EGFR and cancer: In addition, as the majority of patients with EGFR-mutant tumors treated with first-generation EGFR TKIs develop acquired resistance by ERBB-dependent mechanisms (18), and considering that dacomitinib showed activity in gefitinib-resistant preclinical lung cancer models (19), it was also rational to test its clinical activity in patients with EGFR-mutant, TKI-resistant cancers.