Ionis presents Phase 2 data from open label extension study of donidalorsen

Ionis Pharmaceuticals presented positive results from a Phase 2 open-label extension study evaluating the safety and efficacy of its investigational antisense medicine, donidalorsen, in patients with hereditary angioedema, a rare and devastating inflammatory disease. Interim data after all patients completed 1 year of treatment in the study showed a sustained reduction in HAE attacks and no new safety signals following treatment with donidalorsen. Treatment with donidalorsen resulted in an overall sustained mean reduction in HAE attack rates of 95% from baseline. For patients treated with donidalorsen, 99.6% of study days were HAE attack-free. The data were presented at the American College of Allergy, Asthma & Immunology Annual Scientific Meeting in Louisville, Ky. Patients completing the Phase 2 study were eligible for enrollment in the OLE study. There were 20 Type 1 or Type 2 HAE patients in the Phase 2 study, and 17 entered the OLE. Following a 13-week fixed-dose period where participants received subcutaneous donidalorsen 80 mg every four weeks, eight patients switched to subcutaneous donidalorsen 80 mg every eight weeks. Patients who remained on donidalorsen 80 mg every 4 weeks had a mean reduction in attack rate of 95.3% and 98.3%, from Week 1 and Week 5, respectively. Patients receiving donidalorsen 80 mg every eight weeks experienced a mean reduction in attack rate of 75.6% from baseline and the mean monthly attack rate was 0.28. Five of these patients remained attack free over the one-year duration of this analysis, and three patients returned to 80 mg every four weeks. No serious adverse events were reported in the OLE study and no treatment-emergent adverse events led to study discontinuation. There were no clinically relevant abnormalities in any laboratory measurements.