Eftrenonacog Alfa: A Review in Haemophilia B

Eftrenonacog alfa (Alprolix™) is a recombinant fusion protein comprising human factor IX (FIX) covalently linked to the constant region (Fc) domain of human IgG1 (i.e. rFIXFc). The presence of the Fc domain extends the terminal half-life (t_½) of rFIXFc, permitting prolonged treatment intervals. rFIXFc is available for intravenous use for the prophylaxis and treatment of bleeding in patients with haemophilia B. In two multinational, phase III studies in previously treated children, adolescents and adults with severe haemophilia B, rFIXFc prophylaxis resulted in low median annualized bleeding rates (ABRs), and was associated with reductions in median weekly factor consumption and dosing frequency compared with pre-study FIX regimens. Preliminary data from an extension of both studies indicated sustained efficacy, as demonstrated by low median ABRs, with longer-term rFIXFc prophylaxis. rFIXFc was also effective in the treatment of bleeding episodes and when used in the perioperative setting in all age groups. rFIXFc was well tolerated in clinical studies in previously treated patients, with the majority of treatment-emergent adverse events considered to be unrelated to rFIXFc; there were no reports of inhibitor development. In conclusion, rFIXFc provides an effective alternative to plasma-derived and recombinant FIX products for the management of patients with haemophilia B, with its extended t_½ permitting a less frequent administration schedule and potentially providing a prolonged protective haemostatic effect, which eases the treatment burden on the patient.