Study to Evaluate the Safety and Effectiveness of ELEVIDYS in Participants With Duchenne Muscular Dystrophy Treated in a Post-Marketing Setting

Key Inclusion Criteria:

• Cohort 1 only: Is male at birth, ambulatory, and ≥ 4 years of age at the time of dosing.
• Cohort 1 only: Is eligible for commercial ELEVIDYS.
• Cohort 2 only: Is male at birth and has previously received ELEVIDYS in a commercial setting after pre-treatment with sirolimus and corticosteroids.
• Cohort 1 only: Participants who are sexually active must agree to use, for the entire duration of the study, a condom and the female sexual partner must also use a medically acceptable form of birth control (eg, oral contraceptive).
• Has (a) parent(s) or legal guardian(s) who is (are) able to understand and comply with the study visit schedule and all other protocol requirements, or is ≥ 18 years of age and personally able to understand and comply with the protocol requirements.
• Either has a parent or legal guardian who is willing to provide informed consent, or is ≥ 18 years of age and able to provide informed consent independently.

Key Exclusion Criteria:

• Cohort 1 only: Contraindicated to receive ELEVIDYS per the United States Package Insert (USPI).
• Cohort 1 only: Has serological evidence of current, chronic, or active human immunodeficiency virus, hepatitis C, or hepatitis B infection.
• Has a medical condition or confounding circumstances (eg, prior traumatic limitation for mobility or significant behavioral comorbidity) that, in the opinion of the Investigator, might compromise:

• The participant's ability to comply with the protocol-required procedures, and/or
• The participant's well-being or safety, and/or
• The clinical interpretability of the data collected from the participant
• Cohort 1 only: Has a symptomatic infection (eg, upper respiratory tract infection, pneumonia, pyelonephritis, meningitis) within 4 weeks prior to Day 1.
• Cohort 1 only: Has received a live virus vaccine within 4 weeks or inactive vaccine within 2 weeks of the Day 1 visit or expects to receive a vaccination during the first 3 months after Day 1.
• Cohort 1 only: Any confounding factors that would prevent the use of oral sirolimus including a known hypersensitivity to sirolimus or any of its excipients.
• Cohort 1 only: Any wounds or recent injuries that, in the opinion of the Investigator, would be at risk of dehiscence or impaired healing in the setting of sirolimus administration.

Other inclusion/exclusion criteria may apply, per protocol.