A Proactive FDA Is Already Reviewing Sarepta's Muscular Dystrophy Drug

CAMBRIDGE, Mass. ( TheStreet) -- The U.S. Food and Drug Administration is actively reviewing the efficacy and safety of Sarepta Therapeutics' ( SRPT) Duchenne muscular dystrophy drug eteplirsen even though the drug has not been formally filed for approval yet.

Weird, huh? But also good news for Sarepta. While investors have been obsessing over whether or not FDA will allow an eteplirsen accelerated approval, the agency is already reviewing the drug as if it was filed.

Why? Because FDA understands that a decision to allow Sarepta to file for accelerated approval filing means eteplirsen will be approved. What's going on with eteplirsen now at FDA is not a "file or don't file" decision, it's a mini review.

Read carefully Sarepta's announcement Monday because the evidence of an ongoing eteplirsen review is all there. FDA has asked the company to provide written summaries supporting the use of dystrophin as a surrogate endpoint for approval, as well as a discussion of clinical outcomes from the phase II study.

The FDA doesn't ask for this type of information from companies who haven't yet filed a drug for approval. Instead, these are the types of questions FDA asks of a drug sponsor during the review process.

So, what happens now? Sarepta puts together the data and submits it to FDA. The agency will then review the new data and make a final decision on accelerated approval. We don't know what the FDA will ultimately decide or when, but if the agency tells Sarepta, "Yes, you can file," then investors should interpret this as eteplirsen being approved.

Why is this good news, again? Because the FDA could have easily told Sarepta to come back with data from the planned phase III study. That would have told us FDA didn't believe the existing eteplirsen data.

I spoke briefly with Jenn McNary and Christine McSherry, DMD advocates who have met with top officials at FDA several times to lobby for eteplirsen's rapid approval. Both women are pleased with today's news because it shows the FDA is willing to work with Sarepta to get the drug to market as soon as possible.

"What we're seeing is a progressive, creative FDA," said McSherry, co-founder of the Duchenne Alliance.

"I feel pretty good about this," said McNary, whose son, Max, received eteplirsen in the phase II study. "This is what the FDA told us they'd do."

Sarepta shares were down 12% to $34.25 in Monday after-hours trading.

-- Reported by Adam Feuerstein in Boston.

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.