A Study to Test a Medicine (Fitusiran) for Preventing Bleeds in People With Severe Hemophilia Who Previously Received Preventive Treatment With Emicizumab

Study of Investigational Medication for Severe Hemophilia A

Recruiting
12 years or above
Male
Phase 4
20 participants needed
1 Location

Study Overview

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.

Eligibility Criteria

You may be eligible for this study if you meet the following criteria:

  • Conditions: Hemophilia A
  • Age: 12 years or above
  • Gender: Male

Inclusion Criteria:

  • 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.

Exclusion Criteria:

Participants are excluded from the study if any of the following criteria apply:

  • Known coexisting bleeding disorders
  • History of antiphospholipid antibody syndrome.
  • History of arterial or venous thromboembolism, atrial fibrillation, significant valvular disease, myocardial infarction, angina, transient ischemic attack, or stroke. Participants who have experienced thrombosis associated with indwelling venous access may be enrolled.
  • Presence of clinically significant liver disease
  • Current or prior participation in a fitusiran trial
  • Current or prior participation in a gene therapy trial
  • AT activity <60% at Screening, as determined by central laboratory measurement
  • Coexisting thrombophilic disorder - Hepatitis C virus antibody positive, except participants who have negative Hepatitis C viral load and no evidence of cirrhosis
  • Presence of acute hepatitis, ie, hepatitis A, hepatitis E.
  • Presence of acute or chronic hepatitis B infection
  • Known to be HIV positive with CD4 count <200 cells/μL.
  • Reduced renal function

The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.

This study investigates the safety of switching to an investigational medication after stopping another treatment called emicizumab. The purpose of this study is to understand how male participants with severe hemophilia A, a condition where blood does not clot properly, respond to this change in treatment. Hemophilia A is a genetic disorder caused by a lack of clotting factor VIII, which is important for blood clotting.

Participants in the study will switch from emicizumab to a new investigational medication. During the study, participants will have regular check-ups to monitor their health and the effects of the investigational medication. A transition period will occur before starting the new treatment, and participants will be observed for any changes in their condition.

  • Who can participate: Male participants aged 18 years or older with severe hemophilia A can join. They must have been receiving emicizumab prophylaxis and meet specific health criteria. Individuals with certain health conditions, such as liver disease or reduced renal function, are not eligible.
  • Study details: Participants will switch from emicizumab to an investigational medication. They will attend regular check-ups to monitor their health. A placebo is not used in this study.
  • Study timelines and visits: The study will last up to approximately 28 months. The study requires visits at monthly or every 2 months intervals.
Updated on 30 Sep 2025. Study ID: NCT06145373

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