Open-label Study of WVE-N531 in Patients With Duchenne Muscular Dystrophy (FORWARD-53)

Following completion of Part A, eligible patients rolled over into Part B to continue to receive treatment. In addition, new patients were enrolled up to a total of 11 patients in Part B. All patients received WVE-N531 at 10 mg/kg every other week (Q2W) until competent authority approval of a protocol update, when all patients were switched to Q4W dosing. Muscle biopsies were performed following 24 weeks and for new Part B patients (those that did not take part in Part A) following 48 weeks of treatment. Following completion of Part B, all patients elected to continue to receive study drug at Q4W for up to 1 year in an optional Part B Extension Arm. For this portion of the study, up to 15 new patients will be enrolled into Part C of the study. All patients will undergo an open muscle biopsy, at baseline and following 24 weeks of treatment. The primary endpoint for Part B is the measurement of dystrophin protein levels. Participants will also be evaluated for safety, tolerability, digital and functional endpoints. The primary endpoint for Part C is the measurement of dystrophin protein levels. Participants will also be evaluated for safety, tolerability, digital and functional endpoints. Safety monitoring will occur through 10 months after the last dose.