WASHINGTON – Drugmaker Sarepta Therapeutics said late Friday it won’t comply with a request from the Food and Drug Administration to halt all shipments of its gene therapy following the death of a third patient receiving one of its treatments for muscular dystrophy.

The highly unusual move is a latest in a string of events that have hammered the company’s stock for weeks and recently forced it to lay off 500 employees. The company’s decision not to comply with the FDA also places future availability of its leading therapy, called Elevidys, in doubt.

The FDA said in a statement Friday night that officials met with Sarepta and requested it suspend all sales but “the company refused to do so.” The agency has the authority to pull drugs from the market, but the cumbersome regulatory process can take months or even years. Instead, the agency usually makes an informal request and companies almost always comply.

“We believe in access to drugs for unmet medical needs but are not afraid to take immediate action when a serious safety signal emerges,” FDA Commissioner Marty Makary said in a statement.

Elevidys is the first gene therapy approved in the U.S. for Duchenne’s muscular dystrophy, the fatal muscle-wasting disease that affects males, though it has faced scrutiny since its clearance in 2023. The one-time treatment received accelerated approval against the recommendations of some FDA scientists who doubted its effectiveness.

The FDA granted full approval last year and expanded the therapy’s use to patients 4 years and older, including those who can no longer walk. Previously, it was only available for younger patients who were still walking.

Sarepta said Friday that its scientific review showed “no new or changed safety signals” for younger patients with Duchenne’s who have earlier stages of the disease. The company said it plans to keep the drug available for those patients.

“We look forward to continued discussions and sharing of information with FDA,” the company said in a statement.

Sarepta halted shipments last month of the therapy for older boys with Duchenne’s, which gradually destroys muscle and skeletal strength, resulting in early death. The move followed the deaths of two teenage boys taking the therapy.

The company also confirmed a third death Friday: a 51-year-old patient who was taking an experimental gene therapy in a trial for a different form of muscular dystrophy. Sarepta said it reported the death to the FDA on June 20. The FDA said Friday it placed that trial on hold.

Sarepta noted that the gene therapy involved in the incident uses “a different dose and is manufactured using a different process,” than Elevidys.

All three patient deaths were linked to liver injury, a side effect noted in Sarepta’s prescribing information.

Earlier this week Sarepta announced it would add a bold warning to drug and lay off a third of its employees. The company did not mention the third patient death in its news release or conference call announcing those changes, sparking pointed criticism from Wall Street analysts.

Company shares fell more than 35% Friday to close at $14.07.

Cambridge, Massachusetts-based Sarepta has received FDA approval for three other Duchenne’s drugs since 2016, none of which have been confirmed to work. The company has long been criticized for failing to complete several studies needed to secure full FDA approval of its drugs.

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