Failure of Combined Factor VIII and Cyclophosphamide to Suppress Antibody to Factor VIII in Hemophilia

Two patients with hemophilia A and antifactor VIII antibodies were treated with infusions of factor VIII concentrates and intravenous cyclophosphamide in an attempt to suppress the antibody response. Factor VIII levels of 23% and 95% were achieved immediately postinfusion, and prompt control of bleeding ensued. Sequential antibody titers demonstrated no change in antibody response in either patient when compared to previous studies following factor VIII infusion alone. These results are in contrast to the previously reported suppression of factor VIII antibody in a nonhemophilic patient using an identical regimen.