This is a Phase 2 open-label extension (OLE) study to evaluate the long-term safety, tolerability, efficacy, pharmacokinetics, and the pharmacodynamics (PD) through potential exploratory biomarker(s) of intravenous (IV) WVE-N531 in patients with DMD who participated in another study of WVE-N531. All patients will have rolled over from a previous study of WVE-N531.

The study will include up to 175 patients from planned and ongoing WVE-N531 studies globally. All patients will continue to receive 10 mg/kg WVE-N531 IV every 4 weeks (Q4W), through Week 96. Safety monitoring will continue for approximately 11 months after the final dose. The primary objective of the study is to evaluate the long-term safety and tolerability of WVE-N531.

Inclusion Criteria:

1. Participated in a prior study of WVE-N531 and has not experienced any significant toxicities due to WVE-N531 or significant clinical deterioration of general health since the last dose or early discontinuation visit.
2. Of note: if there will be a greater than 31-day gap between the last dose on the prior study and the FD on this study, the case should be discussed between the Investigator and Medical Monitor.

Exclusion Criteria:

1. Any clinically significant medical finding or change during or following participation in the prior WVE-N531 study, other than DMD that, in the judgment of the Investigator, would affect the potential safety of the patient to receive WVE-N531 or interfere with participation in the study.
2. Any recreational substance use (including prescribed cannabinoids), with the exception of alcohol and nicotine, irrespective of legality, within 2 months prior to FD and/or unwilling to refrain from such use for the duration of the study.