Update from 10 am EST: The FDA has listed Jan. 22, 2016 as a tentative date for a Sarepta FDA advisory panel, according to theFDA web site.

BOSTON (TheStreet) -- There is yet another twist in the crazy Duchenne muscular disease drug development story.

On Wednesday morning, the U.S. Food and Drug Administration confirmed Nov. 24 as the date for an advisory committee meeting to review BioMarin Pharmaceuticals' (BMRN) - Get BioMarin Pharmaceutical Inc. Report Duchenne drug drisapersen. Notice of the meeting was posted in the Federal Register.

Where is the concurrent FDA advisory panel for Sarepta Therapeutics (SRPT) - Get Sarepta Therapeutics, Inc. Report and its Duchenne drug eteplirsen? Everyone expected FDA to schedule back-to-back panels on Nov. 23 and 24, but there is no discussion of a Sarepta meeting in Wednesday's Federal Register.


Sarepta shares were down 8% to $30.42 Wednesday on the omission. Before investors panic, remember, FDA already instructed Sarepta to prepare for an advisory panel to discuss eteplirsen.

It's entirely possible Thursday's Federal Register will communicate details of the Nov. 23 FDA panel date for Sarepta. There is precedent. In 2012, FDA held back-to-back advisory panels to review competing cholesterol-lowering drugs from Aegerion Pharmaceuticals (AEGR) and Genzyme. Advance details about the two panels were posted in Federal Registers on consecutive days.

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One knock on this theory: In the case of Aegerion and Genzyme, the separate Federal Register postings mirrored the order of the FDA advisory panels. That would not true in for Biomarin and Sarepta, since Biomarin's panel is Nov. 24, presumably the second of the two-day meeting. 

It's also entirely possible the FDA schedules an eteplirsen review at a later date. Sarepta filed its new drug application for eteplirsen two months after BioMarin, so perhaps FDA didn't have time to prepare for a back-to-back advisory panels.

That's just speculation, of course. I reached out to Sarepta for comment but have not heard back yet.

The FDA is holding the BioMarin drisapersen panel on its D.C.-area campus, so presumably, the meeting will be webcast for free. The FDA has also allotted two hours for public comments during the meeting, twice as much time as usually given.

BioMarin shares were up 4% to $102.98.

The Duchenne drug development story is never boring.

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.