A panel of high resolution melting (HRM) technology-based assays with direct sequencing possibility for effective mutation screening of EGFR and K-ras genes

Background: Increasing data from clinical trials support EGFR and K-ras mutation status as predictive markers of tumour response to EGFR-targeted therapies. Consequently, rapid and reliable mutation screening assays are demanded to guide rational use of EGFR-targeted therapies. Methods: In this study, we describe the development of high resolution melting (HRM) technology-based assays with di- rect sequencing confirmation possibility for mutation screening of the EGFR gene (exons 19, 20 and 21) in routine diagnostic specimens, and compared assay findings to those of conventional nested-PCR following cycle-sequencing. Results: In reconstruction experiments, each HRM assay following sequencing demonstrated a sensitivity of 5% of mutated DNA in a background of wild-type DNA. The panel of EGFR HRM assays following sequencing applied to a series of genomic DNA samples isolated from 68 FFPE NSCLC specimens correctly identified all EGFR mutations that were previously found by nested-PCR following cycle-sequencing. The HRM approach additionally scored two mutations not detected by the conventional assay. Complementary HRM following sequencing for K-ras revealed three mutations. EGFR and K-ras mutations were mutually exclusive. Conclusions: The panel of designed HRM assays with direct reflex sequencing possibility provides an effective method for mutation screening of EGFR and K-ras genes in routine diagnostic specimens, thereby allowing the selection of the treatment of choice in clinical practice.