In vitro and in vivo antitumor activity of cetuximab in human gastric cancer cell lines in relation to epidermal growth factor receptor (EGFR) expression and mutational phenotype.
BACKGROUND
Targeting the epidermal growth factor receptor (EGFR) pathway is an important approach for a variety of tumors. This study assessed the effect of cetuximab, an anti-EGFR monoclonal antibody, on three gastric cancer cell lines with different phenotypes in vitro and in a therapeutic orthotopic murine gastric cancer model.


METHODS
Three human gastric cancer cell lines (AGS, MKN-45, NCI-N87) were evaluated for cell surface EGFR expression, and K-ras and BRAF mutations. In vitro, the effects of cetuximab, carboplatin, irinotecan, and docetaxel were investigated. Orthotopic tumors derived from MKN-45 and NCI-N87 were established in nude mice. After 4 weeks, the animals received cetuximab (1 mg/kg, weekly i.p.) or carboplatin (20 mg/kg, weekly i.p.), or both agents. The volume of the primary tumor and local and systemic tumor spread were determined at autopsy at 14 weeks. Tumor sections were immunostained for EGFR, as well as stained for CD31 to analyze microvessel density.


RESULTS
Cell surface expression of EGFR was found only in AGS and NCI-N87 cells. AGS cells displayed a codon 12 K-ras mutation, and all three cell lines were BRAF wild-type. In vitro, cetuximab significantly reduced cell viability and proliferation only in EGFR-positive/K-ras wild-type NCI-N87 cells (-48%). In vivo, cetuximab in combination with carboplatin synergistically reduced tumor volume (-75%), dissemination (-63%), and vascularization (-47%) in NCI-N87 xenografts. Tumors derived from EGFR-negative MKN-45 cells were unaffected by cetuximab.


CONCLUSIONS
Cetuximab is effective in K-ras wild-type, EGFR-expressing gastric cancer cell lines and xenografts. In vivo, the combination of cetuximab with carboplatin displayed synergistic antitumor activity.
Department of Surgery, Charité-School of Medicine, Campus Benjamin Franklin, Hindenburgdamm 30, 12203, Berlin, Germany.
Birgit
B
Hotz
Ulrich
U
Keilholz
Alberto
A
Fusi
Heinz J
HJ
Buhr
Hubert G
HG
Hotz
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D002166:Camptothecin / Q000031:analogs & derivatives / Q000494:pharmacology; D016190:Carboplatin / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D000068818:Cetuximab; D000077143:Docetaxel; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D011905:Genes, ras; D006801:Humans; D000077146:Irinotecan; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D043823:Taxoids / Q000494:pharmacology; D023041:Xenograft Model Antitumor Assays
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D043823:Taxoids; D000077143:Docetaxel; D000077146:Irinotecan; D016190:Carboplatin; D066246:ErbB Receptors; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D000068818:Cetuximab; D002166:Camptothecin