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Nearly fifty monoclonal antibodies have been approved to date, and the market for monoclonal antibodies is expected to continue to grow. Since global competition in the field of antibody therapeutics is intense, we need to establish novel antibody engineering technologies to provide true benefit for patients, with differentiated product values. Bispecific antibodies are among the next generation of antibody therapeutics that can bind to two different target antigens by the two arms of immunoglobulin G (IgG) molecule, and are thus believed to be applicable to various therapeutic needs. Until recently, large scale manufacturing of human IgG bispecific antibody was impossible. We have established a technology, named asymmetric re-engineering technology (ART)-Ig, to enable large scale manufacturing of bispecific antibodies. Three examples of next generation antibody therapeutics using ART-Ig technology are described. Recent updates on bispecific antibodies against factor IXa and factor X for the treatment of hemophilia A, bispecific antibodies against a tumor specific antigen and T cell surface marker CD3 for cancer immunotherapy, and bispecific antibodies against two different epitopes of soluble antigen with pH-dependent binding property for the elimination of soluble antigen from plasma are also described.

Unmet needs of current hemophilia A treatment include the requirement for frequent intravenous infusions, inhibitor development, and containment of high medical costs. In order to overcome these issues, we produced FVIII which mimics a bispecific antibody against FIXa/FX. ACE910 demonstrated hemostatic effects on both ongoing and spontaneous joint bleeding in the primate acquired hemophilia A model. Recently, a phase 1 study for PK, PD, and the safety of ACE910 was initiated. The t1/2 was approximately 30 days. There were no severe ACE910 related adverse events. Furthermore, bleeding was remarkably decreased by weekly subcutaneous administration in patients with severe hemophilia A, regardless of whether an inhibitor was used. ACE910 has the remarkable advantages of prophylactic efficacy which can be achieved by convenient subcutaneous administrations at a markedly reduced frequency.

Monoclonal antibody therapies have conducted to not only hematologic malignancies but also disorders of hemostasis and coagulation. This article describes the recent advances of monoclonal antibody therapy for bleeding disorders such as idiopathic thrombocytopenic purpura(ITP), hemophilia A, disseminated intravascular coagulation(DIC), and thrombosis. Rituximab, chimeric anti-CD20 monoclonal antibody treatment has a valuable effect in the patients with ITP, and clinical trials using anti-CD40 ligand monoclonal antibody for ITP are underway. Anti-CD40 ligand monoclonal antibody can be an alternative therapy for hemophilia A patients with inhibitors to factor VIII. In thrombosis, anti-tissue factor monoclonal antibody and anti-factor IX(a) monoclonal antibody were established as novel anticoagulant regents. Plasminogen activator inhibitor-1(PAI-1) increases in endotoxin-induced DIC and many thrombotic diseases such as myocardial infarction, type 2 diabetes mellitus, and hyperlipidemia. Anti-PAI-1 monoclonal antibody reduced fibrin deposition in DIC mouse model. Treatment of these monoclonal antibodies for the molecules regulating coagulation-fibrinolysis system may be utilized for acute coronary syndrome and venous thrombosis.