SOUTH SAN FRANCISCO, Calif., Feb. 15 /PRNewswire-FirstCall/ -- Cell Genesys, Inc. today reports the results of an analysis examining the potential association between immune responses to GVAX immunotherapy for prostate cancer and increased patient survival in a Phase 2 trial in patients with metastatic, hormone refractory prostate cancer (HRPC). More than 400 patient-specific GVAX-induced antibody responses were identified in the sera of the treated patients by three different biochemical techniques confirming, as previously reported, that GVAX treatment results in a broad, multi-antigen immune response. An ongoing analysis of these GVAX-induced antibody responses has shown that at least two of the antibody responses are associated with patient survival, an association that is independent of the dose and number of treatments administered. These data will be presented today by Dr. Thomas Harding and colleagues from Cell Genesys at the American Society of Clinical Oncology’s Genitourinary Cancer Symposium being held in San Francisco, California.
Cell Genesys has previously reported the results of two multicenter Phase 2 trials of GVAX immunotherapy for prostate cancer in metastatic HRPC. The second of these two trials enrolled 80 patients. The serum of 65 patients (the total number for whom adequate sera were available) were examined to determine each patient’s immune response to two specific antigens, HLA-A24 and FLJ14668, following GVAX treatment. Thirty-four of 65 patients demonstrated an FLJ14668-specific antibody immune response. These 34 patients had a median survival of 43 months, compared to a median survival of 21 months achieved by the patients who did not generate anti-FLJ14668 antibodies (p=0.002). Twenty-two of these 65 patients received a dose of GVAX immunotherapy for prostate cancer comparable to that being evaluated in ongoing Phase 3 clinical trials. Of these 22 patients, 16 patients (73 percent) mounted an immune response to FLJ14668. These 16 patients achieved a median survival of 44.9 months. As previously reported, the median survival for all 22 patients in this treatment group was 35.0 months. Finally, of the 58 patients who were HLA-A24 genotype negative and therefore potentially able to mount anti-HLA-A24 specific antibody responses, 30 patients were found to be anti-HLA-A24 antibody positive. These 30 patients had a median survival of 43 months, compared to a median survival of 18 months in the patients who did not generate anti-HLA-A24 antibodies (p=0.05). Importantly, the apparent associations between the presence of these two specific antibody responses and survival were shown by multivariate analysis to be independent of both dose and duration of treatment.
“The findings being reported today indicate a potential association between two specific GVAX-induced antibody responses and patient survival, an association consistent with the proposed mechanism of action for this product. We look forward to expanding these findings in a prospective analysis of the sera of patients treated in our two randomized controlled Phase 3 trials,” stated Peter K. Working, Ph.D., senior vice president of research and development at Cell Genesys. “Since GVAX immunotherapy for prostate cancer is a multi-antigen product that can induce a broad immune response, we believe we have a unique opportunity to identify the widest possible array of specific antibody responses that may be associated with clinical benefit.”
Cell Genesys is currently evaluating GVAX immunotherapy for prostate cancer in two Phase 3 multicenter, randomized, controlled clinical trials. VITAL-1, which is fully enrolled with 626 patients, is designed to compare GVAX cancer immunotherapy to Taxotere(R) (docetaxel) chemotherapy plus prednisone in HRPC patients with metastatic disease who are asymptomatic with respect to cancer-related pain. The primary endpoint of the trial is an improvement in survival. An interim analysis of the trial was recently conducted by an independent data monitoring committee in the timeframe originally estimated and resulted in the recommendation to continue the trial. The company expects to have enough events to trigger the final analysis of VITAL-1 in the second half of 2009. VITAL-2, which the company expects to fully enroll with approximately 600 patients in the first half of 2009, is designed to evaluate the safety and efficacy of GVAX immunotherapy for prostate cancer used in combination with Taxotere chemotherapy compared to the use of Taxotere chemotherapy and prednisone in HRPC patients with metastatic disease who are symptomatic with cancer-related pain. The primary endpoint of the trial is also an improvement in survival. The company expects to have enough events to trigger an interim analysis of VITAL-2 in the first half of 2009.
About GVAX Cancer Immunotherapies
GVAX cancer immunotherapies are non patient-specific investigational products comprised of whole tumor cells that have been modified to secrete GM- CSF (granulocyte-macrophagecolony-stimulating factor), an immune stimulatory cytokine, and then irradiated for safety. GVAX is administered via intradermal injections on an outpatient basis. To date, over 600 patients have been treated with GVAX cancer immunotherapies in Phase 1 and Phase 2 clinical trials for multiple indications, including prostate cancer, pancreatic cancer, and leukemia. The company is currently manufacturing GVAX immunotherapy for prostate cancer in its bioreactor-based manufacturing plant in Hayward, California, a facility that is also capable of manufacturing the product for commercialization.
About Cell Genesys
Cell Genesys is focused on the development and commercialization of novel biological therapies for patients with cancer. The company is currently pursuing two clinical stage product platforms - GVAX(TM) cancer immunotherapies and oncolytic virus therapies. Ongoing clinical trials include Phase 3 trials of GVAX immunotherapy for prostate cancer, Phase 2 trials of GVAX immunotherapies for pancreatic cancer and for leukemia, and a Phase 1 trial of CG0070 oncolytic virus therapy for bladder cancer. Cell Genesys continues to hold an equity interest in its former subsidiary, Ceregene, Inc., which is developing gene therapies for neurodegenerative disorders. Cell Genesys is headquartered in South San Francisco, CA and has its principal manufacturing operation in Hayward, CA. For additional information, please visit the company’s website at http://www.cellgenesys.com.
Statements made herein about the company, other than statements of historical fact, including statements about potential association between immune response and patient survival, about the company’s progress, results, analysis, and timing of VITAL-1 and VITAL-2 and other clinical trials and preclinical programs and the nature of product pipelines are forward-looking statements. and These statements are subject to a number of uncertainties that could cause actual results to differ materially from the statements made, including the risk that the Phase 3 trials do not confirm the Phase 2 findings regarding potential association between immune response and patient survival as well as risks associated with the success of clinical trials and research and development programs, regulatory requirements and the regulatory approval process for clinical trials, manufacture and commercialization of the company’s products, competitive technologies and products, patents, the need for and reliance on partnerships with third parties, and the need for additional financings. For information about these and other risks which may affect Cell Genesys, please see the company’s reports on Form 10-Q, 10-K, and 8-K and other reports filed from time to time with the Securities and Exchange Commission. The company assumes no obligation to update the forward-looking information in this press release.
CONTACT: Susan Ferris, Investor Relations of Cell Genesys, Inc.,
+1-650-266-3200
Web site: http://www.cellgenesys.com/
