Mechanisms of G-CSF- or GM-CSF-stimulated tumor cell killing by Fc receptor-directed bispecific antibodies.
Studies with gene-modified mice have recently reinforced the importance of Fc receptor-mediated effector mechanisms for the therapeutic efficacy of rituxan and herceptin - two clinically approved antibodies for the treatment of tumor patients. We investigated Fc receptor-dependent tumor cell killing by mononuclear and granulocytic effector cells - comparing human IgG1 antibodies against CD20 or HER-2/neu with their respective FcgammaRI (CD64)-, FcgammaRIII (CD16)-, or FcalphaRI (CD89)-directed bispecific derivatives. With blood from healthy donors as effector source, human IgG1 and FcgammaRIII (CD16)-directed bispecific antibodies proved most effective in recruiting mononuclear effector cells, whereas tumor cell killing by granulocytes was most potently triggered by FcalphaRI-directed bispecific constructs. Granulocyte-mediated tumor cell lysis was significantly enhanced when blood from G-CSF- or GM-CSF-treated patients was investigated. Interestingly, however, both myeloid growth factors improved effector cell recruitment by different mechanisms, which were furthermore dependent on the tumor target antigen, and on the selected cytotoxic Fc receptor.
Stockmeyer
B
B
Division of Hematology/Oncology, Department of Medicine III, University of Erlangen-Nürnberg, Krankenhausstrasse 12, D-91054, Erlangen, Germany. bernhard.stockmeyer@med3.imed.uni-erlangen.de
Elsässer
D
D
Dechant
M
M
Repp
R
R
Gramatzki
M
M
Glennie
M J
MJ
van de Winkel
J G
JG
Valerius
T
T
D000818:Animals; D018033:Antibodies, Bispecific / Q000627:therapeutic use*; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D058846:Antibodies, Monoclonal, Murine-Derived; D000920:Antibody-Dependent Cell Cytotoxicity; D015703:Antigens, CD / Q000276:immunology*; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D051379:Mice; D011961:Receptors, Fc / Q000276:immunology*; D017452:Receptors, IgG / Q000276:immunology*; D000069283:Rituximab; D000068878:Trastuzumab; D014407:Tumor Cells, Cultured
D018033:Antibodies, Bispecific; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D058846:Antibodies, Monoclonal, Murine-Derived; D015703:Antigens, CD; D000970:Antineoplastic Agents; C036832:Fc(alpha) receptor; D011961:Receptors, Fc; D017452:Receptors, IgG; D016179:Granulocyte Colony-Stimulating Factor; D000069283:Rituximab; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D000068878:Trastuzumab