EGFR/KRAS mutations and gefitinib therapy in Chinese NSCLC patients

For gefitinib treatment for non-small cell lung cancer (NSCLC), KRAS mutations reportedly behave as a resistance marker, and the epidermal growth factor receptor (EGFR) as a responsive marker. It is known that Asians and Caucasians have different responses to gefitinib. We investigated the KRAS and EGFR mutation status in a group of Chinese patients with advanced NSCLC who were treated with gefitinib after a failed chemotherapy.

Genomic DNA extracted from tumor specimens of 24 patients with advanced NSCLC, who failed at least 1 prior platinum-based chemotherapy regimen before gefitinib treatment, was subjected to nested polymerase chain reaction (PCR) to amplify codons 12, 13, 59, and 61 of the KRAS gene and exons 18-21 of the EGFR gene for direct sequencing.

For the 24 patients, no KRAS gene mutation was found. 15 patients (62.5%, 15/24) harbored EGFR mutations which included deletion mutations in exon 19 and missense mutations in exon 21.

KRAS mutation may occur at a very low frequency in Chinese NSCLC patients regardless of pathology, smoking status, or gender. Unlike EGFR, the low incidence of KRAS mutations may undermine its role in predicting the clinical response to EGFR tyrosine kinase inhibitors.