Sarepta's Gene Therapy Shows Sustained Slowing of DMD Progression in Landmark Three-Year Data

CAMBRIDGE, Mass. – Sarepta Therapeutics announced compelling three-year data from its EMBARK study on Thursday, providing the most robust evidence to date that its one-time gene therapy, ELEVIDYS, can durably slow the progression of Duchenne muscular dystrophy (DMD). The findings, hailed by company executives as a first for the field, suggest the treatment's benefits may widen over time compared to the disease's natural history.

DMD, a devastating genetic disorder causing progressive muscle degeneration, typically sees functional abilities peak around age six before an irreversible decline. The new analysis from EMBARK—which combines the initial two-year trial data with a year of follow-up from an extension study—aims to demonstrate whether ELEVIDYS can fundamentally change that arc. The therapy works by delivering a gene to muscle cells to produce a functional, if shortened, form of the crucial dystrophin protein.

"This three-year dataset directly tests our core hypothesis: that a disease-modifying therapy should show a meaningful and growing divergence from the expected natural course," said Sarepta CEO Doug Ingram. "We are moving beyond symptomatic management toward altering the underlying biology."

With all trial participants having received the therapy by the one-year mark, Sarepta researchers employed a "propensity-weighted external control"—a statistical method considered the gold standard—to compare treated patients to a matched group reflecting contemporary standard of care. Dr. James Richardson, Sarepta's Chief Medical Officer, reported that key functional measures, including the North Star Ambulatory Assessment (NSAA), continued to show a statistically significant treatment benefit at the three-year point.

Notably, only two treated patients lost the ability to walk over three years, approximately half the number observed in the external control group. Dr. Richardson cautioned that absolute numbers remain small but called the trend "encouraging." The safety profile remained consistent, with no new signals identified and no treatment-related serious adverse events reported in the third year.

The clinical implications were underscored by independent neurologist Dr. Crystal Proud. "In practice, we see tangible differences," she said. "A measure like the 10-meter walk test isn't just a number—it translates directly to prognosis and family planning. Slowing this decline is fundamentally changing what we can expect for these boys."

Analysts note the data could strengthen Sarepta's case with global regulators and payers. While the current U.S. label is for ambulatory patients four and older, Ingram stated the company is evaluating the impact of the new data on future regulatory discussions. Sarepta is also ramping up commercial efforts, doubling its sales force and expanding educational initiatives.

Expert Commentary:

Dr. Anya Sharma, Pediatric Neurologist at Stanford Children's Health: "This is the longitudinal data the community has been waiting for. The sustained separation from the control curve is critical. It moves the conversation from 'Does it work?' to 'How much can it change the long-term outlook?' The external control methodology is robust, which adds credibility."

Michael T. Rossi, Parent Advocate and Founder of the DMD Hope Foundation: "Every day of retained function is a victory. Seeing data that suggests walking ability is preserved longer is emotionally overwhelming for families. This isn't just a statistical win; it's more birthdays celebrated on their feet, more time with peers. We need access expanded, now."

David K. Chen, Biotech Analyst at Horizon Capital: "The market's focus has been on short-term functional gains. This three-year data is strategically important for Sarepta—it begins to build the long-term value argument. However, the high price tag remains a massive hurdle. Proving a durable effect is the first step in justifying the cost to healthcare systems."

Dr. Helen Pierce, Bioethics Professor: "Let's temper the enthusiasm. A slowed decline is progress, but it's not a cure. The therapy's astronomical cost creates a devastating access divide. We're celebrating data for a few hundred patients while thousands worldwide have no options. This is a biotech success story shadowed by a profound failure in equity."

Sarepta expects further updates later this year, including cardiac function data from a subgroup and readouts from other neuromuscular disease programs.