A Phase 2 Open-label Extension Study to Evaluate the Long-Term Safety, Tolerability, and Efficacy of AOC 1020 Administered Intravenously to Participants with Facioscapulohumeral Muscular Dystrophy (FSHD)

This study will continue to evaluate the safety, tolerability, and efficacy of AOC 1020 in participants who were treated in the randomized, placebo-controlled, Phase 1/2 AOC 1020-CS1 clinical study.

Participants from AOC 1020-CS1 are eligible to enroll in AOC 1020-CS2 if they have satisfactorily completed AOC 1020-CS1. All participants who enroll in AOC 1020-CS2 will receive AOC 1020 regardless of whether they received AOC 1020 or placebo in AOC 1020-CS1. Dosing will occur every 6 to 7 weeks (twice quarterly).

The total duration of active treatment in AOC 1020-CS2 is approximately 46 months. Once participants have completed active treatment, they will be followed through a 18-week safety follow-up period to monitor for adverse events (AEs), concomitant medications, and pregnancy status (as applicable). Total duration on study is up to approximately 50 months (4 years 2 month), excluding the potential 8-week screening period.

Inclusion Criteria:

1. Ability to provide written informed consent (signed and dated) and any authorizations required by local law and be willing and able to comply with all study requirements. When enrolling participants who are minors, it is necessary to also obtain consent from a legally designated representative and the participant will receive information in a way adapted to their age and mental maturity.

2. Completion of AOC 1020-CS1 with the following as judged by the Investigator and Sponsor:

   1. No significant tolerability issues
   2. Satisfactory compliance with the AOC 1020-CS1 protocol requirements

Exclusion Criteria:

1. Pregnancy, intent to become pregnant during the clinical study, or active breastfeeding.
2. Unwilling or unable to continue to comply with contraceptive requirements for the length of AOC 1020-CS2.
3. Any new conditions or worsening of existing condition(s) that in the opinion of the Investigator or Sponsor would make the participant unsuitable for the study or could interfere with participation or completion of the study. (Note: FSHD progression is not exclusionary, even if the participant no longer has the ability to walk 10 meters without a walker or two canes.)