Successful inhibitor eradication with ofatumumab in a patient with acquired hemophilia A
R. Fischer, M. Alrifai, K. Heidinger, B. Kemkes-Matthes (Giessen, Germany)
Acquired problems and alterations of coagulation
Time: 17:15 - 18:15
Objective: Acquired hemophilia (AH) is a rare autoimmune disorder characterized by the development of neutralizing autoantibodies against clotting factors, mainly factor VIII, leading to various bleeding patterns up to severe and life-threatening bleedings in patients with a negative personal and family history of hemorrhagic disorders. The management of AH focuses on the goals: control and prevention of bleeding (if present or significant), inhibitor eradication, and treatment of the underlying disease (if applicable). Bleeding control can be achieved with recombinant activated factor VII (rFVIIa or NovoSeven® RT), activated prothrombin complex concentrate (aPCC or FEIBA®), or recombinant porcine factor VIII (OBIZUR). First-line therapy in inhibitor eradication is prednisolone or cyclophosphamide, second-line is rituximab.
Results: Case report: 73-year-old man with Morbus Waldenström and acquired hemophilia (factor VIII < 1%, max. inhibitor titer 36 BU). First-line treatment with prednisolone and cyclophosphamide did not lead to inhibitor reduction and application of mycophenolic acid in exchange for cyclophosphamide was not successful either. Due to an anaphylactic reaction to rituximab in the past which was given for treatment of the M. Waldenström ofatumumab was given alternatively (4 cycles). This lead to a successful inhibitor eradication.
Conclusion: Ofatumumab and rituximab are specific human monoclonal IgG1 antibodies. Both bind to the CD20 antigen which is expressed on almost all B-cells and eliminates B-cells through several mechanisms, including complement-dependent cytotoxicity. The binding sites of ofatumumab and rituximab to the B-lymphocytes differ. Our case shows that ofatumumab can be applied as an alternative therapy for inhibitor eradication in acquired hemophilia.