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 company had previously halted shipments to certain older patients following the deaths of two teenagers treated with the therapy, Elevidys.

At the FDA's request, delandistrogene moxeparvovec (Elevidys), the only approved gene therapy for Duchenne muscular dystrophy, will carry a black box warning for acute liver injury and acute liver failure,