Confirmatory trial results return Sarepta to the doldrums

Tuesday is shaping up to be another dark day in the stock market for US genetic medicines company Sarepta Therapeutics (Nasdaq: SRPT) as key trial data were announced.

Shares in Sarepta looked set to open around 40% lower due to the results of ESSENCE, its global, Phase III randomized, double-blind study of Amondys 45 (casimersen) and Vyondys 53 (golodirsen) compared to placebo in 225 patients, aged six to 13 years old, with Duchenne muscular dystrophy (Duchenne) amenable to exon 45 or 53 skipping. 

In 2021, the US Food and Drug Administration (FDA) had granted accelerated approval to Vyondys 53 for patients with DMD amenable to exon 53 skipping in 2019, and to Amondys 45 for those amenable to exon 45 skipping. It was hoped that the confirmatory ESSENCE trial would support conversion into full approvals.