How the U.S. FDA might respond became a serious question for Wall Street as Sarepta Therapeutics Inc. made known a second death due to acute liver failure with gene therapy Elevidys (delandistrogene moxeparvovec), cleared for Duchenne muscular dystrophy (DMD). Shares of Cambridge, Mass.-based Sarepta (NASDAQ:SRPT) closed June 16 at $20.94, down $15.24, or 42%, as Wall Street digested the news.