Sarepta Therapeutics Inc. (NASDAQ: SRPT) announced it intends to submit supplemental new drug applications to the FDA by the end of April 2026 seeking conversion of AMONDYS 45 and VYONDYS 53 from accelerated approval to traditional approval status.

The company received feedback from the FDA confirming it can submit data from its ESSENCE confirmatory study and real-world evidence as part of the supplemental applications. The adequacy of the data to support conversion to traditional approval will be subject to FDA review.

AMONDYS 45 (casimersen) and VYONDYS 53 (golodirsen) are exon-skipping therapies currently approved under the FDA's accelerated approval pathway for patients with Duchenne muscular dystrophy who have mutations amenable to exon 45 and exon 53 skipping, respectively.

The ESSENCE study was a global Phase 3 randomized, double-blind, placebo-controlled trial evaluating the therapies in 225 patients ages 6-13 years old. Topline results showed numerical trends favored treatment versus placebo, but the observed difference of 0.06 steps/second in least square means did not reach statistical significance on the primary endpoint of 4-step ascend velocity at 96 weeks.

An updated analysis excluding data from 23 participants whose baseline measurements occurred during the COVID-19 impact period showed a least square means difference of 0.12 steps/second with a p-value of 0.050.

The company stated that more than 1,800 patients worldwide have been treated with its PMO therapies for over a decade, ranging from infants as young as 7 months to adults in their 30s.