TY - JOUR AB - Erlotinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), shows superior efficacy in patients with non-small cell lung cancer (NSCLC) harboring activating EGFR mutations (EGFR Mut+). However, almost all tumors eventually develop resistance to erlotinib. Recently, the Phase II JO25567 study reported significant prolongation of progression-free survival (PFS) by erlotinib plus bevacizumab combination compared with erlotinib in EGFR Mut+ NSCLC. Herein, we established a preclinical model which became refractory to erlotinib after long-term administration and elucidated the mode of action of this combination. In this model, tumor regrowth occurred after remarkable shrinkage by erlotinib; regrowth was successfully inhibited by erlotinib plus bevacizumab. Tumor vascular endothelial growth factor (VEGF) was greatly reduced by erlotinib in the erlotinib-sensitive phase but significantly increased in the erlotinib-refractory phase despite continued treatment with erlotinib. Although EGFR phosphorylation remained suppressed in the erlotinib-refractory phase, phosphorylated extracellular signal-regulated kinase (pERK), phosphorylated AKT, and phosphorylated signal transducer and activator of transcription 3 (pSTAT3) were markedly higher than in the erlotinib-sensitive phase; among these, pERK was suppressed by erlotinib plus bevacizumab. MVD was decreased significantly more with erlotinib plus bevacizumab than with each drug alone. In conclusion, the erlotinib plus bevacizumab combination demonstrated promising efficacy in the B901L xenograft model of EGFR Mut+ NSCLC. Re-induction of VEGF and subsequent direct or indirect VEGF-dependent tumor growth was suggested as a major mechanism of erlotinib resistance, and erlotinib plus bevacizumab achieved remarkably prolonged antitumor activity in this model. AD - Product Research Department, Kamakura Research Laboratories, Chugai Pharmaceutical Co., Ltd., Kamakura, Kanagawa 247-8530, Japan AU - Masuda,Chinami AU - Yanagisawa,Mieko AU - Yorozu,Keigo AU - Kurasawa,Mitsue AU - Furugaki,Koh AU - Ishikura,Nobuyuki AU - Iwai,Toshiki AU - Sugimoto,Masamichi AU - Yamamoto,Kaname DA - 2017/08/01 DO - 10.3892/ijo.2017.4036 EP - 434 IS - 2 JO - Int J Oncol KW - EGFR mutation VEGF bevacizumab erlotinib PY - 2017 SN - 1019-6439 1791-2423 SP - 425 ST - Bevacizumab counteracts VEGF-dependent resistance to erlotinib in an EGFR-mutated NSCLC xenograft model T2 - International Journal of Oncology TI - Bevacizumab counteracts VEGF-dependent resistance to erlotinib in an EGFR-mutated NSCLC xenograft model UR - https://doi.org/10.3892/ijo.2017.4036 VL - 51 ER -