The Food and Drug Administration is asking Swiss drugmaker

Roche

to take its experimental hepatitis C therapy to an advisory panel -- an unexpected decision that could benefit

Enzon

(ENZN)

and

Schering-Plough

( SGP), which already market a competing treatment.

Friday, the FDA announced that its Antiviral Drugs Advisory Committee would convene Nov. 14, to discuss Roche's two-drug cocktail aimed at treating the serious liver disease. Roche's experimental therapy combines Pegasys, a longer-acting version of the immune-boosting drug interferon with the antiviral medicine ribavirin. Roche manufactures both drugs.

The only problem with this meeting is that Roche, in its guidance to analysts, has never mentioned the need for an advisory panel meeting, forecasting instead, an FDA approval of the Pegasys therapy in December. Sometimes, the FDA schedules advisory panels because it has clinical concerns with drugs -- it could be about a drug's safety or efficacy -- and it wants to gather outside opinions. If that's the case with Pegasys, it could signal a potential delay in the drug's approval.

That would be welcome news for Schering-Plough and Enzon, which generated sales of $1.4 billion in 2001 for its competing PEG-Intron/Rebetol combination therapy for hepatitis C. (Schering-Plough records sales on its books, paying a royalty revenue to Enzon.) Looming competition from Roche has been a big concern for Schering-Plough and contributed, in part, to the drugmaker's

profit warning last week.

"The scheduling of a panel meeting at such a late date is unusual, and if there's a delay in Pegasys' approval, it would be helpful to Schering-Plough and Enzon," says Legg Mason biotech analyst Stefan Loren. By his reckoning, even if the panel meeting goes extremely well for Roche, it still could push back FDA action into January. He rates Enzon buy, and his firm has a banking relationship with the company.

At this point, the FDA intention vis-a-vis the Pegasys panel meeting is unclear. Roche spokeswoman Pamela Van Houten says the panel members will be asked to address specific questions about the Pegasys combination therapy, but will not be asked to pass judgment on its overall approvability. The FDA has dinged Roche for some manufacturing problems recently, but those kinds of issues are not dealt with at advisory panel meetings.

"There is nothing out of the ordinary here," she says, adding that the company expects an FDA approval decision for Pegasys as a stand-alone treatment for hepatitis C by Oct. 16.

Because Schering-Plough is dealing with a host of problems outside of its hepatitis C franchise, Enzon stands to benefit more if Roche finds itself in an FDA-imposed holding pattern. But so far, investors don't seem to be biting. Enzon closed down 4% Friday and lost another 1.9%, to $16.58, Monday.

That could be because of questions surrounding the company's $370 million acquisition last week of Abelcet, an antifungal drug sold by troubled Irish drugmaker Elan. While Enzon says the purchase will be accretive to earnings, some analysts questioned the move because Abelcet has not performed well for Elan and is perceived as a drug with relatively little sales growth left.