Will the FDA Approve Affymax's Peginesatide?

After a 15-1 vote by an advisory panel recommending approval of Affymax's (NAS: AFFY) anemia drug peginesatide, you'd think the chance of approval would be pretty good. And it is.

Just be careful in assuming that the panel's solid recommendation means a Food and Drug Administration approval tomorrow is guaranteed. It isn't.

The FDA has gone against its outside advisors before, even when the vote was by a wide margin. Bristol-Myers Squibb (NYS: BMY) , for instance, got a solid 13-to-5 vote by the advisory panel recommending approval of belatacept, which helps avoid rejection of transplanted kidneys, but the FDA still asked for more data. Four years ago, Schering-Plough got a unanimous recommendation on Bridion, a drug used to reverse the effects of anesthesia, but the FDA rejected it, and Merck (NYS: MRK) , the drug's new owner, still hasn't gained approval in the U.S. yet.

Affymax and partner Takeda asked the FDA to approve peginesatide for patients on dialysis because the drug seems to increase the risk of cardiovascular events in patients not on dialysis. The advisory panel brushed off the data and concentrated on the data in dialysis patients where the side effect wasn't seen, but it's not clear to me that the FDA will do the same.

If peginesatide was the first treatment for anemia or had vastly better efficacy than the current offerings, it would be easy to assume the FDA will ignore safety concerns. But the main advantage of peginesatide over Amgen's (NAS: AMGN) Epogen or Johnson & Johnson's (NYS: JNJ) Procrit is that it has to be used only once a month. That will certainly help with sales, but I'm not sure the FDA will see it as much of an advance toward saving patients' lives.

As I said at the outset of this article, I think an approval is more likely than not, but figuring out how much weight investors should give to the "not" is difficult, because it's hard to read what the FDA is thinking. Based on the option prices, it doesn't look as if investors are all that worried, but that means there isn't a tremendous upside in the stock, either. Don't expect an instant double after an approval.

I can't see much reason for buying Affymax now unless you're buying it as a long-term purchase, and then, given the unknowns, waiting until its de-risked post-approval might be the best move for some or all of your investment. Analysts at the Fool's Rule Breakers newsletter service have a health-care investment they think would make a good long-term purchase. Find out the company and see why they think it'll be a success in their new free report, "Discover the Next Rule-Breaking Multibagger."

At the time thisarticle was published Fool contributorBrian Orelliholds no position in any company mentioned. Check out hisholdings and a short bio. The Motley Fool owns shares of Johnson & Johnson.Motley Fool newsletter serviceshave recommended buying shares of Johnson & Johnson and creating a diagonal call position in Johnson & Johnson. The Motley Fool has adisclosure policy. We Fools don't all hold the same opinions, but we all believe thatconsidering a diverse range of insightsmakes us better investors. Try any of our Foolish newsletter servicesfree for 30 days.

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