Experience with Recombinant Factor IX (Benefix) in Pediatrics

Benefix is a lyophilized stable recombinant factor IX formulation containing no preservatives, blood or plasma products. With regard to its structural, functional, and clinical qualities, recombinant factor IX has proved to be comparable to monoclonal plasma-derived factor IX. The only difference found was a 72% lower recovery rate for recombinant factor IX compared to plasma-derived factor IX; this is most probably caused by minor differences in the post-translational modification [1]. In a canine model study, recombinant factor IX proved to be as effective as highly purified plasma-derived factor IX in normalizing hemostasis. Canine pharmacokinetic studies showed a dose-proportional profile, and experiments in a model of throm- bogenicity indicated a low thrombogenic potential for recombinant factor IX [2]. In between pharmacokinetics, the safety and efficacy of recombinant factor IX have been evaluated in both previously treated and previously untreated hemophilia B patients. In a study including 56 previously untreated patients, 80% of 1070 bleeding episodes resolved after a single recombinant factor IX infusion. In 87% of a total of 1514 infusions, the clinical response was rated as excellent or good. Recombinant factor IX has also been successfully used in a surgical setting. In a total of 13 surgical procedures, 97% of the clinical responses following a bolus or continuous infusion of recombinant factor IX were rated excellent or good [3].