FVIII-independent FIX-mutant proteins for hemophilia A treatment

摘要

The present invention relates to recombinant blood coagulation factor IX (rFIX) mutants having factor VIII (FVIII) independent factor X (FX) activation potential. Five full length FIX proteins with combinations of mutations of amino acids important for functional activity of FIX and FIX wild type were cloned and expressed in HEK 293 cells. The proteins were tested by an activated partial thromboplastin time (aPTT) assay in FVIII-depleted plasma as well as in FVIII-inhibited patient plasma. In FVIII-depleted plasma functional activity of the FIX mutants was calculated as increased FVIII equivalent activity. The mutant proteins had increased FVIII equivalent activity. In FVIII-inhibited patient plasma the FEIBA equivalent activity was calculated for analysis of FVIII independent FX activation potential. The proteins had also increased FEIBA equivalent activity. Furthermore, the pre-activated FIX proteins had an increased activity in FIX-depleted plasma containing FVIII inhibitors. Therefore these FIX mutants are alternatives as bypassing agents for treatment of FVIII inhibitor patients.