The U.S. Food and Drug Administration (FDA) announced on Friday, after market close, that it is investigating the death of an 8-year-old boy who had received Elevidys, Sarepta Therapeutics Inc.’s gene therapy for Duchenne muscular dystrophy.

The death occurred on June 7, 2025, prompting the FDA to request and receive a voluntary suspension of product distribution to investigate the safety concerns.

Elevidys is an adeno-associated virus vector-based gene therapy using Sarepta Therapeutics’ AAVrh74 Platform Technology for Duchenne muscular dystrophy. The product is administered as a single intravenous dose.

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Despite the FDA’s investigation, Sarepta issued a statement on Friday asserting, “The death of this patient was deemed unrelated to treatment with Elevidys.”

Roche Holding AG ( RHHVF ) , which markets Elevidys outside the U.S., echoed this sentiment, stating the boy was not a clinical trial participant and the reporting physician assessed his death as unrelated to the gene therapy. Both companies have reported the death to the health authorities.

Sarepta formally reported this event to the FDA on June 18, 2025, via the FDA’s postmarketing electronic database, FAERS. A separate report from Stat News indicated that Brazilian regulators and physicians attributed the boy’s death to a severe flu infection exacerbated by immunosuppression.

William Blair noted that the FDA reported the boy who died was 8 years old, even though Elevidys is approved in Brazil only for boys aged 4 to 7 who can still walk.

This suggests the treatment may have been given quickly before the child became too old to qualify, meaning it couldn’t be postponed until after Brazil’s flu season.

While it’s known that immunosuppression raises the risk of infections and related complications, this case highlights the need for more research and better understanding of those risks in gene therapy. However, there is still not enough information to clearly determine what led to the child’s death.

Analyst Sami Corwin said, “In addition, we are puzzled as to why FDA is investigating a death deemed unrelated to the gene therapy and why the investigation was initiated more than a month after it was submitted into FAERS.”

This incident is not isolated for Sarepta. This year, the company has reported three fatalities linked to acute liver failure in individuals who received either Elevidys or an investigational gene therapy using the same AAVrh74 platform. One of these deaths occurred during a clinical trial for limb girdle muscular dystrophy.

Adding to Sarepta’s challenges, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) issued a negative opinion on Friday regarding conditional marketing authorization (CMA) for Elevidys in ambulatory individuals aged three to seven years with Duchenne muscular dystrophy.

In other news, Arrowhead Pharmaceuticals, Inc. ( ARWR ) announced on Monday a $100 million milestone payment from Sarepta.

The milestone was triggered when Arrowhead reached the first of two prespecified enrollment targets and subsequent authorization to dose escalate in a Phase 1/2 study of ARO-DM1, an investigational RNA interference (RNAi) therapeutic for type 1 myotonic dystrophy (DM1), the most common adult-onset muscular dystrophy.

Arrowhead expects to achieve the second enrollment target by the end of 2025, which would trigger an additional $200 million milestone payment from Sarepta.

Price Action: SRPT stock was trading lower by 1.34% to $11.77 premarket at last check Monday.

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