Sarepta Therapeutics, Inc. (NASDAQ:SRPT), the leader in precision genetic medicine for rare diseases, today provided a safety update regarding ELEVIDYS (delandistrogene moxeparvovec-rokl), the only approved gene therapy for patients with Duchenne muscular dystrophy, and steps the Company is taking to strengthen the safety profile in non-ambulatory patients. These steps follow a second reported case of acute liver failure (ALF) resulting in death. The cases of ALF to date have both occurred in non-ambulatory individuals with Duchenne. Sarepta extends its deepest sympathies to the affected families and care teams.

Key Safety Initiatives

Evaluating and Enhancing Immunosuppressive Regimen: As part of a comprehensive review of safety data, Sarepta is taking proactive steps to mitigate the risk of acute liver failure in non-ambulatory patients. Sarepta is working to immediately convene an independent group of leading experts in Duchenne and liver health to consider an enhanced immunosuppression regimen for ELEVIDYS. This panel will evaluate data and assess our proposed regimen, which includes sirolimus and is supported by preclinical data demonstrating the effectiveness of additional immunosuppression in moderating liver enzyme elevations, a key factor in mitigating potential safety events. Sarepta will share the panel's recommendations with the U.S. Food & Drug Administration (FDA), and implementation of any new regimen will be subject to FDA guidance and allowance.

Suspending Shipments of ELEVIDYS for Non-Ambulatory Patients: Sarepta is temporarily suspending shipments of ELEVIDYS for non-ambulatory patients while an enhanced immunosuppressive regimen is evaluated, discussed with regulatory bodies, and put in place.

For ambulatory patients, no treatment changes are being proposed and the current practice of administering corticosteroids before and after ELEVIDYS infusion, along with post-treatment monitoring, remains the same.

ENVISION Study Paused: Sarepta has voluntarily paused dosing in the ENVISION clinical study (also known as Study SRP-9001-303). FDA concurs with this action. The pause will allow for the evaluation of a protocol amendment to incorporate an enhanced immunosuppressive regimen for the non-ambulatory patient cohort and incorporate any additional feedback from the FDA. Regulatory alignment is needed before screening and dosing in ENVISION may resume.

ENVISION is a global, randomized, double-blind, placebo-controlled trial evaluating ELEVIDYS in older ambulatory and non-ambulatory individuals living with Duchenne muscular dystrophy. In the U.S., it serves as the confirmatory trial required under the FDA’s accelerated approval pathway for non-ambulatory patients.

“Our paramount priority is the safety and well-being of the patients we serve. We are taking immediate, decisive steps to better understand and mitigate the risk of acute liver failure, including enhancing the immunosuppressive regimen, for those with Duchenne who are non-ambulatory,” said Louise Rodino-Klapac, Ph.D., chief scientific officer and head of research & development, Sarepta. “We are deeply saddened by the loss of a second patient and extend our heartfelt condolences to the patient's family and his care team during this incredibly difficult time. Duchenne muscular dystrophy is a devastating disease that profoundly affects lives and often cuts them far too short. With more than 900 individuals treated to-date, we know how much hope families place in new treatment options like ELEVIDYS – and we are committed to honoring that hope by acting swiftly, guided by scientific rigor and the insights of leading experts, to strengthen safety for all future patients.”

Commitment to Long-Term Safety and Understanding

Sarepta remains committed to a thorough approach and the highest standards of patient safety and scientific rigor. The event has been reported to FDA and global health authorities and will inform ongoing discussions around a potential label update to reflect the risk of severe ALF and additional immune management strategies for non-ambulatory patients. While elevated liver enzymes are a known class effect of all AAV-based gene therapies, the exact mechanism behind AAV-related liver toxicity remains unclear. Current evidence suggests it is likely driven by an adaptive immune response. The Company will provide additional updates as appropriate.