FDA panel favors accelerated approval of SRP-9001 for DMD

Advisory committee makes recommendation on Sarepta's experimental gene therapy

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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An illustration of a DNA strand.

An advisory committee of the U.S. Food and Drug Administration (FDA) has voted narrowly in favor of accelerated approval for SRP-9001 (delandistrogene moxeparvovec), an experimental gene therapy for Duchenne muscular dystrophy (DMD).

While the FDA is not obligated to abide by the committee’s vote, the agency will consider the outcome as part of its ongoing review of SRP-9001, which is being evaluated as a potential treatment for DMD patients who are able to walk. A decision from the FDA is expected before the end of this month.

“Today’s advisory committee outcome is extremely important to the patient community, who are in urgent need of new therapies,” Doug Ingram, president and CEO of SRP-9001’s developer Sarepta Therapeutics, said in a press release. “With the May 29 action date our top priority, we will work collaboratively with the FDA to complete the review of our [biologics license application] for SRP 9001.”

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DMD is caused by mutations that interfere with the production of dystrophin, a protein that’s important for maintaining muscle health. SRP-9001 is designed to deliver to muscle cells a gene that provides instructions for making micro-dystrophin, a shortened but functional version of this protein.

Sarepta submitted a biologics license application for SRP-9001 last year, and the FDA put the application under priority review, shortening the review time from the usual 10 months down to six months.

Sarepta’s application is seeking approval of the gene therapy under the accelerated approval pathway. Under this process, the FDA can authorize drug developers to market a therapy based on early clinical data suggesting that the treatment is likely to be effective. If accelerated approval is granted, the developers are required to conduct additional testing to confirm efficacy.

In this case, Sarepta’s application is based on data from clinical trials showing that treatment with SRP-9001 led to an increase in micro-dystrophin levels as designed. The application includes data from a proof-of-concept Phase 1/2 study (NCT03375164) in which four boys with DMD experienced improvements in motor function following a one-time treatment with SRP-9001.

The application also includes findings from a Phase 2 trial (NCT03769116) that evaluated the gene therapy in 41 DMD boys, as well as data from the open-label Phase 1 study ENDEAVOR (NCT04626674). Across these studies, findings have generally suggested that boys given SRP-9001 had better motor development than what’s typically seen in DMD.

Wording of the question

At the advisory committee meeting, a panel of experts reviewed available data from the therapy before voting on the question: “Do the overall considerations of benefit and risk, taking into account the existing uncertainties, support accelerated approval of SRP-9001, using as a surrogate endpoint expression of Sarepta’s micro-dystrophin at Week 12 after administration, for the treatment of ambulatory patients with DMD with a confirmed mutation in the DMD gene?”

Eight of the committee members voted yes, while six voted no.

“We extend our sincere appreciation to the families, clinicians, FDA presenters and committee members who participated in today’s panel and to all those who provided input and comments both in the written record and in the open public hearing,” Ingram said.

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