Sarepta slips as FDA seeks more data on eteplirsen

Sarepta Therapeutics ($SRPT) has kept hopes alive for gaining accelerated approval for its lead drug eteplirsen for Duchenne muscular dystrophy. Yet the FDA wants additional information from the company's existing dataset before the agency decides whether to grant the company's request for accelerated approval, which would allow Sarepta to seek approval based largely on efficacy data from a 12-patient Phase II study.

An accelerated approval also would give Cambridge, MA-based Sarepta an inside track on having the first disease-modifying therapy for muscular dystrophy on the U.S. market. The company has won over investors with tantalizing data from the Phase II study, with its share price more than tripling over the past 12 months. Its small trial has shown significant gains in a 6-minute walk test in patients on its RNA therapy as well as increases in dystrophin, a key protein that protects muscle and is lacking in boys with the rare muscle-wasting disorder.

Yet whether the U.S. regulator grants accelerated approval is up in the air, and shares of Sarepta fell more than 8% in after-hours trading amid uncertainty about the approval pathway for the lead program. Part of the decision hinges on whether the agency accepts dystrophin production as a surrogate to predict clinical benefit. Based on minutes from Sarepta's meeting on eteplirsen with the FDA in March, the company reported Monday that regulators wanted "a comprehensive summary to support dystrophin as a surrogate" as well as details on outcomes from the study of the lead drug. Sarepta expects to submit the requested info in the coming weeks and seek a follow-up meeting with the FDA later in the second quarter.

President and CEO Chris Garabedian

"We are encouraged by our interactions with the FDA and their Division of Neurology Products and we view their request for more data as a reflection of the thorough and comprehensive approach that the agency takes in evaluating a new surrogate marker," Chris Garabedian, Sarepta's president and CEO, said in a statement.

In his own reading of Sarepta's update, TheStreet's Adam Feuerstein, who has been bullish about the prospects of an eteplirsen approval, argues that the agency's request for info signals that the regulator is essentially already reviewing the treatment. And he advised that an FDA acceptance of accelerated approval would indicate that the agency would approve the drug.

Regardless of the agency's decision on accelerated approval, Sarepta aims to compete planning for a confirmatory trial of eteplirsen and begin dosing patients for that study in the first quarter of 2014. The company is in a race with a rival DMD therapy called drisapersen from GlaxoSmithKline ($GSK), which had also considered accelerated approval and has already begun Phase III development of the drug. Last week GSK revealed long-awaited mid-stage study results from the program, showing an improvement over placebo in patients treated with drisapersen in the walk test used to gauge efficacy.

Analysts will slice and dice every comment and press release detail from Sarepta in an effort to handicap its chances for an accelerated regulatory pathway. For now, it's only clear that the company is still in the running to win a rapid review of eteplirsen, but investors will have to wait months before they know for sure whether the agency will green-light an early application for approval. And anything resembling a delay in drug development tends to disappoint.

- here's the release
- see the update from Barron's
- check out TheStreet's take
- and Reuters' article

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