Sarepta plunges 40% after-hours as muscle disease drugs fail confirmatory trial

Shares of Sarepta Therapeutics, a mid-cap developer of therapies for rare diseases, plummeted nearly 40% in post-market trading yesterday, November 3, after the company announced that it had failed extended trials for two of its main drugs. Both are already available in the U.S., but the new data could prompt regulators to reconsider their approval.

Sarepta’s stock collapsed 36.6% to $15.50 per share in after-hours trading yesterday. During the regular session, shares had gained 1.8%. In premarket trading today, November 4, the stock has clawed back 1.5% as of this writing.

The sharp decline followed the company’s announcement that post-registration trials for Amondys 45 and Vyondys 53, both designed to treat Duchenne muscular dystrophy (DMD), had failed to meet clinically significant endpoints.

The nine-year ESSENCE study tested the two gene-targeted therapies in boys with DMD, a rare genetic disorder that causes progressive muscle weakening and ultimately death. Sarepta said that while the drugs showed some efficacy, the results were not statistically or clinically meaningful.

Both drugs are already on the market: Vyondys 53 received accelerated approval from the U.S. Food and Drug Administration in December 2019, and Amondys 45 in February 2021. U.S. law allows expedited approval for treatments targeting life-threatening diseases based on early data, with companies required to submit confirmatory results later. Sarepta used this pathway, but the latest results raise the likelihood that the FDA could decide to withdraw both drugs from the market, Bloomberg reports.

Company executives said during a call with shareholders and analysts that they do not expect to lose marketing authorization, Reuters reports. Sarepta argues that the pandemic skewed the trial data, making reliable collection difficult. When that data is excluded, the management says, the results show a clinically meaningful treatment effect. The company plans to meet with the FDA to discuss removing the COVID-affected data from the analysis and transitioning from accelerated to standard approval.

“We do see a fairly clear rationale for the miss (COVID)" and supportive trends when excluding these patients said JPMorgan analyst Anupam Rama, as quoted by Reuters. He added, "we do see strong rationale for potential full approval," before cautioning that "regulatory processes can be a wild card in the current environment."

The situation is compounded by safety issues involving Sarepta’s other gene therapy, Elevidys, used for DMD patients. Three teenagers have died after receiving the treatment. Elevidys generated nearly a third of Sarepta’s third-quarter 2025 revenue ($131.5 million out of $370.0 million). Before the first death was reported in mid-March, analysts had expected Elevidys sales to exceed $2 billion this year and account for most of Sarepta’s projected $3.1 billion in total 2025 revenue, wrote Barron’s, citing FactSet data.

Sarepta said it is in discussions with the FDA on modifying the drug’s label, which could include removing its indication for non-ambulatory patients.

Sarepta shares have fallen around 80% year to date.

Wall Street sentiment toward the stock remains mixed, according to MarketWatch. Fifteen analysts recommend holding Sarepta shares, six advise buying, and five rate them a sell. The average target price is $23 per share, below the closing price on November 3.

The AI translation of this story was reviewed by a human editor.