title: Carcinoembryonic antigen (CEA)-specific T-cell activation in colon carcinoma induced by anti-CD3 x anti-CEA bispecific diabodies and B7 x anti-CEA bispecific fusion proteins.
abstract: Two bispecific recombinant molecules, an anti-CD3 x anti-carcinoembryogenic antigen (CEA) diabody and a B7 x anti-CEA fusion protein, were tested for their capacity to specifically activate T cells in the presence of CEA-expressing colon carcinoma cells. T-cell activation by the anti-CD3 x anti-CEA diabody required close contact to CEA-positive cells and resulted in diabody-mediated cytotoxicity against the target cells. Additionally, CD28-mediated costimulation in combination with anti-CD3 x anti-CEA diabodies induced activation of autologous T cells in CEA-positive primary colon carcinoma specimens, as determined by flow cytometry. The high specificity of the bispecific diabody approach could be further enhanced by the use of B7 x anti-CEA fusion proteins because the costimulatory CD28-signaling to the T cells strictly depended on the expression of CEA on the target cells. We demonstrate that displaying engagement sites for the T-cell antigens CD3 and CD28 on the surface of colon carcinoma cells is a suitable way to activate and retarget T cells in a highly tumor-specific manner. For clinical purposes, B7 x anti-tumor-associated antigen (TAA) fusion proteins, which are equally effective but more specific compared with anti-CD28 monoclonal anti-bodies, thus may improve the tumor specificity of anti-CD3 x anti-TAA bispecific antibodies. Furthermore, B7-negative tumors can be converted into B7-positive tumors by B7 x anti-TAA fusion proteins without the need for B7 gene transfer to the malignant cells.
authors.affiliation: MRC Centre for Protein Engineering, Cambridge, United Kingdom.
authors.forename: P
authors.initials: P
authors.lastname: Holliger
authors.forename: O
authors.initials: O
authors.lastname: Manzke
authors.forename: M
authors.initials: M
authors.lastname: Span
authors.forename: R
authors.initials: R
authors.lastname: Hawkins
authors.forename: B
authors.initials: B
authors.lastname: Fleischmann
authors.forename: L
authors.initials: L
authors.lastname: Qinghua
authors.forename: J
authors.initials: J
authors.lastname: Wolf
authors.forename: V
authors.initials: V
authors.lastname: Diehl
authors.forename: O
authors.initials: O
authors.lastname: Cochet
authors.forename: G
authors.initials: G
authors.lastname: Winter
authors.forename: H
authors.initials: H
authors.lastname: Bohlen
mesh_terms: D000595:Amino Acid Sequence; D018033:Antibodies, Bispecific / Q000096:biosynthesis / Q000276:immunology*; D018122:B7-1 Antigen / Q000276:immunology*; D018106:CD28 Antigens / Q000276:immunology; D017252:CD3 Complex / Q000276:immunology*; D002272:Carcinoembryonic Antigen / Q000276:immunology*; D003110:Colonic Neoplasms / Q000139:chemically induced / Q000276:immunology*; D003602:Cytotoxicity, Immunologic; D017931:DNA Primers; D006801:Humans; D008213:Lymphocyte Activation; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D018033:Antibodies, Bispecific; D018122:B7-1 Antigen; D018106:CD28 Antigens; D017252:CD3 Complex; D002272:Carcinoembryonic Antigen; D017931:DNA Primers; D011993:Recombinant Fusion Proteins