EGFR and lung cancer: Indeed, most patients with CCDC6-RET and FGFR3-TACC3 received prior EGFR TKI treatment; thus, suggesting that CCDC6-RET and FGFR3-TACC3 may function as resistance mechanisms to EGFR TKIs in lung cancer, and may also highlight the differences in acquired resistance to TKIs through gene fusions between EGFR L858R and ex19del-mutant variants.