described under the heading "Risk Factors" contained in this prospectus beginning on page 5 and the applicable prospectus supplement, and under similar headings in the other documents that are incorporated by reference into this prospectus.

        Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

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The date of this prospectus is July 17, 2015.

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TABLE OF CONTENTS

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        Unless the context specifically indicates otherwise, all references to "the Company," "we," "us," "our," "our company," and "Epirus," refer to Public Epirus and its subsidiaries following the Merger, effective on July 15, 2014, and to Private Epirus and its subsidiaries prior to the Merger.

ABOUT THIS PROSPECTUS

        This prospectus is part of a registration statement filed with the Securities and Exchange Commission, or SEC, utilizing a shelf registration process. Under this shelf registration process, we may sell any combination of the securities described in this prospectus, either individually or in units, in one or more offerings, up to a total dollar amount of $125,000,000.

        This prospectus provides you with a general description of the securities we may offer. Each time we sell securities, we will provide a prospectus supplement that will contain specific information about the terms of that specific offering. The prospectus supplement may also add, update or change information contained in this prospectus. You should read this prospectus and the applicable prospectus supplement together with the additional information described under the heading "Where You Can Find More Information" before making an investment decision.

        You should rely only on the information we have provided or incorporated by reference in this prospectus or any prospectus supplement. We have not authorized anyone to provide you with information different from that contained or incorporated by reference in this prospectus. No dealer, salesperson or other person is authorized to give any information or to represent anything not contained or incorporated by reference in this prospectus. You must not rely on any unauthorized information or representation. This prospectus is an offer to sell only the securities offered hereby, but only under circumstances and in jurisdictions where it is lawful to do so. You should assume that the information in this prospectus or any prospectus supplement is accurate only as of the date on the front of the document and that any information we have incorporated herein by reference is accurate only as of the date of the document incorporated by reference, regardless of the time of delivery of this prospectus or any sale of a security.

        This prospectus may not be used to consummate sales of our securities, unless it is accompanied by a prospectus supplement. To the extent there are inconsistencies between any prospectus supplement, this prospectus and any documents incorporated by reference, the document with the most recent date will control.

ABOUT EPIRUS BIOPHARMACEUTICALS, INC.

Explanatory Note

        On July 15, 2014, EPIRUS Biopharmaceuticals, Inc., a Delaware corporation and private company ("Private Epirus"), completed its merger with EB Sub, Inc., a wholly-owned subsidiary of Zalicus Inc., a Delaware corporation ("Zalicus") (the "Merger"). As part of the Merger, Zalicus was renamed EPIRUS Biopharmaceuticals, Inc. ("Public Epirus") and Private Epirus was renamed EB Sub, Inc. ("EB Sub"). The boards of directors of Private Epirus and Zalicus approved the Merger on April 15, 2014, and the stockholders of Private Epirus and Zalicus approved the Merger and related matters on July 15, 2014. Following completion of the Merger, EB Sub, Inc. (formerly Private Epirus), is the surviving corporation of the Merger and a wholly-owned subsidiary of Public Epirus.

Overview

        We are a biopharmaceutical company focused on building a pure-play, sustainable and profitable biosimilar business by improving patient access to these important, cost-effective medicines worldwide. Biosimilars are highly similar versions of approved patented biological drug products, referred to as reference or innovator products. Based on projected global sales estimates from EvaluatePharma®,

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more than $80 billion in major biological drug sales is expected to face competition from biosimilars as a result of the expiration of patents over the next decade.

        Building a pure-play biosimilar company requires strong technical capabilities. We are a global company with an experienced product development team based in Boston, Massachusetts and a robust clinical, regulatory and business development infrastructure based in Zug, Switzerland. Our strategy for biosimilars relies on global partnerships and distinct strategies to address the diverse and evolving regulatory, legal and commercial landscape. We have segmented the global market into three types: Developed Markets, which include the United States and Europe; Local Production Markets, which include China and Brazil; and Accessible Markets, which include India and Latin America.

        We seek to build a sustainable platform focusing on a therapeutically-focused pipeline of Immunoglobulin G (IgG), Chinese Hamster Ovary (CHO) cell derived monoclonal antibodies, or MAbs. Our pipeline of products includes BOW015, a biosimilar version of Remicade® (infliximab), BOW050, a biosimilar version of Humira® (adalimumab) and BOW070, a biosimilar version of Actemra® (tocilizumab). Collectively, Remicade, Humira and Actemra generated approximately $23 billion in global innovator sales in 2014, according to EvaluatePharma, with Remicade alone generating approximately $8.8 billion in global sales in 2014. All three our of programs focus on the treatment of overlapping inflammatory and immune-mediated disorders. The standardization of the platform and the clustering of the therapeutic area will allow us to have a greater degree of focus, synergy and cost management across product development, manufacturing, clinical and eventual commercialization. Additionally, there are over 20 other IgG, CHO cell derived MAbs with near-term patent expiries clustered in five therapeutic areas which provide mid- to long-term pipeline growth options for us.

        For our lead program, BOW015, we have reported bioequivalence and efficacy data from a Phase 1 clinical trial in the United Kingdom and a Phase 3 clinical trial in India, both of which demonstrated the equivalence of BOW015 to Remicade. We also announced positive 58 week follow up data from the Phase 3 trial. In this open label phase, we demonstrated that patients can be safely initiated and effectively maintained on BOW015 for 58 weeks, and that patients can be safely switched from Remicade to BOW015 and effectively maintained out to 58 weeks. We intend to initiate a global clinical program for BOW015 in late 2015 or early 2016. We have been designing this clinical program in consultation with European regulatory bodies in order to obtain the data necessary to support eventual approval of BOW015 in North America and Europe.

        To build a profitable business over time, we intend to design and execute on partnerships that optimize value retention via distribution or profit sharing deals while effectively managing our tax basis worldwide. Our Swiss-based tax structure will allow us to efficiently manage future cash for operations outside the United States.

        In Accessible Markets, in which our current BOW015 regulatory data are expected to be sufficient for approval, we intend to pursue near-term product launches. This will enable us to gain in-market exposure needed to support eventual filings in Developed Markets and allow us to build important commercial and commercial support services with and for our partners. In collaboration with our commercialization partner Sun Pharmaceutical Industries Ltd., we launched BOW015 in India in November 2014. BOW015 is sold under the brand name Infimab^TM and is the first infliximab biosimilar approved in India. We expect to utilize our existing regulatory data package to gain regulatory approval for BOW015 in additional countries. In May 2015, we also entered into a development and future distribution agreement with mAbxience, S.A., a wholly owned subsidiary of CHEMO Group, for BOW015 in Latin American markets, including Argentina, Chile, Ecuador, Paraguay, Uruguay and Venezuela. In China, which requires local production, we have an established partnership with Livzon Mabpharm Inc. for the production of biosimilars for China and associated markets.

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        Developed Markets, predominately North America and Europe, are expected to be the financial anchor of our business. In European markets, we intend to execute a commercial plan that may include distribution or profit sharing partnerships in specific markets. In the United States, we intend to retain rights and evaluate market conditions prior to determining a commercial plan commensurate with our objectives to create value.

        Our long-term ability to deliver these important medicines to patients worldwide can only be achieved through a disciplined approach. Our experienced management team plans to address the diverse regulatory, legal and commercial landscape by gaining near-term market access, creating a strong technical platform with opportunities for sustainable pipeline growth, and finding tax-optimized partnership deals that maximize future value to provide us with a path forward to build a sustainable and profitable biosimilar business.

Corporate Information

        We were incorporated in Delaware in 2000. Our principal executive offices are located at 699 Boylston Street, 8th Floor, Boston, MA 02116, and our telephone number is (617) 600-3497. We have the following subsidiaries: EB Sub, Inc., a Delaware corporation, Epirus Biopharmaceuticals Ltd., a United Kingdom corporation, Epirus Switzerland GmbH, a Swiss corporation, Epirus Brasil Tecnologia Ltda, a Brazilian corporation and Zalicus Pharmaceuticals Ltd., a Canadian corporation. We maintain an internet website at www.epirusbiopharma.com and the information contained in, or that can be accessed through, our website is not incorporated by reference into this prospectus and is not part of this prospectus. "Epirus" and the Epirus logo are trademarks of Epirus.

Offerings Under This Prospectus

        Under this prospectus, we may offer up to $125,000,000 of debt securities, common stock, preferred stock, warrants and/or units in one or more offerings and in any combination. This prospectus provides you with a general description of the securities we may offer. A prospectus supplement, which we will provide each time we offer securities, will describe the specific amounts, prices and terms of these securities, including, to the extent applicable:

•

designation or classification;



•

aggregate principal amount or aggregate offering price;



•

maturity, if applicable;



•

rates and times of payment of interest or dividends, if any;



•

redemption, conversion or sinking fund terms, if any;



•

voting or other rights, if any; and



•

conversion or exercise prices, if any.

        The prospectus supplement also may add, update or change information contained in this prospectus or in documents we have incorporated by reference into this prospectus. However, no prospectus supplement will fundamentally change the terms that are set forth in this prospectus or offer a security that is not registered and described in this prospectus at the time of its effectiveness.

        We may sell the securities directly to investors or to or through agents, underwriters or dealers. We, and our agents or underwriters, reserve the right to accept or reject all or part of any proposed purchase of securities. If we offer securities through agents or underwriters, we will include in the applicable prospectus supplement:

•

the names of those agents or underwriters;

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applicable fees, discounts and commissions to be paid to them;



•

details regarding over-allotment options, if any; and



•

the net proceeds to us.

        This prospectus may not be used to consummate a sale of any securities unless it is accompanied by a prospectus supplement.

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RISK FACTORS

        Investing in our securities involves a high degree of risk. The prospectus supplement applicable to each offering of our securities will contain a discussion of the risks applicable to an investment in Epirus. Prior to making a decision about investing in our securities, you should carefully consider the specific factors discussed under the heading "Risk Factors" in the applicable prospectus supplement, together with all of the other information contained or incorporated by reference in the prospectus supplement or appearing or incorporated by reference in this prospectus. You should also consider the risks, uncertainties and assumptions discussed under the heading "Risk Factors" included in our most recent annual report on Form 10-K, as revised or supplemented by our subsequent quarterly reports on Form 10-Q or our current reports on Form 8-K that we have filed with the SEC, all of which are incorporated herein by reference, and which may be amended, supplemented or superseded from time to time by other reports we file with the SEC in the future. The risks and uncertainties we have described are not the only ones facing our company. Additional risks and uncertainties not presently known to us or that we currently deem immaterial may also affect our business operations. The occurrence of any of these risks might cause you to lose all or part of your investment in the offered securities. The discussion of risks includes or refers to forward-looking statements; you should read the explanation of the qualifications and limitations on such forward-looking statements discussed elsewhere in this prospectus.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

        Various statements throughout this prospectus and the documents incorporated by reference herein are "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Forward-looking statements may appear throughout this prospectus and the documents incorporated by reference herein. Words such as "believe," "anticipate," "expect," "estimate," "intend," "plan," "project," "will be," "will continue," "will result," "seek," "could," "may," "might," or the negative of these terms and similar expressions or words, identify forward-looking statements. Forward-looking statements are based upon current expectations that involve risks, changes in circumstances, assumptions and uncertainties. Important factors that could cause actual results to differ materially from those reflected in our forward-looking statements include, among others:

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our inability to obtain regulatory approval for, or successfully commercialize, our leading product candidate, BOW015 or our other product candidates, BOW050 and BOW070;



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our inability to secure and maintain relationships with collaborators and single-source contract manufacturers;



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our history of operating losses and inability to ever become profitable;



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our limited history of complying with public company reporting requirements;



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our limited sales and marketing infrastructure;



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uncertainty and volatility in the price of our common stock;



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our inability to meet the continued listing requirements of the NASDAQ Capital Market;



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our inability to develop, implement and maintain appropriate internal controls in the future;



•

uncertainty as to our employees', independent contractors' and other collaborators' compliance with regulatory standards and requirements and insider trading rules;



•

uncertainty as to the relationship between the benefits of our product candidates and the risks of their side-effect profiles;

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our inability to effectively compete with the reference biologic products for our biosimilar product candidates and from other pharmaceuticals approved for the same indication as the reference biologic products;



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dependence on the efforts of third-parties to conduct and oversee our clinical trials for our product candidates, to manufacture nonclinical and clinical supplies of our product candidates, to store critical components of our product candidates, and to commercialize our product candidates;



•

the extent of government regulations;



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uncertainty of clinical trial results;



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a loss of any of our key management personnel;



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our inability to develop or commercialize our product candidates due to intellectual property rights held by third parties and our inability to protect the confidentiality of our trade secrets;



•

the cost and effects of potential litigation; and



•

our limited financial resources and inability to access capital to fund proposed operations.

