title: Diabody-based recombinant formats of humanized IgG-like bispecific antibody with effective retargeting of lymphocytes to tumor cells.
abstract: Recently, recombinant antibodies have been dissected into antigen-binding regions and rebuilt into multivalent high-avidity formats. These new structural designs are expected to improve in vivo pharmacokinetics and efficacy in clinical use. Here, we designed effective recombinant bispecific antibody (BsAb) formats based on hEx3, a humanized bispecific diabody with epidermal growth factor receptor and CD3 retargeting. The bispecific and bivalent IgG-like antibodies engineered from hEx3 (or its single-chain form, hEx3-scDb) and the human Fc region showed stronger binding to each target cell than did monovalent diabody formats, and their affinity was identical to that of the corresponding parent IgG. The bivalent effect of the constructed IgG-like BsAbs resulted in cell cytotoxicity 10 times that of monovalent diabodies, and further, the fusion of Fc portion contributed intense cytotoxicity in peripheral blood mononuclear cells by the induction of the antibody-dependent cellular cytotoxicity. The growth-inhibition effects of IgG-like BsAbs were superior to those of the approved therapeutic antibody cetuximab, which recognizes the same epidermal growth factor receptor antigen, even when peripheral blood mononuclear cells were used as effector cells. We thus demonstrated a critical improvement in the effect of hEx3 by the bottom-up construction of IgG-like BsAbs; in adoptive immunotherapy, monotherapy without supplemental molecules may be able to induce antibody-dependent cellular cytotoxicity.
authors.affiliation: Department of Biomolecular Engineering, Graduate School of Engineering, Institute of Development, Aging, and Cancer, Tohoku University, Sendai, Japan.
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Asano
authors.forename: Hiroko
authors.initials: H
authors.lastname: Kawaguchi
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakanishi
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Umetsu
authors.forename: Hiroki
authors.initials: H
authors.lastname: Hayashi
authors.forename: Yu
authors.initials: Y
authors.lastname: Katayose
authors.forename: Michiaki
authors.initials: M
authors.lastname: Unno
authors.forename: Toshio
authors.initials: T
authors.lastname: Kudo
authors.forename: Izumi
authors.initials: I
authors.lastname: Kumagai
mesh_terms: D000818:Animals; D018033:Antibodies, Bispecific / Q000235:genetics / Q000276:immunology*; D000920:Antibody-Dependent Cell Cytotoxicity / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology* / Q000378:metabolism; D016466:CHO Cells; D045744:Cell Line, Tumor; D006224:Cricetinae; D003412:Cricetulus; D066246:ErbB Receptors / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000235:genetics / Q000276:immunology*; D015979:Killer Cells, Lymphokine-Activated / Q000276:immunology*; D009369:Neoplasms / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic; D014162:Transfection
chemical_list: D018033:Antibodies, Bispecific; D017252:CD3 Complex; D007074:Immunoglobulin G; D011993:Recombinant Fusion Proteins; D066246:ErbB Receptors