Readers Digest Article

Hi, me again! Didn't realize the article I sent B4 was so old! Here's a newer one:
GVAX® prostate cancer vaccine is a non patient-specific GVAX® product currently in clinical-stage development for patients with advanced-stage, hormone-refractory prostate cancer. The vaccine is comprised of prostate cancer cell lines that have been irradiated and 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. GVAX® prostate cancer vaccine is designed to stimulate a systemic immune response against the patient's prostate cancer destroying prostate cancer cells that persist or recur following surgery, hormone or radiation therapy.

Based on encouraging data from previous Phase 2 trials, Cell Genesys is conducting a Phase 2 trial in hormone-refractory prostate cancer patients evaluating a high potency form of GVAX® prostate cancer vaccine, a form which is more potent than the vaccine used in previous trials. Interim findings reported at the American Society of Clinical Oncology Meeting in June 2003 demonstrate the safety and clinical activity of the vaccine in the four treatment groups analyzed to date. The data for measurements of ICTP (an independent marker of bone destruction), PSA (an indicator of prostate cancer) and prostate cancer-associated antibodies were pooled for purposes of the interim analysis. There was an improvement or stabilization in bone metastatic activity as measured by ICTP levels in 59 percent of patients (16 of 27 patients tested to date). Among 61 patients followed for a median of four months, there was one patient with a greater than 50 percent reduction in PSA levels and 10 patients with lesser reductions or stabilization, including four whose PSA levels decreased after initial progression. Prostate cancer-associated antibodies were detected post-vaccination in 83 percent of patients (15 of 18 tested to date) at levels that are significantly higher than those previously published for other cell-based cancer vaccines. Median survival--an endpoint reported in an earlier Phase 2 trial that compared favorably to the results reported for chemotherapy--had not yet been reached for any treatment group.

Cell Genesys expects to enter Phase 3 development with this high potency form of GVAX® prostate cancer vaccine in hormone-refractory, bone-metastatic patients by the second quarter of 2004. It is likely that there will be two separate Phase 3 clinical trials in the product registration program--one in patients without bone pain which will compare GVAX® prostate cancer vaccine to chemotherapy, and one in patients with bone pain which will compare GVAX® prostate cancer vaccine plus chemotherapy to chemotherapy alone.

The company has significantly expanded its manufacturing capabilities in order to produce the GVAX® product needed for this trial as well as for market launch. Product for this Phase 3 GVAX® prostate cancer vaccine trial is expected to be manufactured at the company's manufacturing facility located in Hayward, CA.

In September 2002, data were updated from the initial Phase 2 multicenter trial of GVAX® prostate cancer vaccine in hormone-refractory patients. Thirty-four of the 55 patients entered in the trial had metastatic prostate cancer 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. Five of 10 (50 percent) patients receiving the higher dose level of the vaccine were reported to be alive 2.5 years after treatment (median survival = 31 months), and seven of 22 patients (32 percent) receiving the lower dose of the vaccine, were reported to be alive 2.5 years after treatment (median survival 23 months). Two patients were lost to follow-up. The overall median survival of the 34 patients was 26.2 months, which is longer than that previously reported for any chemotherapy, which is the current standard of care for hormone-refractory prostate cancer patients with bone metastases.

Previously reported data from this initial Phase 2 trial demonstrated compelling evidence of antitumor activity. 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). 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.

(The data referenced in the preceding paragraphs represent the most recently announced data pertaining to this program.)

Information About Fully Enrolled GVAX® Prostate Cancer Vaccine Clinical Trials Currently Under Way:


• G-0010: A Dose Escalation and Efficacy Trial of GVAX® Prostate Cancer Vaccine in Patients with Metastatic Hormone-Refractory Prostate Cancer

Benji