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.