Replacement
therapy for
hemophilia B (
factor IX deficiency) using
prothrombin complex concentrate (PCC) has been associated with serious complications of thromboembolic events and transmission of
viral infections.
Monoclonal antibody-purified
factor IX (
Mononine) provides a highly purified
factor IX concentrate, while eliminating other
vitamin K-dependent factors (II, VII, and X).
Mononine was evaluated for in vivo recovery, half-life, and for its safety and efficacy in 10 patients with
hemophilia B. The in vivo recovery of
factor IX with
Mononine was a 0.67 +/- 0.14 U/dL (mean +/- SD) increase per 1U/kg of infused
factor IX, and the
biologic half-life (t1/2), determined using the terminal phase of elimination, was 22.6 +/- 8.1 hours. Comparison of in vivo recovery of other
vitamin K-dependent factors following a single infusion of either
Mononine or PCC showed that, whereas
Mononine infusion caused no changes in other
vitamin K-dependent factors or in
prothrombin activation fragment (F1+2), PCC infusion was associated with significant increases of factors II (2.7 U/dL per 1 U/dL of IX increase) and X (2.2 U/dL for 1 U/dL for 1 U/dL of IX). Patients who used
Mononine as their sole therapeutic material during the 12-month period showed an excellent response in hemostasis for their
bleeding episodes. Their experience with long-term use of
Mononine was at least equivalent to their previous experience with PCC in the frequency and amount of factor usage. No patients developed antibody against mouse
IgG or an increase in IX inhibitor during the 12-month period. These results indicate that
monoclonal antibody-purified
factor IX concentrate provides hemostatically effective
factor IX replacement while avoiding extraneous thrombogenic substances.