Sarepta's stock plummets as disappointing trial data raise questions on DMD drug's success

By Tomi Kilgore

A treatment of Duchenne muscular dystrophy worked better than placebos, but not at a statistically significant rate

Sarepta's stock sank after studies of Duchenne muscular dystrophy treatments failed their primary endpoints.

Shares of Sarepta Therapeutics Inc. plunged in extended trading Monday after the biotechnology company disclosed disappointing drug-trial data, which could lengthen the timeline of the regulatory approval process.

While studies showed that Sarepta's Amondys 45 and Vyondys 53 treatments for Duchenne muscular dystrophy worked better than placebos, the company said the results did not reach statistical significance. That means the Essence Phase 3 study, evaluating the treatments in patients ages 6 to 13, failed their primary end points.

Meanwhile, safety was not an issue, as 88% of adverse events following treatment were mild and 10.3% were moderate, the company noted.

Sarepta's stock (SRPT) plunged about 38% in after-hours trading, after it closed the regular session up 1.8%. That decline would put it on track for its biggest one-day drop since it shed 42.1% on June 16, after a second patient treated with its approved DMD drug Elevidys died of liver failure.

In mid-July, the stock tumbled further after reports surfaced that the Food and Drug Administration would ask the company to stop shipping Elevidys after multiple people who took the treatment died from liver failure.

Read: Sarepta Therapeutics' stock slips further as company bows to FDA pressure to halt shipments.

On Monday, Sarepta explained that the studies in question had been conducted over a nine-year period, and that the outcomes and study participants were impacted by the COVID-19 pandemic. If data affected by the pandemic were excluded, the company said the study would have showed that the treatments led to a "clinically meaningful change."

Given encouraging data from the Essence study, "substantial real-world evidence" and positive safety data, Sarepta said it plans to schedule a meeting with the FDA to discuss potentially converting the approval process to "traditional," after it was granted an "accelerated" approval timeline that looks to expedite the process for serious, unmet medical needs.

Separately, Sarepta said it swung to a third-quarter net loss of $179.9 million, from net income of $33.6 million in the same period a year ago, due in part to a $40.5 million restructuring charge and a $138.6 million loss on the extinguishment of debt.

Excluding nonrecurring items, the company reported an adjusted per-share loss of 13 cents, after earnings per share of 64 cents last year. That beat the average analyst estimate for a per-share loss of 32 cents.

Total revenue fell 14.5% to $399.4 million, due primarily to the company's decision to halt shipments of Elevidys. But the results topped the analyst consensus of $335.8 million in revenue.

Sarepta's stock has tumbled 79.9% in 2025 through Monday's close, while the iShares Biotechnology ETF IBB has rallied 19.1% and the S&P 500 index SPX has advanced 16.5%.

-Tomi Kilgore

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11-03-25 2149ET