A Randomized, Double-blind, Placebo-controlled, Phase 3 Study to Evaluate the Efficacy and Safety of Intravenous AOC 1020 for the Treatment of Facioscapulohumeral Muscular Dystrophy (FSHD)

The study consists of a Screening Period of up to 6 weeks and 72-week Treatment Period. The anticipated duration is approximately 78 weeks.

Participants will be randomized to receive an intravenous infusion of either del-brax or placebo at the clinical study site every 6 weeks for a total of 13 doses. The final dose will occur at Week 72, followed by a final assessment at Week 78.

After completion of the Week 78 visit, eligible participants will have the option to enroll into an open label extension (OLE) study, pending regulatory approval. Participants who decline participation in the OLE will be followed for a period of 12 weeks for safety.

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.

Inclusion Criteria:

• Clinical and genetic diagnosis of FSHD1 or FSHD2
• Ability to walk independently at pre-specified walking speed (orthoses and ankle braces allowed) for at least 10 meters at screening
• Adequate muscle strength based on QMT composite score

Exclusion Criteria:

• Breastfeeding, pregnancy, or intent to become pregnant during the study
• Unwilling or unable to comply with contraceptive requirements
• Abnormal lab values, conditions or diseases that would make the participant unsuitable for the study
• Blood Pressure > 140/90 mmHg at Screening
• Treatment with another investigational drug or biological agent within 1 month of Screening or 5 half-lives of the drug, whichever is longer
• Treatment with an oligonucleotide within 9 months of Screening