For an oral drug to break into a market dominated by injectable and infused treatments, a company just needs to prove that its drug is as effective as and safe as the current treatments. Patients' disdain for needles will likely do the rest.

Novartis' (NYSE: NVS) oral multiple sclerosis drug, Gilenia, has the first one covered; in briefing documents released today, the Food and Drug Administration said the "pivotal efficacy studies provide robust evidence of the efficacy." But on the safety side, Novartis is in for a tough battle in front of the advisory committee on Thursday.

It's not so much any one side effect, but the sheer number of potential issues that could trip up Gilenia that should have investors worried. Patients taking the drug developed an eye problem called macular edema, heart issues, and skin cancer. The risks are fairly low, but the FDA is worried that they might be higher in an at-risk population that's possibly more prone to developing eye or heart complications. Gilenia will be delayed if the FDA requires data on the subgroup before approval.

Gilenia could also be delayed if the FDA advisory panel recommends testing Gilenia at a lower dose to see if the risk-reward profile is better. The drug already looks better at 0.5 milligrams per day than 1.25 mg per day, and the FDA wants to know if stepping down to 0.25 mg per day would work as well with even fewer side effects.

The opinion of the committee on Thursday and the subsequent decision by the FDA -- most likely in September -- will be watched not only by Novartis, but also the slew of drugmakers that sell injectable and infused multiple sclerosis drugs: Bayer, Merck KGaA, Pfizer (NYSE: PFE), Teva Pharmaceutical (Nasdaq: TEVA), Biogen Idec (Nasdaq: BIIB), and Elan (NYSE: ELN). They all are at risk of losing sales if the FDA approves an oral drug.

Figuring out which way the advisory committee will decide on Thursday is difficult because a risk-benefit analysis is fairly subjective. For instance, Elan and Biogen's multiple sclerosis drug Tysabri can cause a very rare, but life-threatening brain infection called progressive multifocal leukoencephalopathy. Whether the panel of experts will want more studies performed or will be willing to live with the current data remains to be seen.

Todd Wenning suggests taking money off the table when the risk-reward picture doesn't look quite as appealing.

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