Low-dose Immune Tolerance Induction in Hemophilia: A Single-Center Experience

Abstract

Introduction: The development of inhibitors against factors VIII/IX is the most serious complication in hemophilia. The best treatment strategy for inhibitor eradication is immune tolerance induction (ITI). The aim of this study was to evaluate patients treated with low-dose ITI at a single center with limited resources. Materials and Methods: In total, 29 (8.05%) of 360 hemophilia A patients exhibited inhibitors. The data from hemophilia patients with inhibitors undergoing ITI between 1999 and 2017 were collected and analyzed. Results: Seventeen ITIs administered to 15 hemophilia A patients with inhibitors were analyzed, and the data from 13 ITIs conducted in 12 patients were evaluated. The median age at ITI onset was 10 years (range: 1.25 to 52 y). The maximum inhibitor titer before ITI was 30 Bethesda Units (BU) (range: 4.48 to 135), and the median inhibitor titer was 1.25 BU (range: 0 to 5.6) at the onset of ITI. The median time interval between the inhibitor development and ITI onset was 60 months (range: 7 to 264 mo). The median inhibitor titer during ITI was 3.4 BU (range: 0 to 158.7). At the end of the treatment, 4 of the 12 patients (33.3%) exhibited a complete response, 4 (33.3%) had partial responses (with continuing ITI), and 4 (33.3%) exhibited ITI failure. Conclusions: Treatment of hemophilia patients with inhibitors is challenging, and ITI is the best treatment method; however, a high-dose daily ITI regimen cannot be given to every patient in every country due to its high cost. Our results show that low-dose ITI may be a choice for selected patients with inhibitors.