Decline of factor VIII and factor IX inhibitors during long-term treatmentwith NovoSeven (R)

Recombinant factor VIIa (rFVIIa) (NovoSeven(R)) is used to treat bleeding e pisodes in hemophilia A and B patients with inhibitor antibodies against fa ctor VIII (FVIII) and factor IX. rFVIIa has been studied in home treatment of mild-to-moderate joint, muscle, and mucocutaneous bleeds to assess safet y and efficacy. Treatment with other factor concentrates was allowed accord ing to treating physician's judgment. Blood samples were drawn before study start and after 6 and 12 months. It has thus been possible to follow the i nhibitor titres during this period. Analyses of 53 patients (49 hemophilia A, four hemophilia B) showed inhibitor levels up to 1208 BU/ml before study start. Based on the first analysis, hemophilia A patients were divided int o high responders (> 5 BU/ml; 28 patients), low responders (> 1 and < 5 BU/ ml; 15 patients) and very low responders (less than or equal to 1 BU/ml; si x patients). In high responders receiving rFVIIa as only treatment, FVIII i nhibitor titre decreased to one-third of the initial level. For high respon ders receiving other factor treatments such as FVIII or prothrombin complex concentrates, inhibitor titre remained unchanged. Titres for low responder s and very low responders remained unchanged independent of treatment. Thus , when rFVIIa is used as the only coagulation factor to treat hemophilia A/ B high-responder inhibitor patients, inhibitor level declines significantly . Blood Coagul Fibrinolysis 11:239-242 (C) 2000 Lippincott Williams & Wilki ns.