Participant disposition. ∗Among the 19 screen failures, the main reasons for screen failure were exclusion criterion of the coexisting thrombophilic disorder (7 [7.1%] of the overall participants screened; 2 [5.7%] in cohort A; and 5 [7.8%] in cohort B) or withdrawn consent (7 [7.1%] of the overall participants screened; 1 [2.9%] in cohort A; and 6 [9.4%] in cohort B). ^†A subgroup of cohort A included PwHB with inhibitors who were not responding adequately to BPA prophylaxis before enrollment (historical ABR, ≥ 20). ^‡After sponsor initiated pause in dosing and subsequent protocol amendment. ^§Nine participants with fitusiran 80 mg prophylaxis who discontinued therapy remained in the study to complete study assessments and follow-up to allow for the best study integrity and interpretation. ^¶One participant with fitusiran 50 mg prophylaxis who discontinued therapy remained in the study to complete study assessments and follow-up to allow for the best study integrity and interpretation.