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Orlando, FL--Treatment with a novel form of immunotherapy known as APC8015 (Provenge) offers a substantial survival advantage in asymptomatic prostate cancer patients with metastatic disease who have failed to respond to hormone treatment, according to findings from a placebo-controlled phase III trial. At 36 months, 34% of the treated patients were alive versus 11% of those on placebo.
Eric J. Small, MD, professor of medicine and urology at the University of California, San Francisco, presented the final overall survival data from the trial at the American Society of Clinical Oncology annual meeting, held here.
Primary endpoints were objective disease progression and new cancer-related pain. Disease-related pain progression was the secondary endpoint. All patients were followed for survival for 36 months after randomization or until death. The drug was well tolerated, with only minor, flu-like side effects.
"There is a trend toward improved median time to progression in asymptomatic androgen-independent prostate cancer patients treated with APC8015 compared with placebo," Dr. Small said in summarizing the study's results. "More importantly, the survival at 36 months was threefold higher in the Provenge arm compared to placebo, and the median survival was 4.5 months longer in the treated group than in the placebo group."
Dr. Small indicated that there exist several possible explanations for this outcome, including imbalance of prognostic factors in the treated groups, imbalance in chemotherapy following protocol treatment, and a small sample size, suggesting that the difference may be due to chance.
"Survival advantage is not likely due to imbalances," Dr. Small responded, citing a statistical analysis of the data. "In addition, there was no difference in the percentage of patients in each treatment arm that went on to receive chemotherapy after APC8015.
"APC8015 is the first non-chemotherapeutic agent providing a survival advantage in androgen-independent prostate cancer patients."
Commenting on Dr. Small's report, James J. Mulé, PhD, of the H. Lee Moffitt Cancer Center in Tampa, FL, called it a very intriguing clinical trial.
"I believe it's going in the right direction. It's clearly one of the trials in the dendritic cell vaccine arena that is showing promising results. Clearly, the number of patients was limited, so we need a more robust clinical trial, which will be conducted in a larger patient number," Dr. Mulé told Urology Times.