A Study to Test a Medicine (Fitusiran) Injected Under the Skin for Preventing Bleeding Episodes in Male Adolescent or Adult Participants With Severe Hemophilia

Open to males ages 12 years and up

• Diagnosis of severe congenital hemophilia A or B (FVIII <1% or FIX level ≤2%) as evidenced by a central laboratory measurement at screening or documented medical record evidence.
• For participants currently not on prophylaxis (CFC or BPA on-demand): A minimum of 4 bleeding episodes requiring BPA (inhibitor participants) or CFC (non-inhibitor participants) treatment within the last 6 months prior to screening.
• Willing and able to comply with the study requirements and to provide written informed consent and assent in the case of participants under the age of legal consent, per local and national requirements

• Known co-existing bleeding disorders other than congenital hemophilia A or B
• History of arterial or venous thromboembolism, not associated with an indwelling venous access
• History of intolerance to SC injection(s).
• Current participation in immune tolerance induction therapy (ITI)
• Prior gene therapy
• Current or prior participation in a fitusiran trial
• Current or prior participation in a gene therapy trial
• Received an investigational drug or device within 30 days prior to the screening visit or within 5 half-lives of the investigational drug (or device) prior to the screening visit, whichever is longer
• Presence of clinically significant liver disease AT activity <60% at Screening
• Co-existing 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.