Sarepta Plunges on Harsh FDA Eteplirsen Review Ahead of Next Week's Advisory Panel Meeting

Updated below with additional information and analysis.

Sarepta Therapeutics' (SRPT) stock price plummeted Friday on a very negative clinical review of the company's Duchenne muscular dystrophy drug, eteplirsen, released by the U.S. Food and Drug Administration.

The FDA is convening an outside advisory panel on Jan. 22 to review the eteplirsen data, but Friday's internal assessment by the agency's review team appears to cast significant doubt on the drug's approval chances. Sarepta, of course, will get an opportunity to defend the eteplirsen data and convince the Jan. 22 panel members to vote in favor of the drug's approval.

"Although FDA is prepared to be flexible with respect to a devastating illness with no treatment options, we cannot approve drugs for which substantial evidence of effectiveness has not been established," the FDA states in a summary of the eteplirsen medical review.

A full copy of the FDA's eteplirsen review can be found here. 

Sarepta shares are down 55% to $14.21 in Friday trading.

The FDA, on Thursday, formally rejected drisapersen, a competing DMD drug from Biomarin Pharmaceuticals (BMRN) .

Update: Additional analysis, thoughts and observations on what lies ahead for Sarepta and its DMD drug eteplirsen:

Had you asked me Thursday to sketch out the plot line for the Jan. 22 FDA advisory panel, I would have said something like this: The FDA will be very critical of Sarepta's tiny, 12-patient study, but the agency will also be open to a positive interpretation of the long-term (three year) walk benefit observed in the study.

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