EGFR Gene Polymorphism Predicts Improved Outcome in Patients With EGFR Mutation-positive Non–small cell Lung Cancer Treated With Erlotinib

Abstract

BackgroundPatients with advanced-stage non–small cell lung cancer with epidermal growth factor receptor (EGFR) mutations are successfully treated with tyrosine kinase inhibitors (TKIs). However, treatment outcome varies significantly. Previously, we found the polymorphism 181946C>T (rs2293347) located in exon 25 of the EGFR gene to be a predictor of improved outcome. However, these data were based on a subgroup analysis. Furthermore, other minor studies have found conflicting data. Thus, the aim of this study was to demonstrate the association of 181946C>T with clinical outcome in an independent cohort of EGFR-mutated patients treated with erlotinib. Patients and MethodsSeventy-five patients were prospectively enrolled. Blood samples were collected, and genotype for 181946C>T was determined by allele-specific polymerase chain reaction. Genotype was correlated with outcome. ResultsIn 73 patients, 181946C>T was successfully measured. Patients harboring the 181946CT genotype had a significantly longer median progression-free survival compared with patients harboring the 181946CC genotype (49.9 months [95% confidence interval (CI), 5.9-93.9 months] versus 11.1 months (95% CI, 7.4-14.9 months); P = .020). Moreover, a significantly longer median overall survival of 65.6 months (95% CI, 11.0-120.3 months) versus 31.2 months (95% CI, 10.9-51.6 months) was found (P = .019). Both results remained significant in a multivariate analysis adjusting for potential confounders. ConclusionWe demonstrate that the 181946C>T polymorphism is a significant predictor of prolonged progression-free survival and overall survival in an independent cohort of EGFR mutation-positive patients treated with erlotinib. The polymorphism could be an important predictor of treatment response in these patients. A large multicenter cohort study involving other concurrent genetic alterations is warranted.