De novo T790M mutations constitute a small subgroup of EGFR mutations, which are observed in approximately 3% of all EGFR-mutated NSCLC patients with standard methods [92], and are generally associated with reduced sensitivity to first- or second-generation EGFR TKIs, with an ORR of 14–33% and a median PFS of 1.94–2.9 months [37,45,91]. Here, EGFR is linked to non-small cell lung carcinoma.