Sarepta Begins Enrollment for Key 25-Patient Safety Study
Sarepta Therapeutics (NASDAQ:SRPT) announced on March 16, 2026, that it has begun screening and enrolling patients for Cohort 8 of its ENDEAVOR study. This pivotal trial will evaluate an enhanced immunosuppression safety protocol for its gene therapy, ELEVIDYS, in non-ambulant individuals with Duchenne muscular dystrophy (DMD). The cohort is set to enroll approximately 25 participants in the United States.
The study's design directly targets the safety concerns that have hampered the therapy. Participants will receive the immunosuppressant sirolimus for 14 days before the ELEVIDYS infusion and for 12 weeks afterward. The trial's primary endpoints are the incidence of acute liver injury (ALI) and the measurement of ELEVIDYS-dystrophin expression at the 12-week mark, providing a clear data package for regulatory review.
Path to Reclaim Market After Restriction Dropped Sales to $131.5M
This clinical effort is a direct response to a significant regulatory setback from the U.S. Food and Drug Administration (FDA). The agency previously restricted ELEVIDYS's commercial label, removing non-ambulatory patients after two individuals in this group died from acute liver failure following treatment. This move was made to protect a vulnerable patient population with more advanced disease.
The commercial impact of the restriction was immediate and severe. Sarepta's sales for ELEVIDYS fell to $131.5 million in the third quarter of 2025, a sharp decline from $282 million in the second quarter. By proving the new sirolimus regimen can mitigate liver risks, Sarepta aims to provide the FDA with the necessary data to resume commercial dosing for the non-ambulatory population and recover this lost revenue stream.
Analysts Eye 2027 for Potential Label Expansion
Analysts view this study as a critical step toward restoring the therapy's full market potential. William Blair analysts called the FDA's go-ahead for the study design in November 2025 a "constructive step" that offers a "viable pathway" to a broader label. Should the trial produce positive results, Sarepta could be positioned to pursue a label change, with analysts projecting a potential approval as early as 2027.
This outlook is supported by preliminary independent research. A retroactive analysis by Vanderbilt University Medical Center on six DMD patients who received sirolimus as a prophylaxis before their ELEVIDYS infusion showed that none developed acute liver failure. While the sample size is small, this result provides an early proof-of-concept for the Cohort 8 protocol and adds to investor confidence in Sarepta's strategy.
