Efficacy of tyrosine kinase inhibitors in routine clinical practice: Epidermal growth factor mutations and their implications

Abstract

Activating mutations in the epidermal growth factor (EGFR) gene confer sensitivity to the tyrosine kinase inhibitors (TKIs) in patients with advanced non-small cell lung cancer (NSCLC). TKI treatment efficacy and EGFR mutation implications were evaluated in clinically selected advanced NSCLC patients treated with TKIs in routine clinical practice. A retrospective chart review for clinicopathological characteristics and mutation status (EGFR, KRAS) analysis of 40 consecutive patients treated with TKIs between 2005 and 2010 was performed. PFS and OS were estimated by the Kaplan-Meier method, the log-rank test was used to test for differences. The strength of the associations between the EGFR mutation status and clinicopathological characteristics were tested with the Mann-Whitney U-test or the Kruskal-Wallis H-test. The prevalence of EGFR mutations was 45% with a predominance of deletion mutations in exon 19 (55.5%). Significant correlations between gender, histology, and EGFR mutations were observed. Median progression-free survival (mPFS) for the entire group of patients was 8.7 months and median overall survival (mOS) was not yet reached. Patients with EGFR mutant tumors derived significantly higher benefit from TKI therapy compared to patients with mutation-negative disease; with mPFS of 22.0 vs. 3.2 months (HR: 3.9, 95% CI 1.56-9.89) and with a trend towards better OS (probability of survival at 12 months 82.0 vs. 63.0%, P = 0.080). We demonstrated that screening for EGFR mutations is reliable in a routine clinical setting and might allow for a better selection of NSCLC patients for anti-EGFR TKI therapy.