Biotech Stock Mailbag: Sarepta, Inovio, FDA Calendar, Ken Luskin's Angry Vical Voice Mail

BOSTON ( TheStreet) -- The Biotech Stock Mailbag is open. Jeff H. writes:

I have a long position in Sarepta Therapeutics (SRPT) and I'm having a hard time filtering through the many opinions/angles on their latest announcement to file for the new drug application. Seems like it's good news generally, but I can't quite wrap my head around the bad news part of it other than the short term "not approved yet" aspect. What is the real take on this announcement? Is this just the FDA covering themselves but not favoring a superior drug (eteplirsen over drisapersen) publicly while privately thinking it will get approved? Is the waffling on dystrophin endpoint just an excuse since Sarepta is superior in that arena too? I know you've written a little about it since the announcement but wondering if any more Big Picture thoughts have occurred to you. Thanks.

Sarepta announced the intention to seek U.S. approval for eteplirson on July 24. Here's the stock chart, before and after: SRPT Chart SRPT data by YCharts

Um... Wasn't an early eteplirsen filing supposed to be good news?

I've often said stocks prices can lie, especially over the short term. To say this about the current Sarepta situation would be facile. Even bulls (hand raised) need to acknowledge the significant risks to the eteplirsen early approval thesis. Feel free to label me delusional, but I was pleased with Sarepta's July 24 announcement. It was everything I expected, including the cautious language describing the FDA's apparent uncertainty with dystrophin as an approvable endpoint. The only disappointment, minor, is the eteplirsen filing potentially not being completed until the second quarter 2014.

I still expect FDA to approve eteplirsen on the current phase II data, most likely the six-minute walk benefit rather than purely on dystrophin production. (Although dystrophin data will support the approval.)

On the company's earnings call Thursday, Sarepta CEO Chris Garabedian did a nice job explaining the routes FDA can use to review and approve eteplirsen, including granting full approval. If you've been following the Sarepta story closely, you knew this already. Hopefully, though, Garabedian's explanation resolved the confusion which exists.

Before the eteplirsen filing and FDA review happens, GlaxoSmithKline ( GSK) and Prosensa ( RNA) will be announcing results from a phase III study of drisapersen during the fourth quarter. The companies may also release dystrophin production data from a previous drisapersen phase II study.

I can conjure multiple scenarios for how Sarepta's stock price reacts to these data. Best case for Sarepta: Drisapersen data that are "meh" -- meaning efficacy and toxicity in line with the current view of the drug: Drisapersen improves walking ability but at the cost of serious side effects, including kidney toxicity and thrombocytopenia, with extended use.

Worst case for Sarepta: The drisapersen data are super strong, meaning better-than-expected walking improvements with few reported side effects. If this scenario plays out, expect the Sarepta short story to switch to something like this: "With drisapersen data so strong, FDA is no longer under any pressure to approve eteplirsen early. DMD patients will be happy if just drisapersen is approved."

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