Sarepta Therapeutics has reported that the U.S. Food and Drug Administration (FDA) accepted its supplemental new drug applications (sNDAs) for two Duchenne muscular dystrophy (DMD) treatments, Amondys 45 (casimersen) and Vyondys 53 (golodirsen), and set a target decision date of Feb. 28, 2027.
An sNDA is a formal request to the FDA to change or expand the approved use of a medicine already on the market. Both Amondys 45 and Vyondys 53 first reached patients through accelerated approval, a pathway that allows a therapy to be cleared early based on promising signs of benefit while the company continues to gather evidence. These applications ask the FDA to grant traditional, or full, approval, a step that would confirm that the drugs deliver the benefit anticipated by their earlier accelerated approval.
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The rationale for Sarepta’s submission rests on the ESSENCE confirmatory trial and years of published real-world evidence.
While the trial did not meet its primary goal, further analyses at week 96 linked treatment to two encouraging signs: higher levels of dystrophin — the muscle-protecting protein that people with DMD cannot produce properly — and a slower decline in the time it took patients to climb four steps. Across more than 144 weeks, both drugs were well tolerated, with no new safety concerns.
Beyond the ESSENCE trial results, real-world data from patients already using these therapies indicate meaningful long-term benefits. Treatment with Vyondys 53 has been linked to a 7.5-year delay in needing nighttime breathing support, while Amondys 45 has been tied to a slower decline in lung function and a possible delay before patients need a device to help clear the lungs.
Learn more about DMD therapies
Amondys 45 and Vyondys 53 are exon-skipping therapies. The DMD gene that encodes for dystrophin is read in segments called exons. In many patients a missing or faulty exon disrupts the genetic “reading frame,” stopping the cell from building dystrophin. These drugs cover the problem exon so the cell skips over it, allowing production of a shorter but partly functional protein. Each targets a different mutation — Amondys 45 for patients amenable to exon 45 skipping, and Vyondys 53 for exon 53.
“The acceptance of these supplemental applications for review reflects both the progress the Duchenne community has made over the past several years and the needs that remain, while maintaining a commitment to evaluating therapies with rigor,” said Pat Furlong, president and founder of Parent Project Muscular Dystrophy.
