Drugmaker Sarepta Therapeutics says it won’t comply with a request from U.S. regulators to halt all shipments of its gene therapy.

The agency also revoked Sarepta's platform technology designation for AAVrh74 Friday and issued a safety communication saying the agency was investigating the three deaths due to acute liver failure following treatment with Sarepta's AAVrh74 gene therapies.

Sarepta Therapeutics has paused U.S. shipments of its gene therapy Elevidys after two teenagers with Duchenne muscular dystrophy died of liver failure. The suspension follows an FDA request and affects non-ambulatory patients.