Erlotinib Combined With Chemotherapy in TKI Resistant Non-Small Cell Lung Cancers

patients will received a 28 days gemcitabine platinum combined with erlotinib scheme, after 4 cycles combined chemotherapy, patients will receive erlotinib for maintain treatment until progression disease.Gemcitabine for day 1 and day 8, 1250mg/m2. Platinum for day 1, 75mg/m2. Erlotinib for day 9-21 during combined chemotherapy, 150mg/day, then erlotinib should be used daily until patients develop progression disease.