WASHINGTON, March 29 (UPI) -- A government advisory panel backed a new biotech vaccine for treating advanced prostate cancer Thursday, saying the treatment showed limited evidence of prolonging life in seriously ill patients.
In a 13-4 vote, the Food and Drug Administration advisors backed Dendreon Corp's. claim that Provenge, its new generation cellular treatment, can extend survival in men who no longer respond to hormone treatment.
Several experts said they were uneasy about supporting the treatment because it showed only marginal evidence of benefit. But a majority recommend approval anyway, citing scant options available to advanced prostate cancer patients, many of whom are facing a terminal illness.
"Given the dire landscape of other drugs out there, it should be opened up," said Dr. Steven M. Dubinett, a cancer researcher at UCLA who was a member of the advisory panel.
Dendreon touted the treatment as the first cellular therapy against cancer. To undergo treatment, patients have white blood cells removed and treated with immune agents. The cells are then reintroduced back into the body with chemical programming that, in theory, allows them to mount an immune response against cancer cells.
A pair of studies suggested Provenge may slow by one to two weeks the progression of prostate cancer in men whose cancer no longer responds to treatment with hormones.
Men who used the treatment also showed some evidence of living longer than those who took a placebo. In one trial men who got active treatment lived an average of 3.3 months longer. In another, they lived four-and-a-half months longer.
Experts criticized the studies for enrolling only about 100 to 130 patients, a relatively small number that can limit scientists' ability to interpret results.
But most said they support Provenge anyway, given the limited choices for men with advanced disease.
"I think that patients and physicians could look at some of this data in labeling and make their own decisions," said Dr. Kurt C. Gunter, medical director of Hospira, Inc., and a member of the panel.
Nearly 30,000 American men died of prostate cancer in 2003, according to the Centers for Disease Control and Prevention. Dendreon estimated 27,000 patients per year could be candidates for Provenge.
"If approved, Provenge could become a breakthrough treatment for patients with advanced prostate cancer who currently have few treatment options," company CEO Michael Gold said in a statement.
Federal regulations compel FDA to make a decision on the treatment by May 15. The agency isn't required to follow advisory panels' recommendations, but it usually does.
Despite the vote, several experts said they were unconvinced that Dendreon had established Provenge's effectiveness. Many backed the treatment anyway when FDA officials asked them to vote only on whether evidence was "substantial."
"I wish we all could have voted 'maybe' on this, but I don't think we can," said Farshid Guilak, a professor of surgery at Duke University and member of the panel.
But panelists urged FDA to base its final decision largely on the results of a third study designed to test whether Provenge improves survival in more than 400 patients.
Panelist Dr. Richard Alexander, chief of urology at the Department of Veterans Affairs' Maryland Health Care System in Baltimore, voted against approving the drug. "But very close," he said.
Several patients testified before the committee about the need for more therapies, even ones of questionable benefit.
Patients "are pleading for something other than the one drug that's been approved in the last 30 years," said Jim Kiefert, chairman of Us Too, a non-profit group for prostate cancer patients.
