In a tragic development for the Duchenne muscular dystrophy (DMD) community, a patient has died while receiving Elevidys, the first gene therapy approved in the United States for treating the rare, progressive muscle-wasting disease. This marks the first known death linked to the treatment, according to Sarepta Therapeutics, the Cambridge-based biotechnology company behind the drug.

The patient reportedly suffered from acute liver injury, a known but typically manageable side effect of the therapy. However, Sarepta stated that the severity of this case was unprecedented. Although specific details about the patient have not been disclosed, the company noted that a recent infection may have exacerbated the liver complications.

Since its initial approval, Elevidys has been administered to more than 800 patients worldwide. The company now plans to update the prescribing information to reflect this fatal case, adding caution to the therapy's use.

Following news of the death, shares of Sarepta plummeted more than 27%, closing at approximately $73 on Tuesday.

Approved in 2023 through the FDA’s accelerated pathway, Elevidys costs $3.2 million for a single infusion. It works by using a disabled virus to deliver a functional gene that helps the body produce dystrophin, a protein critical for muscle function. The therapy is designed to slow the progression of Duchenne muscular dystrophy, a condition that predominantly affects boys, leading to severe muscle weakness, mobility loss, and early death.

Despite initial skepticism from parts of the scientific community regarding the therapy’s efficacy, the FDA expanded full approval in 2024 to include all patients aged four and older, regardless of their mobility status.

Sarepta has received accelerated FDA approval for three other DMD treatments since 2016, though none have yet received full confirmation of effectiveness as clinical studies remain ongoing.

The recent fatality casts new scrutiny on the safety profile of gene therapies and the balance between fast-tracking treatments for rare diseases and ensuring long-term patient safety. As Sarepta and regulators assess this case, families affected by Duchenne and the wider medical community will be watching closely for guidance on the future use of Elevidys.