REVEAL: A Phase 3 Study of Obudanersen (ION582) in Angelman Syndrome

This is a Phase 3, randomized, double-blind, placebo-controlled study in people with Angelman syndrome. The study will consist of 4 periods: a screening period of up to 28 days, an approximate 60-week double blind, placebo-controlled treatment period, followed by an approximate 25-month Long-Term Extension (LTE) treatment period, and an approximate 8-month Post-LTE follow-up period. The study will be comprised of 2 cohorts. Cohort 1 will include pediatric participants, aged 2 to less than (\<)18 years old and serve as the population for evaluation of primary and secondary outcome measures; Cohort 2 will include adult participants, aged 18 to ≤50 years old. Participants will be randomized 1:1 to 80 mg obudanersen or placebo during the double-blind placebo-controlled treatment period. Participants from both cohorts completing the placebo-controlled treatment period will be eligible to transition into the LTE Treatment Period wherein all trial participants will receive obudanersen. Participant, Caregiver, Investigator and Sponsor will remain blinded to the obudanersen dose administered to participants during the LTE. The study initiated in 2024 with three dosing groups (40 mg obudanersen, 80 mg obudanersen, and placebo). Following additional review of data from the ongoing Phase 1/2 trial of obudanersen (HALOS), REVEAL was amended in December 2025 to its current form as a two-arm study: 80 mg obudanersen and placebo. Following the amendment, participants who were randomized to receive 40 mg obudanersen will be transitioned to receive 80 mg obudanersen.