        All written and verbal forward-looking statements attributable to us or any person acting on our behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. We caution investors not to rely too heavily on the forward-looking statements we make or that are made on our behalf. We undertake no obligation, and specifically decline any obligation, to update or revise publicly any forward-looking statements, whether as a result of new information, future events or otherwise. You are advised, however, to consult any further disclosures we make on related subjects in any annual, quarterly or current reports that we may file with the SEC.

        In addition, you should refer to the section of this prospectus entitled "Risk Factors" as well as the documents we have incorporated by reference for a discussion of other important factors that may cause our actual results to differ materially from those expressed or implied by our forward-looking statements. As a result of these factors, we cannot assure you that the forward-looking statements in this prospectus will prove to be accurate. Furthermore, if our forward-looking statements prove to be inaccurate, the inaccuracy may be material. In light of the significant uncertainties in these forward-looking statements, you should not regard these statements as a representation or warranty by us or any other person that we will achieve our objectives and plans in any specified time frame, or at all.

RATIOS OF EARNINGS TO FIXED CHARGES

        Any time debt securities are offered pursuant to this prospectus, we will provide a table setting forth our ratio of earnings to fixed charges on a historical basis in the applicable prospectus supplement, if required.

USE OF PROCEEDS

        We cannot assure you that we will receive any proceeds in connection with securities which may be offered pursuant to this prospectus. Unless otherwise provided in the applicable prospectus supplement, we intend to use the net proceeds from the sale of the securities under this prospectus for general corporate purposes, which may include commercial launch activities, sales and marketing expenditures, funding of clinical trials, research and development, regulatory activities, acquisitions of companies, products, intellectual property or other technology, investments, capital expenditures, and for any other purposes that we may specify in any prospectus supplement. We will set forth in the prospectus supplement our intended use for the net proceeds received from the sale of any securities.

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DESCRIPTION OF THE SECURITIES

        We may offer, from time to time, in one or more offerings, up to $125,000,000 of the following securities:

•

senior debt securities;



•

subordinated debt securities;



•

preferred stock;



•

common stock;



•

warrants;



•

units; or



•

any combination of the foregoing securities.

        The aggregate initial offering price of the offered securities that we may issue will not exceed $125,000,000. If we issue debt securities at a discount from their principal amount, then, for purposes of calculating the aggregate initial offering price of the offered securities issued under this prospectus, we will include only the initial offering price of the debt securities and not the principal amount of the debt securities.

        This prospectus contains a summary of the general terms of the various securities that we may offer. The prospectus supplement relating to any particular securities offered will describe the specific terms of the securities, which may be in addition to or different from the general terms summarized in this prospectus. Because the summary in this prospectus and in any prospectus supplement does not contain all of the information that you may find useful, you should read the documents relating to the securities that are described in this prospectus or in any applicable prospectus supplement. Please read "Where You Can Find More Information" to find out how you can obtain a copy of those documents.

        The applicable prospectus supplement will also contain the terms of a given offering, the initial offering price and our net proceeds. Where applicable, a prospectus supplement will also describe any material United States federal income tax consequences relating to the securities offered and indicate whether the securities offered are or will be quoted or listed on any quotation system or securities exchange.

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DESCRIPTION OF DEBT SECURITIES

        This prospectus describes the general terms and provisions of the debt securities we may issue. When we offer to sell a particular series of debt securities, we will describe the specific terms of the securities in a supplement to this prospectus, including any additional covenants or changes to existing covenants relating to such series. The prospectus supplement also will indicate whether the general terms and provisions described in this prospectus apply to a particular series of debt securities. You should read the actual indenture if you do not fully understand a term or the way we use it in this prospectus.

        We may offer senior or subordinated debt securities. Each series of debt securities may have different terms. The senior debt securities will be issued under one or more senior indentures, dated as of a date prior to such issuance, between us and the trustee identified in the applicable prospectus supplement, as amended or supplemented from time to time. We will refer to any such indenture throughout this prospectus as the "senior indenture." Any subordinated debt securities will be issued under one or more separate indentures, dated as of a date prior to such issuance, between us and the trustee identified in the applicable prospectus supplement, as amended or supplemented from time to time. We will refer to any such indenture throughout this prospectus as the "subordinated indenture" and to the trustee under the senior or subordinated indenture as the "trustee." The senior indenture and the subordinated indenture are sometimes collectively referred to in this prospectus as the "indentures." The indentures will be subject to and governed by the Trust Indenture Act of 1939, as amended. We included copies of the forms of the indentures as exhibits to our registration statement and they are incorporated into this prospectus by reference.

        If we issue debt securities at a discount from their principal amount, then, for purposes of calculating the aggregate initial offering price of the offered securities issued under this prospectus, we will include only the initial offering price of the debt securities and not the principal amount of the debt securities.

        We have summarized below the material provisions of the indentures and the debt securities, or indicated which material provisions will be described in the related prospectus supplement. The prospectus supplement relating to any particular securities offered will describe the specific terms of the securities, which may be in addition to or different from the general terms summarized in this prospectus. Because the summary in this prospectus and in any prospectus supplement does not contain all of the information that you may find useful, you should read the documents relating to the securities that are described in this prospectus or in any applicable prospectus supplement. Please read "Where You Can Find More Information" to find out how you can obtain a copy of those documents. Except as otherwise indicated, the terms of the indentures are identical. As used under this caption, the term "debt securities" includes the debt securities being offered by this prospectus and all other debt securities issued by us under the indentures.

General

        The indentures:

•

do not limit the amount of debt securities that we may issue;



•

allow us to issue debt securities in one or more series;



•

do not require us to issue all of the debt securities of a series at the same time;



•

allow us to reopen a series to issue additional debt securities without the consent of the holders of the debt securities of such series; and



•

provide that the debt securities may be secured or unsecured.

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        Unless we give you different information in the applicable prospectus supplement, the senior debt securities will be unsubordinated obligations and will rank equally with all of our other unsecured and unsubordinated indebtedness. Payments on the subordinated debt securities will be subordinated to the prior payment in full of all of our senior indebtedness, as described under "Description of the Debt Securities—Subordination" and in the applicable prospectus supplement.

        Each indenture provides that we may, but need not, designate more than one trustee under an indenture. Any trustee under an indenture may resign or be removed and a successor trustee may be appointed to act with respect to the series of debt securities administered by the resigning or removed trustee. If two or more persons are acting as trustee with respect to different series of debt securities, each trustee shall be a trustee of a trust under the applicable indenture separate and apart from the trust administered by any other trustee. Except as otherwise indicated in this prospectus, any action described in this prospectus to be taken by each trustee may be taken by each trustee with respect to, and only with respect to, the one or more series of debt securities for which it is trustee under the applicable indenture.

        The prospectus supplement for each offering will provide the following terms, where applicable:

•

the title of the debt securities and whether they are senior or subordinated;



•

the aggregate principal amount of the debt securities being offered, the aggregate principal amount of the debt securities outstanding as of the most recent practicable date and any limit on their aggregate principal amount, including the aggregate principal amount of debt securities authorized;



•

the price at which the debt securities will be issued, expressed as a percentage of the principal and, if other than the principal amount thereof, the portion of the principal amount thereof payable upon declaration of acceleration of the maturity thereof or, if applicable, the portion of the principal amount of such debt securities that is convertible into common stock or preferred stock or the method by which any such portion shall be determined;



•

if convertible, the terms on which such debt securities are convertible, including the initial conversion price or rate and the conversion period and any applicable limitations on the ownership or transferability of common stock or preferred stock received on conversion;



•

whether such debt securities are secured or unsecured;



•

the maturity date and the date or dates, or the method for determining the date or dates, on which the principal of the debt securities will be payable;



•

the fixed or variable interest rate or rates of the debt securities, or the method by which the interest rate or rates is determined;



•

the date or dates, or the method for determining the date or dates, from which interest will accrue;



•

the dates on which interest will be payable;



•

the record dates for interest payment dates, or the method by which we will determine those dates;



•

the persons to whom interest will be payable;



•

the basis upon which interest will be calculated if other than that of a 360-day year of twelve 30-day months;



•

any make-whole amount, which is the amount in addition to principal and interest that is required to be paid to the holder of a debt security as a result of any optional redemption or

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accelerated payment of such debt security, or the method for determining the make-whole amount;

•

the place or places where the principal of, and any premium, or make-whole amount, and interest on, the debt securities will be payable;



•

where the debt securities may be surrendered for registration of transfer or conversion or exchange;



•

where notices or demands to or upon us in respect of the debt securities and the applicable indenture may be served;



•

the times, prices and other terms and conditions upon which we may redeem the debt securities;



•

any obligation we have to redeem, repay or purchase the debt securities pursuant to any sinking fund, amortization or analogous provision or at the option of holders of the debt securities, and the times and prices at which we must redeem, repay or purchase the debt securities as a result of such an obligation;



•

the currency or currencies in which the debt securities are denominated and payable if other than United States dollars, which may be a foreign currency or units of two or more foreign currencies or a composite currency or currencies and the terms and conditions relating thereto, and the manner of determining the equivalent of such foreign currency in United States dollars;



•

whether the principal of, and any premium, or make-whole amount, or interest on, the debt securities of the series are to be payable, at our election or at the election of a holder, in a currency or currencies other than that in which the debt securities are denominated or stated to be payable, and other related terms and conditions;



•

whether the amount of payments of principal of, and any premium, or make-whole amount, or interest on, the debt securities may be determined according to an index, formula or other method and how such amounts will be determined;



•

whether the debt securities will be in registered form, bearer form or both and (1) if in registered form, the person to whom any interest shall be payable, if other than the person in whose name the security is registered at the close of business on the regular record date for such interest, or (2) if in bearer form, the manner in which, or the person to whom, any interest on the security shall be payable if otherwise than upon presentation and surrender upon maturity;



•

any restrictions applicable to the offer, sale or delivery of securities in bearer form and the terms upon which securities in bearer form of the series may be exchanged for securities in registered form of the series and vice versa if permitted by applicable laws and regulations;



•

whether any debt securities of the series are to be issuable initially in temporary global form and whether any debt securities of the series are to be issuable in permanent global form with or without coupons and, if so, whether beneficial owners of interests in any such permanent global security may or shall be required to exchange their interests for other debt securities of the series, and the manner in which interest shall be paid;



