Background: Delandistrogene moxeparvovec-rokl is the first FDA-approved gene therapy indicated to treat ambulatory and nonambulatory children ≥4 years of age with Duchenne muscular dystrophy (DMD) who have a confirmed mutation in the gene. Long-term follow-up of participants treated with delandistrogene moxeparvovec provides important real-world treatment experience and data to inform decisions being made by families, clinicians, regulators, and payers.
Objective: To describe the design of ENDURE (NCT06270719, SRP-9001-401), a Phase 4, multicenter, prospective, observational study providing longitudinal follow-up on effectiveness and safety of delandistrogene moxeparvovec in a broad population of participants with DMD.
Methods: Medical history and prospective data on treatment outcomes and safety will be collected for up to 10 years from at least 500 participants with DMD receiving either delandistrogene moxeparvovec or standard-of-care therapy (comparator group). Eligible participants must be male with a clinical and genetic DMD diagnosis at baseline recruited from routine clinical practice at participating sites in the United States. Participants must meet delandistrogene moxeparvovec label criteria at enrollment, including age 4+ years without deletion of exons 8 and/or 9 and is currently receiving or has been prescribed chronic glucocorticoids. Comparator group participants must be naïve to DMD gene therapy. Primary endpoint is mean change from baseline in time to walk/run 10 meters at month 12 among ambulatory participants at baseline. Secondary endpoints include functional (time to rise, time to loss of ambulation, performance of upper limb version 2.0 entry item score), clinical (pulmonary, cardiac, age at loss of ambulation), patient-reported (Patient-reported Outcomes Measurement Information mobility, upper extremity, and fatigue), and safety outcomes.
Conclusions: ENDURE began enrollment in the United States in 2024 and will compare the long-term effectiveness and safety of delandistrogene moxeparvovec–treated participants with DMD participants receiving standard of care.