Abstract 2131: Significant combination benefit of anti-VEGFR antibody and oncogene-targeted agents in EGFR or ALK mutant NSCLC cells
Authors: Watanabe Hiromi , Ichihara Eiki , Kayatani Hiroe , Higo Hisao , Makimoto Go , Kano Hirohisa , Nishii Kazuya , Hara Naofumi , Ninomiya Kiichiro , Kubo Toshio , Ohashi Kadoaki , Rai Kammei , Hotta Katsuyuki , Tabata Masahiro , Maeda Yoshinobu , Kiura Katsuyuki 
Published: August 2019

Background: Non-small cell lung cancers (NSCLCs) harboring driver oncogene such as epidermal growth factor receptor (EGFR) mutation or anaplastic lymphoma kinase (ALK) rearrangement are sensitive to the corresponding molecular targeted tyrosine kinase inhibitors (TKIs). However, acquired resistance inevitably develops, and more effective treatment strategies are needed. Anti-vascular endothelial growth factor (VEGF) antibody bevacizumab significantly prolongs progression free survival when added to first-generation EGFR TKIs in EGFR mutant NSCLC. However, it remains unknown whether anti-VEGF receptor (VEGFR) antibody enhances the efficacy of molecular targeted agents as well. In this study, we investigated combinations with an anti-VEGFR antibody and EGFR or ALK TKIs in preclinical models

Materials and Methods: We treated mice bearing subcutaneous tumor cell lines harboring EGFR mutation (PC-9, H3255) or ALK rearrangement (ABC-11, H3122) using combinations of anti-mouse VEGFR antibody DC101 and erlotinib (EGFR TKI) /alectinib (ALK TKI). Neovascularization of the tumors were determined by CD31 immunostaining. To determine the effects of VEGFR antibody on cancer cell itself, we also examined the efficacy of the combinations in vitro.

Results: Combination therapy demonstrated significantly better tumor inhibition compared to erlotinib or alectinib alone in all the examined xenograft tumors. CD31 positive blood vessel staining was significantly reduced in the tumors treated with combination therapy. Mutant EGFR transfection in HEK293T cells increased VEGF expression in the cell culture supernatant. Furthermore, MTT assay showed significantly enhanced cell growth inhibition when anti-human VEGFR antibody ramucirumab combined with erlotinib (against PC-9 or H3255 cells) or alectinib (against ABC-11 or H3122 cells) suggesting that anti-VEGFR antibody affects not only on tumor vasculature but cancer cell itself. Consistent with this finding, combination with siVEGFR and erlotinib also inhibited the cell proliferation significantly better than erlotinib alone in PC-9 cells.

Conclusion: A significant combination benefit was observed with anti-VEGFR2 antibody and EGFR or ALK TKI both in vivo and in vitro, suggesting anti-VEGFR antibody inhibits not only the blood vessels but may also exert direct anticancer effects. Combination therapy of erlotinib or alectinib and anti-VEGFR2 antibody could be a promising treatment strategy for oncogene addicted NSCLC.

Citation Format: Hiromi Watanabe, Eiki Ichihara, Hiroe Kayatani, Hisao Higo, Go Makimoto, Hirohisa Kano, Kazuya Nishii, Naofumi Hara, Kiichiro Ninomiya, Toshio Kubo, Kadoaki Ohashi, Kammei Rai, Katsuyuki Hotta, Masahiro Tabata, Yoshinobu Maeda, Katsuyuki Kiura. Significant combination benefit of anti-VEGFR antibody and oncogene-targeted agents in EGFR or ALK mutant NSCLC cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2131.