Sarepta stock catapulted Thursday after the company announced a restructuring that includes 500 layoffs in the wake of two patient deaths.

The head of the US Food and Drug Administration said the agency will “take a hard look” at a gene therapy from Sarepta Therapeutics Inc. after two patient deaths, adding pressure to the biotech company which also announced a third patient had recently died on a similar treatment.

The FDA called for Sarepta Therapeutics to stop shipping its muscular dystrophy gene therapy, but the company said no.