Abstract Number: PB1043
Meeting: ISTH 2020 Congress
Background: Low dose of plasma-derived factor VIII/Von Willebrand factor (pdVWF/FVIII) complex concentrate might be effective as immune tolerance therapy (ITI) in inhibitor-positive severe Hemophilia A patients with high-titer inhibitors.
Aims: To assess the effectiveness of low-dose ITI regimen (time to achieve response, response rates, annual bleeding and joint bleeds during study period compared to recorded bleeds in the year before) and compare results with our publication in “Haemophilia”, 2 decades ago.
Methods: A prospective study on previously treated children with severe hemophilia A having poor-risk status for ITI treatment success and high-titer inhibitors (inhibitor titer > 10 Bethesda units (BU) pre-ITI initiation; delay in ITI initiation [2-16 months]). Patients received ~50 IU/kg pdVWF/FVIII complex concentrate (Koate®), three times a week. Annual bleeding rate, annual joint bleeds and school attendance were compared retrospectively (12 months prior to study initiation)
Results: Fourteen patients with median age of 4.9 (2.4-11.2) years and median pre-ITI inhibitor titer 42.7 (11-168) BU were enrolled and followed-up during 6-22 months. Analysis at median 14 (9-22) months´ follow-up showed a total response rate of 71.4%. This included success (achieving inhibitor < 0.6 BU) in 9 patients, (57.2%) in a median of 10.8 (5.2-15.8) months, and partial success (achieving inhibitor < 5 BU but > 0.6 BU) in 2 (14.2%). Compared to the pre-ITI period, median annual bleeds during ITI was 9 (75.0% reduction), and median annual joint bleeds was 4 (80% reduction). School attendance improved by 50%. Study limitations; single arm study and short follow-up (1-6 months after ITI discontinuation). However, ITI outcome in this study was better than reported 2 decades ago.
Conclusions: Low-dose ITI treatment strategy using pdVWF/FVIII complex concentrate (Koate®) achieved relatively satisfactory outcomes (71.4% response) in children with inhibitor-positive severe Hemophilia A and poor-risk status for ITI treatment success, improving school attendance.
To cite this abstract in AMA style:Elalfy M, Hassan T, Elghamry I, Elalfy O. Pilot Study on Low-Dose Immune Tolerance Induction (ITI) Therapy in Severe Hemophilia A Children with High-Titer Inhibitors [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/pilot-study-on-low-dose-immune-tolerance-induction-iti-therapy-in-severe-hemophilia-a-children-with-high-titer-inhibitors/. Accessed September 29, 2023.
« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/pilot-study-on-low-dose-immune-tolerance-induction-iti-therapy-in-severe-hemophilia-a-children-with-high-titer-inhibitors/