FDA adds strongest warning to Sarepta gene therapy linked to 2 patient deaths

The Food and Drug Administration announced Friday it will impose stricter safety measures on Sarepta Therapeutics’ gene therapy for Duchenne muscular dystrophy following the deaths of two teenage patients.

Elevidys, the first FDA-approved gene therapy for the fatal muscle-wasting disease, will now carry a boxed warning—the agency’s most serious safety alert—warning doctors and patients about the risk of potentially fatal liver failure associated with the treatment.

The regulatory action comes after months of scrutiny that began when Sarepta reported the first patient death in March, followed by a second death in June. Those incidents initially prompted the FDA to temporarily halt all shipments of the drug, but the agency quickly reversed its decision after facing significant pushback from patient families and libertarian activists with connections to President Donald Trump.

“Patient safety remains our top priority,” said Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, in a statement. “These new safety measures will help ensure healthcare providers have the information they need to appropriately monitor patients and manage potentially serious risks.”

Beyond the boxed warning, the FDA has narrowed the therapy’s approved use to ambulatory patients aged 4 years and older who can still walk. Previously, the agency had permitted treatment of non-ambulatory patients with more advanced disease progression. The updated labeling will also recommend weekly liver function monitoring during the first three months of treatment, along with other precautionary measures.

Duchenne muscular dystrophy primarily affects boys and young men, causing progressive muscle deterioration that typically leads to death by early adulthood. The disease affects approximately 1 in 3,500 male births worldwide, with patients often becoming wheelchair-dependent by their early teens.

Elevidys works by delivering a modified version of the dystrophin gene to muscle cells, addressing the underlying genetic cause of the disease. The therapy, administered as a one-time infusion, carries a list price of $3.2 million, making it one of the most expensive treatments in the United States.

The safety concerns surrounding Elevidys have created significant challenges for Sarepta, as the treatment represents the company’s flagship product. The Cambridge, Massachusetts-based biotech firm announced in July it would lay off approximately 500 employees—roughly 40% of its workforce—amid mounting regulatory uncertainty.

However, investors appeared to welcome Friday’s announcement, which provided clarity on the drug’s future. Sarepta Therapeutics shares rose 7.7% in trading following the FDA’s decision, suggesting the market viewed the agency’s actions as less severe than feared.

“This announcement removes a significant overhang for the company,” said Joseph Schwartz, an analyst at SVB Securities. “While the boxed warning and restricted indication will impact sales, the fact that the therapy remains on the market is ultimately a positive outcome for Sarepta.”

Industry analysts estimate that despite these new restrictions, Elevidys could still generate annual sales exceeding $1 billion by 2026, though projections have been scaled back from earlier forecasts.

The FDA’s decision highlights the complex balance regulators must strike between providing access to potentially transformative therapies for deadly diseases and ensuring adequate safety protections. Gene therapies, while offering revolutionary treatment approaches for previously untreatable conditions, can carry significant risks that may only become apparent after broader clinical use.

For families affected by Duchenne muscular dystrophy, the continued availability of Elevidys—even with additional warnings and restrictions—represents an important treatment option for a disease with limited therapeutic alternatives.

The FDA indicated it would continue monitoring the safety profile of Elevidys and could implement additional safety measures if warranted by emerging data.