Hemophilia A and hemophilia B are X-linked inherited bleeding disorders caused by deficiency of functional coagulation factor Ⅷ (FⅧ) or coagulation factor Ⅸ (FⅨ).The diseases are characterized by spontaneous hemorrhage and excessive bleeding after injury and are treated by replacement therapy with recombinant or plasma derived FⅧ or FⅨ.Prophylaxis is the preferred treatment because it reduces bleedings and joint damages and improves quality of life in comparison to on-demand treatment.However, the short half-life of FⅧ (10-12 hrs) and FⅨ (~18 hrs) necessitates dosing 2-4 times per week by intravenous injection for prophylaxis.Therefore, longer-acting FⅧ and FⅨ would represent a key advancement in the management of hemophilia A and B.We have developed a novel monomeric recombinant Fc fusion technology to extend the half-life of coagulation factors by leveraging a naturallyoccurring biologic pathway employed by human immunoglobulin G.Recombinant FⅨFc, FⅧFc and FⅦaFc all demonstrated increased half-life and improved PK profile in animal models.Phase Ⅰ clinical trials for rFⅨFc and rFⅧFc have been completed and both showed extended half-life in humans.Phase Ⅲ clinical trials of rFⅧFc and rFⅨFc are currently in progress.