Treatment of factor VIII inhibitors

Factor VIII inhibitors are antibodies of the IgG class that neutralize the procoagulant activity of FVIII. They arise as alloantibodies in multitransfused haemophilia A patients and spontaneously in some individuals. Therapeutic strategy must be separated into two concepts: treatment of bleeding episodes and treatment of the inhibitor itself. Treatment of an haemorrhagic complication is dependent on the inhibitor titre and the status of the patient as a 'high' or 'low' responder. The choice has to be made between massive amounts of human FVIII concentrate, porcine FVIII and plasma preparations with 'bypassing' activity. Adjuvant therapy such as plasma exchange or extracorporeal passage of plasma over a Protein A sepharose column might be helpful. More recent products are still under evaluation such as FVIIa or recombinant tissue factor. Intravenous immunoglobulins have proven to be helpful mainly in patients with spontaneous inhibitors. Treatment of the inhibitor itself must be started as soon as possible. Several approaches are being used, immunosuppressive therapy or induction of immune tolerance using high intermediate or low doses of FVIII concentrate.