Osimertinib as first-line treatment of EGFR mutant advanced nonsmall- cell lung cancer

The epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) gefitinib, erlotinib and afatinib are currently recommended for first-line treatment of patients with advanced non-small cell lung cancer (NSCLC) harboring EGFR-TKI-sensitizing mutations ( EGFRm ) (1,2). However, after a period of 9 to 11 months of treatment, acquired resistance to these first- and secondgeneration EGFR-TKIs inevitably develops. In 50–60% of the cases, acquired resistance is due to EGFR T790M mutation, which is the substitution of threonine with methionine at amino acid position 790, EGFR T790M (3,4).