Emicizumab Succeeds in Phase 3 Study of Children With Hemophilia

Bypassing agent reduces bleeds during 12 weeks of treatment

Positive interim results have been reported from a phase 3 study evaluating emicizumab (Chugai Pharmaceuticals/Genentech/Roche) prophylaxis in children less than 12 years of age with hemophilia A and inhibitors to factor VIII. After a median of 12 weeks of treatment, emicizumab prophylaxis achieved a clinically meaningful reduction in the number of bleeds over time. Injection-site reactions and nasopharyngitis were the most-common adverse events.

The HAVEN 2 trial is a multicenter, single-arm, open-label study investigating the efficacy, safety, and pharmacokinetics of once-weekly administration of subcutaneous emicizumab. The interim analysis after a median of 12 weeks of treatment included 19 children less than 12 years of age with hemophilia A and inhibitors to factor VIII who required treatment with bypassing agents. The objectives of the study are to evaluate the number of bleeds over time with emicizumab prophylaxis; safety; pharmacokinetics; health-related quality of life (HRQoL); and proxy HRQoL with aspects of caregiver burden. The study will enroll 60 children for its final analysis after 52 weeks of treatment with emicizumab.

Hemophilia affects approximately 20,000 people in the United States, with hemophilia A being the most common form. People with hemophilia A either lack or do not have enough of a clotting protein called factor VIII. In a healthy person, when a bleed occurs, factor VIII brings together the clotting factors IXa and X, which is a critical step in the formation of a blood clot to help stop bleeding.

Depending on the severity of their disorders, people with hemophilia A can bleed frequently, especially into their joints or muscles. These bleeds can present a significant health concern as they often cause pain and can lead to chronic swelling, deformity, reduced mobility, and long-term joint damage. In addition to affecting a person’s quality of life, these bleeds can be life threatening if they enter vital organs, such as the brain.

A serious complication of hemophilia treatment is the development of inhibitors to factor-VIII replacement therapies. Inhibitors are antibodies developed by the body’s immune system that bind to and block the efficacy of replacement factor VIII, making it difficult, if not impossible, to obtain a level of factor VIII sufficient to control bleeding.

Source: Genentech; April 17, 2017.