Safety and Tolerability of WVE-210201 in Patients With Duchenne Muscular Dystrophy

Inclusion Criteria:

- Diagnosis of Duchenne muscular dystrophy (DMD) based on clinical phenotype with
increased serum creatine kinase

- Documented mutation in the Dystrophin gene associated with DMD that is amenable to
exon 51 skipping

- Ambulatory or non-ambulatory male patients aged ≥5 - ≤18 years

- Stable pulmonary and cardiac function as measured by:

1. Reproducible percent predicted forced vital capacity (FVC) ≥50%

2. Left ventricular ejection fraction (LVEF) >55% in patients <10 years of age and
>45% in patients ≥10 years of age, as measured (and documented) by echocardiogram
within one year prior to enrollment into the study.

Exclusion Criteria:

- Severe cardiomyopathy; cardiomyopathy that is managed by angiotensin-converting enzyme
(ACE) inhibitors or beta blockers is acceptable provided the patient meets the LVEF
inclusion criteria.

- Need for mechanical or non-invasive ventilation OR anticipated need for mechanical or
non-invasive ventilation within the next year, in the opinion of the Investigator.

- Changes in nutritional or herbal supplements or concomitant medications within 1 month
prior to Screening visit or plans to modify dose or regimen during the study.

- Currently on anticoagulants or antithrombotics.

- Received treatment with eteplirsen or ataluren within the past 14 weeks.

- Received prior treatment with drisapersen.

- Received any investigational drug within the past 3 months or 5 half-lives, whichever
is longer.