•

the identity of the depositary for securities in registered form, if such series are to be issuable as a global security;



•

the date as of which any debt securities in bearer form or in temporary global form shall be dated if other than the original issuance date of the first security of the series to be issued;



•

the applicability, if any, of the defeasance and covenant defeasance provisions described in this prospectus or in the applicable indenture;

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•

whether and under what circumstances we will pay any additional amounts on the debt securities in respect of any tax, assessment or governmental charge and, if so, whether we will have the option to redeem the debt securities in lieu of making such a payment;



•

whether and under what circumstances the debt securities being offered are convertible into common stock or preferred stock, as the case may be, including the conversion price or rate or manner or calculation thereof;



•

the circumstances, if any, specified in the applicable prospectus supplement, under which beneficial owners of interests in the global security may obtain definitive debt securities and the manner in which payments on a permanent global debt security will be made if any debt securities are issuable in temporary or permanent global form;



•

any provisions granting special rights to holders of securities upon the occurrence of such events as specified in the applicable prospectus supplement;



•

if the debt securities of such series are to be issuable in definitive form only upon receipt of certain certificates or other documents or satisfaction of other conditions, then the form and/or terms of such certificates, documents or conditions;



•

the name of the applicable trustee and the nature of any material relationship with us or any of our affiliates, and the percentage of debt securities of the class necessary to require the trustee to take action;



•

any deletions from, modifications of, or additions to our events of default or covenants and any change in the right of any trustee or any of the holders to declare the principal amount of any of such debt securities due and payable;



•

whether the debt securities will restrict our ability to pay dividends, or will require us to maintain any asset ratios or reserves;



•

whether we will be restricted from incurring any additional indebtedness;



•

any addition to or change in the events of default described in this prospectus or in the indenture and any change in the acceleration provisions so described;



•

applicable CUSIP numbers; and



•

any other terms of such debt securities not inconsistent with the provisions of the applicable indenture.

        We may issue debt securities at a discount below their principal amount and provide for less than the entire principal amount thereof to be payable upon declaration of acceleration of the maturity of the debt securities. We refer to any such debt securities throughout this prospectus as "original issue discount securities." The applicable prospectus supplement will describe the United States federal income tax consequences and other relevant considerations applicable to original issue discount securities.

        We also may issue indexed debt securities. Payments of principal of and premium and interest on, indexed debt securities are determined with reference to the rate of exchange between the currency or currency unit in which the debt security is denominated and any other currency or currency unit specified by us, to the relationship between two or more currencies or currency units or by other similar methods or formulas specified in the prospectus supplement.

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        Except as described under "—Merger, Consolidation or Sale of Assets" or as may be set forth in any prospectus supplement, the debt securities will not contain any provisions that (1) would limit our ability to incur indebtedness or (2) would afford holders of debt securities protection in the event of (a) a highly leveraged or similar transaction involving us, or (b) a change of control or reorganization, restructuring, merger or similar transaction involving us that may adversely affect the holders of the debt securities. In the future, we may enter into transactions, such as the sale of all or substantially all of our assets or a merger or consolidation, that may have an adverse effect on our ability to service our indebtedness, including the debt securities, by, among other things, substantially reducing or eliminating our assets.

        Neither the Delaware General Corporation Law nor our governing instruments define the term "substantially all" as it relates to the sale of assets. Additionally, Delaware cases interpreting the term "substantially all" rely upon the facts and circumstances of each particular case. Consequently, to determine whether a sale of "substantially all" of our assets has occurred, a holder of debt securities must review the financial and other information that we have disclosed to the public.

        We will provide you with more information in the applicable prospectus supplement regarding any deletions, modifications, or additions to the events of default or covenants that are described below, including any addition of a covenant or other provision providing event risk or similar protection.

Payment

        Unless we give you different information in the applicable prospectus supplement, the principal of, and any premium, or make-whole amount, and interest on, any series of the debt securities will be payable at the corporate trust office of the trustee. We will provide you with the address of the trustee in the applicable prospectus supplement. We may also pay interest by mailing a check to the address of the person entitled to it as it appears in the applicable register for the debt securities or by wire transfer of funds to that person at an account maintained within the United States.

        All monies that we pay to a paying agent or a trustee for the payment of the principal of, and any premium, or make-whole amount, or interest on, any debt security will be repaid to us if unclaimed at the end of two years after the obligation underlying payment becomes due and payable. After funds have been returned to us, the holder of the debt security may look only to us for payment, without payment of interest for the period which we hold the funds.

Denomination, Interest, Registration and Transfer

        Unless otherwise described in the applicable prospectus supplement, the debt securities of any series will be issuable in denominations of $1,000 and integral multiples of $1,000.

        Subject to the limitations imposed upon debt securities that are evidenced by a computerized entry in the records of a depository company rather than by physical delivery of a note, a holder of debt securities of any series may:

•

exchange them for any authorized denomination of other debt securities of the same series and of a like aggregate principal amount and kind upon surrender of such debt securities at the corporate trust office of the applicable trustee or at the office of any transfer agent that we designate for such purpose; and



•

surrender them for registration of transfer or exchange at the corporate trust office of the applicable trustee or at the office of any transfer agent that we designate for such purpose.

        Every debt security surrendered for registration of transfer or exchange must be duly endorsed or accompanied by a written instrument of transfer satisfactory to the applicable trustee or transfer agent. Payment of a service charge will not be required for any registration of transfer or exchange of any

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debt securities, but we or the trustee may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection therewith. If in addition to the applicable trustee, the applicable prospectus supplement refers to any transfer agent initially designated by us for any series of debt securities, we may at any time rescind the designation of any such transfer agent or approve a change in the location through which any such transfer agent acts, except that we will be required to maintain a transfer agent in each place of payment for such series. We may at any time designate additional transfer agents for any series of debt securities.

        Neither we, nor any trustee, will be required to:

•

issue, register the transfer of or exchange debt securities of any series during a period beginning at the opening of business 15 days before the day that the notice of redemption of any debt securities selected for redemption is mailed and ending at the close of business on the day of such mailing;



•

register the transfer of or exchange any debt security, or portion thereof, so selected for redemption, in whole or in part, except the unredeemed portion of any debt security being redeemed in part; and



•

issue, register the transfer of or exchange any debt security that has been surrendered for repayment at the option of the holder, except the portion, if any, of such debt security not to be so repaid.

Merger, Consolidation or Sale of Assets

        The indentures provide that we may, without the consent of the holders of any outstanding debt securities, (1) consolidate with, (2) sell, lease or convey all or substantially all of our assets to, or (3) merge with or into, any other entity provided that:

•

either we are the continuing entity, or the successor entity, if other than us, assumes the obligations (A) to pay the principal of, and any premium (or make-whole amount) and interest on, all of the debt securities and (B) to duly perform and observe all of the covenants and conditions contained in each indenture;



•

after giving effect to the transaction, there is no event of default under the indentures and no event which, after notice or the lapse of time, or both, would become such an event of default, occurs and continues; and



•

an officers' certificate and legal opinion covering such conditions are delivered to each applicable trustee.

Covenants

        Existence.    Except as permitted under "—Merger, Consolidation or Sale of Assets," the indentures require us to do or cause to be done all things necessary to preserve and keep in full force and effect our existence, rights and franchises. However, the indentures do not require us to preserve any right or franchise if we determine that any right or franchise is no longer desirable in the conduct of our business.

        Payment of taxes and other claims.    The indentures require us to pay, discharge or cause to be paid or discharged, before they become delinquent (1) all taxes, assessments and governmental charges levied or imposed on us, our subsidiaries or our subsidiaries' income, profits or property, and (2) all lawful claims for labor, materials and supplies which, if unpaid, might by law become a lien upon our property or the property of our subsidiaries. However, we will not be required to pay, discharge or cause to be paid or discharged any such tax, assessment, charge or claim whose amount, applicability or validity is being contested in good faith by appropriate proceedings.

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        Provision of financial information.    The indentures require us to (1) within 15 days of each of the respective dates by which we are required to file our annual reports, quarterly reports and other documents with the SEC, file with the trustee copies of the annual report, quarterly report and other documents that we file with the SEC under Section 13 or 15(d) of the Exchange Act, (2) file with the trustee and the SEC any additional information, documents and reports regarding compliance by us with the conditions and covenants of the indentures, as required, (3) within 30 days after the filing with the trustee, mail to all holders of debt securities, as their names and addresses appear in the applicable register for such debt securities, without cost to such holders, summaries of any documents and reports required to be filed by us pursuant to (1) and (2) above, and (4) supply, promptly upon written request and payment of the reasonable cost of duplication and delivery, copies of such documents to any prospective holder.

        Additional covenants.    The applicable prospectus supplement will set forth any additional covenants of Epirus relating to any series of debt securities.

Events of Default, Notice and Waiver

        Unless the applicable prospectus supplement states otherwise, when we refer to "events of default" as defined in the indentures with respect to any series of debt securities, we mean:

•

default in the payment of any installment of interest on any debt security of such series continuing for 30 days;



•

default in the payment of principal of, or any premium, or make-whole amount, on any debt security of such series for five business days at its stated maturity;



•

default in making any sinking fund payment as required for any debt security of such series for five business days;



•

default in the performance or breach of any covenant or warranty in the debt securities or in the indenture by Epirus continuing for 60 days after written notice as provided in the applicable indenture, but not of a covenant added to the indenture solely for the benefit of a series of debt securities issued thereunder other than such series;



•

a default under any bond, debenture, note, mortgage, indenture or instrument:



(1)

having an aggregate principal amount of at least $30,000,000; or



(2)

under which there may be issued, secured or evidenced any existing or later created indebtedness for money borrowed by us or our subsidiaries, if we are directly responsible or liable as obligor or guarantor,

if the default results in the indebtedness becoming or being declared due and payable prior to the date it otherwise would have, without such indebtedness having been discharged, or such acceleration having been rescinded or annulled, within 30 days after notice to the issuing company specifying such default. Such notice shall be given to us by the trustee, or to us and the trustee by the holders of at least 10% in principal amount of the outstanding debt securities of that series. The written notice specifying such default and requiring us to cause such indebtedness to be discharged or cause such acceleration to be rescinded or annulled and shall state that such notice is a "Notice of Default" under such indenture;

•

bankruptcy, insolvency or reorganization, or court appointment of a receiver, liquidator or trustee of Epirus or any significant subsidiary of Epirus; and



•

any other event of default provided with respect to a particular series of debt securities.

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        When we use the term "significant subsidiary," we refer to the meaning ascribed to such term in Rule 1-02 of Regulation S-X promulgated under the Securities Act of 1933, as amended, or Securities Act.

        If an event of default occurs and is continuing with respect to debt securities of any series outstanding, then the applicable trustee or the holders of 25% or more in principal amount of the debt securities of that series will have the right to declare the principal amount of all the debt securities of that series to be due and payable. If the debt securities of that series are original issue discount securities or indexed securities, then the applicable trustee or the holders of 25% or more in principal amount of the debt securities of that series will have the right to declare the portion of the principal amount as may be specified in the terms thereof to be due and payable. However, at any time after such a declaration of acceleration has been made, but before a judgment or decree for payment of the money due has been obtained by the applicable trustee, the holders of at least a majority in principal amount of outstanding debt securities of such series or of all debt securities then outstanding under the applicable indenture may rescind and annul such declaration and its consequences if:

•

we have deposited with the applicable trustee all required payments of the principal, any premium, or make-whole amount, interest and, to the extent permitted by law, interest on overdue installment of interest, plus applicable fees, expenses, disbursements and advances of the applicable trustee; and



•

all events of default, other than the non-payment of accelerated principal, or a specified portion thereof, and any premium, or make-whole amount, have been cured or waived.

