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. 2025 Jan 26:16:20406207241311535.
doi: 10.1177/20406207241311535. eCollection 2025.

Real-world usage and effectiveness of recombinant factor IX Fc in haemophilia B from the B-SURE study in France

Hervé Chambost  1 , Yohann Repessé  2 , Fabienne Genre-Volot  3 , Dominique Desprez  4 , Sabine Marie Castet  5 , Stéphane Vanderbecken  6 , Meriem Zidi  7 , Corinne Gandossi  7 , Eveline Nüesch  8 , Helena Palmborg  9 , Elena Santagostino  8 ; B-SURE Study Group
Collaborators, Affiliations

Real-world usage and effectiveness of recombinant factor IX Fc in haemophilia B from the B-SURE study in France

Hervé Chambost et al. Ther Adv Hematol. .

Abstract

Background: More real-world data are needed to complement existing phase III studies on the efficacy and safety of recombinant factor IX Fc fusion protein (rFIXFc) in people with haemophilia B.

Objectives: We report final data from the B-SURE study, evaluating the real-world usage and effectiveness of rFIXFc in France.

Methods: Previously treated patients (all ages/severities) received on-demand or prophylactic rFIXFc during B-SURE. Annualised bleeding rate (ABR), injection frequency (IF) and factor consumption (FC) were prospectively evaluated for patients on rFIXFc prophylaxis (primary endpoints). Six months of retrospective factor IX (FIX) data were collected for comparison; patients with ⩾3 months of treatment pre- and post-switch to rFIXFc were analysed.

Design: B-SURE was a 24-month, prospective, non-interventional, real-world study across haemophilia treatment centres in France.

Results: Ninety-one male patients enrolled across 21 centres (34% <18 years, 89% severe haemophilia B). Eighty-four patients received prophylaxis at rFIXFc initiation; mean prospective observation period was 21.5 months. Sixty-eight of 84 patients had prior FIX prophylaxis; on rFIXFc prophylaxis, these patients achieved low median ABR (1.2), IF (47.45 injections/year) and mean FC (2844 IU/kg/year). Compared with previous FIX, mean ABR was reduced by 40% (n = 63); mean IF and FC were reduced by 38.20 injections/year and 1008 IU/kg/year (n = 57). In patients with prior FIX on-demand (n = 15), mean ABR reduced by 84% on rFIXFc prophylaxis (n = 14), mean IF reduced by 2.13 injections/year and mean FC increased by 381.8 IU/kg/year (n = 15). Most physicians and patients were satisfied/highly satisfied with rFIXFc prophylaxis. rFIXFc was well tolerated with no new safety concerns.

Conclusion: Findings support the safety and effectiveness of rFIXFc, with reduced IF and FC while maintaining/improving bleed protection. Trial registration: NCT03655340.

Keywords: factor IX; haemophilia B; prophylaxis; recombinant fusion proteins.

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Conflict of interest statement

H.C.: consulting fees from BioMarin, CSL Behring, Novo Nordisk, Pfizer, Roche Chugai and Sobi; payment/honoraria for lectures/speakers bureau from BioMarin, CSL Behring, Novo Nordisk, Roche Chugai and Sobi; payment for expert testimony from BioMarin; support for attending meetings from BioMarin, Novo Nordisk, Roche and Sobi. Y.R.: grant/research support from CSL Behring and Octapharma; consultant for (scientific advisory board honoraria) Sobi; invitation as speaker in symposia for CSL Behring, LFB, Novo Nordisk, Octapharma, Roche, Sobi and Takeda; participation in data safety monitoring or advisory board for CSL Behring and LGB. F.G.-V.: investigator in clinical trials for CSL Behring, Roche, Sobi and Takeda; consultant for LFB, Pfizer, Roche, Sobi and Takeda; payment/honoraria for lectures/speakers bureau from CSL Behring, Roche Chugai, Sobi and Takeda. D.D.: grant or honoraria or invitation as speaker in symposia for CSL Behring, Novo Nordisk, Roche, Sobi and Takeda. S.M.C.: consultant (advisory board honoraria or invitation as speaker in symposia) for CSL Behring, LFB, Novo Nordisk, Roche, Sobi and Takeda. S.V.: investigator in clinical trials for Sobi. M.Z.: employee of Sobi. C.G., E.N., H.P., E.S.: employees and shareholders of Sobi.

Figures

Graphical Abstract
Graphical Abstract
Figure 1.
Figure 1.
B-SURE study design. FIX, factor IX; rFIXFc, recombinant factor IX Fc fusion protein.
Figure 2.
Figure 2.
Treatment regimens pre- and post-switch to rFIXFc. aFinal rFIXFc regimen refers to the last documented regimen. bOne patient had multiple switches between prophylaxis and on-demand treatment regimens since rFIXFc prophylaxis initiation; final regimen was on-demand treatment. FIX, factor IX; rFIXFc, recombinant factor IX Fc fusion protein.
Figure 3.
Figure 3.
ABR of patients with available data both pre- and post-switch to rFIXFc prophylaxis from (a) FIX prophylaxis (n = 63) or (b) FIX on-demand treatment (n = 14). Figure shows means (triangles), IQR (box boundaries) and ranges (error bars); orange line indicates equal median/quartile. The period prior to rFIXFc initiation refers to the 6 months prior to the first rFIXFc injection; the period since rFIXFc initiation refers to the period from the first rFIXFc injection to the end of the prospective period. Means were estimated using a negative binomial model with the total number of treated bleeding episodes during the efficacy period as the response variable and log-transformed period duration (in years) as an offset variable. RRs were estimated using a repeated negative binomial model with treatment period (prior versus post rFIXFc initiation) as a covariate. an = 63/65 patients with available data both pre- and post-switch to rFIXFc prophylaxis were included. bn = 14/18 patients with available data both pre- and post-switch to rFIXFc prophylaxis were included. ABR, annualised bleeding rate; AJBR, annualised joint bleeding rate; FIX, factor IX; IQR, interquartile range; rFIXFc, recombinant factor IX Fc fusion protein; RR, rate ratio.
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