Osimertinib for advanced non-small cell lung cancer harboring EGFR mutation exon 20 T790M, acquired resistant mutation for first- or second-generation EGFR-TKI

Since the results of IDEAL-1 (1) and the approval of gefitinib, a first-class epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), 15 years have passed. The efficacy of first-line EGFR-TKI, gefitinib (2,3), erlotinib (4), icotinib (5), and second-line EGFR-TKI, afatinib (6), is 6.3–11.0 months for median progression-free survival (PFS), 19.4–28.2 months for median overall survival (OS), and 44.1–73.7% for the response rates, respectively.