        The indentures also provide that the holders of at least a majority in principal amount of the outstanding debt securities of any series or of all debt securities then outstanding under the applicable indenture may, on behalf of all holders, waive any past default with respect to such series and its consequences, except a default:

•

in the payment of the principal, any premium, or make-whole amount, or interest;



•

in respect of a covenant or provision contained in the applicable indenture that cannot be modified or amended without the consent of the holders of the outstanding debt security that is affected by the default; or



•

in respect of a covenant or provision for the benefit or protection of the trustee, without its express written consent.

        The indentures require each trustee to give notice to the holders of debt securities within 90 days of a default unless such default has been cured or waived. However, the trustee may withhold notice if specified persons of such trustee consider such withholding to be in the interest of the holders of debt securities. The trustee may not withhold notice of a default in the payment of principal, any premium or interest on any debt security of such series or in the payment of any sinking fund installment in respect of any debt security of such series.

        The indentures provide that holders of debt securities of any series may not institute any proceedings, judicial or otherwise, with respect to such indenture or for any remedy under the indenture, unless the trustee fails to act for a period of 60 days after the trustee has received a written request to institute proceedings in respect of an event of default from the holders of 25% or more in principal amount of the outstanding debt securities of such series, as well as an offer of indemnity reasonably satisfactory to the trustee. However, this provision will not prevent any holder of debt securities from instituting suit for the enforcement of payment of the principal of, and any premium, or make-whole amount, and interest on, such debt securities at the respective due dates thereof.

        The indentures provide that, subject to provisions in each indenture relating to its duties in the case of a default, a trustee has no obligation to exercise any of its rights or powers at the request or

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direction of any holders of any series of debt securities then outstanding under the indenture, unless the holders have offered to the trustee reasonable security or indemnity. The holders of at least a majority in principal amount of the outstanding debt securities of any series or of all debt securities then outstanding under an indenture shall have the right to direct the time, method and place of conducting any proceeding for any remedy available to the applicable trustee, or of exercising any trust or power conferred upon such trustee. However, a trustee may refuse to follow any direction which:

•

is in conflict with any law or the applicable indenture;



•

may involve the trustee in personal liability; or



•

may be unduly prejudicial to the holders of debt securities of the series not joining the proceeding.

        Within 120 days after the close of each fiscal year, we will be required to deliver to each trustee a certificate, signed by one of our several specified officers, stating whether or not that officer has knowledge of any default under the applicable indenture. If the officer has knowledge of any default, the notice must specify the nature and status of the default.

Modification of the Indentures

        The indentures provide that modifications and amendments may be made only with the consent of the affected holders of at least a majority in principal amount of all outstanding debt securities issued under that indenture. However, no such modification or amendment may, without the consent of the holders of the debt securities affected by the modification or amendment:

•

change the stated maturity of the principal of, or any premium, or make-whole amount, on, or any installment of principal of or interest on, any such debt security;



•

reduce the principal amount of, the rate or amount of interest on or any premium, or make-whole amount, payable on redemption of any such debt security;



•

reduce the amount of principal of an original issue discount security that would be due and payable upon declaration of acceleration of the maturity thereof or would be provable in bankruptcy, or adversely affect any right of repayment of the holder of any such debt security;



•

change the place of payment or the coin or currency for payment of principal of, or any premium, or make-whole amount, or interest on, any such debt security;



•

impair the right to institute suit for the enforcement of any payment on or with respect to any such debt security;



•

reduce the percentage in principal amount of any outstanding debt securities necessary to modify or amend the applicable indenture with respect to such debt securities, to waive compliance with particular provisions thereof or defaults and consequences thereunder or to reduce the quorum or voting requirements set forth in the applicable indenture; and



•

modify any of the foregoing provisions or any of the provisions relating to the waiver of particular past defaults or covenants, except to increase the required percentage to effect such action or to provide that some of the other provisions may not be modified or waived without the consent of the holder of such debt security.

        The holders of a majority in aggregate principal amount of the outstanding debt securities of each series may, on behalf of all holders of debt securities of that series, waive, insofar as that series is concerned, our compliance with material restrictive covenants of the applicable indenture.

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        We and our respective trustee may make modifications and amendments of an indenture without the consent of any holder of debt securities for any of the following purposes:

•

to evidence the succession of another person to us as obligor under such indenture;



•

to add to our covenants for the benefit of the holders of all or any series of debt securities or to surrender any right or power conferred upon us in such indenture;



•

to add events of default for the benefit of the holders of all or any series of debt securities;



•

to add or change any provisions of an indenture (1) to change or eliminate restrictions on the payment of principal of, or premium, or make-whole amount, or interest on, debt securities in bearer form, or (2) to permit or facilitate the issuance of debt securities in uncertificated form, provided that such action shall not adversely affect the interests of the holders of the debt securities of any series in any material respect;



•

to change or eliminate any provisions of an indenture, provided that any such change or elimination shall become effective only when there are no debt securities outstanding of any series created prior thereto which are entitled to the benefit of such provision;



•

to secure the debt securities;



•

to establish the form or terms of debt securities of any series;



•

to provide for the acceptance of appointment by a successor trustee or facilitate the administration of the trusts under an indenture by more than one trustee;



•

to cure any ambiguity, defect or inconsistency in an indenture, provided that such action shall not adversely affect the interests of holders of debt securities of any series issued under such indenture; and



•

to supplement any of the provisions of an indenture to the extent necessary to permit or facilitate defeasance and discharge of any series of such debt securities, provided that such action shall not adversely affect the interests of the holders of the outstanding debt securities of any series.

Voting

        The indentures provide that in determining whether the holders of the requisite principal amount of outstanding debt securities of a series have given any request, demand, authorization, direction, notice, consent or waiver under the indentures or whether a quorum is present at a meeting of holders of debt securities:

•

the principal amount of an original issue discount security that shall be deemed to be outstanding shall be the amount of the principal thereof that would be due and payable as of the date of such determination upon declaration of acceleration of the maturity thereof;



•

the principal amount of any debt security denominated in a foreign currency that shall be deemed outstanding shall be the United States dollar equivalent, determined on the issue date for such debt security, of the principal amount or, in the case of an original issue discount security, the United States dollar equivalent on the issue date of such debt security of the amount determined as provided in the preceding bullet point;



•

the principal amount of an indexed security that shall be deemed outstanding shall be the principal face amount of such indexed security at original issuance, unless otherwise provided for such indexed security under such indenture; and



•

debt securities owned by us or any other obligor upon the debt securities or by any affiliate of ours or of such other obligor shall be disregarded.

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        The indentures contain provisions for convening meetings of the holders of debt securities of a series. A meeting will be permitted to be called at any time by the applicable trustee, and also, upon request, by us or the holders of at least 25% in principal amount of the outstanding debt securities of such series, in any such case upon notice given as provided in such indenture. Except for any consent that must be given by the holder of each debt security affected by the modifications and amendments of an indenture described above, any resolution presented at a meeting or adjourned meeting duly reconvened at which a quorum is present may be adopted by the affirmative vote of the holders of a majority of the aggregate principal amount of the outstanding debt securities of that series represented at such meeting.

        Notwithstanding the preceding paragraph, except as referred to above, any resolution relating to a request, demand, authorization, direction, notice, consent, waiver or other action that may be made, given or taken by the holders of a specified percentage, which is less than a majority of the aggregate principal amount of the outstanding debt securities of a series, may be adopted at a meeting or adjourned meeting duly reconvened at which a quorum is present by the affirmative vote of such specified percentage.

        Any resolution passed or decision taken at any properly held meeting of holders of debt securities of any series will be binding on all holders of such series. The quorum at any meeting called to adopt a resolution, and at any reconvened meeting, will be persons holding or representing a majority in principal amount of the outstanding debt securities of a series. However, if any action is to be taken relating to a consent or waiver which may be given by the holders of at least a specified percentage in principal amount of the outstanding debt securities of a series, the persons holding such percentage will constitute a quorum.

        Notwithstanding the foregoing provisions, the indentures provide that if any action is to be taken at a meeting with respect to any request, demand, authorization, direction, notice, consent, waiver or other action that such indenture expressly provides may be made, given or taken by the holders of a specified percentage in principal amount of all outstanding debt securities affected by such action, or of the holders of such series and one or more additional series:

•

there shall be no minimum quorum requirement for such meeting; and



•

the principal amount of the outstanding debt securities of such series that vote in favor of such request, demand, authorization, direction, notice, consent, waiver or other action shall be taken account in determining whether such request, demand, authorization, direction, notice, consent, waiver or other action has been made, given or taken under such indenture.

Subordination

        Unless otherwise provided in the applicable prospectus supplement, subordinated securities will be subject to the following subordination provisions.

        Upon any distribution to our creditors in a liquidation, dissolution or reorganization, the payment of the principal of and interest on any subordinated securities will be subordinated to the extent provided in the applicable indenture in right of payment to the prior payment in full of all senior debt. However, our obligation to make payments of the principal of and interest on such subordinated securities otherwise will not be affected. No payment of principal or interest will be permitted to be made on subordinated securities at any time if a default on senior debt exists that permits the holders of such senior debt to accelerate its maturity and the default is the subject of judicial proceedings or we receive notice of the default. After all senior debt is paid in full and until the subordinated securities are paid in full, holders of subordinated securities will be subrogated to the rights of holders of senior debt to the extent that distributions otherwise payable to holders of subordinated securities have been applied to the payment of senior debt. The subordinated indenture will not restrict the

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amount of senior debt or other indebtedness of Epirus and its subsidiaries. As a result of these subordination provisions, in the event of a distribution of assets upon insolvency, holders of subordinated securities may recover less, ratably, than our general creditors.

        The term "senior debt" will be defined in the applicable indenture as the principal of and interest on, or substantially similar payments to be made by us in respect of, other outstanding indebtedness, whether outstanding at the date of execution of the applicable indenture or subsequently incurred, created or assumed. The prospectus supplement may include a description of additional terms implementing the subordination feature.

        No restrictions will be included in any indenture relating to subordinated securities upon the creation of additional senior debt.

        If this prospectus is being delivered in connection with the offering of a series of subordinated securities, the accompanying prospectus supplement or the information incorporated in this prospectus by reference will set forth the approximate amount of senior debt outstanding as of the end of our most recent fiscal quarter.

Discharge, Defeasance and Covenant Defeasance

        Unless otherwise indicated in the applicable prospectus supplement, the indentures allow us to discharge our obligations to holders of any series of debt securities issued under any indenture when:

•

either (1) all securities of such series have already been delivered to the applicable trustee for cancellation; or (2) all securities of such series have not already been delivered to the applicable trustee for cancellation but (A) have become due and payable, (B) will become due and payable within one year, or (C) if redeemable at our option, are to be redeemed within one year, and we have irrevocably deposited with the applicable trustee, in trust, funds in such currency or currencies, currency unit or units or composite currency or currencies in which such debt securities are payable, an amount sufficient to pay the entire indebtedness on such debt securities in respect of principal and any premium, or make-whole amount, and interest to the date of such deposit if such debt securities have become due and payable or, if they have not, to the stated maturity or redemption date;



•

we have paid or caused to be paid all other sums payable; and



•

an officers' certificate and an opinion of counsel stating the conditions to discharging the debt securities have been satisfied has been delivered to the trustee.

