An Open-Label Extension Study for Patients With Duchenne Muscular Dystrophy Who Participated in Studies of SRP-5051

Inclusion Criteria:

• Has completed Study 5051-101 (NCT03375255) and continues to meet the Safety Eligibility
Criteria of Study 5051-101 (NCT03375255).

Exclusion Criteria:

- Initiation or change of dosing (except for modifications to accommodate changes in
weight) since entering Study 5051-101 (NCT03375255) and while participating in this
study for any of the following: angiotensin converting enzyme (ACE) inhibitors,
angiotensin receptor blocking agents (ARBs), beta-blockers, potassium and steroids*.

- Requires antiarrhythmic and/or diuretic therapy for heart failure.

- Use of any herbal medication/supplement containing aristolochic acid.

- Treatment with any experimental therapy since entering original study or any
experimental gene therapy for the treatment of DMD at any time.

- Participation in an interventional clinical trial since completing original study.

Other inclusion/exclusion criteria apply.

* The dose of steroids must remain constant except for modifications to accommodate changes
in weight.