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Prostate Cancer Vaccine Trials
An experimental treatment tripled the survival rate of men with advanced prostate cancer in a clinical trial, doctors said yesterday, a result they said represents perhaps the first significant success for therapies known as cancer vaccines.
The treatment, developed by Dendreon, a Seattle biotechnology company, is called a vaccine not because it prevents disease but because it tries to harness the body's own immune system to fight cancer after the disease has developed. Many such cancer vaccines have failed in clinical trials and none have reached the market in the United States.
But Dendreon's treatment, called Provenge, now seems to have a shot at becoming the first to win approval from the Food and Drug Administration, especially if another trial expected to be completed by the end of the year confirms the results.
In a final-stage clinical trial involving 127 men with advanced prostate cancer, 34 percent of those who received Provenge were alive after three years, compared with 11 percent of those who took a placebo. The median survival, meaning the time by which half the patients had died, was 25.9 months for those who received Provenge, compared with 21.4 months for those who took the placebo. This study has shown a survival advantage to using this drug in patients with very limited options.
The 4.5-month increase in survival that was achieved by Provenge is greater than the roughly 2.5-month benefit shown in clinical trials of Taxotere, a drug from Sanofi-Aventis. Taxotere is the only approved chemotherapy for patients, like those in the Provenge trial, whose cancer has spread beyond the prostate gland and is no longer being controlled by hormonal therapy. The trial results are scheduled to be presented Saturday at a prostate cancer symposium in Orlando, Fla., organized by three medical societies and the Prostate Cancer Foundation. Dendreon, which sponsored the trial, announced in October that the drug had prolonged lives, but the actual statistics will be revealed for the first time at the symposium.
The main goal of the Provenge prostate cancer vaccine trial was to see if the drug delayed the worsening of cancer, a measure known as time to progression. Dendreon had previously announced that the drug failed to do that by a statistically significant amount, though the company said the drug did delay progression in patients with less aggressive cancer. Jim Shaw
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