Background: Immune tolerance induction (ITI) is the only proven method for removing inhibitors in hemophilia A patients receiving FVIII replacement. ITI able to increase FVIII level, and important in management of low-responder patients whom FVIII treatment is unfeasible in spite of increased doses.

Aims: To measure the efficacy of ITI treatment.

Methods: Medical records of three adults with severe, moderate and mild hemophilia A with inhibitors < 0.05 BU on ITI at our center were reviewed. The efficacy of ITI measured by demonstrating an increase in FVIII level after 6 months and 2 years of ITI and significant reduction in all bleeding events during period of ITI. The quality of life (QoL) assessed by the ability to participate in normal daily activities.

Results: First patient, 38 yo, severe hemophilia A (FVIII 0.8% in 2012); second patient, 32 yo, moderate hemophilia A (FVIII 1% in 2012); and third patient, 31 yo, mild hemophilia A (FVIII 11% in 2010). All three of them were low-responder, usually receiving prophylactic treatment with human FVIII with increased doses. The ITI treatment with high-purity human FVIII/ von willebrand factor (vWF) 1000 iu weekly was started in August 2017. The FVIII level increase to 1%, 2%, and 12% after 6 months and 2%, 4%, and 12% after 2 years of ITI in 1^st, 2^nd, and 3^rd patient respectively. No bleeding events observed and improvement in QoL showed in the restoration of normal daily activities.

Conclusions: Our study indicates a successful ITI treatment with high-purity human FVIII/ von willebrand factor (vWF). No adverse effects were detected. Potential benefits of avoiding hospitalizations and the prevention of long term complications, makes ITI treatment a real option.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/the-2-years-successful-experience-of-immune-tolerance-induction-iti-with-high-purity-human-fviii-von-willebrand-factor-vwf-in-hemophilia-a-patients/