Afatinib inhibited auto-phosphorylation of HER members and proliferation in cancer cell lines representing different mutational status of EGFR and HER2, including wild-type EGFR (A431), activating mutant EGFR (PC-9 and H3255, EC50 = 0.4 and 0.5 nM, respectively), L858R-T790M mutant EGFR (NCI-H1975), L858R-T854A mutant EGFR (transfected 293T), and HER2 amplification (BT474) with EC50 below 100 nM, whereas NCI-H1975, T854A transfected 293T, and BT474 were resistant to erlotinib and/or gefitinib (98, 100). This evidence concerns the gene EGFR and cancer.