Resolution of target joints during once-weekly prophylaxis with rIX-FP in patients with hemophilia B

H. J. Laws1, H. Hanabusa2, C. Négrier3, T. Lissitchkov4, G. Castaman5,6, A. Tagliaferri7, K. Fukutake2, M. F. López Fernández8, A. Veldman9, E. Santagostino10 (1Dusseldorf, Germany, 2Tokyo, Japan, 3Lyon, France, 4Sofia, Bulgaria, 5Vicenza, Italy, 6Florence, Italy, 7Parma, Italy, 8La Coruna, Spain, 9Marburg, Germany, 10Milan, Italy)

Bleeding disorders, coagulation and fibrinolytic factors
Date: 17.02.2017,
Time: 17:15 - 18:15

Objective: rIX-FP is a fusion protein genetically linking recombinant human coagulation factor IX with recombinant human albumin. It was specifically designed to have an improved pharmacokinetic profile compared with standard factor IX products that allows dosing interval to be increased.

Methods: The PROLONG-9FP clinical program evaluated the safety and efficacy of rIX-FP as prophylactic and on-demand therapy, and comprised five clinical studies enrolling over 100 patients from 42 hemophilia treatment centers in 12 countries. In a Phase II/III study (3001), patients (12–65 years) received either once-weekly prophylaxis for 6 months before switching to 7-, 10- or 14-day prophylaxis, or on-demand treatment for 6 months followed by once-weekly prophylaxis. The total treatment period in both groups was 12–18 months. In a separate Phase III study (3002), pediatric patients (<12 years) received once-weekly prophylaxis for approximately 12 months.

Results: In the adult study, 52.5% (21/40) of patients previously receiving routine prophylaxis and 60.9% (14/23) of those treated on-demand reported target joints prior to study entry. A total of 19 patients switched from on-demand to weekly prophylaxis with rIX-FP. Of these patients, 10 (52.6%) had target joints at the start of the study and 9 (47.3%) patients had confirmed target joints after 6 months of on-demand treatment with rIX-FP. After switching to once-weekly prophylaxis with rIX-FP, 100% of these target joints resolved. Median annualized joint bleeding rate (joint ABR) fell from 15.3 with on-demand therapy (n=23) to 1.19 with weekly prophylaxis (n=19). For patients receiving prophylaxis, median joint ABR was 0.00 with all regimens. In the pediatric study, target joints were reported in three patients on prophylaxis prior to study entry; all target joints resolved with once-weekly rIX-FP prophylaxis treatment. Median joint ABR was 0.5 and 1.13 in patients aged 1–5 years (n=12) and 6–11 years (n=15), respectively, and 0.99 overall (n=27).

Conclusion: In both adult and pediatric patients, weekly prophylaxis with rIX-FP resolved all target joints. rIX-FP is not only effective for the prevention of bleeding episodes, but also for resolving target joints in patients previously on-demand or under-treated with prophylaxis.