Shares of Dendreon are up about 250% in pre-market trading after Federal health advisers endorsed the company's experimental vaccine to treat advanced prostate cancer as safe and apparently effective.
The Food and Drug Administration advisers voted unanimously Thursday to say Provenge is safe. They then voted 13-4 to say there is substantial evidence that it works in treating advanced prostate cancer that no longer responds to hormone treatment.
Dendreon shares were halted after Wednesday's close. In pre-market trading Dendreon was trading as high as $19.00.
Dendreon shares rose sharply on Wednesday after CNBC reported the planned FDA hearing. About one third of Dendreon shares are sold short.
Dendreon sought a positive recommendation for FDA approval of what would be the first-ever therapeutic cancer vaccine, reported CNBC pharmaceuticals reporter Mike Huckman. The drug, Provenge, has failed to meet some testing endpoints, but also shows signs of conferring survival benefits. Another key hurdle was cleared: the panel voted unanimously -- 17-0 -- that Provenge is "reasonably safe," Huckman said.
The FDA isn't required to follow the advice of its advisory committees, but it usually does. A final FDA decision on whether to approve Provenge, also called sipuleucel-T, is expected May 15.
Neither of two studies Dendreon submitted to the FDA in support of its application achieved their primary goal in showing Provenge delayed the progress of the disease, according to the agency.
However, the results of the first study suggested the vaccine could extend the lives of patients by 4.5 months compared to those given only dummy treatment.
The only other prostate cancer drug shown to prolong the lives of patients is Taxotere, also called docetaxel.
If ultimately approved, Provenge would become the first of a new class of therapies designed to stimulate a patient's own immune system against cancer, according to Dendreon.
Prostate cancer is the most common cancer in American men, other than skin cancer. The American Cancer Society estimates there will be about 220,000 new cases this year, and about 27,000 deaths.
The vaccine combines a protein found in most prostate cancers with a substance that helps specialized immune system cells recognize cancer as a threat, just as they recognize and confront germs that enter the body.
The treatment is customized for each patient. Doctors collect these cells from a patient's blood, mix them with the vaccine, and then give the concoction back to the patient.
Dendreon also is testing Provenge for less serious cases of prostate cancer.