Treatment of acquired hemophilia by the Bonn-Malmo Protocol: documentation of an in vivo immunomodulating concept

Abstract

Acquired hemophilia (AH) is an extremely rare condition in which autoantibodies (inhibitors) against clotting factor VIII induce acute and life-threatening hemorrhagic diathesis because of abnormal blood clotting. The mortality rate of AH is as high as 16%, and current treatment options are associated with adverse side effects. We investigated a therapeutic approach for AH called the modified Bonn-Malmo Protocol (MBMP). The aims of MBMP include suppression of bleeding, permanent elimination of inhibitors, and development of immune tolerance, thereby avoiding long-term reliance on coagulation products. The protocol included immunoadsorption for inhibitor elimination, factor VIII substitution, intravenous immunoglobulin, and immunosuppression. Thirty-five high-titer patients with critical bleeding who underwent MBMP were evaluated. Bleeding was rapidly controlled during 1 or 2 apheresis sessions, and no subsequent bleeding episodes occurred. Inhibitor levels decreased to undetectable levels within a median of 3 days (95% confidence interval [95% CI], 2-4 days), factor substitution was stopped within a median of 12 days (95% CI, 11-17 days), and treatment was completed within a median of 14 days (95% CI, 12-17 days). Long-term follow-up (7 months-7 years) showed an overall response rate of 88% for complete remission (CR). When cancer patients were excluded, the CR rate was 97%.