Shares of Sarepta Therapeutics plunged more than 30% on Friday as the future of its key gene therapy treatment appeared at risk. The Food and Drug Administration will request that the company voluntarily stop all shipments of the treatment, Elevidys, a person familiar with the matter told CNBC.

When three patients die after taking a cutting-edge drug, most companies hit the brakes. Not Sarepta Therapeutics. The Massachusetts-based biotech company is under fire for refusing a request from the U.

The death of a 51-year-old man in the study follows two other deaths of Duchenne patients treated with Sarepta’s marketed gene therapy Elevidys.