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.

What could go wrong? Sarepta fails to convince FDA that its data on dystrophin production is strong enough to warrant eteplirsen's approval. If that happens, FDA will "reject" eteplirsen following this mini-review, meaning the agency will tell Sarepta to revisit the drug's approval with more data following the conduct of the phase III trial.

I spoke briefly with Jenn McNary and Christine McSherry, mothers of boys with DMD and 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 are down 7% to $36.60 in Tuesday pre-market trading. The stock was down as much as 12% last night following Sarepta's announcement.

-- 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.

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