Real‐world data demonstrate improved bleed control and extended dosing intervals for patients with haemophilia B after switching to recombinant factor IX Fc fusion protein (rFIXFc) for up to 5 years

Abstract

Introduction: In clinical trials, recombinant factor IX fusion protein (rFIXFc) has demonstrated safety, efficacy and prolonged activity with extended dosing intervals for treatment of haemophilia B. Aim: To assess the real-world clinical utility of rFIXFc in a variable patient population and routine clinical practice. Methods: A multicentre, retrospective chart review was conducted of patients with haemophilia B who had received rFIXFc prophylaxis or on-demand treatment for ≥6 months across six sites in the United States. Results: Sixty-four eligible patients were identified who had a median (range) duration on rFIXFc of 2.7 (0.5-5.0) years. Of 32 patients on rFIXFc prophylaxis who switched from prophylaxis with another factor treatment (ie pre-rFIXFc) and had a known pre-rFIXFc dosing interval, the initial dosing interval was lengthened for 26 (81%) patients and maintained for the remaining 6 (19%) patients. Most (n = 48 [91%]) patients who received rFIXFc prophylaxis from the beginning to the end of the chart review period (n = 53) maintained or lengthened the dosing interval from first through last dose of rFIXFc. For patients receiving rFIXFc prophylaxis, there was an approximate 50% reduction in weekly factor consumption compared with pre-rFIXFc prophylaxis. Overall annualized bleed rates, annualized spontaneous bleed rates and annualized joint bleed rates decreased after switching to rFIXFc prophylaxis (n = 24 with bleed data). Compliance to recommended treatment improved or remained stable in most patients with available data (30/31). Conclusion: Recombinant factor IX fusion protein prophylaxis improved bleed control, reduced overall consumption, reduced frequency of infusion and improved compliance for patients with haemophilia B in a real-world setting. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Real‐world outcomes with recombinant factor IX Fc fusion protein (rFIXFc) prophylaxis: Longitudinal follow‐up in a national adult cohort

“…Our study reports a significant reduction in ABR with rFIXFc prophylaxis compared with SHL rFIX treatment (ABR 2.0 vs ABR 3.3) and is similar to that reported in the pivotal clinical trial, ABR 3.0 for the dose‐adjusted prophylaxis group and ABR 1.4 for the interval‐adjusted prophylaxis group 9 . Similar ABRs have been reported in other real‐world studies 17,18,20 . This improvement is multifactorial, influenced by higher trough levels achieved with rFIXFc prophylaxis and more PWSHB able to achieve effective prophylaxis.…”

“…Other real-world studies have demonstrated a reduction in factor consumption with rFIXFc prophylaxis. 17,19,20 This study also demonstrated that rFIXFc was effective in the management of bleeds in the acute setting. One or two infusions of rFIXFc resolved 90% of acute bleeds, which is similar to that reported in the phase 3 clinical trial where 97% of bleeding episodes resolved with one or two infusions.…”

“…9 Similar ABRs have been reported in other real-world studies. 17,18,20 This improvement is multifactorial, influenced by higher trough levels achieved with rFIXFc prophylaxis and more PWSHB able to achieve effective prophylaxis. The longer prophylaxis intervals possible with rFIXFc enabled patients to consider prophylaxis who were previously only able to access episodic treatment with SHL rFIX, primarily due to poor venous access, fulfilling one of the expectations of EHL products.…”

“…18 Treatment with EHL-FIX products has also demonstrated nearly 50% reduction in factor consumption compared with SHL factors. 19,20 This study evaluates the real-world experience of transitioning an unselected, complete cohort of PWSHB (≥18 years) from conventional SHL rFIX treatment to rFIXFc prophylaxis in an adult European haemophilia comprehensive care centre. We report prophylaxis regimens, bleeding rates, management of bleeding episodes and factor usage with rFIXFc in an Irish adult male cohort of PWSHB, who all received rFIXFc prophylaxis for a two-year period from 2017 to 2019.…”

“…The use of lower weekly doses of rFIXFc prophylaxis (30 IU/kg) in a small cohort of PWSHB has reported median trough levels of 0.04 IU/ml and ABR of 4 18 . Treatment with EHL‐FIX products has also demonstrated nearly 50% reduction in factor consumption compared with SHL factors 19,20 …”