Sarepta Therapeutics, Inc. has provided an update on its discussions with the US Food and Drug Administration (FDA) regarding a potential application for accelerated approval of eteplirsen for the treatment of Duchenne muscular dystrophy (DMD). The FDA has requested Sarepta to provide additional information from the existing eteplirsen dataset to inform a decision on the acceptability of this dataset for an NDA filing under the Subpart H Accelerated Approval regulatory pathway.

This feedback was provided in meeting minutes from Sarepta's End-of-phase II meeting with the FDA's Division of Neurology Products that occurred last month.

Specifically, Sarepta received feedback on both the acceptability of dystrophin as a surrogate endpoint that would reasonably predict clinical benefit in DMD patients and the acceptability of the eteplirsen safety database for a Subpart H Accelerated Approval filing.

"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," said Chris Garabedian, president and chief executive officer of Sarepta Therapeutics. "We are confident that the method in which we've collected dystrophin, the degree and consistency of the dystrophin levels, and the supporting clinical data will provide the Agency the information it needs to determine if dystrophin is a feasible surrogate marker that is reasonably likely to predict clinical benefit."

At the End-of-Phase II Clinical Meeting in March, there was a productive discussion on the suitability of dystrophin as a surrogate marker, including a presentation by Sarepta detailing the methodologies used to analyze dystrophin in the studies and supportive data suggesting that the dystrophin produced is functional. As follow up to the discussion, and as reflected in the meeting minutes from the Division of Neurology Products, the Agency requested two written summaries: "a coherent and comprehensive summary to support dystrophin as a surrogate" and "a detailed discussion of all clinical outcomes in the eteplirsen study."

Furthermore, the meeting minutes contained the following statement:

"The Agency stated that they had not made a final decision regarding acceptability of the proposed Subpart H (Accelerated Approval) NDA filing, and that the Agency would consider the additional data submitted by the sponsor before making a final decision."

Sarepta also discussed the eteplirsen and phosphorodiamidate morpholino oligomer (PMO) safety database at the End-of-Phase II meeting and asked if the 38 patient eteplirsen safety database was sufficient for a Subpart H Accelerated Approval filing. While Sarepta will continue to collect long-term safety from the ongoing eteplirsen extension study for a potential submission, the meeting minutes stated that: "In the event (the Agency) agrees to file the Subpart H NDA submission, additional safety data to support approval could come from the first few months of the... pivotal confirmatory study." Sarepta still intends to begin dosing patients in a pivotal confirmatory study in the first quarter of 2014.

Sarepta is preparing to submit the dystrophin and clinical outcomes summaries and will be requesting a follow-up meeting with the FDA to discuss these later this quarter. As a result, the End-of-Phase II CMC meeting with the FDA is now expected to occur in the third quarter, however all eteplirsen manufacturing and clinical development activities continue as planned and are not anticipated to delay the potential timeline of an Accelerated Approval NDA submission.

DMD is an X-linked rare, degenerative neuromuscular disorder causing severe progressive muscle loss and premature death and one of the most common fatal genetic disorders.

Eteplirsen is Sarepta's lead drug candidate that is designed to address the underlying cause of DMD by enabling the production of a functional dystrophin protein. Eteplirsen uses Sarepta's phosphorodiamidate morpholino oligomer (PMO)-based chemistry and exon-skipping technology to skip exon 51 of the dystrophin gene enabling the repair of specific genetic mutations. By skipping exon 51, eteplirsen may restore the gene's ability to make a shorter, but still functional, form of dystrophin from messenger RNA, or mRNA. Promoting the synthesis of a truncated dystrophin protein is intended to improve, stabilize or significantly slow the disease process and prolong and improve the quality of life for patients with DMD.

Sarepta Therapeutics is focused on developing first-in-class RNA-based therapeutics to improve and save the lives of people affected by serious and life-threatening rare and infectious diseases.