Ionis and Otsuka secure EU approval for HAE therapy DAWNZERA

Ionis Pharmaceuticals (NASDAQ:IONS) and Otsuka Pharmaceutical achieved a major regulatory victory Wednesday as the European Commission (EC) granted marketing authorization for DAWNZERA (donidalorsen).

The approval clears the RNA-targeted therapy for the routine prevention of hereditary angioedema (HAE) attacks in adults and adolescents aged 12 and older across the European Union.

The decision triggers a $15 million milestone payment from Otsuka to Ionis, with the California-based biotech also eligible for tiered royalties of up to 30% on net sales in the region.

DAWNZERA distinguishs itself as the first RNA-targeted prophylactic for HAE, offering a flexible dosing schedule of every four or eight weeks via a self-administered subcutaneous autoinjector.

Clinical data from the Phase 3 OASISplus study underscored the drug's efficacy, showing a 94% mean monthly attack rate reduction at the one-year mark.

"We believe DAWNZERA has the potential to become the prophylactic therapy of choice for many patients across the EU," said Ionis CEO Brett P. Monia.

The drug previously received FDA approval in August 2025, and Otsuka now holds exclusive rights to commercialize the treatment throughout Europe and the Asia Pacific region.