The duration of treatment with fitusiran was 9 months. The estimated total time on study, inclusive of screening, was up to 11 months for all participants in the factor on-demand arm and for participants in the fitusiran arm who enrolled in the extension study (LTE15174). The estimated total time on the study was up to 17 months for participants in the fitusiran treatment arm who did not enroll in the extension study due to the requirement for up to an additional 6 months of follow-up monitoring for antithrombin levels.
Participants who completed the study will be eligible for an open-label extension study LTE15174 (NCT03754790).