Gvax Prostate Cancer Vaccine Demonstrates Antitumor Activity

FOSTER CITY, CA -- December 11, 2000 -- Cell Genesys, Inc. reported that the company's Gvax® prostate cancer vaccine demonstrated antitumor activity in an initial Phase II trial in patients with advanced metastatic prostate cancer who have failed hormone therapy.

Thirty-four of the 55 patients entered in the trial had metastatic prostate cancer in the bone with positive bone scans at the start of therapy and were assigned to receive either low dose (24 patients) or high dose (10 patients) vaccine treatment as their only therapy. Post treatment follow-up of the 34 patients with positive bone scans prior to treatment revealed a trend toward prolonged progression free survival as measured by bone scan in patients who received the higher dose of vaccine as compared to patients who received the lower dose (median time to progression of 140 days v. 85 days).

The median progression free survival in the remaining 21 patients who did not have positive bone scans at study entry was 179 days. One patient with metastatic prostate cancer in the bone had a complete response with normalization of both PSA (prostate-specific antigen) and bone scan which is ongoing at 12 months.

Treatment with Gvax vaccine was safe and well-tolerated with the most common side effect being inflammation at the vaccination site, a safety profile that compares favorably with chemotherapy which is the only treatment available to prostate cancer patients who fail hormone therapy. These data were presented at the International Conference on Gene Therapy for Cancer in Coronado, California by Gvax clinical investigator Jonathan Simons, M.D., Professor of Medicine at Emory University which was one of the eight clinical trial sites participating in the Gvax prostate cancer vaccine study.

"We are encouraged by these initial Phase II clinical trial results for our Gvax prostate cancer vaccine and intend to advance this clinical development program as rapidly as possible," stated Stephen A. Sherwin, M.D. chairman and chief executive officer of Cell Genesys. "Gvax cancer vaccines have shown objective evidence of antitumor activity in all five types of cancer in which they have been tested. We will therefore continue to increase our investment in both the clinical trials and manufacturing infrastructure required to bring these products to market."

The reported Phase II study employed a six month treatment regimen for Gvax prostate cancer vaccine. Patients received an initial "priming" dose followed by 12 biweekly "booster" doses using either a low dose or three-fold higher dose regimen. No other cancer therapies were administered during either the treatment or post treatment follow-up period. Gvax prostate cancer vaccine was administered by an intradermal injection into the skin of the arms and legs and was safely administered in the outpatient setting. No serious or dose-limiting toxicities related to vaccine treatment were observed.

The efficacy endpoint used in the study-disease progression as measured by bone scan-is a clinical measure of the efficacy of Gvax prostate cancer vaccine. The reported trial is the first Phase II trial conducted by Cell Genesys using this endpoint. Prior to the initiation of a potential Phase III trial, Cell Genesys plans to initiate further trials of Gvax prostate cancer vaccine in 2001 which will employ a higher potency version of the same product. In addition, this product may be tested in combination with chemotherapy since future Phase III trials in hormone refractory prostate cancer patients may compare Gvax vaccine in combination with chemotherapy to chemotherapy alone.

Gvax cancer vaccines are comprised of tumor cells which have been genetically modified to secrete granulocyte-macrophage colony stimulating factor (GM-CSF), a hormone which plays a key role in stimulating the body's immune response to vaccines. The genetically modified tumor cells which are irradiated for safety prior to administration are used to vaccinate patients to stimulate an immune response against their tumor. Gvax cancer vaccines have demonstrated antitumor effects in each of the human clinical trials they have been tested in to date-prostate cancer, pancreatic cancer, lung cancer, renal cancer and melanoma. The company's Gvax cancer vaccine program for prostate cancer and other cancers employs a non patient-specific cell line form of the vaccine product which will be commercialized as an "off-the-shelf" pharmaceutical.

Information on this website is not intended as medical advice nor to be taken as such. Consult qualified physicians specializing in the treatment of prostate cancer. Neither the editors nor the publisher accepts any responsibility for the accuracy of the information or consequences from the use or misuse of the information contained on this website.

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