Acquired factor inhibitors are a significant probelm in patieints with hemophilia and other conditions. All patients who develop an inhibitor should be considered for immune tolerance induction (ITI). The decision to attempt ITI for FIX inhibitors must be carefully weighed against the relatively high risk of reactions and the nephrotic syndrome and the relatively low response rate observed in this group. The start of ITI should be deferred until the inhibitor has declined below 10 Bethesda Units/ml, where possible. ITI should continue, even in resistant patients, where it is well tolerated and so long as there is a convincing downward trend in the inhibitor titre. The choice of treatment for bleeding in inhibitor patients is dictated by the severity of the bleed, the current inhibitor titre, the previous anamnestic response to FVIII/IX, the previous clinical response and the side-effect profile of the agents available. We have reviewed novel dose-regimens and modes of administration of FEIBA (factor VIII inhibitor bypassing activity) and recombinant activated FVII (rVIIa) and the extent to which these agents may be used for prophylaxis and surgery. Bleeding in acquired haemophilia is usually treated with FEIBA or rVIIa. Immunosuppressive therapy should be initiated at the time of diagnosis with Prednisolone 1 mg/kg/d ± cyclophosphamide. In the absence of a response to these agents within 6 weeks, second-line therapy with Rituximab, Ciclosporin A, or other multiple-modality regimens may be considered.
Wenche Jy et al, Life-Threatening Bleeding from Refractory Acquired FVIII Inhibitor Successfully Treated with Rituximab Acta haematol Vol. 109, No. 4, 2003
Hay CRM, Baglin TP, Collins PW, Hill FGH, Keeling DM: The diagnosis and management of factor VIII and factor IX inhibitors: A guideline from the UK haemophilia center Doctors’ organization (UKHCDO). Br J Haematol 2000;111:78-90