Patients diagnosed with (i) stage IIIB~IV non-small cell lung cancer, (ii) tumor harbors activating mutation at EGFR, (iii) radiological confirmation of progressive disease with one or more lines of EGFR tyrosine kinase inhibitors but have not yet been exposed to palliative chemotherapy, will be eligible for screening procedure. The lung cancer stage will be determined according to the 8th edition of the International Association for the Study of Lung Cancer (IASLC) Tumor, Node, Metastasis (TNM) staging system for lung cancer.~In addition to screening of baseline bone marrow function, organ functions, and CT assessment of measurable target lesion(s), patients after TKI treatment failure must receive tumor EGFR genotyping by testing tumor DNA in re-biopsied tumor samples. Testing report from local laboratories will be accepted.~Enrollment of patients into the study will depend on EGFR testing results in re-biopsied tumor samples.~Duration induction phase, four cycles of atezolizumab 1200 mg will be administered over 60 min (1st cycle) and 30 min (2nd cycle onwards); bevacizumab 7.5mg/kg over 90 min in 1st cycle, 60 min in 2nd cycle and 30 min in 3rd cycle onward; pemetrexed 500 mg/m2 over 10 min; and cisplatin 75mg/m2 or carboplatin (CCr < 60) area under curve 5 mg/mL per min over 15-60 min intravenously every 3 weeks in the order listed.~Following the induction phase, patients will continue atezolizumab, bevacizumab and pemetrexed as maintenance therapy. Patients will continue treatment with bevacizumab and pemetrexed until progressive disease, unacceptable toxicity, or death. Patients may continue treatment with atezolizumab beyond radiographic progression by RECIST v1.1, provided they are experiencing clinical benefit as assessed by investigator (i.e., in the absence of unacceptable toxicity or symptomatic deterioration attributed to disease progression as determined by the investigator after an integrated assessment of radiographic data, biopsy results [if available], and clinical status.~Atezolizumab and bevacizumab dose reduction will not be allowed. Modification of carboplatin or cisplatin, and pemetrexed doses will be done according to the local guidelines of National Taiwan University Hospital
using Atezolizumab, a PD-L1 inhibitor, in combination with bevacizumab, platinum and pemetrexed to treat patients with EGFR mutated, advanced non-small cell lung cancer (NSCLC) after failure of EGFR tyrosine kinase inhibitors.