Tomorrow's advisory-panel showdown between Genzyme (NASDAQ:GENZ) and the Food and Drug Administration should be a good one. The company aims to get its leukemia drug, Clolar, expanded to treat elderly patients with acute myeloid leukemia (AML). The FDA, however, seems less than thrilled about the path Genzyme took toward this goal.

The debate surrounds the clinical trial that Genzyme ran in hopes of proving that Clolar helps elderly AML patients. The drug is already approved to treat children with acute lymphoblastic leukemia (ALL). This latest trial didn't have a control group of subjects who didn't get the drug, so it's difficult to determine how patients might have fared compared to the 45.5% remission rate for the patients taking Clolar. In 2005, an FDA advisory panel failed to recommend an AML drug from Johnson & Johnson (NYSE:JNJ) because it was missing a control group, so things aren't looking good for Genzyme.

The company says that the patients wouldn't really have any other treatment options -- and I'm assuming spontaneous remission is much, much rarer than 45% -- but the FDA panel seems to be disappointed that there was no placebo control group, nor a test against chemotherapy, which might have benefited some of the patients.

The problem for Genzyme tomorrow: Even if it convinced a majority of the advisory committee members that there was enough data to prove the drug's success in AML patients, the FDA has the final say. The agency seems set to reject the expansion of Clolar, no matter what the panel votes.

Remember Dendreon's (NASDAQ:DNDN) 2007 panel meeting? The panel voted 13 to 4 that there was "substantial evidence" of Provenge's efficacy, but the FDA decided that wasn't enough data to approve the drug. Since that very famous case, there have been plenty of other examples -- Schering-Plough's (NYSE:SGP) Bridion and Cardiome's (NASDAQ:CRME) Kynapid, just to name a couple -- where the FDA failed to approve drugs that were recommended by the advisory panel.

Good luck, Genzyme.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. Johnson & Johnson is a selection of the Income Investor newsletter. The Fool has a disclosure policy.