A Gene Transfer Therapy Study to Evaluate the Safety of and Expression From Delandistrogene Moxeparvovec (SRP-9001) in Participants With Duchenne Muscular Dystrophy (DMD) - Non-Ambulatory Cohort

Cohort 8 (non-ambulatory participants) is currently enrolling new participants. Enrollment for Cohorts 1 through 7 has been completed. This is an open-label gene transfer therapy study evaluating the safety of and expression from delandistrogene moxeparvovec in participants with Duchenne Muscular Dystrophy (DMD). The maximum participant duration for this study is 156 weeks.

Inclusion Criteria: * For Cohorts 1-8: Has a definitive diagnosis of DMD based on documented clinical findings and prior genetic testing. * Cohort 8: Non-ambulatory per protocol-specified criteria at the time of Screening, has a performance upper limb (PUL) entry item score ≥3 at the Screening visit and has a total PUL score of ≥20 and ≤40 at the time of Screening. * Cohorts 1, 2, 3, 5, 7 and 8 only: Stable dose equivalent of oral glucocorticoids for at least 12 weeks before screening and the dose is expected to remain constant (except for modifications to accommodate changes in weight) throughout the first year of the study. * Cohort 1: Is ambulatory, and ≥4 to \