Description of Medical ServiceEmicizumab is a monoclonal antibody that is bispecific for Factor IXa and Factor X. The two arms bind to each of these factors, mimicking the action of Factor VIII and allowing the normal clotting cascade to continue. Emicizumab offers the following advantages over the recombinant or plasma-derived factors for patients requiring prophylaxis (Shima 2016):
- Subcutaneous vs intravenous administration;
- Weekly vs every other day administration;
- Sustained plasma concentrations;
- No risk of FVIII inhibitor development;
- Activity irrespective of the presence of FVIII inhibitors.
Emicizumab is registered as a prescription medicine by the Therapeutic Goods Administration (TGA).
Description of Medical ConditionHaemophilia A (HMA) is an X-linked congenital bleeding disorder caused by a deficiency of the coagulation factor VIII (FVIII). HMA can be mild, moderate or severe depending on the level of deficiency.
- Mild: usually bleed as a result of injury or major surgery;
- Moderate: bleed spontaneously but usually as a result of injury;
- Severe: frequent spontaneous bleeding into muscles and joints.
The mainstay of treatment for HMA is replacement of the deficient Factor VIII by intravenous (IV) recombinant or plasma-derived Factor VIII, either on demand (to treat a bleed) or as prophylaxis. Prophylaxis prevents bleeding and irreversible joint destruction and is considered advisable before HMA patients engage in activities with higher risk of injury. Development of inhibitors (antibodies that neutralise replacement FVIII) is considered the most severe treatment-related complication in HMA, with a lifetime risk of development of ~20–30% in severe HMA and 5–10% in mild or moderate disease (ACHDO 2016).