German recommendations for immune tolerance therapy in type A haemophiliacs with antibodies

Abstract

Haemophilia A is the most common X-chromosomal-linked congenital bleeding disorder and is caused by decreased activity of blood coagulation factor VIII. Affected individuals develop a variable phenotype of haemorrhages, mainly into joints and muscles depending on the amount of the residual factor VIII. The exogenous factor VIII-substitution by plasma-derived or recombinant products are the only treatments either on demand or prophylactically. The most important complication of treatment is the development of inhibitors that affect about 20%-50% of the severe cases. These antibodies neutralize the therapeutic effect of factor VIII-concentrates, leading to recurrent bleeding episodes, progredient joint damages and sometimes life-threatening situations. The only chance for a complete and permanent eradication of the inhibitors in these patients is the induction of Immune-Tolerance (ITT) to substituted factor VIII by the application of high-doses of factor VIII. The treatment demands a strict compliance of the patient and a much higher effort of the physician, to non-compared inhibitor patients. Requirements for a consistent realization of the ITT to increase the successful outcome was carried out by German Haemophilia Center Directors.