Another second-generation irreversible inhibitor, dacomitinib, is also approved for first-line treatment of patients with metastatic NSCLC with the EGFR exon 19 deletion or the L858R substitution mutation (55) based on a study that has shown that first-line dacomitinib is superior over gefitinib in improving PFS in patients with NSCLC with sensitizing EGFR mutations (58). Here, EGFR is linked to non-small cell lung carcinoma.