        Unless otherwise indicated in the applicable prospectus supplement, the indentures provide that, upon our irrevocable deposit with the applicable trustee, in trust, of an amount, in such currency or currencies, currency unit or units or composite currency or currencies in which such debt securities are payable at stated maturity, or government obligations, or both, applicable to such debt securities, which through the scheduled payment of principal and interest in accordance with their terms will provide money in an amount sufficient to pay the principal of, and any premium, or make-whole amount, and interest on, such debt securities, and any mandatory sinking fund or analogous payments thereon, on the scheduled due dates therefor, the issuing company may elect either:

•

to defease and be discharged from any and all obligations with respect to such debt securities; or



•

to be released from its obligations with respect to such debt securities under the applicable indenture or, if provided in the applicable prospectus supplement, its obligations with respect to any other covenant, and any omission to comply with such obligations shall not constitute an event of default with respect to such debt securities.

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        Notwithstanding the above, we may not elect to defease and be discharged from the obligation to pay any additional amounts upon the occurrence of particular events of tax, assessment or governmental charge with respect to payments on such debt securities and the obligations to register the transfer or exchange of such debt securities, to replace temporary or mutilated, destroyed, lost or stolen debt securities, to maintain an office or agency in respect of such debt securities, or to hold monies for payment in trust.

        The indentures only permit us to establish the trust described in the paragraph above if, among other things, it has delivered to the applicable trustee an opinion of counsel to the effect that the holders of such debt securities will not recognize income, gain or loss for United States federal income tax purposes as a result of such defeasance or covenant defeasance and will be subject to United States federal income tax on the same amounts, in the same manner and at the same times as would have been the case if such defeasance or covenant defeasance had not occurred. Such opinion of counsel, in the case of defeasance, will be required to refer to and be based upon a ruling received from or published by the Internal Revenue Service or a change in applicable United States federal income tax law occurring after the date of the indenture. In the event of such defeasance, the holders of such debt securities would be able to look only to such trust fund for payment of principal, any premium, or make-whole amount, and interest.

        When we use the term "government obligations," we mean securities that are:

•

direct obligations of the United States or the government that issued the foreign currency in which the debt securities of a particular series are payable, for the payment of which its full faith and credit is pledged; or



•

obligations of a person controlled or supervised by and acting as an agency or instrumentality of the United States or other government that issued the foreign currency in which the debt securities of such series are payable, the payment of which is unconditionally guaranteed as a full faith and credit obligation by the United States or such other government, which are not callable or redeemable at the option of the issuer thereof and shall also include a depository receipt issued by a bank or trust company as custodian with respect to any such government obligation or a specific payment of interest on or principal of any such government obligation held by such custodian for the account of the holder of a depository receipt. However, except as required by law, such custodian is not authorized to make any deduction from the amount payable to the holder of such depository receipt from any amount received by the custodian in respect of the government obligation or the specific payment of interest on or principal of the government obligation evidenced by such depository receipt.

        Unless otherwise provided in the applicable prospectus supplement, if after we have deposited funds and/or government obligations to effect defeasance or covenant defeasance with respect to debt securities of any series, (1) the holder of a debt security of such series is entitled to, and does, elect under the terms of the applicable indenture or the terms of such debt security to receive payment in a currency, currency unit or composite currency other than that in which such deposit has been made in respect of such debt security, or (2) a conversion event occurs in respect of the currency, currency unit or composite currency in which such deposit has been made, the indebtedness represented by such debt security will be deemed to have been, and will be, fully discharged and satisfied through the payment of the principal of, and premium, or make-whole amount, and interest on, such debt security as they become due out of the proceeds yielded by converting the amount so deposited in respect of such debt security into the currency, currency unit or composite currency in which such debt security becomes payable as a result of such election or such cessation of usage based on the applicable market exchange rate.

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        When we use the term "conversion event," we mean the cessation of use of:

•

a currency, currency unit or composite currency both by the government of the country that issued such currency and for the settlement of transactions by a central bank or other public institutions of or within the international banking community;



•

the European Currency Unit both within the European Monetary System and for the settlement of transactions by public institutions of or within the European Communities; or



•

any currency unit or composite currency other than the European Currency Unit for the purposes for which it was established.

        Unless otherwise provided in the applicable prospectus supplement, all payments of principal of, and any premium, or make-whole amount, and interest on, any debt security that is payable in a foreign currency that ceases to be used by its government of issuance shall be made in United States dollars.

        In the event that (1) we effect covenant defeasance with respect to any debt securities and (2) those debt securities are declared due and payable because of the occurrence of any event of default, the amount in the currency, currency unit or composite currency in which such debt securities are payable, and government obligations on deposit with the applicable trustee, will be sufficient to pay amounts due on such debt securities at the time of their stated maturity but may not be sufficient to pay amounts due on such debt securities at the time of the acceleration resulting from such event of default. However, the issuing company would remain liable to make payments of any amounts due at the time of acceleration.

        The applicable prospectus supplement may further describe the provisions, if any, permitting such defeasance or covenant defeasance, including any modifications to the provisions described above, with respect to the debt securities of or within a particular series.

Conversion Rights

        The terms and conditions, if any, upon which the debt securities are convertible into common stock or preferred stock will be set forth in the applicable prospectus supplement. The terms will include whether the debt securities are convertible into shares of common stock or preferred stock, the conversion price, or manner of calculation thereof, the conversion period, provisions as to whether conversion will be at the issuing company's option or the option of the holders, the events requiring an adjustment of the conversion price and provisions affecting conversion in the event of the redemption of the debt securities and any restrictions on conversion.

Global Securities

        The debt securities of a series may be issued in whole or in part in the form of one or more global securities that will be deposited with, or on behalf of, a depository identified in the applicable prospectus supplement relating to such series. Global securities, if any, issued in the United States are expected to be deposited with The Depository Trust Company, or DTC, as depository. We may issue global securities in either registered or bearer form and in either temporary or permanent form. We will describe the specific terms of the depository arrangement with respect to a series of debt securities in the applicable prospectus supplement relating to such series. We expect that unless the applicable prospectus supplement provides otherwise, the following provisions will apply to depository arrangements.

        Once a global security is issued, the depository for such global security or its nominee will credit on its book-entry registration and transfer system the respective principal amounts of the individual debt securities represented by such global security to the accounts of participants that have accounts

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with such depository. Such accounts shall be designated by the underwriters, dealers or agents with respect to such debt securities or by us if we offer such debt securities directly. Ownership of beneficial interests in such global security will be limited to participants with the depository or persons that may hold interests through those participants.

        We expect that, under procedures established by DTC, ownership of beneficial interests in any global security for which DTC is the depository will be shown on, and the transfer of that ownership will be effected only through, records maintained by DTC or its nominee, with respect to beneficial interests of participants with the depository, and records of participants, with respect to beneficial interests of persons who hold through participants with the depository. Neither we nor the trustee will have any responsibility or liability for any aspect of the records of DTC or for maintaining, supervising or reviewing any records of DTC or any of its participants relating to beneficial ownership interests in the debt securities. The laws of some states require that certain purchasers of securities take physical delivery of such securities in definitive form. Such limits and laws may impair the ability to own, pledge or transfer beneficial interest in a global security.

        So long as the depository for a global security or its nominee is the registered owner of such global security, such depository or such nominee, as the case may be, will be considered the sole owner or holder of the debt securities represented by the global security for all purposes under the applicable indenture. Except as described below or in the applicable prospectus supplement, owners of beneficial interest in a global security will not be entitled to have any of the individual debt securities represented by such global security registered in their names, will not receive or be entitled to receive physical delivery of any such debt securities in definitive form and will not be considered the owners or holders thereof under the applicable indenture. Beneficial owners of debt securities evidenced by a global security will not be considered the owners or holders thereof under the applicable indenture for any purpose, including with respect to the giving of any direction, instructions or approvals to the trustee under the indenture. Accordingly, each person owning a beneficial interest in a global security with respect to which DTC is the depository must rely on the procedures of DTC and, if such person is not a participant with the depository, on the procedures of the participant through which such person owns its interests, to exercise any rights of a holder under the applicable indenture. We understand that, under existing industry practice, if DTC requests any action of holders or if an owner of a beneficial interest in a global security desires to give or take any action which a holder is entitled to give or take under the applicable indenture, DTC would authorize the participants holding the relevant beneficial interest to give or take such action, and such participants would authorize beneficial owners through such participants to give or take such actions or would otherwise act upon the instructions of beneficial owners holding through them.

        Payments of principal of, and any premium, or make-whole amount, and interest on, individual debt securities represented by a global security registered in the name of a depository or its nominee will be made to or at the direction of the depository or its nominee, as the case may be, as the registered owner of the global security under the applicable indenture. Under the terms of the applicable indenture, we and the trustee may treat the persons in whose name debt securities, including a global security, are registered as the owners thereof for the purpose of receiving such payments. Consequently, neither we nor the trustee have or will have any responsibility or liability for the payment of such amounts to beneficial owners of debt securities including principal, any premium, or make-whole amount, or interest. We believe, however, that it is currently the policy of DTC to immediately credit the accounts of relevant participants with such payments, in amounts proportionate to their respective holdings of beneficial interests in the relevant global security as shown on the records of DTC or its nominee. We also expect that payments by participants to owners of beneficial interests in such global security held through such participants will be governed by standing instructions and customary practices, as is the case with securities held for the account of customers in bearer form or registered in street name, and will be the responsibility of such participants. Redemption notices

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with respect to any debt securities represented by a global security will be sent to the depository or its nominee. If less than all of the debt securities of any series are to be redeemed, we expect the depository to determine the amount of the interest of each participant in such debt securities to be redeemed to be determined by lot. Neither we, the trustee, any paying agent nor the security registrar for such debt securities will have any responsibility or liability for any aspect of the records relating to or payments made on account of beneficial ownership interests in the global security for such debt securities or for maintaining any records with respect thereto.

        Neither we nor the trustee will be liable for any delay by the holders of a global security or the depository in identifying the beneficial owners of debt securities, and we and the trustee may conclusively rely on, and will be protected in relying on, instructions from the holder of a global security or the depository for all purposes. The rules applicable to DTC and its participants are on file with the SEC.

        If a depository for any debt securities is at any time unwilling, unable or ineligible to continue as depository and we do not appoint a successor depository within 90 days, we will issue individual debt securities in exchange for the global security representing such debt securities. In addition, we may at any time and in their sole discretion, subject to any limitations described in the applicable prospectus supplement relating to such debt securities, determine not to have any of such debt securities represented by one or more global securities and in such event will issue individual debt securities in exchange for the global security or securities representing such debt securities. Individual debt securities so issued will be issued in denominations of $1,000 and integral multiples of $1,000.

        The debt securities of a series may also be issued in whole or in part in the form of one or more bearer global securities that will be deposited with a depository, or with a nominee for such depository, identified in the applicable prospectus supplement. Any such bearer global securities may be issued in temporary or permanent form. The specific terms and procedures, including the specific terms of the depositary arrangement, with respect to any portion of a series of debt securities to be represented by one or more bearer global securities will be described in the applicable prospectus supplement.

No Recourse

        There is no recourse under any obligation, covenant or agreement in the applicable indenture or with respect to any security against any of our or our successor's past, present or future stockholders, employees, officers or directors.

