Pattern of use and clinical outcomes with rIX-FP in pediatric/adolescent patients with haemophilia B in Italy: Results from IDEAL real-world study

Objectives: To evaluate pattern of use and clinical outcomes in pediatric/adolescent patients enrolled in the IDEAL study.Methods: This post-hoc analysis of IDEAL retrospective-prospective observational study focused on patients <18 years, 100% on prophylaxis during the entire observation period.Results: Thirteen subjects (median age 10.0 years; 61.5% <= 11 years) were analyzed. The infusion frequency changed from 2/week in 84.6% (N = 11) of patients with previous rFIX, to less than 1/weekly in 76.9% (N = 9) with rIX-FP and the annualized number of infusions reduced of 57% (p = .002), from a mean +/- SD of 95.1 +/- 22.77 to 40.4 +/- 6.79, respectively. Annualized mean consumption decreased of about 56% (p = .001), from 3748.4 +/- 1155.40 IU/kg with previous rFIX, to 1656.8 +/- 456.63 IU/kg of rIX-FP. Mean FIX trough level changed from 3.0% +/- 1.98% to 10.92% +/- 3.6%. Low mean Annualized Bleeding Rate was maintained across all prophylaxis regimens (0.8 +/- 1.69 vs. 0.3 +/- 0.89) and zero bleeding patients moved from 69.2% (N = 9) with previous rFIX to 84.6% (N = 11) with rIX-FP (p = .63). Two adverse events, none related to rIX-FP, occurred in two patients. No inhibitors development was reported.Conclusions: The results in this pediatric/adolescent subgroup support rIX-FP prophylaxis may reduce infusion frequency, while providing high FIX trough levels, stable annualized bleeding rate and a good safety profile.