Silly me. I believed (foolishly) that volatility in Sarepta Therapeutics' (SRPT) - Get Report stock price would lessen (at least temporarily) because we already know eteplirsen will be filed for U.S. approval at the end of the year. The next big event for Sarepta (HUGE, actually) was going to be the inevitable FDA advisory committee meeting in 2015 where both etepirsen -- and Prosensa's (RNA) drisaspersen -- will be put through their respective paces. 

Wrong. Sarepta is down 6% to $28.01 Monday on new worries about eteplirsen efficacy. Of course, these are really just old worries, recycled. With today's sell off, Sarepta shares have almost round-tripped back to where the stock traded in April before the announcement about the eteplirsen filing.

New (old) worry No. 1: OMG! The 144-week eteplirsen data might be terrible! 

Sarepta has committed publicly to disclosing updated results from the ongoing, phase II study of eteplirsen in the 12 DMD patients. For those keeping track, this is the 144-week update. All previous updates from the study have been non-events, which is terrific because it means the DMD boys continue to show a remarkable stability in their ability to walk.

Sarepta spokesman Jim Baker says the eteplirsen data from the 144-week update of the phase II study will be presented at the World Muscle Society meeting in October. Ahead of the conference, the company may issue a press release announcing the results in the third quarter, Baker told me, via phone Monday. 

"We have always been transparent with respect to the eteplirsen data, so we won't sit on things that are material," said Baker. 

New (old) worry No. 2: OMG! The Willis twins are declining.

Jack and Nolan Willis are the two DMD boys who entered the eteplirsen phase II study at its onset but quickly lost the ability to walk. As a result, Sarepta excluded them from the analysis of the phase II study results -- a decision which has sparked much discussion and controversy from the very beginning, none of which is new. However, both of the Willis boys continue treatment with eteplirsen despite being in wheelchairs and have shown stability in other muscular functions, according to updated study data already reported by Sarepta. 

Last week, Allison Willis, the mother of Jack and Nolan, was quoted in a local news story lamenting her sons' loss of upper body strength. Here's the relevant passage from the article:

Handing out cups of water during the Cazenovia 4th of July Foot Races is a family tradition for Alison Dwyer Willis, but she recently realized her 12-year-old twins wouldn't be able to take part this year. "The upper body strength of my twins is just not enough to even hold the cups. So I was faced with the decision of what do we do at the Fourth of July now? We've always been out there," said Willis.

Investors saw the article and freaked out on Sarepta.

In response, Allison Willis wrote an email to the DMD community, addressing her comments in the article. Here's her email, in full:

Dear Duchenne community and Alliance supporters: It has come to my attention through multiple outlets that there is skepticism as to whether Eteplirsen actually works given my recent comments to local and national media groups.  My comments about my boys not being able to hold a cup during a running race to hand out water was taken bit out of context.  Jack and Nolan have no problem drinking, eating, nor brushing their own teeth.  They are still able to write proficiently, use video game controllers, and type on their computers.  It is absolutely MADDENING that there are those out there looking to deep-six this drug so quickly based on and out-of-context remark.  True...they struggle holding their arms outstretched with 12 oz cups of water waiting for hundreds of runners to pass by and rip them from their hands. Hell, I have a problem doing it sometimes.  SHAME on those casting dispersions about Eteplirsen; looking to use this as an opportunity to tear down this drug...especially after what Jack, Nolan, and 10 other boys, their families, and Sarepta have been through these past 4 years to get this drug off the launch pad.  Talk about being kicked while you're down?  I'm disappointed that I even have to address this situation to a community I have immersed my life in and and fought so hard for.  Shame...

Sarepta cannot comment publicly about individual patients in the eteplirsen study, said company spokesman Baker. 

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;

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