Dendreon prostate therapy improves survival rates, company reports

Dendreon's experimental immune therapy extended prostate cancer patients' lives by 4.1 months and improved three-year survival by 38 percent, the Seattle biotech firm announced today.

Results for the therapy, called Provenge, confirmed findings of a previous trial of a smaller group, prolonging survival without major side effects, Dendreon said.

"The results are fabulous. It's better than we expected," said David Miller, chief executive of Biotech Stock Research. "We can't see any reason why the [U.S. Food and Drug Administration] wouldn't approve it,"

Dendreon's stock dropped about 45 percent today before its trading was halted on the Nasdaq.

Miller said he did not know the reason for the plunge, but it may have been caused by rumors before the announcement.

The results were presented at the American Urological Association (AUA) annual meeting in Chicago.

The company also exceeded its targets for "p-value," or the chance that results from patients receiving the therapy are the same as those receiving a placebo. The study was desiged to hit a number less than 0.043, and came in at 0.032.

It also showed the vaccine reduced risk of death by 22.5 percent.

More than 500 patients were enrolled in the trial. Dendreon reported side effects in Provenge-treated patients as "chills, fever, and headache. These events were primarily low grade with a short duration of 1-2 days following infusion," the company said.

In an earlier, smaller group study of Provenge, men treated with the vaccine lived an average 4.5 months longer than a control group. About 34 percent of men survived after three years, compared with 11 percent of those in the group that received no actual treatment.

"The ability to boost survival for patients is the gold standard endpoint in prostate cancer clinical trials," said Dr. Ira D. Sharlip, AUA spokesman. "The ability to give these patients both increased survival and, possibly, improved quality of life is very important."

Kristi Heim: 206-464-2718 or kheim@seattletimes.com