PB0669 - Final Analysis of Long-term Clinical Outcomes of Recombinant Factor IX Fc Fusion Protein Prophylaxis in Adults ≥50 Years With Severe Hemophilia B

Monday, June 26, 2023

18:30 – 19:30 ET

Room: Exhibition

Presenting Author(s)

Margaret V. Ragni, MD, MPH (she/her/hers)

Professor of Medicine and Clinical and Translational Science
Department of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
Pittsburgh, Pennsylvania, United States

Co-Author(s)

Savita Rangarajan, MD, FRCP, FRCPath

Associate Professor of Clinical Haematology
Faculty of Medicine, University of Southampton, Southampton, UK
Southampton, England, United Kingdom
SC

Sandra Casiano

Senior Global Medical Director
Sanofi, Cambridge, MA, USA
Cambridge, Massachusetts, United States
UK

Umer Khan

Biostatistics Lead
Sanofi, San Diego, CA, USA
San Diego, California, United States

Background: B-LONG (NCT01027364) and the B-YOND extension (NCT01425723) studies evaluated recombinant factor IX Fc fusion protein (rFIXFc) in previously treated male subjects with severe hemophilia B (SHB).

Aims: Post hoc analysis of final data from subjects aged ≥50 years with SHB in B-LONG/B-YOND.

Methods: Treatment groups included weekly prophylaxis (WP; 20–100 IU/kg every 7 days), individualized prophylaxis (IP; 100 IU/kg every 8–16 days), modified prophylaxis (more tailored), and on-demand treatment (OD; bleed-dependent dosing). In B-YOND, subjects could change regimens at any time and may appear in >1 group. Outcomes included annualized bleed rates (ABRs; overall and joint), hemophilia quality of life questionnaire for adults (Haem-A-QoL), cumulative exposure, and factor consumption. Subjects provided informed consent.

Results: Twenty-six subjects aged ≥50 (median [range], 56 [50–71]) years were enrolled in B-LONG and/or
B-YOND. The median (interquartile range [IQR]) duration of rFIXFc treatment was 3.4 (1.0–5.4) years, encompassing a median (IQR) of 101 (44–220) rFIXFc exposure days. At baseline, 16/26 (62%) had ≥1 documented comorbidity, and 18/26 (69%) received ≥1 concomitant medication (Table). rFIXFc prophylaxis in older subjects with SHB resulted in low overall and joint ABRs (Figure). All 19 evaluable target joints resolved. Factor consumption decreased from B-LONG end to B-YOND end in 2 OD subjects (median [range] change, −6.01 [−14.24–2.22] IU/kg) but increased in 2 WP subjects (15.25 [4.13–26.37] IU/kg) and 5 IP subjects (7.67 [−11.41–18.17] IU/kg]) who did not change regimens. Subjects always on prophylaxis reported improvements in Haem-A-QoL domains of sports and leisure, work and school, and physical health.

Conclusion(s): rFIXFc is effective and safe for subjects with SHB aged ≥50 years. rFIXFc prophylaxis resulted in low ABR and improved quality of life, suggesting long-term benefit of rFIXFc in this subgroup. Data are consistent with overall study population. Funded by Sanofi and Sobi.