EGFR and non-small cell lung carcinoma: In order to explore the mechanisms of acquired resistance to AZD9291, AZD9291‐resistant NSCLC cell lines (H1975/AR and HCC827/AR) were established from the parental H1975 (EGFR L858R + T790M) and HCC827 (EGFR E746‐A750del) AZD9291‐sensitive cell line respectively by gradually increasing concentrations of AZD9291, as described in Methods.