Treatment of Factor VIII Inhibitors with Selective IgG Immunoadsorption – a Single Center Experience in 50 Patients with Acquired Hemophilia*

Background: Acquired hemophilia (AH) is a potentially lifethreatening disease in which severe bleeding events lead to a mortality of up to 22%. In AH autoantibodies of the IgG subtype inactivate clotting factors. Although the incidence of this disease is low (1-3 per 106), the treatment cost can be immense due to long-term clotting factor substitution. The treatment should aim at a rapid and permanent elimination of autoantibodies and the induction of a new immune tolerance to prevent further bleedings. Patients and Methods: 50 high-titer (>5 Bethesda Units(BU)/ml) AH patients were treated by the following protocol: i) inhibitor elimination via IgG immunoadsorption, ii) immunosuppression, iii) i.v. immunoglobulin, and iv) high-dose factor VIII substitution. Follow-up time ranged between 12 months and 7 years. Results: A complete remission was achieved in 46 of 50 patients (92%). Neither bleeding nor therapy-associated mortality occurred after initiation of treatment. The median time to reach undetectable inhibitor levels was 3 days (95% CI 3-6 days), coagulation factors were given at a median of 15 days (95% CI 12-18 days). The median treatment duration was 17 days (95% CI, 14-20 days). Conclusions: IgG immunoadsorption allows for a fast and permanent inhibitor elimination, being the basis of the high immunomodulatory potency of our protocol which results in long lasting complete remissions in 92% of our patients.