Regarding the prevalence of EGFR p.T790M in combination with either of the primary activating EGFR mutations, EGFR Exon 19-mutant tumours acquired an EGFR p.T790M mutation as resistance mechanism more frequently than tumours with EGFR exon 21 mutations after reversible first-generation EGFR TKI therapy (75 and 54%, respectively, p = 0.07). This evidence concerns the gene EGFR and neoplasm.