Shares of Sarepta Therapeutics closed down as much as 42% to hit a nine-year low of $18.30 on Monday after a second death of a male teenage patient who had received its gene therapy, Elevidys, raising doubts on the safety and future demand for the treatment.

Cambridge-based Sarepta Therapeutics said it was halting shipments of its Duchenne muscular dystrophy gene therapy for patients who can no longer walk, following the death of a second person who received the treatment.

Sarepta Therapeutics shares plunged 36% after the company reported a second case of acute liver failure resulting in death from taking Elevidys, which is a gene therapy for patients with Duchenne muscular dystrophy.

Sarepta suspends Elevidys use in non-ambulatory Duchenne patients after two liver failure deaths, triggering FDA review and clinical trial pause.