title: Antibody-dependent cellular cytotoxicity mediated by cetuximab against lung cancer cell lines.
abstract: OBJECTIVE
  Epidermal growth factor receptor (EGFR) is commonly overexpressed in lung cancer. Cetuximab is a chimeric mouse-human antibody targeted against EGFR. Compared with its inhibitory properties, its immunologic mechanisms have not been well studied. In this study, we investigated the antibody-dependent cellular cytotoxicity (ADCC) activity of cetuximab against lung cancer cell lines.
  
  
  METHODS
  We studied the correlation between EGFR expression in lung cancer cell lines and the ADCC activity of cetuximab as well as the influence of interleukin-2 and chemotherapy on the ADCC activity. EGFR expression was measured by a quantitative flow cytometric analysis and immunohistochemistry. The ADCC activity was assessed by a 4-h (51)Cr release assay. Peripheral blood mononuclear cells, purified T cells, natural killer (NK) cells, and monocytes from healthy donors or lung cancer patients were used as effector cells.
  
  
  RESULTS
  Fresh peripheral blood mononuclear cells exhibited cetuximab-mediated ADCC activity against lung cancer cell lines at a low concentration of cetuximab (0.25 microg/mL). A logarithmic correlation was observed between the number of EGFRs and ADCC activity. Even low EGFR expression, which was weakly detectable by immunohistochemistry, was sufficient for maximum ADCC activity, and further increases in EGFR expression on the target cells had no further effect on the ADCC activity. In addition, ADCC activity was enhanced by interleukin-2 mainly through activation of NK cells and was less susceptible to immunosuppression by chemotherapy than NK activity in lung cancer patients.
  
  
  CONCLUSIONS
  These observations suggest the importance of ADCC activity as an immunologic mechanism of cetuximab in biological therapy for lung cancer patients.
authors.affiliation: Division of Medical Oncology and Molecular Respirology, Department of Multidisciplinary Internal Medicine, Tottori University, Tottori-ken, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Kurai
authors.forename: Hiroki
authors.initials: H
authors.lastname: Chikumi
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Hashimoto
authors.forename: Kosuke
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Akira
authors.initials: A
authors.lastname: Yamasaki
authors.forename: Takanori
authors.initials: T
authors.lastname: Sako
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Touge
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Makino
authors.forename: Miyako
authors.initials: M
authors.lastname: Takata
authors.forename: Masanori
authors.initials: M
authors.lastname: Miyata
authors.forename: Masaki
authors.initials: M
authors.lastname: Nakamoto
authors.forename: Naoto
authors.initials: N
authors.lastname: Burioka
authors.forename: Eiji
authors.initials: E
authors.lastname: Shimizu
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D000920:Antibody-Dependent Cell Cytotoxicity / Q000187:drug effects*; D000970:Antineoplastic Agents / Q000276:immunology / Q000494:pharmacology*; D045744:Cell Line, Tumor; D000068818:Cetuximab; D066246:ErbB Receptors / Q000096:biosynthesis*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000276:immunology; D008297:Male; D051379:Mice; D008875:Middle Aged
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D066246:ErbB Receptors; D000068818:Cetuximab