Comparison of Clinical Outcomes Following Gefitinib and Erlotinib Treatment in Non-Small-Cell Lung Cancer Patients Harboring an Epidermal Growth Factor Receptor Mutation in Either Exon 19 or 21

Background: Gefitinib and erlotinib, small-molecule kinase inhibitors that block epidermal growth factor receptor (EGFR) signaling, have demonstrated a dramatic response rate and prolonged progression-free survival (PFS) in patients harboring an activating EGFR mutation. We compared the clinical outcomes in gefitinib- and erlotinib-treated patients harboring EGFR mutations who had recurrent or metastatic non-small-cell lung cancer (NSCLC). Methods: A total of 375 patients with recurrent or metastatic stage IIIB/IV NSCLC, who had either exon 19 deletion or the L858R mutation in exon 21, and had received either gefitinib (n = 228) or erlotinib (n = 147), were included in the study. A matched-pair case-control study design was implemented in the analysis, where 121 pairs of gefitinib-treated and erlotinib-treated patients were matched according to sex, smoking history, Eastern Cooperative Oncology Group performance status, and types of EGFR mutation. Results: The median age of all patients was 58 years (range, 30-84), and more than half of patients had never been smokers (63.6%). Most patients had adenocarcinoma (98.3%) and good Eastern Cooperative Oncology Group performance status (0, 1) (90.9%). The median number of cycles of EGFR tyrosine kinase inhibitor (TKI) treatment was 12.7 in the gefitinib group and 10.8 in the erlotinib group. Of the 242 patients, 63 (26%) received EGFR TKI as first-line therapy. The overall response rates and disease control rates in the gefitinib- or erlotinib-treated groups were 76.9% versus 74.4% (p = 0.575) and 90.1% versus 86.8%, respectively (p = 0.305). There was no statistically significant difference with regard to PFS (median, 11.7 versus 9.6; p = 0.056) between the gefitinib- and erlotinib-treated groups. For patients receiving EGFR TKI as the first-line treatment, there was no significant difference between the two treatment groups in overall response rates (76.7% and 90.0%) (p = 0.431) and median PFS (11.7 versus 14.5 months) (p = 0.507). Conclusion: In NSCLC patients harboring EGFR mutation, treatment with gefitinib and erlotinib resulted in similar effectiveness.