Numerous evidences verified that erlotinib could dramatically improve the PFS and OS of non-small cell lung cancers who harbor EGFR sensitive mutations, however, primary or secondary resistance will be developed after TKI treatment, doctors do plenty of researches to overcome TKI resistance. FAST ACT-2 study present that, first line erlotinib combined with chemotherapy could improved mOS to more than 30 months in NSCLCs who harbor EGFR sensitive mutations, several study shows that sensitive mutations still exist after TKI resistance, because of the next generation TKIs(such as BIBW2992) are not avaliable at present, agents for met amplification(such as Crizotinib) are so expensive that many Chinese patients could not support. Thus, the investigators hypothesis that, after first line TKI treatment, the patients who developed TKI resistance could still benefit from second line TKI combined with chemotherapy.