Efectividad de inducción de tolerancia inmune en niños con hemofilia A y aloanticuerpos neutralizantes / Immunotolerance induction effectivity in hemophilia A children and neutralizing alloantibodies

Resumen: Introducción: El desarrollo de aloanticuerpos neutralizantes anti-factor VIII en hemofilia A es la complicación más seria relacionada al tratamiento. La inducción de tolerancia inmune (ITI) o inmunotolerancia es el único tratamiento que erradica inhibidores, permitiendo utilizar nuevamente factor VIII para el tratamiento o profilaxis de eventos hemorrágicos. Objetivo: reportar la experiencia en niños sometidos a inmunotolerancia en la red pública del país. Pacientes y Método: Análisis retrospectivo y descriptivo de 13 niños con Hemofilia A severa e inhibidores persistentes de alto título, que recibieron ITI y seguimiento completo. Se utilizó concentrado de FVIII plasmático en dosis de 70-180 UI/Kg/diarias, definiendo éxito como la negativización del inhibidor y recu peración de la vida media del FVIII. Resultados expresados en media (rango). Resultados: En 13 pacientes se identificó el inhibidor, a una edad de 17,6 meses (2-48), tras 35,2 días (9-112) de exposición a FVIII. Once pacientes (84,6%) recuperaron la vida media del FVIII, tras 49,6 meses (26-70) de tratamiento. En los pacientes que respondieron, el título del inhibidor se negativizó en 7,3 meses (1-20). Conclusiones: En niños con hemofilia A e inhibidores persistentes de alto título, la ITI tiene un elevado éxito. Dado que el tiempo de respuesta es variable, la inmunotolerancia debe ser personalizada.

Abstract: Introduction: The development of anti-factor VIII neutralizing antibodies in hemophilia A is the most severe com plication related to treatment. Immune tolerance induction (ITI) is the only known treatment for eradicating inhibitors. A successful ITI allows using factor VIII (FVIII) again for the treatment or prophylaxis of hemorrhagic events. Objective: To report the experience of pediatric patients who underwent ITI in the country's public health care network. Patients and Method: Retrospective and descriptive analysis of 13 pediatric patients with severe Hemophilia A and high-titer inhibitors persis tence who underwent ITI and complete follow-up. Plasma-derived FVIII concentrate was used at 70 180 IU/kg/day doses. The success of the treatment is defined by achieving a negative titer and a half life recovery of the FVIII. The results were expressed in median (range). Results: In 13 patients, the inhibitor was identified at an average age of 17.6 months, after 35.2 days of exposure to the FVIII. 11 patients (84.6%) recovered the half-life of FVIII after 49.6 months of treatment. In the patients who responded to treatment, the inhibitor titer was negative at 6 months on average. Conclusions: ITI is the treatment of choice for patients with hemophilia A and inhibitors persistence. ITI must be perso nalized since the time response is variable in each patient.

Immune tolerance induction in a case of hemophilia B with inhibitor with prothrombin complex concentrate and rituximab / 中华血液学杂志

Objective@#To explore the immune tolerance induction (ITI) in a case of severe hemophilia B patient with inhibitor.@*Methods@#The F Ⅸ∶C was detected using a one-stage method and FIX inhibitor was assayed using Bethesda method. ITI was performed with prothrombin complex concentrates (PCC) in combination with rituximab.@*Results@#His past exposure days (ED) with PCC were 20 ED and his peak FⅨ inhibitor titer was 56 BU/ml. When his FIX inhibitor titer decreased to 10.4 BU/ml in Nov. 2015 and after receiving the informed consent from his parents, ITI was started. PCC with low dose rituximab successfully eradicated the high titer inhibitor within 17 months. There was no anaphylaxis, thrombotic event and infection.@*Conclusion@#This is the first case report for successful immune tolerance induction therapy in Chinese hemophilia B patient. ITI using PCC combined with rituximab is an effective choice to induce immune tolerance of hemophilia B with inhibitor.

The Use of Rituximab with Immune Tolerance Induction Therapy for Hemophilia A with Inhibitors / 임상소아혈액종양

Inhibitor development is one of the major adverse events associated with increased morbidity and mortality in patients with congenital hemophilia. Recent treatment for them is immune tolerance induction (ITI), which involves the administration of high doses of factor concentrates over a prolonged period, sometimes combined with immunosuppressive agents. We report a case of inhibitor elimination with Rituximab, and high-dose factor VIII concentrates in a 5-year-old boy with hemophilia A. The patient improved clinically, with fewer bleeding episodes. However, he continued to have low immunoglobulin levels, which led to recurrent infections. After an infusion of intravenous immunoglobulin, inhibitor titers increased rapidly and his ITI was deemed a failure. In conclusion, even though it failed in the present study, Rituximab may be an alternative adjuvant therapy to eliminate the inhibitor in patients with hemophilia. The appropriate schedule and long-term side effects need further investigation.

Immune tolerance induction in patients with severe hemophilia A with inhibitors

BACKGROUND: Inhibitory antibodies to factor VIII (FVIII) are an important complication when managing patients with hemophilia A. Immune tolerance induction (ITI) has been regarded as a useful method 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 underwent ITI from March 2004 to December 2014. ITI was started with FVIII concentrates at 100 IU/kg, 3 times per week. The dose of FVIII was reduced according to the inhibitor titer and recovery of FVIII. Inhibitor elimination was defined as the time taken to achieve a negative inhibitor assay with no anamnestic response and normal FVIII recovery and/or normal half-life. RESULTS: In total, 17 patients with severe hemophilia A were evaluated. Complete tolerance was achieved in 14 of 17 patients (83%). The mean peak inhibitor titer before ITI was 38.4 BU/mL. The mean treatment duration was 26.2 months. The mean duration between inhibitor detection and ITI was 5.1 years in the complete tolerance group and 10.8 years in the partial tolerance and failed group. CONCLUSION: This study shows that ITI can be an effective and well-tolerated method for eradicating inhibitors. Possible influencing factors for ITI success were age at the start of ITI treatment and duration after inhibitor detection. More research to provide further insight about other factors and conditions is needed.

The Use of Rituximab with Immune Tolerance Induction Therapy for Hemophilia A with Inhibitors / 임상소아혈액종양

Inhibitor development is one of the major adverse events associated with increased morbidity and mortality in patients with congenital hemophilia. Recent treatment for them is immune tolerance induction (ITI), which involves the administration of high doses of factor concentrates over a prolonged period, sometimes combined with immunosuppressive agents. We report a case of inhibitor elimination with Rituximab, and high-dose factor VIII concentrates in a 5-year-old boy with hemophilia A. The patient improved clinically, with fewer bleeding episodes. However, he continued to have low immunoglobulin levels, which led to recurrent infections. After an infusion of intravenous immunoglobulin, inhibitor titers increased rapidly and his ITI was deemed a failure. In conclusion, even though it failed in the present study, Rituximab may be an alternative adjuvant therapy to eliminate the inhibitor in patients with hemophilia. The appropriate schedule and long-term side effects need further investigation.