Detection of EGFR and KRAS somatic mutations in tumor tissue and peripheral blood by a liquidchip technology for patients with advanced non-small cell lung cancer.

Abstract

e18142 Background: Responsiveness of non-small cell lung cancer (NSCLC) to EGFR tyrosine kinase inhibitors has been confirmed to relate to mutations in the epidermal growth factor receptor (EGFR) signaling pathway genes. This study’s aim is to detect mutations in two important components of the EGFR signaling pathway, EGFR and KRAS, using a novel liquidchip technology, and to evaluate the correspondence between tumor and plasma DNA in the same patient. Methods: 58 advanced primary NSCLC ( IIIB or ‡W) tumor tissues and matched peripheral blood samples (MPBS) were obtained. The procedures for multiplex PCR, allele specific primer extension (ASPE) and hybridization were performed after DNA extraction. A novel liquidchip platform for simultaneous detection multiple alleles of DNA somatic mutations was applied to detect the EGFR and KRAS status in matched samples. Results: EGFR exon 19 and exon 21 mutation rate was detected to be 29.3% (17/58) and 17.2% (10/58) respectively in tumor tissues, while 20.7% (12/58) and 12.1% (7/58) in MPBS. Among those 27 patients who harbor either EGFR exon 19 or exon 21 mutations in tissues, 19 (70.4%) of them were detected to have the same mutations in their peripheral blood samples. EGFR exon 20 T790M mutations were found in one of the paired samples. All the patients who were detected to have wild-type EGFR in tissues were detected to have wild-type in MPBS as well. In 50 of 58 (86.2%) of the paired samples, the EGFR mutation status in the tumors was consistent with those in the MPBS. The KRAS exon 2 mutation was also found in both blood and tumor samples in one patient; however only in the blood of another patient, not in his tumor. Conclusions: The liquidchip technology may serve as an effective method for detecting multiple gene mutations. EGFR and KRAS gene mutations in blood DNA were highly consistent with the corresponding tissue samples, and therefore, peripheral blood could be used as an alternative sample to predict patients’ response to the anti-EGFR targeted therapy. Further studies to evaluate the clinical application are suggested.