A second patient has died after receiving the gene therapy Elevidys, which was approved by the Food and Drug Administration despite concerns from staffers, according to the company that makes it.
The 15-year-old boy who died, and the 16-year-old boy whose death was reported earlier in the year, had both received Elevidys, the only gene therapy approved by the FDA for the treatment of a rare form of muscular dystrophy called Duchenne muscular dystrophy (DMD), Sarepta officials said in a call on June 16.
The boys were both non-ambulatory and both died within 90 days of treatment, according to Sarepta.
The 15-year-old died from acute liver failure, Sarepta said in a statement on Sunday. Acute liver injury is listed as a side effect of the product.
Sarepta said it was investigating the cases independently and in relation to each other to identify any common risk factors. The company suspended its Elevidys sales forecast for this year and said it would provide an update with its second-quarter results.
Sarepta officials said the company is pausing shipments of Elevidys for non-ambulatory patients and halting a clinical trial while it develops an “enhanced immunosuppressive regimen,” utilizing the sirolimus drug. They said there is no timeline right now for resuming dosing for the population and that they would try to speak soon with FDA officials about the situation.
“Our paramount priority is the safety and well-being of the patients we serve. We are taking immediate, decisive steps to better understand and mitigate the risk of acute liver failure, including enhancing the immunosuppressive regimen, for those with Duchenne who are non-ambulatory,” Louise Rodino-Klapac, chief scientific officer and head of research & development at Sarepta, said in a statement. “We are deeply saddened by the loss of a second patient and extend our heartfelt condolences to the patient’s family and his care team during this incredibly difficult time.”
“The FDA is aware of the second reported fatal case of severe liver failure and are treating this situation with the highest level of concern. The FDA will take all appropriate regulatory actions to protect patients during our review of gene therapy products,” an FDA spokesperson said in an email.
Non-ambulatory patients face a greater risk with the treatment because they tend to be older boys who weigh more, which in turn requires higher dosing, Piper Sandler analyst Biren Amin said. The analyst does not expect the therapy to be withdrawn from the market, based on Sarepta’s efforts to mitigate risk.
“While these two deaths occurred in non-ambulatory patients, we view the risk profile as now heightened for all DMD patients,” H.C. Wainwright analyst Raghuram Selvaraju wrote in a note.
No changes are being implemented for ambulatory people with DMD, an inherited disorder that features weakening muscles with no cure. Elevidys helps treat the disorder.
The trial for Elevidys failed to meet its primary endpoint, an improvement in an ambulatory assessment. FDA staffers said that clinical data did not show a benefit for Elevidys patients. Then-Center for Biologics Evaluation and Research Director (CBER) Dr. Peter Marks said the benefits of the drug outweighed the risks and overrode the staffers, drawing disapproval from some groups such as Doctors for America. The FDA fully approved the drug in 2024 for individuals aged 4 and older, with accelerated, or conditional approval, for non-ambulatory patients.
Marks, who could not be reached for comment, resigned earlier this year. Dr. Vinay Prasad, who now heads CBER, has in the past been critical of the decision. In a social media post before joining the government, he wrote that Marks “is approving Gene Therapies that don’t work,” while in another post he said that Marks “overrode 3 reviewers to approve gene therapy that kills more boys that it saves.”
“Given his previous historical comments online, people are worried that he may go against Sarepta and may try to pull the drug,” BMO Capital Markets analyst Kostas Biliouris said.
Sarepta officials said during Monday’s call that they believed the FDA would not impose restrictions beyond the steps the company is taking.
Reuters contributed to this report.