Biochemical Characterization of a Recombinant FIX Drug Candidate for Treatment of Hemophilia B

Abstract 4658

Human coagulation factor IX (FIX) is a vitamin-K-dependent coagulation factor whose absence or dysfunction causes hemophilia B. Treatment of hemophilia B is based on replacement therapy using highly purified FIX concentrates.

Baxter has developed a recombinant factor IX for treating hemophilia B patients that is produced in a CHO cell-line using a serum and protein-free fermentation technology. The purification process avoids the use of immune-affinity chromatography and includes two viral reduction steps. The final drug product is formulated in the absence of proteins of animal or human origin. Baxter's recombinant FIX resembles commercially available rFIX in most characteristics with the exception of a significantly lower FIXa content, which might improve standardization compared to commercial rFIX products.

Preclinical and clinical lots of rFIX were characterized with respect to their hemostatic potency, efficiency of activation by FXIa and FVIIa in the presence of tissue factor, and capacity to bind to phospholipid vesicles. Three lots of commercial rFIX with different potencies and one lot of a plasma-derived FIX product were included in the study. Similarity could be shown between the preclinical and clinical lots of rFIX in all these assays. Furthermore, the functional and biochemical characterization of Baxter's recombinant FIX showed that it resembles the recombinant comparator product. The phase I clinical trial which has been initiated will now have to show whether Baxter's rFIX can become an alternative drug candidate product for treating patients suffering from hemophilia B.