Efficacy of EGFR tyrosine kinase inhibitors for non-adenocarcinoma NSCLC patients with EGFR mutation

Abstract

The epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) gefitinib and erlotinib have shown dramatic response rate (RR) and significant prolongation of progression-free survival (PFS) in non-small-cell lung cancer (NSCLC) patients with EGFR mutation. Since only a few patients with non-adenocarcinoma histology have been enrolled in clinical trials, the efficacy of EGFR TKIs in non-adenocarcinoma NSCLC patients with EGFR mutation has not yet been fully determined. We retrospectively analyzed clinical outcomes, including RR, PFS, and OS, in patients who were treated with the EGFR TKIs gefitinib or erlotinib and compared the results with those of adenocarcinoma patients with EGFR mutation and non-adenocarcinoma patients with wild-type EGFR. Among 250 patients with non-adenocarcinoma of the lung who underwent EGFR mutation genotyping, 21 were found to have an EGFR mutation (8.4%). Twelve of the 21 patients were treated with the EGFR TKIs gefitinib (n=6) or erlotinib (n=6). The most common mutation was exon 19 deletion (n=7). The RR and disease control rate for 12 patients receiving EGFR TKIs were 50 and 75%, respectively. The median PFS was 3.67months (95% CI: 1.34-5.99), which was significantly lower than that of 269 adenocarcinoma patients with EGFR mutation (13.53months) but better than that of 32 non-adenocarcinoma patients with wild-type EGFR (1.83months) who were treated with EGFR TKIs. The results of this study show that the EGFR mutation rate in Korean patients with non-adenocarcinoma of the lung is relatively high and that the clinical outcomes of EGFR TKIs are modest.