Sarepta tumbles after patient dies following gene therapy treatment

Shares of gene therapy developer Sarepta Therapeutics SRPT.O slump 23% to $78.02, their lowest since 2023

SRPT says 16-year-old boy with Duchenne muscular dystrophy (DMD) died following treatment with its gene therapy, Elevidys

Says patient suffered from acute liver failure, known side effect of Elevidys

"We view the negative stock reaction as overblown given this is the first Elevidys-related death in over 800 treated patients and Elevidys has continued to demonstrate efficacy in a population with a high unmet need," William Blair says

Brokerage says event is unlikely to affect patient-physician interest in Elevidys in near term

DMD is severe, inherited genetic disorder that causes progressive muscle weakness and degeneration

Up to last close, stock down 18.2% in last 12 months