In vivo efficacy of human recombinant factor IX produced by the human hepatoma cell line HuH-7.

INTRODUCTION: Post-translational modifications of the CHO-cell-derived-recombinant human factor IX (FIX) currently used for the treatment of hemophilia B (HB) are different from plasma derived FIX. Our previous studies described a rFIX (HIX) having better profile of post-translational modifications than rFIX produced by CHO cells. The aim of the study consisted to verify the improved post-translational modifications effect of HIX on in vivo recovery.

MATERIALS AND METHODS: HIX has been produced in a bioreactor and then purified from supernatants. In vitro activation and activity were evaluated measured by thrombin generation tests (TGT) and compared to commercial molecules, Benefix(®) , Mononine(®) . The three molecules were then administrated (i.v.) to FIX-knockout mice and two minutes after injection, blood samples were collected and subjected to human FIX-specific-ELISA and TGT.

RESULTS: The clotting function of HIX, activation courses of HIX by FXIa and FVIIa-TF complex appear normal as did activation of Benefix(®) , Mononine(®) and TG constants of each FIX were equivalent. After injection to HB mice, circulating HIX did not present any significant difference in term of antigen value with Benefix(®) . Intriguingly, TGT were clearly exhibiting a better velocity for HIX than Benefix(®) and Mononine(®) . These data suggested that HIX may improve in vivo coagulant efficacy in comparison with the two commercial FIX injected at the same dose.

CONCLUSION: The study shows that HuH-7-derived-rFIX has better in vivo haemostatic activity in hemophilia B mice compared to the reference rFIX molecule despite similar in vivo recovery rates, suggesting that HuH-7 cells could represent an effective cellular system for production of rFIX.