On Men by Ford Vox, MD
Women were the beneficiaries of the first cancer vaccine―Gardasil, approved in 2006 to prevent cervical cancer. Several weeks ago, the same drug was made available to young males to prevent genital warts. And now it looks as if the first vaccine approved to fight cancer, by enhancing the body’s immune response to cancer cells, will benefit males. Last month the Food and Drug Administration committed to deciding the fate of the prostate cancer vaccine Provenge by May 1, 2010. Prostate cancer is an appealing target because it moves slowly (even men whose cancer comes back after prostate surgery often live for well over a decade). That wide window of opportunity gives a vaccine time to prompt the immune system into fighting the body’s own cells when they’ve become cancerous. (The routinely fends off some tumors on its own, generally tiny cancers that are never detected, much less diagnosed.)
But while Provenge is on track to enter the market first, a less-sexy vaccine that hasn’t caught the eye of biotech investors could work just as well at a much lower cost.
To the chagrin of patient advocates (and investors), the FDA ruled against allowing Provenge into doctor’s hands back in 2007 when the results of its large Phase III trial came in. The trial supported the vaccine’s effectiveness¯men with advanced prostate cancer lived several months longer after getting the vaccine. But Dendreon, the company that owns the technology, hadn’t set out to judge the vaccine’s value for extending life. The company had designed the trial, and had so informed the FDA, to assess disease progression¯how fast the cancer grew and spread. Those results didn’t show that the drug offered a statistically significant improvement. New goal, new game, dictated the FDA. The company had to fund a second large trial, this time designed explicitly to test for survival benefit, if it was ever to see its product enter the U.S. market. The results, announced in April, showed that patients with advanced metastatic prostate cancer who had failed other treatments lived four months longer, on average, if they got the Provenge vaccine. That’s statistically significant, but is it clinically significant? Dendreon wants patients and doctors, not the FDA, to decide.