Phase 2 Study of EDG-5506 in Children and Adolescents With Duchenne Muscular Dystrophy Previously Treated With Gene Therapy (FOX)

Key Inclusion Criteria:

• Aged 6 to 17 with a documented mutation on the DMD gene and phenotype consistentwith DMD.

• Prior receipt of an AAV-based gene therapy (≥ 2 years after study drugadministration in an open-label study or ≥ 3 years after randomization in arandomized study).

• Able to complete stand from supine in ≤ 8 seconds at the Screening visit and able toperform the 4-stair climb in < 10 seconds at the Screening visit.

• Body weight ≥ 15 kg at the Screening visit.

• Treatment with a stable dose of corticosteroids for a minimum of 6 months prior tothe Baseline visit.

Key Exclusion Criteria:

• Medical history or clinically significant physical exam/laboratory result that, inthe opinion of the investigator, would render the participant unsuitable for thestudy. This includes venous access that would be too difficult to facilitaterepeated blood sampling.

• Screening visit cardiac echocardiography showing left ventricular ejection fraction (LVEF) < 40%.

• Receipt of an investigational drug (other than the AAV-based gene therapy perInclusion criteria) within 30 days or 5 half-lives (whichever is longer) of theScreening visit in the present study.

• Receipt of an exon-skipping therapy within 6 months prior to the Screening visit.