The Food and Drug Administration's delaying its decision on whether to approve Human Genome Sciences (Nasdaq: HGSI) and GlaxoSmithKline's (NYSE: GSK) Benlysta shouldn't come as much of a surprise. The FDA gave the drug a six-month priority review and then scheduled the advisory panel meeting 5.25 months into it. Three weeks is a pretty tight time frame to finish up a review.

I was expecting a delay of weeks rather than three months, but the length of the delay isn't that big of a deal. In the long run, it really doesn't matter if the duo launches Benlysta three months later than originally expected.

But the reason for the delay -- the FDA requested new information, which it needs to review -- should be a little more worrisome.

Maybe.

It really depends on what information the FDA requested. Unfortunately, the companies weren't more specific.

The FDA advisory panel recommended approving the drug 13-2. The agency doesn't have to follow its advisors' recommendation -- Merck's (NYSE: MRK) Bridion, Bristol-Myers Squibb's (NYSE: BMY) belatacept, Dendreon's (Nasdaq: DNDN) Provenge, and InterMune's (Nasdaq: ITMN) pirfenidone were all rejected despite positive FDA advisory panels -- but the Benlysta advisory panel seemed fairly convinced the drug worked even though a subset analysis showed the drug doesn't seem to work in African-Americans.

If the information request revolves around that analysis, it could mean the FDA is considering a restrictive label on the drug. Lupus occurs three times more frequently in African-Americans than it does in Caucasians, so removing African-Americans as potential patients would dramatically reduce Benlysta's peak sales.

On the flip side, the FDA could have requested information about the manufacturing of Benlysta or who knows what else. Without any further knowledge, it's really difficult to know if the delay is a minor issue or something a little more serious.

As far as I can see, investors are assuming the issue is fairly minor; Human Genome Sciences hardly moved today and has a market cap of nearly $5 billion despite not having any drugs on the market yet. Maybe they're right, but the unknown risk and muted upside will have me staying away for the next three months.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. 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 Fool owns shares of and has written covered calls on GlaxoSmithKline, which is a Motley Fool Global Gains recommendation. The Fool has a disclosure policy.