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

Inclusion Criteria:

• Male participants must be ≥12 years of age inclusive, at the time of signing theinformed consent

• Diagnosis of severe congenital hemophilia A (FVIII < 1%) as evidenced by a centrallaboratory 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 2consecutive titers ≥0.6 BU/mL, or

• Inhibitor titer of <0.6 BU/mL at Screening with medical record evidence ofanamnestic 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 andrestrictions 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, significantvalvular disease, myocardial infarction, angina, transient ischemic attack, orstroke. Participants who have experienced thrombosis associated with indwellingvenous 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, exceptparticipants 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.