An FDA Advisory Panel Doubleheader

You don't have to head to spring training to see a big doubleheader this week. A panel of outside experts will determine the fate of two drugs affecting three different companies at a pair of advisory panel meetings tomorrow. Whether the companies hit it out of the park or go down swinging depends on whether the advisors think a small benefit in delaying cancer is worth the potential side effects.

First up, GlaxoSmithKline (NYS: GSK) is trying to get Votrient, which is already on the market to treat advanced kidney cancer, expanded to treat another cancer called soft-tissue sarcomas. Votrient increased by three months the progression-free survival, or PFS, defined as the time until the tumor starts growing again or death occurs, whichever comes first. While three months is a fairly small amount of time, patients who got a placebo had a PFS of only 1.6 months. Overall survival was trending in the right direction -- 12.6 months for patients taking Votrient versus 10.7 months for patients that got placebo, but the difference isn't statistically significant.

In the afternoon, the panel will review Merck's (NYS: MRK) and Ariad Pharmaceuticals' (NAS: ARIA) ridaforolimus, which the company is proposing be named Taltorvic if approved. Ridaforolimus was tested in patients with soft-tissue sarcomas, and like Votrient it didn't show a statistically significant increase in overall survival: 20.8 months with ridaforolimus versus 19.6 months with the placebo. More troubling, Merck came up with a different number for PFS -- a 3.1-week increase -- than the FDA, which said it was only 2.1 weeks. Both were statistically significant, but obviously the larger the difference, the better.

Overall survival is what patients and doctors care about, but PFS can be a decent surrogate if there's a clinically meaningful difference. What's the definition of clinically meaningful? It depends on what else is available. Pfizer's (NYS: PFE) Sutent and Novartis' (NYS: NVS) Gleevec are approved for sarcomas that develop in the gastrointestinal track, but there aren't many treatment options for other sarcomas.

Votrient will likely have an easier time getting past the panel because it was being tested in patients who had failed chemotherapy. With no other options, even a small difference is meaningful.

Ridaforolimus was tested as a maintenance therapy for patients who responded to chemotherapy. Because it's designed to be taken for a long period of time, side effects will come into play -- 14% of treated patients dropped out because of adverse events versus just 2% in the placebo arm of the trial. The marginal increase in survival might not be worth experiencing the adverse effects.

The advisory panel will make its recommendation on both drugs tomorrow, but investors will have to wait until the baseball season is in full swing to find out the ultimate fates of the drugs. Votrient is scheduled to get an FDA decision on or around May 6, while the decision on ridaforolimus will come closer to June 5.

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At the time thisarticle was published Fool contributor Brian Orelli holds no position in any company mentioned. Click here to see his holdings and a short bio. Motley Fool newsletter services have recommended buying shares of GlaxoSmithKline, Pfizer, and Novartis. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.

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