NCT07285460

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

An Open-label, Parallel, Phase 3, Two-arm 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 With or Without Inhibitory Antibodies to Factors VIII or IX

• Status: Recruiting
• Phase: Phase 3
• Study type: Interventional
• Enrollment: 85 (estimated)
• Sponsor: Sanofi · Industry
• Sex: Male
• Age: 1 Year – 11 Years
• Healthy volunteers: Not accepted

Summary

This is a parallel, Phase 3, two-arm, open-label study to evaluate the efficacy and safety of treatment with fitusiran prophylaxis administered to male pediatric participants (aged 1 to \<12 years) who have severe hemophilia A or B, with or without inhibitory antibodies to FVIII or FIX. Number of participants: Approximately 85 participants will be enrolled into the study: * Approximately 60 fitusiran-naïve participants with severe hemophilia A or B, with or without inhibitors (fitusiran-naïve arm), and * Approximately 25 participants with severe hemophilia A or B with inhibitors rolling over from the EFC15467\* dose confirmation study (roll-over arm). * Fitusiran has been investigated in the pediatric population in study EFC15467, which enrolled male participants aged 1 to \<12 years with hemophilia A or B with inhibitors to examine the safety and tolerability of fitusiran in the pediatric population. Participants will be enrolled into 1 of 2 arms: * Fitusiran-naïve: these participants have not previously received fitusiran, and they will undergo screening and study eligibility assessments. Once enrolled, they will go through a 24-week standard of care (SOC) period before starting fitusiran prophylaxis. * Roll-over participants from the EFC15467 study: only participants who are still on active treatment in study EFC15467 and consenting to study EFC17905 will be eligible to roll over. They will not need to undergo screening or further eligibility assessments. They will directly enroll into the fitusiran treatment period and continue treatment on their current fitusiran dose. The duration of fitusiran treatment will be up to 160 weeks for the fitusiran-naïve arm and up to 60 weeks for the roll-over arm.

Detailed description

The duration of fitusiran treatment will be up to 160 weeks for the fitusiran-naïve arm and up to 60 weeks for the roll-over arm.

Conditions

• Hemophilia

Interventions

Type	Name	Description
DRUG	Fitusiran	Pharmaceutical form: solution for injection in PBS Route of administration: subcutaneous
BIOLOGICAL	Clotting factor concentrates (CFC) or bypassing agents (BPA)	Pharmaceutical form: solution for injection Route of administration: intravenous injection
BIOLOGICAL	Antithrombin concentrate (ATIIIC)	Pharmaceutical form: solution for injection Route of administration: intravenous injection

Timeline

• Start date: 2025-12-18
• Primary completion: 2029-08-04
• Completion: 2031-12-30
• First posted: 2025-12-16
• Last updated: 2026-04-16

Locations

20 sites across 10 countries: United States, Belgium, Brazil, Canada, India, Italy, Poland, Romania, Spain, Turkey (Türkiye)

Regulatory

• FDA-regulated drug study