FDA panel recommends against approval of Alkermes' antidepressant ALKS 5461

An FDA advisory committee voted 21 to 2 on Thursday against backing approval of Alkermes' ALKS 5461 for the treatment of major depressive disorder (MDD). The panel additionally voted 20 to 3 that the drugmaker failed to provide sufficient evidence of the efficacy of the therapy. The agency is expected to make a decision on whether to approve the once-daily, oral drug by January 31 of next year.  

"I don't feel the evidence that was presented was substantial to show that there was efficacy," said panel member Terri Warholak, adding "I'm not convinced there is a big enough treatment effect to make a clinical difference." Shares in Alkermes fell as much as 9 percent in response to the vote.

The news comes after FDA reviewers questioned the safety of the drug and raised a number of other concerns ahead of the advisory committee meeting. In two prior late-stage studies, ALKS 5461 failed to significantly improve symptoms in certain patients with MDD, although results from a separate study indicated that the drug met its primary endpoint versus placebo. 

The FDA staff also questioned the lack of data on the effects of ALKS 5461 on unborn infants when the treatment was administered to pregnant women. "We don't know what the mechanism of action is...and the likelihood of dependence and withdrawal," commented panel member Jane Acri, adding "I think it's a very vulnerable population at risk for drug dependence in the first place."

Commenting on the vote, Alkermes CEO Richard Pops said "we were disappointed and surprised by the FDA's characterisation of the safety and efficacy data for ALKS 5461 and the resulting outcome of the advisory committee vote." The FDA has previously declined to accept Alkermes' filing seeking approval of ALKS 5461, but later reversed its position following discussions that "clarified certain aspects" of the submission.  

If approved, analysts forecast peak sales in excess of $1 billion for ALKS 5461, which combines buprenorphine with samidorphan. However, Stifel analyst Paul Matteis said "it seems clear that FDA has essentially made up its mind."

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