In the current study, we collected 50 paired pretreatment and post-resistant tumor tissue samples from 25 patients with EGFR T790M mutant NSCLC received third-generation EGFR-TKI from a phase II trial and 34 samples (22 pretreatment and 12 resistant) from 22 EGFR-mutant NSCLC patients received third-generation EGFR-TKIs in a real-world cohort. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.