GPC Must Wait

Taking the most conservative route, an FDA advisory panel voted 12-0 to recommend against approving GPC Biotech's (Nasdaq: GPCB) lead prostate cancer treatment, Satraplatin. As expecte, such a negative outcome hit GPC's stock hard, driving shares down 33% today.

On Friday, the FDA issued a briefing document before the advisory committee meeting, detailing all the concerns that it had with the large phase 3 study at the center of GPC's New Drug Application for Satraplatin.

Even though the panel vote was unanimous against approving the compound at this point, the agency's main issue with the drug was the accelerated approval route that GPC was taking. The FDA recommended waiting until final overall survival data on the drug was completed before possibly approving the compound.

GPC had previously guided that the phase 3 study should meet the required number of events to start collecting the data for overall survival some time around the end of the year.

Whether it was posturing because it feared that the FDA would decide to postpone the drug's approval until these results arrived, or because the timeline for this data actually has changed, GPC noted that "final overall survival results could take longer than the previously communicated timeframe of the fall of this year" to occur.

Interim overall survival results were taken after 463 patients had died, and they showed a strong trend in favor of Satraplatin-treated patients. Final results on the overall survival endpoint will be completed once 700 patients have died.

I was somewhat surprised by the unanimously negative panel vote. I figured that GPC would get a better shake at the advisory committee, since the drug's data generally showed it to have a positive effect in late-stage prostate cancer patients, and also since there are few other treatments available for the condition.

After getting a better look at the data, I still think GPC will be able to eventually get full approval for Satraplatin. It may simply have to wait until the overall survival data comes in. The FDA sometimes goes against the recommendations of its advisory panels, but in this case, I expect the agency to play it safe and issue an approvable letter for the drug in August.

Looking for more Foolish drug stock coverage? Check out the Fool's market-beating Rule Breakers newsletter. You can check out all our recommendations as well as get access to our message boards and exclusive content with a 30-day free trial.

Fool contributor Brian Lawler does not own shares of any company mentioned in this article. The Fool has a disclosure policy.