This is a Phase 3, multi-center, double-blind, randomized, placebo-controlled study of donidalorsen in up to 84 participants. Participants will be randomized in a 2:1 ratio to Cohort A (donidalorsen or placebo every 4 weeks) or Cohort B (donidalorsen or placebo every 8 weeks), respectively. Within each Cohort, participants will be randomized in a 3:1 ratio to receive donidalorsen or matching-placebo. The length of participation in the study is approximately 11 months, which includes an up to 8-week Screening Period, a 25-week Treatment Period, and an up to 13-week Post-treatment Period.
The purpose of this study is to evaluate the safety and efficacy of donidalorsen in participants with HAE and effect of donidalorsen on the quality and pattern of HAE attacks and their impact on quality of life (QoL).