2018 Volume 55 Issue 3 Pages 274-278
Extended half-life (EHL) factor IX products could improve the quality of life in patients with hemophilia B. Here, we report the effectiveness of the EHL product recombinant factor IX Fc fusion protein (rFIXFc) in 4 patients with severe hemophilia B as a prophylactic treatment. Patients 1 and 2 are brothers who have played tennis in junior and senior high schools, respectively. They received prophylaxis with recombinant factor IX (rFIX) at 40 U/kg body weight every 2 or 3 days. On the basis of the factor IX activity in plasma during sport activity, the regimen has been replaced with rFIXFc at 40 U/kg every 4 days. More than 10% of factor IX activity was estimated during club activity after school, resulting in no bleeding episodes. Patients 3 and 4 are also brothers who have prophylactically received pdFIX twice a week. The older brother’s dose was 44 U/kg, and that of the younger brother was 33 U/kg. After switching to rFIXFc, the frequency of infusion was reduced to every 6 days. The older brother’s dose was 56 U/kg, and that of the younger brother was 42 U/kg. The trough level of FIX was more than 3% without the increase in the annual bleeding rate (ABR) in both patients. These results suggest that the prophylactic use of rFIXFc is effective in reducing the frequency of venipuncture and in obtaining the appropriate factor IX level for an individual without the increase in ABR.
