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

Duchenne muscular dystrophy (DMD) is a genetic disease causing progressive muscle weakness, primarily in boys. It is caused by mutations in the gene for dystrophin, a protein that protects muscle fibers. This study is testing delandistrogene moxeparvovec (SRP-9001), a gene therapy that delivers a shortened but functional version of the dystrophin gene into muscles using a harmless virus. The goal is to slow or stop muscle deterioration. The trial has multiple cohorts for different ages and ambulatory status. Some cohorts are for young ambulatory boys, others for older boys, and others for non-ambulatory patients. The therapy involves a single IV infusion of the gene therapy vector. You may be eligible if... - You are a male with a confirmed diagnosis of DMD based on clinical and genetic testing - You fall within the age range for one of the available cohorts (ranging from 2 years old to 18+ years old) - You meet the ambulatory or non-ambulatory criteria for your specific cohort - Your rAAVrh74 antibody levels are within acceptable limits - You are able to cooperate with motor assessment testing You may NOT be eligible if... - You have another serious illness, autoimmune disease, or significant cognitive impairment - You have previously received gene therapy for DMD - You have received any other treatment designed to increase dystrophin expression within the specified time window - You have abnormal laboratory test results as specified by the protocol Talk to your doctor to see if this trial is right for you.