Ionis Pharmaceuticals Inc (Nasdaq: IONS), a provider of RNA-targeted medicines, announced on Tuesday that the US Food and Drug Administration has granted Breakthrough Therapy designation to ION582 for the treatment of Angelman syndrome, a rare neurological disorder characterised by intellectual disability, impaired communication, motor impairment, and seizures.

This designation follows encouraging results from the Phase 1/2 HALOS study, which demonstrated consistent clinical improvement across communication, cognition, and motor function, along with favourable safety and tolerability. Breakthrough Therapy status is intended to expedite regulatory review for therapies addressing serious conditions with potential for substantial improvement over existing treatments.

Ionis initiated the global Phase 3 REVEAL study of ION582 earlier this year, targeting children and adults with Angelman syndrome caused by maternal UBE3A gene deletion or mutation. Enrolment for the pivotal study is expected to be completed in 2026, supporting the ongoing development of ION582 as a potential disease-modifying therapy.