Sarepta Poised to Start Next Trial of SRP-9001 for Duchenne MD

Sarepta Therapeutics has completed a meeting with the Office of Tissues and Advanced Therapies (OTAT) that clarified regulatory requirements to start the company’s next clinical trial of SRP-9001, an investigational gene therapy for Duchenne muscular dystrophy (DMD).

During the type C “written response only” meeting, the OTAT — an arm of the U.S. Food and Drug Administration (FDA) — asked Sarepta to use an additional potency assay to support the release of SRP-9001’s commercial process material. According to the OTAT, this test should be performed before the therapy is given to patients in the upcoming trial.

Potency assays are a type of test used to determine a medication’s ability to induce a specific effect when given at a particular dose. Such tests often are requested by regulatory authorities and must comply with Good Manufacturing Practices (GMP). That means they are produced consistently and follow established quality standards.

Sarepta already conducted several potency assays and has acquired data it believes could be used in response to OTAT’s request, the company stated in a press release. However, additional discussions with regulatory authorities will be needed to determine if existing data will suffice.

“We look forward to working with OTAT to potentially satisfy their requests and to obtain clarity on the timing of the commencement of our commercial supply study. We will provide further updates as we are able,” said Doug Ingram, president and CEO of  Sarepta.

“Every day, thousands of children degenerate from the irreversible damage caused by Duchenne muscular dystrophy. It is for that reason that we will work relentlessly with the Division to satisfy any requests of OTAT and continue the advancement of a potentially transformative therapy for these patients,” Ingram added.

SRP-9001 is an experimental gene therapy that uses a harmless adeno-associated virus (AAV) vector called AAVrh74 to deliver a shorter version of the dystrophin (DMD) gene. This gene version enables muscle cells to produce a smaller but working form of dystrophin (called micro-dystrophin), the protein missing in DMD patients.

Originally developed by investigators at Nationwide Children’s Hospital in Ohio, SRP-9001 was licensed to Sarepta in 2017. Since then, the FDA has given the designations fast track, rare pediatric disease and orphan drug to SRP-9001.

Two clinical trials — the Phase 1/2 Study-101 (NCT03375164) and the Phase 2 Study-102 (NCT03769116) — are assessing the safety and effectiveness of a single infusion of SRP-9001 in young boys with DMD.

Recent one-year data from Study-101 showed that SRP-9001 was safe, well-tolerated, and able to both induce the activity of the micro-dystrophin gene and increase the levels of the resulting protein in boys’ muscle tissues. Treatment also lowered the levels of creatine kinase, a marker of muscle damage and inflammation, and improved participants’ motor abilities. This study is expected to conclude in April 2021.

Study-102 is evaluating the safety and effectiveness of a single dose of SRP-9001 compared to a placebo in 41 boys with DMD, ages 4 to 7. The trial comprises two parts: an initial 48-week period in which SRP-9001 is compared to a placebo; and a 96-week extension study.

Data from Study-102  is expected in October 2022.