Sarepta Therapeutics said it will update its prescribing information for Elevidys® (delandistrogene moxeparvovec-rokl) after acknowledging the sudden death of a patient with Duchenne muscular dystrophy (DMD) following treatment with the company’s marketed gene therapy.
The patient, whom Sarepta described as a young man and later told news outlets was 16 years old, suffered acute liver failure after being treated with Elevidys, the only gene therapy that has won FDA approval as a treatment for DMD.
“Although it is not a new safety signal and the benefit-risk of Elevidys remains positive, acute liver failure (ALF) leading to death represents a severity of acute liver injury not previously reported for Elevidys, which to date has been used to treat more than 800 patients in clinical trials or as a prescribed therapy,” Sarepta said in a statement.
In that statement, Sarepta disclosed that the patient was found through testing to have had a recent cytomegalovirus (CMV) infection, “which was identified by the treating physician as a possible contributing factor.” CMV can infect and damage the liver, resulting in CMV hepatitis.
“Patient safety and well-being are Sarepta’s top priority. We continue to gather and analyze the information from this event,” the company stated, adding that the incident has been reported to health authorities, Elevidys clinical study investigators, and prescribing physicians.
Elevidys is an adeno-associated virus vector (AAV)-based gene therapy indicated for individuals at least four years old to treat DMD in patients who are ambulatory and have a confirmed mutation in the DMD gene, as well as for patients who are non-ambulatory and have a confirmed mutation in the DMD gene—the latter under an accelerated approval based on expression of Elevidys microdystrophin, which may hinge upon confirmatory studies.
Possible side effect highlighted
Sarepta also noted that acute liver injury was highlighted in Elevidys’ prescribing information as a known possible side effect of the treatment as well as other AAV-mediated gene therapies.
“Elevidys can increase certain liver enzyme levels and cause acute serious liver injury,” the prescribing label recommends, adding: “Postpone Elevidys administration in patients with acute liver disease until resolved or controlled. Treatment with Elevidys should be carefully considered in patients with preexisting liver impairment or chronic hepatic viral infection. These patients may be at increased risk of acute serious liver injury.”
The prescribing label also acknowledges, however, that: “Patients with hepatic impairment, acute liver disease, chronic hepatic condition or elevated GGT [gamma-glutamyl transferase, an enzyme primarily found in the liver] have not been studied in clinical trials with Elevidys.”
Investors responded to news of the patient’s death with a stock selloff that sent Sarepta shares tumbling 25% today as of 3:10 p.m. ET, to $75.89 from yesterday’s closing price of $101.35.
“The safety event (unless deemed not drug related) will support the notion that a (-) [negative] safety event is unpredictable with gene therapies, making it challenging to invest in gene therapies broadly,” Jefferies equity analyst Andrew Tsai wrote in a research note. “The benefit/risk calculation of Elevidys has worsened, given increased safety risk.”
It was known, Tsai added, that liver injury can occur within the first 90 days for Elevidys based on an analysis of 156 patients shared as part of a presentation made at the Muscular Dystrophy Association’s 2025 MDA conference this week.
According to that analysis, “liver abnormalities (hepatobiliary disorders and increased liver investigations) were the most frequently reported TR-SAEs [treatment-related severe adverse events] by both patient and event count.”
Commented Tsai: “Presumably, the patient was dosed with Elevidys recently (as opposed to a long time ago), so mitigating these types of events could be manageable with very careful monitoring.”
“Acute liver injury is a known possible side effect of other AAV gene therapies as a whole. Remains TBD how other DMD gene therapies will show on safety with more [and] longer follow-up,” Tsai added.
