Ionis Pharmaceuticals Inc (NASDAQ: IONS), a provider of RNA-targeted therapies, on Monday announced promising results from the Phase 1/2 HALOS Study of ION582 in Angelman syndrome (AS) patients. The multiple ascending dose (MAD) portion of the study demonstrated robust improvements in communication, cognition and motor function. In the medium and high dose groups, 97% of participants experienced overall symptom improvement as measured by the Symptoms of Angelman Syndrome–Clinician Global Impression-Change (SAS-CGI-C).

Results from the Bayley-4 assessment revealed cognitive, communicative and motor function improvements surpassing those noted in natural history studies. Improvements were also evident in parent-reported measures using the Vineland-3 and Observer-Reported Communication Ability (ORCA). ION582 was well-tolerated across all dose levels.

Ionis plans to initiate Phase 3 development in the first half of 2025. Detailed results will be shared in a company webcast and at the 2024 Angelman Syndrome Foundation Family Conference on 24 July 2024.

The HALOS Study, which includes 51 participants aged 2-50 across six countries, is evaluating ION582's safety, tolerability and efficacy. ION582 aims to enhance UBE3A protein production by targeting the UBE3A antisense transcript, addressing a genetic mutation in AS.

Ionis is advancing treatments for various neurological conditions, with its portfolio including SPINRAZA and QALSODY.