Shares of Sarepta Therapeutics (NASDAQ: SRPT) plunged 26.85% in Friday pre-market after a clinical trial participant died following treatment with a gene therapy, marking the third death linked to the company's experimental treatments.

At the FDA's request, delandistrogene moxeparvovec (Elevidys), the only approved gene therapy for Duchenne muscular dystrophy, will carry a black box warning for acute liver injury and acute liver failure, drugmaker Sarepta Therapeutics said.

Sarepta Therapeutics to lay off 493 workers, including 80 in Ohio, amid FDA probe, stock plunge, and concerns over Duchenne gene therapy Elevidys.

New research has identified the enzyme glutamate dehydrogenase 1 (GLUD1) as a new therapeutic target for Duchenne muscular dystrophy (DMD).

Three patients with a muscle-wasting disease died from liver failure after taking the therapy, Ele­vidys, or a similar treatment.

A company spokesperson told Bloomberg that a 51-year-old patient died of acute liver failure last month in an early-stage trial of a gene therapy to treat limb-girdle muscular dystrophy.

Sarepta Therapeutics appears to have right-sized itself after laying off over a third of its staff, announcing a significant pipeline shift, and adding a black box warning to its Duchenne muscular dystrophy gene therapy Elevidys.