A Randomized, Double-blind, Placebo-controlled, Phase 3 Study to Evaluate the Efficacy and Safety of Intravenous AOC 1044 for the treatment of Duchenne Muscular Dystrophy (DMD) with Gene Mutations Amenable to Exon 44 Skipping

The study consists of a Screening Period of up to 44 Days, a Randomized 54 Week Treatment Period, a 54 Week Open Label Extension (OLE), and a Follow-Up Period of 6 weeks. Participants will be randomized to receive an intravenous infusion of either delpacibart-zotadirsen or placebo at the clinical study site every 6 weeks for a total of 9 doses. After completion of the randomized treatment period, all participants may enter the OLE portion of the study consisting of 9 doses of AOC 1044 regardless of group assignment in the randomized period. The final dose will occur at Week 102, followed by a final assessment at Week 108 and a safety follow-up visit at Week 114. An Independent Data Monitoring Committee (IDMC) comprising members independent and external to the Sponsor will review safety, tolerability, and efficacy (as needed) data of this study at regular intervals.

Key Inclusion Criteria:

• Ambulatory males with clinical and genetic diagnosis of DMD
• Acceptable genetic test confirming dystrophin gene mutation amenable to exon 44 skipping
• 7 to 16 years of age at time of consent
• TTR and NSAA assessment completed within the protocol specified parameters at Screening
• On a stable regimen of corticosteroids (including Vamolorone) for at least 6 months prior to Day 1. Steroid regimen must be anticipated to remain stable.

Key Exclusion Criteria:

• Previous treatment cell or gene therapy.
• Treatment with another oligonucleotide within 6 months of informed consent (not including COVID-19 RNA vaccines).
• Lab values outside of the protocol specified range at Screening
• If on any of the following treatments (growth hormone, testosterone or givinostat), participants must be on a stable regimen and must plan to maintain it for the duration of the study. Participants will be excluded if regimen stability prior to informed consent is as follows:
• Less than 1 month, for growth hormone and/or testosterone
• Less than 6 months for givinostat