Ionis Pharmaceuticals Inc (Nasdaq: IONS) on Monday announced the publication of positive Phase 3 OASISplus data in The Journal of Allergy and Clinical Immunology (JACI) In Practice, supporting its investigational therapy donidalorsen for patients with hereditary angioedema (HAE) who transitioned from existing long-term prophylactic treatments.

The study showed that patients switching to donidalorsen experienced no increase in breakthrough attacks during the transition and achieved a 62% additional reduction in mean monthly HAE attacks from their baseline on prior therapies.

By subgroup, attack rates decreased by: 65% for patients previously on lanadelumab; 41% for those on C1-esterase inhibitor (C1INH); and 73% for those on berotralstat.

The switch cohort of the OASISplus trial evaluated 65 patients who transitioned from one of the three standard prophylactic therapies after a 10-week baseline period. After 16 weeks of donidalorsen treatment, 93% of patients reported well-controlled disease, up from 67% at baseline, based on the Angioedema Control Test (AECT).

84% of participants preferred donidalorsen over their prior treatment, citing better disease control, quicker administration and fewer injection site reactions. Donidalorsen was well tolerated, with no serious treatment-emergent adverse events attributed to the drug.

Donidalorsen, an RNA-targeted therapy that inhibits prekallikrein (PKK), is under FDA review for the prevention of HAE attacks in patients aged 12 and older. The Prescription Drug User Fee Act (PDUFA) decision is expected by 21 August 2025.

If approved, donidalorsen would represent a potential first-in-class prophylactic option for patients living with HAE, a rare and potentially life-threatening condition affecting over 20,000 individuals in the US and Europe.