The principle of hemophilia treatment is replacement therapy with factor VIII 
and factor IX concentrates. Recently, extended half-life factor VIII and factor 
IX concentrates have been developed. With these concentrates, improvements in 
patient QOL can be expected. More recently, a novel hemophilia therapy based on 
a very new concept was developed. ACE910 (emicizumab) is a humanized bispecific 
antibody recognizing factor IXa and X mimicking factor VIII function. The 
half-life is reportedly 4-5 weeks and remarkably decreased annual bleeding rates 
have been achieved with subcutaneous weekly injections in the phase 1 clinical 
trial. Clinical trials of anti-antithrombin therapeutics based on siRNA 
(ALN-AT3) and anti-TFPI antibody are currently ongoing and the results are 
eagerly anticipated.