Switching Long-Term Prophylaxis to Donidalorsen for Hereditary Angioedema: 1-Year OASISplus Results

Background: Donidalorsen is an antisense oligonucleotide designed to reduce plasma prekallikrein in patients with hereditary angioedema (HAE). The Switch cohort of the OASISplus study (NCT05392114) evaluated the long-term safety and efficacy of donidalorsen in patients who switched from a long-term prophylactic treatment (LTP) to donidalorsen with 1-year outcomes. Methods: This study enrolled patients with HAE aged ≥ 12 years previously on stable doses of an LTP (lanadelumab, berotralstat, C1 inhibitor). Patients directly switched from an LTP to donidalorsen 80 mg administered subcutaneously once every 4 weeks. Endpoints included incidence and severity of treatment-emergent adverse events (TEAEs; primary endpoint), monthly HAE attack rate, Angioedema Quality of Life (AE-QoL), and Angioedema Control Test (AECT) measured at baseline and Week 52. Results: Sixty-five patients enrolled, and 54 (83.1%) completed 1 year. Eleven (16.9%) patients discontinued treatment during the first year, and one discontinued treatment after 1 year. Donidalorsen reduced HAE attack rates from baseline on the prior LTP by 67.6% over 52 weeks. Fifty-six of 64 (87.5%) dosed patients experienced a TEAE; most reported mild to moderate events. The most common treatment-related TEAEs were injection-site erythema (10.9%) and injection-site pruritus (10.9%). One patient had a serious adverse event that was not treatment-related. AE-QoL total score improved by 12.2 points (clinically meaningful ≥ 6 points) from baseline to Week 52, and 90.4% of patients had well-controlled disease (AECT ≥ 10) at Week 52. Conclusion: In patients who switched from another LTP, donidalorsen was well tolerated and improved long-term HAE attack rates, quality of life, and disease control.