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DESCRIPTION OF PREFERRED STOCK

        We are authorized to issue 5,000,000 shares of preferred stock, par value $0.001 per share. As of the date of this prospectus, no shares of our preferred stock were outstanding. The following summary of certain provisions of our preferred stock does not purport to be complete. You should refer to our sixth amended and restated certificate of incorporation, as amended, and our amended and restated by-laws, both of which are included as exhibits to this registration statement. The summary below is also qualified by provisions of applicable law.

General Terms

        Our board of directors may, without further action by our stockholders, from time to time, direct the issuance of shares of preferred stock in series and may, at the time of issuance, determine the rights, preferences and limitations of each series, including voting rights, dividend rights and redemption and liquidation preferences. Satisfaction of any dividend preferences of outstanding shares of preferred stock would reduce the amount of funds available for the payment of dividends on shares of our common stock. Holders of shares of preferred stock may be entitled to receive a preference payment in the event of any liquidation, dissolution or winding-up of our company before any payment is made to the holders of shares of our common stock. In some circumstances, the issuance of shares of preferred stock may render more difficult or tend to discourage a merger, tender offer or proxy contest, the assumption of control by a holder of a large block of our securities or the removal of incumbent management as discussed below. Upon the affirmative vote of our board of directors, without stockholder approval, we may issue shares of preferred stock with voting and conversion rights which could adversely affect the holders of shares of our common stock.

        If we offer a specific series of preferred stock under this prospectus, we will describe the terms of the preferred stock in the prospectus supplement for such offering and will file a copy of the certificate establishing the terms of the preferred stock with the SEC. To the extent required, this description will include:

•

the title and stated value;



•

the number of shares offered, the liquidation preference per share and the purchase price;



•

the dividend rate(s), period(s) and/or payment date(s), or method(s) of calculation for such dividends;



•

whether dividends will be cumulative or non-cumulative and, if cumulative, the date from which dividends will accumulate;



•

the procedures for any auction and remarketing, if any;



•

the provisions for a sinking fund, if any;



•

the provisions for redemption, if applicable;



•

any listing of the preferred stock on any securities exchange or market;



•

whether the preferred stock will be convertible into our common stock, and, if applicable, the conversion price (or how it will be calculated) and conversion period;



•

whether the preferred stock will be exchangeable into debt securities, and, if applicable, the exchange price (or how it will be calculated) and exchange period;



•

voting rights, if any, of the preferred stock;



•

a discussion of any material and/or special United States federal income tax considerations applicable to the preferred stock;

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•

the relative ranking and preferences of the preferred stock as to dividend rights and rights upon liquidation, dissolution or winding up of the affairs of Epirus; and



•

any material limitations on issuance of any class or series of preferred stock ranking senior to or on a parity with the series of preferred stock as to dividend rights and rights upon liquidation, dissolution or winding up of Epirus.

        The preferred stock offered by this prospectus will, when issued not have, or be subject to, any preemptive or similar rights.

Transfer Agent and Registrar

        The transfer agent and registrar for our preferred stock is Computershare Trust Company, N.A.

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DESCRIPTION OF COMMON STOCK

        The following summary of certain provisions of our common stock does not purport to be complete. You should refer to our sixth amended and restated certificate of incorporation, as amended, and our amended and restated by-laws, both of which are included as exhibits to this registration statement. The summary below is also qualified by provisions of applicable law.

General Terms

        Our authorized capital stock currently consists of 70,000,000 shares of common stock, par value $0.001 per share. On June 29, 2015, we had 23,514,851 shares of common stock outstanding and approximately 54 stockholders of record. Except as otherwise provided in any resolution providing for the issue of any series of preferred stock, holders of our common stock have exclusive voting rights for the election of directors and for all other purposes. Holders of our common stock are entitled to one vote per share on all matters to be voted upon by our stockholders. Neither our sixth amended and restated certificate of incorporation, as amended, nor our amended and restated by-laws authorize cumulative voting. The holders of our common stock are entitled to receive dividends, if any, as may be declared from time to time by our board of directors out of funds legally available for the payment of dividends, subject to the rights of any series of preferred stock. In the event of a liquidation, dissolution or winding up of Epirus, the holders of our common stock are entitled to share ratably in all assets remaining after payment of the preferential amounts, if any, to which the holders of our preferred stock, if any, are entitled. Our common stock has no preemptive, conversion or other subscription rights. There are no redemption or sinking fund provisions applicable to our common stock. All of our outstanding shares of common stock are fully paid and non-assessable.

Our Board of Directors

        Our board of directors currently has eight (8) members. Our sixth amended and restated certificate of incorporation, as amended, and our amended and restated by-laws provide that the number of directors shall be fixed from time to time by resolution adopted by the vote of a majority of the directors then in office, but shall in no event be less than three. Our sixth amended and restated certificate of incorporation, as amended, provides that the board of directors shall be divided into three nearly equal classes, with each class's term expiring on a staggered basis. Vacancies and newly created directorships may be filled by a majority of the directors then in office, though less than a quorum. Directors may be removed only for cause by the affirmative vote of at least seventy-five percent (75%) of the outstanding shares of capital stock entitled to vote generally in the election of directors, voting together as a single class, cast at a meeting of the stockholders called for that purpose.

Transfer Agent and Registrar

        The transfer agent and registrar for our common stock is Computershare Trust Company, N.A.

NASDAQ Capital Market

        Our common stock is listed for quotation on the NASDAQ Capital Market under the symbol "EPRS."

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DESCRIPTION OF WARRANTS

        As of June 29, 2015, 92,892 shares of our common stock were issuable upon the exercise of our outstanding warrants. We may issue warrants to purchase shares of our common stock, preferred stock and/or debt securities in one or more series together with other securities or separately, as described in the applicable prospectus supplement. Below is a description of certain general terms and provisions of the warrants that we may offer. Particular terms of the warrants will be described in the warrant agreements and the prospectus supplement to the warrants.

        The applicable prospectus supplement will contain, where applicable, the following terms of and other information relating to the warrants:

•

the specific designation and aggregate number of, and the price at which we will issue, the warrants;



•

the currency or currency units in which the offering price, if any, and the exercise price are payable;



•

the designation, amount and terms of the securities purchasable upon exercise of the warrants;



•

if applicable, the exercise price for shares of our common stock and the number of shares of common stock to be received upon exercise of the warrants;



•

if applicable, the exercise price for shares of our preferred stock, the number of shares of preferred stock to be received upon exercise, and a description of that series of our preferred stock;



•

if applicable, the exercise price for our debt securities, the amount of debt securities to be received upon exercise, and a description of that series of debt securities;



•

the date on which the right to exercise the warrants will begin and the date on which that right will expire or, if you may not continuously exercise the warrants throughout that period, the specific date or dates on which you may exercise the warrants;



•

whether the warrants will be issued in fully registered form or bearer form, in definitive or global form or in any combination of these forms, although, in any case, the form of a warrant included in a unit will correspond to the form of the unit and of any security included in that unit;



•

any applicable material United States federal income tax consequences;



•

the identity of the warrant agent for the warrants and of any other depositaries, execution or paying agents, transfer agents, registrars or other agents;



•

the proposed listing, if any, of the warrants or any securities purchasable upon exercise of the warrants on any securities exchange;



•

if applicable, the date from and after which the warrants and the common stock, preferred stock and/or debt securities will be separately transferable;



•

if applicable, the minimum or maximum amount of the warrants that may be exercised at any one time;



•

information with respect to book-entry procedures, if any;



•

the anti-dilution provisions of the warrants, if any;



•

any redemption or call provisions;



•

whether the warrants are to be sold separately or with other securities as parts of units; and

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•

any additional terms of the warrants, including terms, procedures and limitations relating to the exchange and exercise of the warrants.

Transfer Agent and Registrar

        The transfer agent and registrar for any warrants will be set forth in the applicable prospectus supplement.

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DESCRIPTION OF UNITS

        This section outlines some of the provisions of the units and the unit agreements. This information may not be complete in all respects and is qualified entirely by reference to the unit agreement with respect to the units of any particular series. The specific terms of any series of units will be described in the applicable prospectus supplement. If so described in a particular supplement, the specific terms of any series of units may differ from the general description of terms presented below.

        We may issue units comprised of shares of preferred stock, shares of common stock, warrants and other securities in any combination. Each unit will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each included security. The unit agreement under which a unit is issued may provide that the securities included in the unit may not be held or transferred separately, at any time or at any time before a specified date.

        The applicable prospectus supplement may describe:

•

the designation and terms of the units and of the securities comprising the units, including whether and under what circumstances those securities may be held or transferred separately;



•

any provisions of the governing unit agreement;



•

the price or prices at which such units will be issued;



•

the applicable United States federal income tax considerations relating to the units;



•

any provisions for the issuance, payment, settlement, transfer or exchange of the units or of the securities comprising the units; and



•

any other terms of the units and of the securities comprising the units.

        The provisions described in this section, as well as those described under "Description of Preferred Stock," "Description of Common Stock" and "Description of Warrants" will apply to the securities included in each unit, to the extent relevant.

Issuance in Series

        We may issue units in such amounts and in as many distinct series as we wish. This section summarizes terms of the units that apply generally to all series. Most of the financial and other specific terms of your series will be described in the applicable prospectus supplement.

Unit Agreements

        We will issue the units under one or more unit agreements to be entered into between us and a bank or other financial institution, as unit agent. We may add, replace or terminate unit agents from time to time. We will identify the unit agreement under which each series of units will be issued and the unit agent under that agreement in the applicable prospectus supplement.

        The following provisions will generally apply to all unit agreements unless otherwise stated in the applicable prospectus supplement.

Modification Without Consent

        We and the applicable unit agent may amend any unit or unit agreement without the consent of any holder:

•

to cure any ambiguity; any provisions of the governing unit agreement that differ from those described below;

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•

to correct or supplement any defective or inconsistent provision; or



•

to make any other change that we believe is necessary or desirable and will not adversely affect the interests of the affected holders in any material respect.

        We do not need any approval to make changes that affect only units to be issued after the changes take effect. We may also make changes that do not adversely affect a particular unit in any material respect, even if they adversely affect other units in a material respect. In those cases, we do not need to obtain the approval of the holder of the unaffected unit; we need only obtain any required approvals from the holders of the affected units.

Modification With Consent

        We may not amend any particular unit or a unit agreement with respect to any particular unit unless we obtain the consent of the holder of that unit, if the amendment would:

•

impair any right of the holder to exercise or enforce any right under a security included in the unit if the terms of that security require the consent of the holder to any changes that would impair the exercise or enforcement of that right; or



•

reduce the percentage of outstanding units or any series or class the consent of whose holders is required to amend that series or class, or the applicable unit agreement with respect to that series or class, as described below.

        Any other change to a particular unit agreement and the units issued under that agreement would require the following approval:

•

If the change affects only the units of a particular series issued under that agreement, the change must be approved by the holders of a majority of the outstanding units of that series; or



•

If the change affects the units of more than one series issued under that agreement, it must be approved by the holders of a majority of all outstanding units of all series affected by the change, with the units of all the affected series voting together as one class for this purpose.

        These provisions regarding changes with majority approval also apply to changes affecting any securities issued under a unit agreement, as the governing document.

        In each case, the required approval must be given by written consent.

Unit Agreements Will Not Be Qualified Under Trust Indenture Act

        No unit agreement will be qualified as an indenture, and no unit agent will be required to qualify as a trustee, under the Trust Indenture Act. Therefore, holders of units issued under unit agreements will not have the protections of the Trust Indenture Act with respect to their units.

