An Open-label, Single-arm Treatment Study to Investigate the Safety and Tolerability of Switching From Emicizumab to Fitusiran Prophylaxis in Male Participants Aged ≥12 Years of Age With Severe Hemophilia A, With or Without Inhibitors
This is an exploratory, single group, Phase 4, study to assess treatment with fitusiran prophylaxis after switching from emicizumab prophylaxis. This study aims to evaluate the safety and tolerability of switching to fitusiran after a transition period from the last dose of emicizumab. The study will be conducted in male participants with severe hemophilia A, with or without inhibitors, aged ≥12 years, who were previously receiving emicizumab prophylaxis. Study details include: * The study duration will be up to approximately 28 months: * There will be an approximately 2-month screening period. * There will be an approximately 2-month period before fitusiran treatment starts (pre-fitusiran treatment period) * The fitusiran treatment duration will be up to 18-months (fitusiran treatment period) * The antithrombin (AT) follow-up (FU) period will be approximately 6 months after the last dose of fitusiran (during which the AT activity level will be monitored at approximately monthly intervals following the final fitusiran dose until AT activity levels return to at least 60%). * The study site visits are scheduled at monthly/ every 2 months intervals of 28 days (4 weeks) / 56 days (8 weeks), respectively, during the fitusiran treatment period.
• Male participants must be ≥12 years of age inclusive, at the time of signing the informed consent
• Diagnosis of severe congenital hemophilia A (FVIII \< 1%) as evidenced by a central laboratory measurement at screening or documented medical record evidence.
‣ Inhibitor titer of ≥0.6 BU/mL at Screening, or
⁃ Inhibitor titer of \<0.6 BU/mL at Screening with medical record evidence of 2 consecutive titers ≥0.6 BU/mL, or
⁃ Inhibitor titer of \<0.6 BU/mL at Screening with medical record evidence of anamnestic response.
• Participants who are currently on the full labeled dose of emicizumab prophylaxis, irrespective of inhibitor/non-inhibitor status.
• Signed informed consent/assent which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol.