Objective: To analyze the association between the EGFR protein level and the EGFR gene mutation status in advanced non-small cell lung cancer (NSCLC), and to explore whether the EGFR protein level is related to the efficacy and survival of the EGFR-TKI drug Gifitinib-treated patients with advanced NSCLC.
Methods: Ninety-nine cases were enrolled in this study. Pathological tissue specimens and paired peripheral blood samples were collected. Exons 19 and 21 of the EGFR gene mutation were detected by direct sequencing. The concentration of plasma EGFR protein was detected by ELISA. Univariate and multivariate statistical analyses of the efficacy and survival were performed using SPSS 13.0 software.
Results: The response rate (RR) and clinical benefit rate (CBR) of Gefitinib-treated patients were 51.5% and 79.8%, respectively. There were 35 (35.4%) with positive EGFR gene mutation of the 99 samples. The concentration limit of EGFR protein was 55.42 µg/L. The RR and CBR of patients with EGFR gene mutation was significantly higher than those without mutation (65.7% vs. 43.8%, P = 0.037; 94.3% vs. 71.9%, P = 0.008). The median PFS was prolonged (23 months vs. 10 months, P = 0.014). The CBR of patients with high EGFR protein expression (concentration ≥ 55.42 µg/L) was significantly higher than those with low expression (90.0% vs 64.1%, P = 0.004), and the median PFS was prolonged (21 months vs. 8 months, P = 0.016). EGFR protein level was an independent factor affecting the EGFR gene mutation status. The Correlation between EGFR gene mutation status and EGFR protein level was positive.
Conclusions: Gefitinib is effective in the treatment of advanced NSCLC patients with EGFR gene mutation and high EGFR protein expression. EGFR protein level in peripheral blood may be a molecular biomarker in prediction of efficacy and survival of the Gefitinib treatment in patients with advanced NSCLC.