Mergers and Similar Transactions Permitted; No Restrictive Covenants or Events of Default

        The unit agreements will not restrict our ability to merge or consolidate with, or sell our assets to, another corporation or other entity or to engage in any other transactions. If at any time we merge or consolidate with, or sell our assets substantially as an entirety to, another corporation or other entity, the successor entity will succeed to and assume our obligations under the unit agreements. We will then be relieved of any further obligation under these agreements.

        The unit agreements will not include any restrictions on our ability to put liens on our assets, including our interests in our subsidiaries, nor will they restrict our ability to sell our assets. The unit agreements also will not provide for any events of default or remedies upon the occurrence of any events of default.

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Governing Law

        The unit agreements and the units will be governed by Delaware law.

Form, Exchange and Transfer

        We will issue each unit in global—i.e., book-entry—form only. Units in book-entry form will be represented by a global security registered in the name of a depositary, which will be the holder of all the units represented by the global security. Those who own beneficial interests in a unit will do so through participants in the depositary's system, and the rights of these indirect owners will be governed solely by the applicable procedures of the depositary and its participants. We will describe book-entry securities, and other terms regarding the issuance and registration of the units in the applicable prospectus supplement.

        Each unit and all securities comprising the unit will be issued in the same form.

        If we issue any units in registered, non-global form, the following will apply to them.

        The units will be issued in the denominations stated in the applicable prospectus supplement. Holders may exchange their units for units of smaller denominations or combined into fewer units of larger denominations, as long as the total amount is not changed.

•

Holders may exchange or transfer their units at the office of the unit agent. Holders may also replace lost, stolen, destroyed or mutilated units at that office. We may appoint another entity to perform these functions or perform them ourselves.



•

Holders will not be required to pay a service charge to transfer or exchange their units, but they may be required to pay for any tax or other governmental charge associated with the transfer or exchange. The transfer or exchange, and any replacement, will be made only if our transfer agent is satisfied with the holder's proof of legal ownership. The transfer agent may also require an indemnity before replacing any units.



•

If we have the right to redeem, accelerate or settle any units before their maturity, and we exercise our right as to less than all those units or other securities, we may block the exchange or transfer of those units during the period beginning 15 days before the day we mail the notice of exercise and ending on the day of that mailing, in order to freeze the list of holders to prepare the mailing. We may also refuse to register transfers of or exchange any unit selected for early settlement, except that we will continue to permit transfers and exchanges of the unsettled portion of any unit being partially settled. We may also block the transfer or exchange of any unit in this manner if the unit includes securities that are or may be selected for early settlement.

        Only the depositary will be entitled to transfer or exchange a unit in global form, since it will be the sole holder of the unit.

Payments and Notices

        In making payments and giving notices with respect to our units, we will follow the procedures as described in the applicable prospectus supplement.

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PLAN OF DISTRIBUTION

        We may sell the securities in any one or more of the following methods from time to time:

•

directly to investors, directly to agents, or to investors through agents;



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through underwriting syndicates led by one or more managing underwriters, or through one or more underwriters acting alone, for resale to the public or investors;



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purchases by a broker or dealer as principal and resale by such broker or dealer for its own account;



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through a block trade (which may involve crosses) in which the broker or dealer so engaged will attempt to sell the securities as agent but may position and resell a portion of the block as principal to facilitate the transaction;



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ordinary brokerage transactions and transactions in which the broker solicits purchasers;



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in "at the market offerings," within the meaning of Rule 415(a)(4) of the Securities Act, to or through a market maker or into an existing trading market, on an exchange or otherwise;



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transactions not involving market makers or established trading markets, including direct sales or privately negotiated transactions;



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exchange distributions and/or secondary distributions;



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by delayed delivery contracts or by remarketing firms;



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transactions in options, swaps or other derivatives that may or may not be listed on an exchange; or



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through a combination of any such methods of sale.

        The distribution of the securities may be effected from time to time in one or more transactions:

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at a fixed price or prices, which may be changed;



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at market prices prevailing at the time of sale;



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at prices related to such prevailing market prices; or



•

at negotiated prices.

        Any of the prices may represent a discount from the prevailing market prices.

        Any underwritten offering may be on a best efforts or a firm commitment basis. If underwriters are used in the sale, the securities acquired by the underwriters will be for their own account. The underwriters may resell the securities in one or more transactions, including without limitation negotiated transactions, at a fixed public offering price or at a varying price determined at the time of sale. The obligations, if any, of the underwriter to purchase any securities will be subject to certain conditions. We may offer the securities to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate. Subject to certain conditions, the underwriters will be obligated to purchase all of the securities if any are purchased, other than securities covered by any over-allotment option. Any public offering price and any discounts or concessions allowed, reallowed or paid to dealers may be changed from time to time.

        If a dealer is used in an offering of securities, we may sell the securities to the dealer, as principal. The dealer may then resell the securities to the public at varying prices to be determined by the dealer at the time of sale.

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        We may sell securities directly or through agents we designate from time to time. We will name any agent involved in the offering and sale of securities and we will describe any commissions we will pay the agent in the prospectus supplement. Unless the prospectus supplement states otherwise, our agent will act on a best-efforts basis for the period of its appointment.

        We may also sell securities directly to one or more purchasers without using underwriters, dealers or agents.

        We may also make direct sales through subscription rights distributed to our stockholders on a pro rata basis, which may or may not be transferable. In any distribution of subscription rights to stockholders, if all of the underlying securities are not subscribed for, we may then sell the unsubscribed securities directly to third parties or may engage the services of one or more underwriters, dealers or agents, including standby underwriters, to sell the unsubscribed securities to third parties.

        In the sale of the securities, underwriters, dealers or agents may receive compensation from us or from purchasers of the securities, for whom they may act as agents, in the form of discounts, concessions or commissions. Underwriters may sell the securities to or through dealers, and such dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters and/or commissions from the purchasers for whom they may act as agents. Underwriters, dealers and agents that participate in the distribution of the securities may be deemed to be underwriters under the Securities Act and any discounts or commissions they receive from us and any profit on the resale of securities they realize may be deemed to be underwriting discounts and commissions under the Securities Act. The applicable prospectus supplement will, where applicable:

•

identify any such underwriter or agent;



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describe any compensation in the form of discounts, concessions, commissions or otherwise received from us by each of such underwriter, dealer or agent and in the aggregate to all underwriters, dealers and agents;



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identify the purchase price and proceeds from such sale;



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identify the amounts underwritten;



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identify the nature of the underwriter's obligation to take the securities;



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identify any over-allotment option under which the underwriters may purchase additional securities from us; and



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identify any quotation systems or securities exchanges on which the securities may be quoted or listed.

        Unless otherwise specified in the related prospectus supplement, each series of securities will be a new issue with no established trading market, other than the common stock, which is listed on the NASDAQ Capital Market. Any common stock sold pursuant to a prospectus supplement will be listed on the NASDAQ Capital Market, subject to applicable notices. We may elect to apply for quotation or listing of any other class or series of our securities, on a quotation system or an exchange but we are not obligated to do so. It is possible that one or more underwriters may make a market in a class or series of our securities, but such underwriters will not be obligated to do so and may discontinue any market making at any time without notice. Therefore, no assurance can be given as to the liquidity of, or the trading market for, any other class or series of our securities.

        In connection with an offering, an underwriter may purchase and sell securities in the open market. These transactions may include short sales, stabilizing transactions and purchases to cover positions created by short sales. Short sales involve the sale by the underwriters of a greater number of securities than they are required to purchase in the offering. "Covered" short sales are sales made in an amount not greater than the underwriters' option to purchase additional securities, if any, from us in

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the offering. If the underwriters have an over-allotment option to purchase additional securities from us, the underwriters may close out any covered short position by either exercising their over-allotment option or purchasing securities in the open market. In determining the source of securities to close out the covered short position, the underwriters may consider, among other things, the price of securities available for purchase in the open market as compared to the price at which they may purchase securities through the over-allotment option. "Naked" short sales are any sales in excess of such option or where the underwriters do not have an over-allotment option. The underwriters must close out any naked short position by purchasing securities in the open market. A naked short position is more likely to be created if the underwriters are concerned that there may be downward pressure on the price of the securities in the open market after pricing that could adversely affect investors who purchase in the offering.

        Accordingly, to cover these short sales positions or to otherwise stabilize or maintain the price of the securities, the underwriters may bid for or purchase securities in the open market and may impose penalty bids. If penalty bids are imposed, selling concessions allowed to syndicate members or other broker-dealers participating in the offering are reclaimed if securities previously distributed in the offering are repurchased, whether in connection with stabilization transactions or otherwise. The effect of these transactions may be to stabilize or maintain the market price of the securities at a level above that which might otherwise prevail in the open market. The impositions of a penalty bid may also affect the price of the securities to the extent that it discourages resale of the securities. The magnitude or effect of any stabilization or other transactions is uncertain. These transactions may be effected on the NASDAQ Capital Market or otherwise and, if commenced, may be discontinued at any time.

        We do not make any representation or prediction as to the direction or magnitude of any effect that the transactions described above might have on the price of the securities. In addition, we do not make any representation that underwriters will engage in such transactions or that such transactions, once commenced, will not be discontinued without notice at any time.

        Under agreements into which we may enter, underwriters, dealers and agents who participate in the distribution of the securities may be entitled to indemnification by us against certain civil liabilities, including liabilities under the Securities Act, or contribution from us to payments which the underwriters, dealers or agents may be required to make.

        Underwriters, dealers and agents may engage in transactions with us or perform services for us in the ordinary course of business.

        If indicated in the applicable prospectus supplement, securities may also be offered or sold by a "remarketing firm" in connection with a remarketing arrangement contemplated by the terms of the securities. Remarketing firms may act as principals for their own accounts or as agents. The applicable prospectus supplement will identify any remarketing firm and the terms of its agreement, if any, with us. It will also describe the remarketing firms' compensation. Remarketing firms may be deemed to be underwriters in connection with the remarketing of the securities.

        If indicated in the applicable prospectus supplement, we will authorize underwriters, dealers or other persons acting as our agents to solicit offers by particular institutions to purchase securities from us at the public offering price set forth in such prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on such future date or dates stated in such prospectus supplement. Each delayed delivery contract will be for an amount no less than, and the aggregate principal amounts of securities sold under delayed delivery contracts shall be not less nor more than, the respective amounts stated in the applicable prospectus supplement. Institutions with which such delayed delivery contracts, when authorized, may be made include commercial and savings banks, insurance companies, pension funds, investment companies, educational and charitable institutions and others, but will in all cases be subject to our approval. The obligations of any purchaser under any such contract will be subject to the conditions that (1) the purchase of the securities shall not at the time of

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delivery be prohibited under the laws of any jurisdiction in the United States to which the purchaser is subject, and (2) if the securities are being sold to underwriters, we shall have sold to the underwriters the total principal amount of the securities less the principal amount thereof covered by the delayed delivery contracts. The underwriters and such other agents will not have any responsibility in respect of the validity or performance of such delayed delivery contracts.

        To comply with applicable state securities laws, the securities offered by this prospectus will be sold, if necessary, in such jurisdictions only through registered or licensed brokers or dealers.

