Preclinical studies with Fc(gamma)R bispecific antibodies and granulocyte colony-stimulating factor-primed neutrophils as effector cells against HER-2/neu overexpressing breast cancer.
Immunotherapies directed to the proto-oncogene product HER-2/neu, which is overexpressed on a subset of breast and other carcinomas, currently receive considerable attention. We have investigated cell-mediated effector mechanisms of HER-2/neu antibodies against breast cancer cell lines. Compared to unfractionated control blood, whole blood from patients during granulocyte colony-stimulating factor (G-CSF) treatment exhibits significantly enhanced lysis (P < 0.001) of SK-BR-3 cells in the presence of HER-2/neu antibody 520C9. The extent of tumor cell killing correlated positively (r = 0.74) to polymorphonuclear neutrophil (PMN) blood counts. Fractionation of whole blood into plasma, mononuclear cells, and PMNs showed major killing capacity to reside in the granulocyte fraction. PMNs were efficiently cytolytic with a panel of HER-2/neu antibodies and against various breast cancer cell lines. Experiments with blocking antibodies to Fc(gamma)R documented Fc(gamma)RII (CD32) as the major trigger molecule for monoclonal antibody 502C9-mediated cytotoxicity. Killing via 520C9 was significantly influenced by an allotypic polymorphism of Fc(gamma)RIIa, the CD32 molecule expressed on PMNs. In reverse antibody-dependent cell-mediated cytotoxicity experiments with a panel of HER-2/neu-directed bispecific antibodies, Fc(gamma)RIII (CD16) proved to be an efficient trigger molecule in blood from healthy volunteers. During G-CSF treatment, however, Fc(gamma)RI (CD64)-expressed on monocytes and G-CSF primed, but not on healthy donor PMNs-became the predominant cytotoxic trigger molecule. Thus, G-CSF application increased effector cell numbers for HER-2/neu-directed immunotherapy, and G-CSF primed PMNs proved particularly effective with a [HER-2/neu x Fc(gamma)RI] bispecific antibody. These findings support clinical trials with HER-2/neu-directed antibodies in combination with G-CSF in breast cancer patients overexpressing HER-2/neu.
Stockmeyer
B
B
Department of Medicine III, University of Erlangen-Nürnberg, Germany.
Valerius
T
T
Repp
R
R
Heijnen
I A
IA
Bühring
H J
HJ
Deo
Y M
YM
Kalden
J R
JR
Gramatzki
M
M
van de Winkel
J G
JG
D018033:Antibodies, Bispecific / Q000627:therapeutic use*; D000920:Antibody-Dependent Cell Cytotoxicity / Q000276:immunology; D001943:Breast Neoplasms / Q000276:immunology / Q000378:metabolism / Q000628:therapy*; D005260:Female; D016179:Granulocyte Colony-Stimulating Factor / Q000627:therapeutic use*; D006098:Granulocytes / Q000276:immunology*; D006801:Humans; D007111:Immunity, Cellular; D007167:Immunotherapy / Q000379:methods*; D000090063:Proto-Oncogene Mas; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000276:immunology* / Q000378:metabolism; D017452:Receptors, IgG / Q000276:immunology*; D014407:Tumor Cells, Cultured
D018033:Antibodies, Bispecific; D016179:Granulocyte Colony-Stimulating Factor; D000090063:Proto-Oncogene Mas; D018719:Erb-b2 Receptor Tyrosine Kinases; D017452:Receptors, IgG; C000715470:MAS1 protein, human