Evaluating Fitusiran Prophylaxis in Boys Aged 1 to Under 12 With Severe Hemophilia A or B With or Without Inhibitors

What this Trial Is About

Researchers are evaluating the efficacy and safety of fitusiran prophylaxis treatment in male children aged 1 to less than 12 years with severe hemophilia A or B, including those with or without inhibitory antibodies. This Phase 3, open-label study includes about 85 participants divided into two groups those who have not previously received fitusiran and those rolling over from a prior study. The goal is to assess how fitusiran affects bleeding rates compared to standard care. Participants in the fitusiran-nafve group will first undergo a 24-week standard of care period before starting fitusiran prophylaxis, which will last up to 160 weeks. The roll-over group, who are already on fitusiran treatment from an earlier study, will continue their current dosing for up to 60 weeks. Dose adjustments may occur based on individual needs according to the study protocol. Fitusiran is administered as a subcutaneous injection, while clotting factor concentrates or bypassing agents and antithrombin concentrate are given intravenously when needed. During the study, participants will be regularly monitored for bleeding rates, physical activity changes, pain intensity, and quality of life. Blood tests and other assessments will track safety, including adverse events and joint health. The primary outcome measure is the annualized treated bleeding rate during the fitusiran treatment period compared to the standard care period. Safety follow-up will continue approximately 24 weeks after the last dose, with total participation potentially lasting several years.

A Study to Investigate the Efficacy and Safety of Fitusiran Prophylaxis in Male Participants Aged 1 to Less Than 12 Years With Hemophilia A or B