Abstract Number: PB0560
Meeting: ISTH 2021 Congress
Theme: Hemophilia and Rare Bleeding Disorders » Hemophilia - Clinical
Background: Immune tolerance induction (ITI) is the treatment of choice for eradication of anti-factor VIII (FVIII) antibodies (inhibitors) in people with inherited haemophilia A and inhibitors (PwHAi). Previous studies (most deriving from registries) have shown that a longer time elapsed between inhibitor development and the start of ITI (∆tinhi-ITI) associates with a lower ITI success rate among PwHAi.
Aims: We aimed to evaluate this association among PwHAi included in the BrazIT Study.
Methods: PwHAi (n = 133) were enrolled from 15 haemophilia treatment centres in Brazil. PwHAi were treated according to the Brazilian ITI Protocol, using a low-dose regimen (50 IU/kg three times weekly). Upon absence of a decline in inhibitor titre, a high-dose regimen (100 IU/kg daily) was indicated. Total success was defined as a negative inhibitor titre (< 0.6 BU/mL) and a normal FVIII pharmacokinetics (recovery 66% or higher of expected values, and half-life of 6 h or higher). Partial success was defined as inhibitor titre between 0.6 and 2 BU/mL; and/or abnormal FVIII pharmacokinetics (recovery below 66% of expected values; and/or half-life less than 6 h). Patients who did not achieve success parameters after 33 months were considered as failure.
Results: The median ages at inhibitor diagnosis and at ITI start were 3.6 years [IQR,1.6-7.2] and 7.0 years [IQR,2.6-19.2], respectively. PwHAi were stratified among four ∆tinhi-ITI quartiles: first (0.00 to 0.63 year), second (0.64 to 1.75 years), third (1.76 to 9.48 years), and fourth quartile (9.49 to 24.52 years). The overall success rate was 67.7% (90/133) of which first, second, third and fourth were 69.7% (23/33 patients), 69.7% (23/33 patients), 64.7% (22/34 patients), and fourth 66.7% (22/33 patients), respectively (p = 0.965).
Conclusions: In this study, about 70% of PwHAi responded to the Brazilian ITI Protocol. A longer ∆tinhi-ITI was not associated with a lower success rate of ITI in PwHAi.
To cite this abstract in AMA style:
Camelo RM, Dias MM, Caram-Deelder C, Gouw S, de Magalhaes LP, Zuccherato LW, Jardim LL, van der Bom J, Rezende SM. Time from the Inhibitor Detection to the Start of Immune Tolerance Induction and the Outcome of Immune Tolerance Induction: Results from the Brazilian Immune Tolerance (BrazIT) Study [abstract]. Res Pract Thromb Haemost. 2021; 5 (Suppl 2). https://abstracts.isth.org/abstract/time-from-the-inhibitor-detection-to-the-start-of-immune-tolerance-induction-and-the-outcome-of-immune-tolerance-induction-results-from-the-brazilian-immune-tolerance-brazit-study/. Accessed March 22, 2024.« Back to ISTH 2021 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/time-from-the-inhibitor-detection-to-the-start-of-immune-tolerance-induction-and-the-outcome-of-immune-tolerance-induction-results-from-the-brazilian-immune-tolerance-brazit-study/