Clinical chemistry and laboratory medicine 2017 04 22() doi 10.1515/cclm-2016-0353
The discovery of mutations in the epidermal growth factor receptor gene (EGFR) related to the clinical response to tyrosine kinase inhibitors, has transformed the management of non-small cell lung cancer (NSCLC). Several methods have been developed for determination of mutations in EGFR, with different sensitivity and potential ability to detect a different number of mutations.
We developed a screening method by high resolution melting (HRM) to detect EGFR mutations, and compared the results of 123 fixed in formalin and paraffin embedded (FFPE) tumor tissue samples with the detection of mutations by allele-specific PCR. In samples with discordant results, Sanger and massive parallel sequencing (MPS) were additionally performed.
Eight samples showed discordant results between both methods. Three samples with negative results by allele specific PCR and positive by HRM were confirmed by Sanger sequencing (p.S768I+p.V769L, T751_I759del and p.E709K+p.G719A; patients 1, 3 and 4, respectively). One sample with a negative result by HRM, and positive by allele specific PCR (p.T790M; patient 2), was confirmed by Sanger sequencing. Additionally, two positive samples for a deletion in exon 19 by allele-specific PCR, were negative by Sanger sequencing and HRM (patients 2 and 5) and finally, two samples were negative by allele-specific PCR and positive by HRM and Sanger sequencing due to synonymous variants in exon 21.
HRM is a good method for mutational screening in EGFR. It is able to detect any change in the sequence of exons 18-21, providing high cost/effectiveness, but samples with low tumor burden may produce false negatives results.