Children’s Hospital Los Angeles paused the use of Sarepta Therapeutics Inc.’s gene therapy for Duchenne muscular dystrophy in the wake of rising safety concerns about liver toxicity, adding to mounting challenges for the drugmaker.

The regulator had asked Sarepta Therapeutics to halt all shipments of its therapy, Elevidys, after three patients died from liver failure after taking it or a similar treatment.

Sarepta Therapeutics will cut 500 jobs and add a serious warning on the label of its muscle-disorder gene therapy Elevidys, the drugmaker said on Wednesday, following the recent deaths of two patients who were on the medicine.