Dyne, Sarepta shares tumble as Novartis setback weighs on muscle disease drug developers ↧ ↧ Dyne, Sarepta shares tumble as Novartis setback weighs on muscle di... Shares of Dyne Therapeutics and Sarepta slumped on Tuesday after Novartis' treatment for a muscle-wasting disorder failed in a trial, fueling investor concerns ​about the prospects of similar therapies for the tough-to-treat rare ‌disease.