NCT05127226

HALOS: A Safety, Tolerability, Pharmacokinetics and Pharmacodynamics Study of Multiple Ascending Doses of ION582 in Participants With Angelman Syndrome

HALOS: A Study to Evaluate the Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of Intrathecally Administered ION582 in Patients With Angelman Syndrome

• Status: Recruiting
• Phase: Phase 1 / Phase 2
• Study type: Interventional
• Enrollment: 70 (estimated)
• Sponsor: Ionis Pharmaceuticals, Inc. · Industry
• Sex: All
• Age: 0 Years – 50 Years
• Healthy volunteers: Not accepted

Summary

The purpose of this study is to evaluate the safety and tolerability of ascending doses of ION582 administered intrathecally in participants with Angelman syndrome.

Detailed description

This is a Phase 1-2a, open-label study consisting of 3 parts in approximately 70 participants. Part 1 is a multiple ascending dose (MAD) study, consisting of a 13-week MAD Treatment Period and a minimum 12-week Post-MAD Follow-Up Period. Part 2 is a multi-center 49-week study where participants who completed Part 1 will receive IT bolus doses of ION582 followed by a minimum 12-week Part 2 follow up period. Part 3 extends the treatment period for participants who completed Part 2 for up to an additional 3 years followed by a 32-week post-LTE follow up period. The study was amended in late 2025 to include a cohort of people with Angelman Syndrome under the age of 2 years old. Recruitment sites listed as "Recruiting" below are eligible to recruit individuals into this new cohort only. This page will continue to be updated to reflect the recruitment status of sites and the study. For more information, speak with your doctor or see the Study Contact information below.

Conditions

• Angelman Syndrome

Interventions

Type	Name	Description
DRUG	ION582	ION582 will be administered by IT injection.

Timeline

• Start date: 2021-12-22
• Primary completion: 2029-03-01
• Completion: 2029-03-01
• First posted: 2021-11-19
• Last updated: 2025-11-14

Locations

11 sites across 6 countries: United States, Australia, France, Israel, Italy, United Kingdom

Regulatory

• FDA-regulated drug study