HBY Hybridon

Hybridon's Immunomodulatory Drug Candidate, IMOxine(TM), Produces Immune Response in Patients with Refractory Advanced Solid Tumor Malignancies - On-Going Phase 1 Trial is Extended to Include Additional Renal Cell Carcinoma and Melanoma Patients - CAMBRIDGE, Mass., May 10 /PRNewswire-FirstCall/ -- Hybridon, Inc. today announced the presentation of new data from its on-going Phase 1 oncology study of HYB2055 (IMOxine(TM)). In the trial, IMOxine was found to be safe and produced immunological activity in patients with advanced metastatic solid tumors. Based on these results, Hybridon has extended the trial to recruit up to 10 additional renal cell carcinoma and melanoma patients at two selected dose levels. Assuming the results of the trial continue to be positive, the Company plans to evaluate IMOxine in Phase 2 trials later this year. The results were presented at the TOLL 2004 meeting in Sicily, Italy, being held May 8-10, 2004. The trial is being conducted at the Vincent T. Lombardi Comprehensive Cancer Center at Georgetown University Medical Center, Washington, D.C. Through April 2004, 23 refractory cancer patients have been enrolled in the study. IMOxine has been well tolerated with no dose limiting side effects over the subcutaneous dosage range of 0.04, 0.16, 0.32, 0.48, and 0.64 mg/kg/week. Of the 23 patients, 18 have completed at least four weeks of treatment to meet the protocol requirements for safety evaluation. Fourteen patients have completed 8 weeks of treatment and 8 were determined to have stable disease by radiography. One of five patients assessed at 16 weeks had stable disease and this patient remained on trial until clinical progression at 32 weeks. Immunological activity as measured by changes in circulating white blood cell subpopulations and/or in serum cytokine levels was observed in 19 out of 23 patients, including all 11 patients who were administered IMOxine at the two dose levels Hybridon has chosen for further exploration. "These patients have renal cell carcinoma, melanoma, sarcoma, colorectal, breast, or other cancers that have progressed through multiple courses of prior therapies, including in some cases other experimental therapies," said John L. Marshall, M.D., principal investigator of the study and Associate Professor of Medicine at the Lombardi Comprehensive Cancer Center. "Our Institutional Review Board recently has approved an amendment to the trial in order to expand the database at 0.16 and 0.32 mg/kg/week in additional renal cell carcinoma and melanoma patients." "In this trial, IMOxine has produced both consistent laboratory evidence of immune response and clinical indications of activity, especially at 0.16 and 0.32 mg/kg/week," said R. Russell Martin, M.D., FACP, Hybridon's Senior Vice President of Drug Development. "These results and the subsequent data from the trial extension will help us identify the optimum biological effect dosage for our anticipated Phase 2 investigations, which are expected to commence later this year." IMOxine is a 2nd-generation immunomodulatory oligonucleotide (IMO(TM)) that functions as an agonist of Toll-like Receptor 9, a specific protein receptor in certain of the immune cells. Other receptors also may play a role in the immunomodulatory activity of IMOxine. The clinical trial presentation was made by Jimmy Hwang, M.D., of Georgetown University Medical Center. Separately, Sudhir Agrawal, D. Phil., of Hybridon, will provide an address at TOLL 2004 entitled "Synthetic nucleic acids as agonists of Toll-like receptors". About the Trial The trial is evaluating the safety and immunopharmacology of IMOxine as a monotherapy in patients with refractory solid tumors that had been classified as progressive disease in spite of multiple courses of prior therapies. Through April 2004, 23 patients have been enrolled: 8 with colorectal cancer; 3 with renal cell carcinoma; 2 each with sarcoma, melanoma, or breast cancer; 1 each with non-small cell lung cancer, Hurthle cell sarcoma of thyroid, salivary gland carcinoma, basal cell carcinoma, pseudomyxoma, or carcinoma of unknown origin. Over 200 weekly subcutaneous doses at 5 dose levels ranging from 0.04 to 0.64 mg/kg have been assessed to date. Treatment duration is open-ended, based on safety