The dominant role of G12C over other KRAS mutation types in the negative prediction of efficacy of epidermal growth factor receptor tyrosine kinase inhibitors in non-small cell lung cancer.

The role of KRAS mutations in molecular targeted therapy by epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in non-small cell lung cancer (NSCLC) has not been fully understood. The present investigation is aimed at an elucidation of the role of specific KRAS mutation types in predicting outcomes of patients with advanced NSCLC receiving EGFR-TKI therapy. Initially, 448 NSCLC patients were tested for the presence of KRAS mutations, to obtain frequencies of specific KRAS mutation types. Subsequently, the clinical outcome of treatment was evaluated in a subgroup of 38 KRAS-positive patients receiving EGFR-TKI therapy. KRAS mutations were detected in 69 of 448 patients (15.4%), mostly in smokers (17.86% vs. 5.8%, P = 0.0048), and appeared more frequently in adenocarcinomas than in squamous cell NSCLC or NSCLC that is not otherwise specified (21% vs. 6.99% vs. 4.4%, P = 0.0004). The most frequent type of KRAS mutation was G12C. The progression-free survival (PFS) was doubled in a group of non-G12C patients compared with that of the G12C group (9.0 wk vs. 4.3 wk, P = 0.009). The overall survival (OS) was not significantly different between non-G12C and G12C groups (12.1 wk vs. 9.3 wk, P = 0.068). The G12C KRAS mutation is a strong negative predictor for EGFR-TKI treatment, whereas other KRAS mutation types have not negatively predicted treatment efficacy compared with that for the wild-type KRAS genotype.