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CERTAIN PROVISIONS OF DELAWARE LAW AND OF OUR SIXTH AMENDED AND RESTATED CERTIFICATE OF INCORPORATION, AS AMENDED, AND OUR AMENDED AND RESTATED BY-LAWS

Anti-Takeover Provisions of our Delaware Certificate of Incorporation and By-laws

        In addition to the board of directors' ability to issue shares of preferred stock, our sixth amended and restated certificate of incorporation, as amended, and our amended and restated by-laws contain other provisions that are intended to enhance the likelihood of continuity and stability in the composition of the board of directors and which may have the effect of delaying, deferring or preventing a future takeover or change in control of our company unless such takeover or change in control is approved by our board of directors. These provisions include a classified board of directors as discussed above, elimination of stockholder action by written consents, elimination of the ability of stockholders to call special meetings, advance notice procedures for stockholder proposals and supermajority vote requirements for amendments to our certificate of incorporation and by-laws.

        Classified Board.    Under the Delaware General Corporation Law, unless the certificate of incorporation otherwise provides, directors serving on a classified board can only be removed by the stockholders for cause. The provision for a classified board could prevent a party who acquires control of a majority of our outstanding common stock from obtaining control of the board until our second annual stockholders meeting following the date the acquirer obtains the controlling stock interest. The classified board provision could have the effect of discouraging a potential acquirer from making a tender offer or otherwise attempting to obtain control of us and could increase the likelihood that incumbent directors will retain their positions.

        Elimination of Stockholder Action Through Written Consent.    Our amended and restated by-laws provide that stockholder action can be taken only at an annual or special meeting of stockholders and cannot be taken by written consent in lieu of a meeting.

        Elimination of the Ability to Call Special Meetings.    Our sixth amended and restated certificate and our amended and restated by-laws provide that, except as otherwise required by law, special meetings of our stockholders can only be called pursuant to a resolution adopted by a majority of our board of directors or by our chief executive officer or the chairman of our board of directors. Stockholders are not permitted to call a special meeting or to require our board to call a special meeting.

        Advanced Notice Procedures for Stockholder Proposals.    Our amended and restated by-laws establish an advance notice procedure for stockholder proposals to be brought before an annual meeting of our stockholders, including proposed nominations of persons for election to our board. Stockholders at our annual meeting may only consider proposals or nominations specified in the notice of meeting or brought before the meeting by or at the direction of our board or by a stockholder who was a stockholder of record on the record date for the meeting, who is entitled to vote at the meeting and who has given to our secretary timely written notice, in proper form, of the stockholder's intention to bring that business before the meeting. Although our amended and restated by-laws do not give our board the power to approve or disapprove stockholder nominations of candidates or proposals regarding other business to be conducted at a special or annual meeting, our amended and restated by-laws may have the effect of precluding the conduct of some business at a meeting if the proper procedures are not followed or may discourage or defer a potential acquirer from conducting a solicitation of proxies to elect its own slate of directors or otherwise attempting to obtain control of us.

        Amendments to the Certificate of Incorporation or By-laws.    Our sixth amended and restated certificate of incorporation, as amended, and our amended and restated by-laws provide that the affirmative vote of holders of at least 75% of the total votes eligible to be cast in the election of directors is required to amend, alter, change or repeal some of their provisions, unless such amendment or change has been approved by either a majority of those directors who are not affiliated or associated

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with any person or entity holding 10% or more of the voting power of our outstanding capital stock. This requirement of a super-majority vote to approve amendments to the certificate and by-laws could enable a minority of our stockholders to exercise veto power over any such amendments.

Provisions of Delaware Law Governing Business Combinations

        We are subject to the "business combination" provisions of Section 203 of the Delaware General Corporation Law. In general, such provisions prohibit a publicly held Delaware corporation from engaging in any "business combination" transactions with any "interested stockholder" for a period of three years after the date on which the person became an "interested stockholder," unless:

•

prior to such date, the board of directors approved either the "business combination" or the transaction which resulted in the "interested stockholder" obtaining such status;



•

upon consummation of the transaction which resulted in the stockholder becoming an "interested stockholder," the "interested stockholder" owned at least 85% of the voting stock of the corporation outstanding at the time the transaction commenced, excluding for purposes of determining the voting stock outstanding (but not the outstanding voting stock owned by the "interested stockholder") those shares owned by (a) persons who are directors and also officers and (b) employee stock plans in which employee participants do not have the right to determine confidentially whether shares held subject to the plan will be tendered in a tender or exchange offer; or



•

at or subsequent to such time the "business combination" is approved by the board of directors and authorized at an annual or special meeting of stockholders, and not by written consent, by the affirmative vote of at least 66²/3% of the outstanding voting stock which is not owned by the "interested stockholder."

        A "business combination" is defined to include mergers, asset sales and other transactions resulting in financial benefit to a stockholder. In general, an "interested stockholder" is a person who, together with affiliates and associates, owns 15% or more of a corporation's voting stock or within three years did own 15% or more of a corporation's voting stock. The statute could prohibit or delay mergers or other takeover or change in control attempts with respect to us and, accordingly, may discourage attempts to acquire us.

Limitations on Liability and Indemnification of Officers and Directors

        Our sixth amended and restated certificate of incorporation, as amended, limits the liability of our directors and executive officers to the fullest extent permitted by the Delaware General Corporation Law and provides that we will indemnify them to the fullest extent permitted by such law. We have entered into indemnification agreements with all of our current directors and executive officers and expect to enter into a similar agreement with any new directors and executive officers.

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INFORMATION INCORPORATED BY REFERENCE

        The SEC allows us to incorporate by reference the information and reports we file with it, which means that we can disclose important information to you by referring you to these documents. The information incorporated by reference is an important part of this prospectus, and information that we file later with the SEC will automatically update and supersede the information already incorporated by reference. We are incorporating by reference the documents listed below, which we have already filed with the SEC, and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act, including all filings made after the date of the filing of the registration statement and prior to the effectiveness of this registration statement, except as to any portion of any future report or document that is not deemed filed under such provisions, until we sell all of the securities:

•

our annual report on Form 10-K for the year ended December 31, 2014 filed with the SEC on March 31, 2015;



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our quarterly report on Form 10-Q for the quarter ended March 31, 2015 filed with the SEC on May 13, 2015;



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our current reports on Form 8-K filed with the SEC on January 26, 2015, January 30, 2015, March 13, 2015, April 24, 2015, and June 9, 2015;



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the portions of our definitive proxy statement on Schedule 14A filed with the SEC on April 24, 2015 that are deemed "filed" with the SEC under the Exchange Act; and



•

the description of our common stock contained in our registration statement on Form 8-A, which was filed with the SEC on February 18, 2005, including any amendment or report filed for the purpose of updating such description.

        Unless otherwise noted, the SEC file number for each of the documents listed above is 000-51171.

        Upon request, we will provide, without charge, to each person, including any beneficial owner, to whom a copy of this prospectus is delivered, a copy of the documents incorporated by reference into this prospectus. You may request a copy of these filings, and any exhibits we have specifically incorporated by reference as an exhibit in this prospectus, at no cost by writing or telephoning us at the following address:

EPIRUS Biopharmaceuticals, Inc.
Attn: Secretary
699 Boylston Street, Eighth Floor
Boston, Massachusetts 02116
(617) 600-3497

        This prospectus is part of a registration statement we filed with the SEC. We have incorporated exhibits into this registration statement. You should read the exhibits carefully for provisions that may be important to you.

        You should rely only on the information incorporated by reference or provided in this prospectus or any prospectus supplement. We have not authorized anyone to provide you with different information. We are not making an offer of these securities in any state where the offer is not permitted. You should not assume that the information in this prospectus or in the documents incorporated by reference is accurate as of any date other than the date on the front of this prospectus or those documents.

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WHERE YOU CAN FIND MORE INFORMATION

        We are subject to the information requirements of the Securities Exchange Act of 1934, as amended, or the Exchange Act, and in accordance with the Exchange Act, file annual, quarterly and special reports, proxy statements and other information with the SEC. You may read and copy any document we file at the SEC's Public Reference Room at 100 F Street, N.E., Washington, D.C. 20549. You may call the SEC at 1-800-SEC-0330 for further information on the operation of the Public Reference Room. These documents also may be accessed through the SEC's electronic data gathering, analysis and retrieval system, or EDGAR, via electronic means, including the SEC's home page on the Internet (www.sec.gov).

        We have the authority to designate and issue more than one class or series of stock having various preferences, conversion and other rights, voting powers, restrictions, limitations as to dividends, qualifications, and terms and conditions of redemption. See "Description of Preferred Stock" and "Description of Common Stock." We will furnish a full statement of the relative rights and preferences of each class or series of our stock which has been so designated and any restrictions on the ownership or transfer of our stock to any stockholder upon request and without charge. Written requests for such copies should be directed to EPIRUS Biopharmaceuticals, Inc., Attn: Secretary, 699 Boylston Street, Eighth Floor, Boston, Massachusetts 02116. Our telephone number is (617) 600-3497. Our website is located at www.epirusbiopharma.com. Information contained on our website is not incorporated by reference into this prospectus and, therefore, is not part of this prospectus or any accompanying prospectus supplement.

EXPERTS

        The consolidated financial statements of EPIRUS Biopharmaceuticals, Inc. appearing in EPIRUS Biopharmaceuticals, Inc.'s Annual Report (Form 10-K) for the year ended December 31, 2014, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their report thereon, included therein, and incorporated herein by reference. Such consolidated financial statements are incorporated herein by reference in reliance upon such report given on the authority of such firm as experts in accounting and auditing.

LEGAL MATTERS

        Certain legal matters, including the legality of the securities offered by this prospectus, will be passed upon for us by Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C., Boston, Massachusetts.

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$30,000,000 of Shares

Common Stock

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Prospectus Supplement

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March 1, 2016

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QuickLinks

Filed Pursuant to Rule 424(b)(5) Registration No. 333- 205420

TABLE OF CONTENTS
PROSPECTUS SUPPLEMENT
PROSPECTUS
ABOUT THIS PROSPECTUS SUPPLEMENT
PROSPECTUS SUPPLEMENT SUMMARY
About Epirus Biopharmaceuticals, Inc.
THE OFFERING
RISK FACTORS
FORWARD-LOOKING STATEMENTS
USE OF PROCEEDS
DESCRIPTION OF COMMON STOCK
CERTAIN PROVISIONS OF DELAWARE LAW AND OF OUR SIXTH AMENDED AND RESTATED CERTIFICATE OF INCORPORATION, AS AMENDED, AND OUR AMENDED AND RESTATED BY-LAWS
DIVIDEND POLICY
DILUTION
PLAN OF DISTRIBUTION
LEGAL MATTERS
EXPERTS
WHERE YOU CAN FIND ADDITIONAL INFORMATION
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE
TABLE OF CONTENTS
ABOUT THIS PROSPECTUS
ABOUT EPIRUS BIOPHARMACEUTICALS, INC.
RISK FACTORS
CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS
RATIOS OF EARNINGS TO FIXED CHARGES
USE OF PROCEEDS
DESCRIPTION OF THE SECURITIES
DESCRIPTION OF DEBT SECURITIES
DESCRIPTION OF PREFERRED STOCK
DESCRIPTION OF COMMON STOCK
DESCRIPTION OF WARRANTS
DESCRIPTION OF UNITS
PLAN OF DISTRIBUTION
CERTAIN PROVISIONS OF DELAWARE LAW AND OF OUR SIXTH AMENDED AND RESTATED CERTIFICATE OF INCORPORATION, AS AMENDED, AND OUR AMENDED AND RESTATED BY-LAWS
INFORMATION INCORPORATED BY REFERENCE
WHERE YOU CAN FIND MORE INFORMATION
EXPERTS
LEGAL MATTERS