PASADENA, Calif.--(BUSINESS WIRE)--Arrowhead Pharmaceuticals, Inc. (NASDAQ: ARWR) announced today that it has dosed the first subjects in a Phase 1/2a double-blinded, placebo-controlled, dose-escalating study (NCT06138743) to evaluate single and multiple ascending doses of ARO-DM1, the company’s investigational RNA interference (RNAi) therapeutic, in up to 48 subjects with type 1 myotonic dystrophy (DM1). DM1 is the most common adult-onset muscular dystrophy. Patients with DM1 have muscle weakness and wast ...