A Study of Fitusiran (ALN-AT3SC) in Severe Hemophilia A and B Patients With Inhibitors

ATLAS-INH: A Phase 3 Study to Evaluate the Efficacy and Safety of Fitusiran in Patients With Hemophilia A or B, With Inhibitory Antibodies to Factor VIII or IX

The purpose of this study was to determine the frequency of bleeding episodes in participants receiving fitusiran as prophylactic treatment of hemophilia compared to participants who were assigned to continue with their regular medication. In addition, the study assessed safety, quality of life, pharmacodynamics (PD), and pharmacokinetics (PK).

The duration of treatment with fitusiran was 9 months. The estimated total time on study, inclusive of screening, for each participant was up to 11 months for all participants who enroll in the extension study and participants in the on-demand arm who did not enroll in the extension study. The estimated total time on study was up to 17 months in fitusiran treatment arm participants who did not enroll in the extension study due to the requirement for up to an additional 6 months of follow-up monitoring for antithrombin levels.

Inclusion Criteria:

• Males, greater than or equal to (>=) 12 years of age.

• Severe hemophilia A or B with inhibitors.

  • (Severity confirmed by a central laboratory where coagulation factor VIII (FVIII) level was less than (<)1% or factor IX (FIX) level was less than or equal to [<=]2% at Screening; Inhibitors defined as inhibitor titer of >=0.6 Bethesda units per milliliter [BU/mL] or as evidenced by medical records).

• A minimum of 6 bleeding episodes requiring BPA 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.

Exclusion Criteria:

• Known co-existing bleeding disorders other than hemophilia A or B.
• Antithrombin (AT) activity <60% at Screening.
• Co-existing thrombophilic disorder.
• Clinically significant liver disease.
• Active hepatitis C virus infection.
• HIV positive with a cluster of differentiation-4 count of <200 cells/microliter.
• History of arterial or venous thromboembolism.
• Inadequate renal function.
• History of multiple drug allergies or history of allergic reaction to an oligonucleotide or N-Acetylgalactosamine.
• History of intolerance to SC injection(s).
• Any other conditions or comorbidities that would make the participant unsuitable for enrollment or could interfere with participation in or completion of the study, per Investigator judgement.