Immune tolerance induction in patients with severe hemophilia A with inhibitors

Abstract

Background Inhibitory antibodies to factor VIII (FVIII) are an important complication when managingpatients with hemophilia A. Immune tolerance induction (ITI) has been regarded as a usefulmethod for eradicating inhibitors. We report the results of a retrospective study in Korean patients with hemophilia A who underwent ITI. Methods We reviewed the records of patients with hemophilia A with inhibitors who underwentITI from March 2004 to December 2014. ITI was started with FVIII concentrates at 100IU/kg, 3 times per week. The dose of FVIII was reduced according to the inhibitor titerand recovery of FVIII. Inhibitor elimination was defined as the time taken to achieve anegative inhibitor assay with no anamnestic response and normal FVIII recovery and/ornormal half-life. Results In total, 17 patients with severe hemophilia A were evaluated. Complete tolerance wasachieved in 14 of 17 patients (83%). The mean peak inhibitor titer before ITI was 38.4BU/mL. The mean treatment duration was 26.2 months. The mean duration between inhibitordetection and ITI was 5.1 years in the complete tolerance group and 10.8 yearsin the partial tolerance and failed group. Conclusion This study shows that ITI can be an effective and well-tolerated method for eradicatinginhibitors. Possible influencing factors for ITI success were age at the start of ITI treatmentand duration after inhibitor detection. More research to provide further insight about otherfactors and conditions is needed.