Ionis Pharmaceuticals Inc (Nasdaq:IONS), a US-based provider of RNA-targeted medicines, and Japanese healthcare company Otsuka Pharmaceutical Co Ltd on Wednesday announced that the European Commission has approved DAWNZERA (donidalorsen) for routine prevention of recurrent hereditary angioedema (HAE) attacks in adults and adolescents aged 12 years and older.

This approval follows a positive opinion from the Committee for Medicinal Products for Human Use.

The decision is based on Phase 3 OASIS-HAE and OASISplus studies, which showed significant and sustained reductions in mean monthly HAE attack rates, including a 94% reduction at one year in the OASISplus open-label extension. DAWNZERA is administered via subcutaneous autoinjector every four or eight weeks.

HAE is a rare genetic disorder causing recurrent severe swelling in multiple body parts and affects approximately 1 in 50,000 people worldwide.

DAWNZERA received US FDA approval in August 2025 for prophylaxis in patients 12 years and older. Otsuka holds exclusive rights for commercialization in Europe and the Asia Pacific.

With this approval in the European Union, Ionis is eligible for a milestone payment of USD15m as well as tiered royalties of up to 30% on net product sales.