Since Elevidys’ accelerated approval in 2023, experts have been clamoring for more data, particularly in older and non-ambulatory children. New results, presented Friday, show mobility improvements in 8- to 9-year-old patients after one year of follow-up.
Sarepta Therapeutics touted “statistically significant and clinically meaningful” functional improvements in kids aged 8 to 9 years with Duchenne muscular dystrophy treated with the company’s gene therapy Elevidys. These findings, according to the company, are indicative of the “stabilization or slowing of disease progression.”
The results, presented Friday at the 2025 annual meeting of the American Society of Gene & Cell Therapy in New Orleans, should help provide a fuller picture of Elevidys’ efficacy. In an interview with BioSpace in October 2024, Craig McDonald, chair of the Department of Physical Medicine & Rehabilitation at UC Davis Health, highlighted gaps in the current understanding of Elevidys. “I think we do still have limited data on the older ambulatory patients that are clearly in the skill-losing phase of the disease,” he said.
“I think it’ll be important to show that either there’s a significant reduction in the rate of slowing of disease progression or the patient’s actually showing stability and stabilization of their disease over time,” McDonald added.
Friday’s data come from a post-hoc analysis of the Phase III EMBARK trial. Results showed that after one year of follow-up, patients infused with Elevidys saw a 0.37-point improvement in the North Star Ambulatory Assessment test, a validated tool used to measure functional abilities in children. Patients in an external control arm who were instead managed with stable doses of oral corticosteroids, saw a 4.38-point decline. The treatment effect of 4.75 points was statistically significant, according to Sarepta’s readout.
Additionally, patients treated with Elevidys saw significant improvements in time to rise and the 10-meter walk/run test, other tests of mobility. The gene therapy likewise resulted in sustained expression of the microdystrophin protein, Elevidys’ genetic payload that replaces the gene damaged in DMD, for up to 64 weeks. Sarepta said that increase suggests “durability of [Elevidys’] treatment effect.”
Sarepta also provided a brief two-year safety update for Elevidys, noting that outcomes “were consistent with prior experience” from the clinical development program. Side effects were overall “manageable with appropriate monitoring.”
The data come two months after news of a patient death shook the Duchenne space—and sent Sarepta’s shares spiraling. In March, the biotech announced that one patient on Elevidys treatment developed acute liver failure, which eventually became fatal.
Sarepta noted at the time that liver toxicities are not new for the therapy but conceded that the death “represents a severity of acute liver injury not previously reported for Elevidys.” The biotech has promised to update Elevidys’ label to reflect this risk, but as of writing, the changes have yet to be made.
