If history holds, it looks as if Arena Pharmaceuticals (Nasdaq: ARNA) is unlikely to have to wait an additional three months before the Food and Drug Administration decides the fate of its obesity drug lorcaserin. The PDUFA date, which is the FDA's goal for making a decision, is next Wednesday.

The drug went in front of an advisory panel last month, where some members suggested that the potential heart risks for the drug weren't enough to derail its approval and could be taken care of post-approval. If Arena had to turn in substantial additional documents -- proposed post-approval clinical trials or a Risk Evaluation and Mitigation Strategy -- the FDA was within its means to delay the decision by three months to review the extra paperwork. That's what happened to VIVUS (Nasdaq: VVUS), which was supposed to hear about its obesity drug in April, but will have to wait until next month for a decision.

Based on recent FDA extensions, Arena would seem to be in the clear at this point. The agency has been notifying companies well ahead of their PDUFA dates.

Drug

Company

Days Before PDUFA That the Delay Announced
Qnexa VIVUS 8
Adasuve Alexza Pharmaceuticals (Nasdaq: ALXA) 12
Lymphoseek Navidea Biopharmaceuticals 69

Source: news reports.

Of course, there are always exceptions to the rules. KV Pharmaceutical (NYSE: KV-A) announced a delay for Makena just one day before its PDUFA date. Not that the agency had a choice; KV's partner, Hologic, provided FDA-requested information within the week before the decision, so a delay couldn't have been announced sooner.

At this point, there are four scenarios I can see for lorcaserin:

  • The FDA sees no need for additional paperwork.
  • Arena turned in paperwork, but the FDA had no problem handling it and didn't require an extension.
  • History be darned, a delay is still coming.
  • The FDA wanted paperwork Arena didn't turn in, so no delay, but don't expect an approval next week.

The first two are obvious wins for Arena. The third might not be so bad; VIVUS has held up well after its delay. A delay is likely to be perceived as a sign that the FDA doesn't have any other issues with the drug. Why worry about post-approval requirements if the drug isn't going to be approved? Mind you, that isn't bulletproof logic. Alexza was still rejected after that delay, but a swift resubmission of Adasuve implies the issues raised in the CRL were easily addressable.

The biggest risk for investors at this point is that the FDA wants paperwork but Arena hasn't turned it in. How does something like that happen? I have no idea who's to blame -- an opaque FDA or an obtuse company -- but it certainly happens. The application to file Roche and ImmunoGen's (Nasdaq: IMGN) T-DM1, for instance, wasn't accepted by the FDA because the agency didn't think Roche tested the drug in the right patient population.

Given the volatility in Arena's shares over the past couple of days, it seems investors aren't sure what's going to happen at the binary event next Wednesday. Assuming it happens at all.

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