A Phase 3 interventional study of Fitusiran and Clotting factor concentrates (CFC) or bypassing agents (BPA) in Hemophilia, sponsored by Sanofi. Active, not recruiting at 50 sites in 17 countries. Open to male participants aged 12 Years and older. Per ClinicalTrials.gov, last updated 2026-02-04.
Sponsored by Sanofi · Phase 3, Interventional, and Treatment
This is a multicenter, multinational, open-label, one-way cross-over, Phase 3, single-arm study for treatment of hemophilia.
The purpose of this study is to measure the frequency of treated bleeding episodes with fitusiran in male adult and adolescent (≥12 years old) participants with hemophilia A or B, with or without inhibitory antibodies to factor VIII or IX who have switched from their prior standard of care treatment.
The total study duration will be up to approximately 50 months (200 weeks, 1 study month is equivalent to 4 weeks) and will include:
The frequency for telephone visits will be approximately every 2 weeks. For site visits the frequency will be approximately every 8 weeks during the SOC period and approximately every 4 weeks during the fitusiran treatment period. If applicable and if allowed by local regulation, home and/or remote visits may be conducted during the study
866 studies on the registry are indexed under Hemophilia A; 137 are open to participants now.
This study's enrollment of 91 is above the median of 28 across 512 interventional studies indexed under Hemophilia A.
Browse Hemophilia A studies →Sanofi is the lead sponsor of 1,508 studies on the registry; 90 are open to participants now.
Of its 198 completed or terminated interventional studies of FDA-regulated products, 118 (60%) have results posted.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
In standard of care (SOC) period, participants will receive on-demand or prophylactic treatment with clotting factor concentrates (CFCs) or bypassing agents (BPAs) for 6 months (from Day -168 to Day -1). In fitusiran treatment period, participants will receive subcutaneous fitusiran prophylaxis once every other month (Q2M) or once monthly (QM) for 36 months (from Day 1 to Day 1009). In case of bleeding events participants will receive IV CFCs or BPAs. Participants may receive Antithrombin concentrate (ATIIIC) as rescue medicine. .
Drug: Fitusiran · Drug: Clotting factor concentrates (CFC) or bypassing agents (BPA) · Drug: Antithrombin concentrate (ATIIIC)
Pharmaceutical form: Solution for injection Route of administration: Subcutaneous (SC)
* Coagulation factor VIII (ATC code: B02BD02) * Coagulation factor IX (ATC code: B02BD04) * Coagulation factor VIIa (ATC code: B02BD08) * Factor VIII inhibitor bypassing activity (ATC code: B02BD03) Pharmaceutical form: Solution for infusion Route of administration: Intravenous (IV)
Antithrombin III (ATC code: B01AB02) Pharmaceutical form: Solution for infusion Route of administration: Intravenous (IV)
Annualized bleeding rate (ABR) in the fitusiran primary efficacy period
A bleeding episode is defined as any occurrence of hemorrhage that requires administration of CFCs or BPAs, e.g., hemarthrosis, muscle, or mucosal bleeding.
Time frame: Day 169 to Day 505 (since the first dose of fitusiran)
Annualized bleeding rate (ABR) while on fitusiran prophylaxis in the fitusiran primary efficacy period and ABR while on prophylaxis standard of care (SOC) in the SOC period
A bleeding episode is defined as any occurrence of hemorrhage that requires administration of CFCs or BPAs, e.g., hemarthrosis, muscle, or mucosal bleeding.
Time frame: Day 169 to Day 505 (primary efficacy period) and Day -168 to Day -1 (SOC period)
Annualized bleeding rate (ABR) while on fitusiran prophylaxis in the fitusiran primary efficacy period and ABR while on on-demand standard of care (SOC) in the SOC period
A bleeding episode is defined as any occurrence of hemorrhage that requires administration of CFCs or BPAs, e.g., hemarthrosis, muscle, or mucosal bleeding.
Time frame: Day 169 to Day 505 (primary efficacy period) and Day -168 to Day -1 (SOC period)
Annualized spontaneous bleeding rate in the fitusiran primary efficacy period and in the SOC period
A bleeding episode is defined as any occurrence of hemorrhage that requires administration of CFCs or BPAs, e.g., hemarthrosis, muscle, or mucosal bleeding. A spontaneous bleeding episode is a bleeding event that occurs for no apparent or known reason, particularly into the joints, muscles, and soft tissues.
Time frame: Day 169 to Day 505 (primary efficacy period) and Day -168 to Day -1 (SOC period)
Annualized joint bleeding rate in the fitusiran primary efficacy period and in the SOC period
A bleeding episode is defined as any occurrence of hemorrhage that requires administration of CFCs or BPAs, e.g., hemarthrosis, muscle, or mucosal bleeding. A joint bleeding episode is characterized by an unusual sensation in the joint ("aura") in combination with 1) increasing swelling or warmth over the skin over the joint, 2) increasing pain, or 3) progressive loss of range of motion or difficulty in using the limb as compared with baseline.
Time frame: Day 169 to Day 505 (primary efficacy period) and Day -168 to Day -1 (SOC period)
Change in Haem-A-QOL physical health score and total score during SOC and during fitusiran prophylaxis
The Haem-A-QoL will be provided to participants ≥17 years of age and includes 46 items contributing to 10 QoL domains (physical health, feelings, view of yourself, sports and leisure, work and school, dealing with hemophilia, treatment, future, family planning, partnership, and sexuality). Scoring for each item is based on a 5-point Likert scale (never, rarely, sometimes, often, and all the time), and higher scores represent greater impairment.
Time frame: Day 1 (D1) to Day 505, and from D1 to Day 1009, and during SOC from Day-168 to D-1
Annualized bleeding rate (ABR) in the fitusiran 18-month efficacy period
A bleeding episode is defined as any occurrence of hemorrhage that requires administration of CFCs or BPAs, e.g., hemarthrosis, muscle, or mucosal bleeding.
Time frame: Day 1 to Day 505
Annualized bleeding rate (ABR) in the fitusiran 36-month treatment period
A bleeding episode is defined as any occurrence of hemorrhage that requires administration of CFCs or BPAs, e.g., hemarthrosis, muscle, or mucosal bleeding.
Time frame: Day 1 to Day 1009
Annualized weight-adjusted consumption of CFC/BPA
All CFC or BPA doses (including doses per kg body weight) administered during the study treatment will be recorded
Time frame: Day -168 until Day 1009
Number of participants with adverse events
All AEs (serious or nonserious) will be collected from the signing of the informed consent form (ICF) until last AT follow up visit.
Time frame: Date of signed ICF (Day -228 to Day -169) until last visit (approximately 50 months after date of signed ICF)
Plan to share: Yes — Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org
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This study is active, not recruiting, as verified in Feb 2026. You cannot join it, but the record below documents what was studied.
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