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.

A second patient receiving its experimental gene therapy Elevidys has died from liver failure, raising serious questions on the drug’s outlook.

Shares of Sarepta Therapeutics have plunged again after the drugmaker reported a second death in connection with its gene therapy for muscular dystrophy.