and assessment of tumor status by RECIST definitions at 8-week intervals. Immunopharmacological assessments performed during the trial include ELISA measurement of serum cytokines (IL-6, IL-10, IL-12, tissue necrosis factor-alpha, interferon-alpha, and interferon-gamma) and flow cytometric analysis of surface markers on circulating leukocytes (total and activated populations). An initial presentation of results was made at the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics in November 2003. Other authors of this clinical presentation are S. Malik, S. Park, and J. Marshall from Georgetown University Medical Center, Washington DC, and R. Martin, T. Sullivan, T. Burns, and S. Agrawal from Hybridon, Inc., Cambridge MA. About Hybridon Hybridon, Inc. is a leader in the discovery and development of novel therapeutics based on synthetic DNA. The Company's focus is to develop therapeutics independently and with partners based on two proprietary technology platforms: i) Synthetic immunomodulatory oligonucleotide (IMOTM) motifs that act to modulate responses of the immune system; and ii) Antisense technology that uses synthetic DNA to block the production of disease-causing proteins at the cellular level. The Company is conducting clinical trials in oncology patients with HYB2055 (IMOxine(TM)), a 2nd-generation IMO, and with GEM(R)231 (a 2nd- generation antisense oligonucleotide targeted to protein kinase A) in combination with irinotecan. Hybridon also is collaborating on development of additional second-generation antisense oligonucleotides for the treatment of cancer and viral infections, and has completed a Phase 1 trial of HYB2055 in healthy volunteers. Hybridon has licensed Amplivax(TM) (an adjuvant application of HYB2055) as an adjuvant for IR103, a potential therapeutic and prophylactic vaccine for HIV infection being developed by The Immune Response Corporation. This press release contains forward-looking statements concerning Hybridon that involve a number of risks and uncertainties. For this purpose, any statements contained herein that are not statements of historical fact may be deemed to be forward-looking statements. Without limiting the foregoing, the words, "believes," "anticipates," "plans," "expects," "estimates," "intends," "should," "could," "will," "may," and similar expressions are intended to identify forward-looking statements. There are a number of important factors that could cause Hybridon's actual results to differ materially from those indicated by such forward-looking statements, including risks as to whether results obtained in preclinical studies or early clinical trials will be indicative of results obtained in future preclinical studies or clinical trials, or warrant further clinical trials and product development; whether products based on Hybridon's technology will advance through the clinical trial process and receive approval from the United States Food and Drug Administration or equivalent foreign regulatory agencies; whether, if such products receive approval, they will be successfully distributed and marketed; whether the patents and patent applications owned or licensed by Hybridon will protect the Company's technology and prevent others from infringing it; whether Hybridon's cash resources will be sufficient to fund product development; and such other important factors as are set forth under the caption "Risk Factors" in Hybridon's Annual Report on Form 10-K filed on March 23, 2004, which important factors are incorporated herein by reference. Hybridon disclaims any intention or obligation to update any forward-looking statements. Hybridon, Inc. Euro RSCG Life NRP 617-679-5500, x5593 212-845-4268 R. Russell Martin, M.D. Robert Stanislaro (media) E-mail: 212-845-4269 Brian Ritchie (investors) Georgetown University Medical Center Lindsey A. Spindle 202-687-7707 DATASOURCE: Hybridon, Inc. CONTACT: R. Russell Martin, M.D. of Hybridon, Inc., +1-617-679-5500, ext. 5593, or ; or Lindsey A. Spindle of Georgetown University Medical Center, +1-202-687-7707; or media, Robert Stanislaro, +1-212-845-4268, or investors, Brian Ritchie, +1-212-845-4269, both of Euro RSCG Life NRP, both for Hybridon, Inc. Web site: http://www.hybridon.com/

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