title: In vivo and in vitro antitumor activity of oxaliplatin in combination with cetuximab in human colorectal tumor cell lines expressing different level of EGFR.
abstract: This study aimed to assess the effect of cetuximab (C225, Erbitux, a chimeric anti-epidermal growth factor receptor (EGFR) monoclonal antibody) in combination with oxaliplatin in vitro and in vivo on four colon cancer cell lines (HCT-8; HT-29, SW620, HCT-116) expressing different levels of EGFR. In vitro, cetuximab combined with oxaliplatin significantly decreased the IC50 values of oxaliplatin in HCT-8 (EGF-R moderate) and HT-29 (EGF-R weak) cell lines, while SW620 (EGF-R negative) and HCT-116 (EGFR strong) cell lines remained unresponsive. This combination was synergistic in HCT-8 and HT-29 cell lines while cetuximab induced no major modification of the IC50 of oxaliplatin in HCT-116 or SW620 cell lines. We then determined the effect of cetuximab on the EGF-induced EGFR phosphorylation and we highlight a correlation between the basal level of phospho-EGFR and the response to the combination. In vivo, the combination of cetuximab plus oxaliplatin significantly inhibited tumor growth of HCT-8 and HT-29 (tumor delay or Td = 21.6+/-2.9 and 18.0+/-2.9 days respectively, synergistic effect) compared to either oxaliplatin (Td=12.6+/-2.3 and 14.4+/-3.2 days respectively) or cetuximab (Td=13.4+/-2.9 and 14.5+/-2.4 days, respectively) alone in xenograft models. The combination had no effect on HCT-116 and SW-620 cell lines. The observed responses are strictly dependent on the cell type, and are not correlated with the level of EGFR expression but related to the basal level of phospho-EGFR. This study provides promising preclinical results for a possible clinical investigation of the combination of oxaliplatin plus cetuximab in chemorefractory colorectal tumors.
authors.affiliation: EA 3035 Laboratoire de Pharmacologie Clinique et Expérimentale des Médicaments Anticancéreux, Université Paul Sabatier, Toulouse, France.
authors.forename: Diane
authors.initials: D
authors.lastname: Balin-Gauthier
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Delord
authors.forename: Philippe
authors.initials: P
authors.lastname: Rochaix
authors.forename: Valérie
authors.initials: V
authors.lastname: Mallard
authors.forename: Fabienne
authors.initials: F
authors.lastname: Thomas
authors.forename: Isabelle
authors.initials: I
authors.lastname: Hennebelle
authors.forename: Roland
authors.initials: R
authors.lastname: Bugat
authors.forename: Pierre
authors.initials: P
authors.lastname: Canal
authors.forename: Cuider
authors.initials: C
authors.lastname: Allal
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D000068818:Cetuximab; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000378:metabolism; D004357:Drug Synergism; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009944:Organoplatinum Compounds / Q000008:administration & dosage; D000077150:Oxaliplatin; D010766:Phosphorylation; D047368:Tumor Burden / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D009944:Organoplatinum Compounds; D000077150:Oxaliplatin; D066246:ErbB Receptors; D000068818:Cetuximab