Investigation of the Efficacy of Epidermal Growth Factor Receptor (EGFR)-Tyrosine Kinase Inhibitor in Patients With EGFR Exon 21 L858R Point Mutation-Positive Non-small Cell Lung Cancer

Treatment of advanced non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) has a higher response rate than with conventional chemotherapy in patients positive for EGFR mutations. However, the efficacy of EGFR-TKI therapy may be reduced in patients positive for the EGFR exon 21 L858R point mutation.