A medicine Stealth Biotherapeutics Inc. has been developing for the potential treatment of primary mitochondrial myopathy (PMM) missed the co-primary endpoints of a key phase III trial, sending company shares (NASDAQ:MITO) down 65.9% to close at $4.75 on Friday.

In August the FDA was skeptical about Sarepta Therapeutics Inc.’s injectable Vyondys 53 (golodirsen), but that changed swiftly Friday with the agency’s accelerated approval for the Duchenne muscular dystrophy (DMD) follow-on therapy, the first treatment specifically for this subtype.

News of a partial FDA clinical hold for pediatric patients after safety reports from an ongoing trial testing palovarotene in fibrodysplasia ossificans progressiva (FOP) identified cases of early growth plate closure sent shares of Ipsen SA (Paris:IPN) falling 13.6% Friday.