Switching from standard to extended half-life FVIII prophylaxis in haemophilia A: Comparison of factor product use, bleed rates and pharmacokinetics.

ABSTRACT

INTRODUCTION: Majority of haemophilia A patients in our comprehensive care centre have switched from standard half-life (SHL) to extended half-life (EHL) FVIII products in a short time. AIM: We compared the clinical and laboratory outcomes between SHL and EHL FVIII prophylaxis in product switchers. METHODS: This is a retrospective inception cohort of all adult haemophilia A patients switched to EHL (rFVIIIFc or rFVIII-PEG) prophylaxis in our centre. Dosing, product utilization, annualized bleed rates (ABR), treatment regimen and pharmacokinetics by Web Accessible Population Pharmacokinetic Service (WAPPS)-Hemo were compared between SHL and EHL. RESULTS: We included 38 patients, whose median age was 38 years (range 17-75). Median FVIII dose was 23 IU/kg for SHL versus 25 IU/kg for EHL. After switching, weekly infusions decreased by 29% from median 2.8 (every 2.5 days) to 2.0 (every 3.5 days) (P = <.001) and factor consumption for prophylaxis by 17% from 60 to 50 IU/kg/week (P = <.001). Weekly infusions decreased in 71% and FVIII utilization in 55% of patients. ABR remained low (1.0 for SHL and .5 for EHL, respectively). In pharmacokinetics, the half-life of FVIII increased from median 13 to 21 h after switching. Times above .01 and .03 IU/ml improved from 85 to 131 h and from 65 to 106 h. Half-lives of the SHL products and von Willebrand factor levels predicted half-lives with the EHL products. CONCLUSIONS: Our cohort study confirms the successful experience of switching to EHL FVIII products, with decreased infusion frequency, factor consumption and excellent clinical efficacy.