CSTL Castle Biosciences Inc

As filed with the Securities and Exchange Commission on February 28, 2024

Registration No. 333-   

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Castle Biosciences, Inc.

(Exact name of registrant as specified in its charter)

Castle Biosciences, Inc. 2019 Equity Incentive Plan

Castle Biosciences, Inc. 2019 Employee Stock Purchase Plan

(Full titles of the plans)

Derek J. Maetzold

President and Chief Executive Officer

Castle Biosciences, Inc.

505 S. Friendswood Drive, Suite 401

Friendswood, Texas 77546

(866) 788-9907

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Thomas A. Coll, Esq.

Carlos Ramirez, Esq.

Cooley LLP

10265 Science Center Drive

San Diego, California 92121

(858) 550-6000

Indicate by check mark whether the Registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the Registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

EXPLANATORY NOTE

This Registration Statement on Form S-8 is being filed by Castle Biosciences, Inc. (the “Registrant”) for the purpose of registering (i) an additional 1,370,526 shares of the Registrant’s Common Stock, $0.001 par value per share (“Common Stock”), under the Registrant’s 2019 Equity Incentive Plan (the “2019 Plan”), pursuant to the provisions of the 2019 Plan providing for an automatic increase in the number of shares of Common Stock reserved and available for issuance under the 2019 Plan, and (ii) 274,105 additional shares of Common Stock under the Registrant’s 2019 Employee Stock Purchase Plan (the “2019 ESPP”) pursuant to the provisions of the 2019 ESPP providing for an automatic increase in the number of shares of Common Stock reserved and available for issuance under the 2019 ESPP, in each case on January 1, 2024.

INCORPORATION OF DOCUMENTS BY REFERENCE

This Registration Statement is being filed for the purpose of registering additional securities of the same class as other securities for which Registration Statements of the Registrant on Form S-8 relating to the same employee benefit plans are effective.

The Registrant previously registered shares of its Common Stock for issuance under the 2019 Plan and 2019 ESPP under Registration Statements on Form S-8 filed with the Securities and Exchange Commission (the “SEC”) on July 29, 2019 (File No. 333-232884), March 10, 2020 (File No.  333-237062), March 11, 2021 (File No.  333-254179), February 28, 2022 (File No.  333-263094) and February 28, 2023 (File No. 333-270141). Pursuant to General Instruction E to Form S-8, this Registration Statement hereby incorporates by reference the contents of the Registration Statements referenced above.

ITEM 8. EXHIBITS.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Friendswood, State of Texas, on February 28, 2024.

POWER OF ATTORNEY

KNOW ALL BY THESE PRESENTS, that each person whose signature appears below constitutes and appoints Derek J. Maetzold and Frank Stokes, and each of them, as his or her true and lawful attorneys-in-fact and agents, each with the full power of substitution, for him or her and in his or her name, place or stead, in any and all capacities, to sign any and all amendments to this Registration Statement (including post-effective amendments), and to file the same, with exhibits thereto and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents, or their substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.

Exhibit 5.1

Carlos Ramirez

+1 858 550 6157

cramirez@cooley.com

February 28, 2024

Castle Biosciences, Inc.

505 S. Friendswood Drive, Suite 401

Friendswood, Texas 77546

Ladies and Gentlemen:

We have acted as counsel to Castle Biosciences, Inc., a Delaware corporation (the “Company”), in connection with the filing by the Company of a Registration Statement on Form S-8 (the “Registration Statement”) with the Securities and Exchange Commission (the “Commission”) covering the offering of up to 1,644,631 shares (the “Shares”) of the Company’s Common Stock, $0.001 par value per share (the “Common Stock”), consisting of (a) 1,370,526 shares of Common Stock issuable pursuant to the Company’s 2019 Equity Incentive Plan (the “Incentive Plan”) and (b) 274,105 shares of Common Stock issuable pursuant to the Company’s 2019 Employee Stock Purchase Plan (together with the Incentive Plan, the “Plans”).

In connection with this opinion, we have examined and relied upon (a) the Registration Statement and the related prospectuses, (b) the Plans, (c) the Company’s certificate of incorporation and bylaws, each as currently in effect, and (d) such other records, documents, opinions, certificates, memoranda and instruments as in our judgment are necessary or appropriate to enable us to render the opinion expressed below. We have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals, the conformity to originals of all documents submitted to us as copies, the accuracy, completeness and authenticity of certificates of public officials; and the due authorization, execution and delivery of all documents by all persons other than by the Company where authorization, execution and delivery are prerequisites to the effectiveness thereof. As to certain factual matters, we have relied upon a certificate of an officer of the Company and have not independently verified such matters.

Our opinion is expressed only with respect to the General Corporation Law of the State of Delaware. We express no opinion to the extent that any other laws are applicable to the subject matter hereof and express no opinion and provide no assurance as to compliance with any federal or state securities law, rule or regulation.

On the basis of the foregoing, and in reliance thereon, we are of the opinion that the Shares, when sold and issued in accordance with the Plans, the Registration Statement and the related prospectuses, will be validly issued, fully paid and nonassessable (except as to Shares issued pursuant to deferred payment arrangements, which will be fully paid and nonassessable when such deferred payments are made in full).

This opinion is limited to the matters expressly set forth in this letter, and no opinion should be implied, or may be inferred, beyond the matters expressly stated. This opinion speaks only as to law and facts in effect or existing as of the date hereof and we have no obligation or responsibility to update or supplement this opinion to reflect any facts or circumstances that may hereafter come to our attention or any changes in law that may hereafter occur.

We consent to the filing of this opinion as an exhibit to the Registration Statement. In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act of 1933, as amended, or the rules and regulations of the Commission thereunder.

Cooley LLP 10265 Science Center Drive, San Diego, CA 92121

t: (858) 550-6000 f: (858) 550-6420 cooley.com

February 28, 2024

Page Two

Sincerely,

Cooley LLP

Cooley LLP 10265 Science Center Drive, San Diego, CA 92121

t: (858) 550-6000 f: (858) 550-6420 cooley.com

Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the use of our report dated February 28, 2024, with respect to the consolidated financial statements of Castle Biosciences, Inc., and the effectiveness of internal control over financial reporting, incorporated herein by reference.

Exhibit 107

Calculation of Filing Fee Table

Form S-8

(Form Type)

Castle Biosciences, Inc.

(Exact Name of Registrant as Specified in its Charter)

Table 1: Newly Registered Securities