Sequence-dependent synergistic cytotoxicity of icotinib and pemetrexed in human lung cancer cell lines in vitro and in vivo

Background Recent Clinical trials of administration of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in combination with standard first-line chemotherapy have failed to improve survival in patients with advanced NSCLC, However, the sequential treatment with EGFR-TKIs and chemotherapy is expected to improve survival of NSCLC. The aim of this study is to test the antiproliferative effect of pemetrexed combined with icotinib in different sequences on non-small cell lung cancer (NSCLC) cell lines to determine the optimal combination schedule, and subsequently elaborated the potential mechanisms.