Study Purpose:

The purpose of this study is to see if fitusiran can reduce the number of bleeds patients experience over the study period. This includes studying any potential improvements in patients’ hemophilia and any side effects that patients may have from taking fitusiran. In addition, the study will examine how the body handles (distributes, breaks down, and eliminates) fitusiran by measuring the amount of fitusiran that gets into the blood after it is given to patients. 


Study Summary:

In this study, you will be randomly (like flipping a coin) assigned to either receive 80 mg of fitusiran or to continue your current on-demand use of factor concentrates. Two out of three participants will receive fitusiran; one out of three participants will continue current on-demand treatment.

If you are assigned to take fitusiran, you will be permitted to use on-demand factor concentrates if necessary for treatment of breakthrough bleeding episodes. If you are assigned to take fitusiran, it will be given at a dose of 80 mg by subcutaneous (under the skin) injection once every 28 days for a total of 9 months. You will most likely receive the injection in your stomach. Your study doctor may decide to inject you in the upper arm or thigh. Each subcutaneous injection syringe contains 80 mg of fitusiran so you will receive one (1) injection at each dosing study visit. Please ask the study doctor if you want to know anything else about dosing.


Basic Eligibility Criteria:

This study will include males with severe hemophilia A or B without inhibitors (defined as Nijmegen modified Bethesda assay inhibitor titer of <0.6 BU/mL at Screening), aged ≥12 years, who have had a minimum of 6 bleeding episodes requiring on-demand treatment with factor concentrates within the last 6 months prior to Screening. Diagnosis of severe hemophilia A or B will be based on a central laboratory measurement or documented medical record evidence of FVIII level <1% or FIX level ≤2%.


Study Location(s):

Phoenix Children’s Hospital – Main Campus


Study Contact(s):

Erica Olson, Research Nurse



Courtney Moyer, Research Coordinator


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