Cell Genesys Announces Encouraging Follow-Up Survival Data From Phase 2 Clinical Trial Of GVAX(R) Immunotherapy For Pancreatic Cancer

Cell Genesys, Inc. (Nasdaq: CEGE) today announced follow-up data from a Phase 2 clinical trial of GVAX(R) immunotherapy for pancreatic cancer in 60 patients with operable pancreatic cancer who received the immunotherapy after surgical resection of their tumor and adjuvant radiation and chemotherapy. The updated results showed a median survival of 26.8 months. This compares favorably with published, historical data from multiple single-arm and randomized studies in patients undergoing pancreatic cancer surgery and adjuvant therapy for whom the median survival has been reported to be in the range of 17 to 22 months, including the most recently reported results for gemcitabine chemotherapy. Of note, 52 of the 60 patients in this study were considered high risk, based on the unfavorable finding that their cancer had spread to regional lymph nodes. Treatment was well tolerated. The details of the follow-up findings were presented by Daniel Laheru, M.D., assistant professor of medical oncology at Johns Hopkins Kimmel Cancer Center, and colleagues, at the 2007 American Society of Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium held this past weekend in Orlando, FL.

"We are encouraged by the updated survival data of GVAX immunotherapy in this Phase 2 study compared to previously reported results for surgery and adjuvant therapy of resectable pancreatic cancer and we are currently reviewing plans for further development," said Kristen Hege, M.D., vice president of Clinical Research at Cell Genesys. "We believe these new findings, along with the results from an earlier Phase 1 trial of GVAX immunotherapy for pancreatic cancer, provide further clinical proof-of-concept for the GVAX cancer immunotherapy platform."

The Phase 2 trial was conducted by the Johns Hopkins Kimmel Cancer Center and enrolled 60 patients with resectable pancreatic cancer. The study was designed to evaluate the safety and efficacy of GVAX immunotherapy for pancreatic cancer which is a non patient-specific immunotherapy being developed as an "off-the-shelf" pharmaceutical product. All patients underwent extensive surgical resection of their tumors. The immunotherapy was administered as an intradermal (under the skin) injection before and after standard post-operative adjuvant radiation therapy and 5-flourouracil chemotherapy. Patients received up to five doses -- the first prior to adjuvant chemoradiotherapy, the next three following adjuvant therapy at approximately one-month intervals and the fifth as a booster injection six months later. Patients were monitored for evidence of relapse and survival, as well as the occurrence of adverse events and induction of immune response.

An earlier Phase 1 trial of GVAX(R) immunotherapy for pancreatic cancer was conducted at the Johns Hopkins Kimmel Cancer Center in 14 patients who also received the immunotherapy following surgical resection of their tumor and standard adjuvant radiation and chemotherapy. As first reported in the Journal of Clinical Oncology in January 2001, three of eight patients who received the therapeutic dose levels of the immunotherapy had prolonged disease-free survival for a period of at least eight years. This outcome is considered particularly significant since all three long-term survivors were judged to be at high risk for recurrent cancer due to microscopic evidence of residual pancreatic tumor following surgery and/or metastatic tumor in regional lymph nodes. In addition, the three patients with prolonged disease-free survival -- but not the five who progressed and died -- showed evidence of treatment-associated antitumor immunity, including induction of T cell responses to the candidate tumor-associated antigen, mesothelin.

Pancreatic cancer is the fourth leading cause of cancer death in the United States. According to the American Cancer Society, approximately 37,170 Americans will be diagnosed with pancreatic cancer in 2007, and 33,370 are expected to die from the disease in 2007. Because symptoms are non-specific, cancer of the pancreas is rarely diagnosed at an early stage leaving surgical removal of the tumor as a treatment option for only approximately 20 to 30 percent of pancreatic cancer patients. The median survival of patients with operable cancer of the pancreas is approximately 17 to 22 months.

Clinical trials of GVAX(R) cancer immunotherapies are under way for multiple types of cancer in addition to pancreatic cancer, including prostate cancer and leukemia. The products are comprised of tumor cells that have been modified to secrete GM-CSF, an immune stimulatory hormone, and then irradiated for safety. GVAX cancer immunotherapies are being developed as non patient-specific "off-the-shelf" pharmaceutical products and have demonstrated a favorable side effect profile in over 600 patients treated in clinical trials to date.

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(R) cancer immunotherapies and oncolytic virus therapies. Ongoing clinical trials include Phase 3 trials of GVAX immunotherapy for prostate cancer, Phase 2 trials of GVAX immunotherapy for pancreatic cancer and 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 the company's progress, results and timing of clinical trials and preclinical programs and the nature of product pipelines are forward-looking statements and are subject to a number of uncertainties that could cause actual results to differ materially from the statements made, including risks associated with the success of clinical trials and research and development programs, the regulatory approval process for clinical trials, competitive technologies and products, patents, continuation of corporate partnerships and the need for additional financings. For information about these and other risks which may affect Cell Genesys, please see the company's Annual Report on Form 10-K for the year ended December 31, 2005 filed on March 13, 2006 as well as Cell Genesys' reports on Form 10-Q 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.

Cell Genesys, Inc.
http://www.cellgenesys.com