Long-term outcome of haemophilia A patients after successful immune tolerance induction therapy using a single plasma-derived FVIII/VWF product: The long-term ITI study

Introduction: Immune tolerance induction (ITI) is a standard intervention to eradicate inhibitors in haemophilic patients. However, information on the long-term condition of patients who eradicated the inhibitor totally or partially after ITI is scarce. Aim: To perform a long-term follow-up to describe the status of patients reported as ITI success in the G-ITI study. Methods: This was an international, multicentre, observational, retrospective study of the 57 haemophilic patients who were reported as ITI success in the G-ITI study. Demographics and post-ITI clinical data recorded until January 2015 were extracted from the medical records. A descriptive analysis was undertaken. Results: Forty-four patients were evaluable. Post-ITI follow-up was 9.1 years in average. Thirty-seven target joints were affected in 21 patients; 38 patients presented bleeding with a mean of 1.0 ± 1.2 episodes year^-1, most of them (271/330) treated with Fanhdi^® (Grifols). Around half of the patients underwent at least one surgical procedure. Most venous access complications were of expected nature, requiring hospital stay in practically all cases. Fanhdi was used in 42 patients as the regular haemophilia treatment after ITI, mainly prophylactically. Three patients (6.8%) who were being treated with Fanhdi (prophylaxis), Kogenate (prophylaxis) and Emoclot (on demand), respectively, showed inhibitor relapse (at 29, 53 and 13 months after ITI, with 0.9, 3.65 and 12.5 BU respectively). All of them were successfully tolerized after rescue ITI. Conclusion: After ITI success, all patients continued with regular successful FVIII treatment for haemophilia for more than 9 years. The few inhibitor relapses were successfully overcome after rescue ITI.