title: Combined vascular endothelial growth factor receptor and epidermal growth factor receptor (EGFR) blockade inhibits tumor growth in xenograft models of EGFR inhibitor resistance.
abstract: OBJECTIVE
  The epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKI) gefitinib and erlotinib benefit some non-small cell lung cancer (NSCLC) patients, but most do not respond (primary resistance) and those who initially respond eventually progress (acquired resistance). EGFR TKI resistance is not completely understood and has been associated with certain EGFR and K-RAS mutations and MET amplification.
  
  
  METHODS
  We hypothesized that dual inhibition of the vascular endothelial growth factor (VEGF) and EGFR pathways may overcome primary and acquired resistance. We investigated the VEGF receptor/EGFR TKI vandetanib, and the combination of bevacizumab and erlotinib in vivo using xenograft models of EGFR TKI sensitivity, primary resistance, and three models of acquired resistance, including models with mutated K-RAS and secondary EGFR T790M mutation.
  
  
  RESULTS
  Vandetanib, gefitinib, and erlotinib had similar profiles of in vitro activity and caused sustained tumor regressions in vivo in the sensitive HCC827 model. In all four resistant models, vandetanib and bevacizumab/erlotinib were significantly more effective than erlotinib or gefitinib alone. Erlotinib resistance was associated with a rise in both host and tumor-derived VEGF but not EGFR secondary mutations in the KRAS mutant-bearing A549 xenografts. Dual inhibition reduced tumor endothelial proliferation compared with VEGF or EGFR blockade alone, suggesting that the enhanced activity of dual inhibition is due at least in part to antiendothelial effects.
  
  
  CONCLUSIONS
  These studies suggest that erlotinib resistance may be associated with a rise in both tumor cell and host stromal VEGF and that combined blockade of the VEGFR and EGFR pathways can abrogate primary or acquired resistance to EGFR TKIs. This approach merits further evaluation in NSCLC patients.
authors.affiliation: Children's Hospital, Division of Hematology/Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, and Massachusetts General Hospital Cancer Center, Boston, MA, USA.
authors.forename: George N
authors.initials: GN
authors.lastname: Naumov
authors.forename: Monique B
authors.initials: MB
authors.lastname: Nilsson
authors.forename: Tina
authors.initials: T
authors.lastname: Cascone
authors.forename: Alexandra
authors.initials: A
authors.lastname: Briggs
authors.forename: Oddbjorn
authors.initials: O
authors.lastname: Straume
authors.forename: Lars A
authors.initials: LA
authors.lastname: Akslen
authors.forename: Eugene
authors.initials: E
authors.lastname: Lifshits
authors.forename: Lauren Averett
authors.initials: LA
authors.lastname: Byers
authors.forename: Li
authors.initials: L
authors.lastname: Xu
authors.forename: Hua-Kang
authors.initials: HK
authors.lastname: Wu
authors.forename: Pasi
authors.initials: P
authors.lastname: Jänne
authors.forename: Susumu
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Balazs
authors.initials: B
authors.lastname: Halmos
authors.forename: Daniel
authors.initials: D
authors.lastname: Tenen
authors.forename: Xi M
authors.initials: XM
authors.lastname: Tang
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Engelman
authors.forename: Beow
authors.initials: B
authors.lastname: Yeap
authors.forename: Judah
authors.initials: J
authors.lastname: Folkman
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Johnson
authors.forename: John V
authors.initials: JV
authors.lastname: Heymach
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000008:administration & dosage / Q000494:pharmacology; D061067:Antibodies, Monoclonal, Humanized; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D000068258:Bevacizumab; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000069347:Erlotinib Hydrochloride; D000077156:Gefitinib; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D041681:NIH 3T3 Cells; D010880:Piperidines / Q000008:administration & dosage / Q000494:pharmacology; D011799:Quinazolines / Q000008:administration & dosage / Q000494:pharmacology; D040262:Receptors, Vascular Endothelial Growth Factor / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014162:Transfection; D047368:Tumor Burden / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D010880:Piperidines; D011799:Quinazolines; D042461:Vascular Endothelial Growth Factor A; D000068258:Bevacizumab; D000069347:Erlotinib Hydrochloride; D066246:ErbB Receptors; D040262:Receptors, Vascular Endothelial Growth Factor; D000077156:Gefitinib; C452423:vandetanib