Direct serum and tissue assay for EGFR mutation in non-small cell lung cancer by high-resolution melting analysis

Biological therapy with epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have noted promising outcomes for patients with non-small cell lung carcinoma (NSCLC), especially those with mutated EGFR. Tissue EGFR gene mutation testing can predict the benefit of taking a first-line EGFR-TKI, thus, allowing the physician to prescribe the most suitable therapy. Unfortunately, most lung cancer patients, especially NSCLC patients present with advanced disease that is surgically unresectable. The goal of this study was to develop high-resolution melting (HRM) assays to detect EGFR mutations in exons 18 to 21, compare their sensitivity and concordance to direct sequencing, and evaluate the feasibility and reliability of serum as a tissue alternate for routine EGFR mutation screening. EGFR mutations of 126 Formalin-Fixed Paraffin-Embedded (FFPE), 47 fresh frozen tissues and from 47 matched pre-operation serum specimens of NSCLC patients were screened by the HRM assays. EGFR mutations by HRM were confirmed through sequencing. We found 78 EGFR mutations in 70 FFPE tissues, 25 EGFR mutations in 24 fresh frozen tissues, with a mutation rate of 55.56% (70/126) and 51.06% (24/47), respectively. Most mutations were correctly identified by sequencing. EGFR mutations were detected in 22 serum samples from 24 tissue EGFR mutation-positive patients. The concordance rate between serum and tissue in EGFR mutation screening was 91.67%. We conclude that the HRM assay can provide convincing and valuable results both for serum and tissues samples, thus, it is suitable for routine serum EGFR mutation screening for NSCLC patients, especially those surgically unresectable.