Annualized FIX usage and bleeds. (A) Annualized FIX usage; (B) annualized bleeds. Cumulative annualized FIX activity excludes use of factors related to surgery. The total use of FIX was collected retrospectively from patient diaries and hospital record data at the year before screening and prospectively after AMT-060 (excluding the tapering/prophylaxis period) as part of the statistical analysis. Follow-up after discontinuation of prophylaxis ranged from 39 to 65 weeks for the participants in cohort 1 and from 11 to 34 weeks for the participants in cohort 2. One participant in cohort 1 continued FIX prophylaxis after AMT-060 infusion. One participant in cohort 2 used on-demand FIX therapy before study entry. One participant in cohort 2 was missing historical bleed data.