This is a Phase 3, multi-center, open-label, global study with donidalorsen in up to approximately 144 participants with HAE-1 (Type I) and HAE-2 (Type II). There are two groups in this study: 1) participants who roll over from another study of donidalorsen (open-label extension [OLE] participants), and 2) new participants who are not rolling over from another study of donidalorsen and were previously maintained on HAE prophylactic therapy with lanadelumab, berotralstat, or a C1-esterase inhibitor (C1-INH). The length of participation in the study is approximately 70 weeks for OLE participants and 76 weeks for other participants. Participants will receive donidalorsen in an Extended Treatment Period for up to an additional 104 weeks.
The purpose of this study is to evaluate the long-term safety and efficacy of donidalorsen in people with HAE and the effects of donidalorsen on the number of HAE attacks and their impact on quality of life (QoL).