Sarepta Therapeutics shares hit a nine-year low on Monday, dropping 42% to $18.30, following the death of a second patient who had received its gene therapy, Elevidys.

Elevidys is a one-time gene therapy treatment for patients with Duchenne muscular dystrophy. The treatment has a known risk of liver failure. Sarepta said the male teen patient died of acute liver failure.

Both patients were teen males and non-ambulatory. Sarepta said it was investing both cases to identify any common risk factors.

The company says it is taking steps to enhance safety protocols. Sarepta temporarily stopped shipments of the treatment to non-ambulatory patients, saying it’s working with regulators to develop a new treatment tailored to their needs and concerns.

This development has raised concerns among investors, leading to the decline in Sarepta’s stock price. Meanwhile, other pharmaceutical companies, such as Roche, have also paused their use of similar therapies, due to associated risks like liver failure. The focus now shifts to ensuring patient safety while advancing critical medical innovations.