Long-term Safety and Efficacy Study of Fitusiran in Patients With Hemophilia A or B, With or Without Inhibitory Antibodies to Factor VIII or IX

Prior treatment

• Completion of a surgical procedure within 14 days prior to screening, or currently receiving additional factor concentrate or BPA infusion for postoperative hemostasis
• Current or prior participation in a gene therapy trial

Other illness

• Current use of factor concentrates or bypassing agents (BPAs) as regularly administered prophylaxis designed to prevent spontaneous bleeding episodes except for participants requiring factor concentrates or BPAs prophylaxis during the study dosing pause period
• Additional exclusions for participants not currently participating in a fitusiran trial at the time of enrollment in the lower dose cohort:
  • Clinically significant liver disease
  • History of arterial or venous thromboembolism
  • The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.

Lab values

• Alanine aminotransferase (ALT) and/or Aspartate aminotransferase (AST) \>1.5 × upper limit of normal reference range (ULN) for patients who are naïve to fitusiran at study start; ALT and/or AST \> 5 x ULN for patients who were in the fitusiran arm in the parent study

Other

• Current participation in immune tolerance induction treatment (ITI)
• Use of compounds other than factor concentrates or BPAs for hemophilia treatment

• Participant must be at least 12 years of age inclusive, at the time of signing the informed consent
• Participants with severe hemophilia A or B who have completed a Phase 3 fitusiran clinical trial
• Male
• Capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in the protocol. In countries where legal age of majority is above 18 years, a specific ICF must also be signed by the participant's legally authorized representative