EGFR Mutational Profiling in Non–Small Cell Lung Cancer: The Clinical Performance of a Sensitive Reverse-Hybridization Assay

Abstract

In patients with non-small cell lung cancer (NSCLC), epidermal growth factor receptor (EGFR) mutations have been associated with the tumor response to targeted therapy with EGFR tyrosine kinase inhibitors. Although labor intensive and not very sensitive (ie, an analytical sensitivity of 20%), direct sequencing is widely used for mutation detection. This study aimed at evaluating the potential of a test strip-based reverse-hybridization assay (EGFR StripAssay), designed for the simultaneous detection of 16 mutations in exons 18 to 21 of the EGFR gene, to sensitively identify EGFR mutation in DNA from NSCLC tissue samples. Formalin-fixed paraffin-embedded (FFPE) DNA samples from 59 patients with a histologically confirmed primary NSCLC tumor were used to compare the performance of the EGFR StripAssay against that of the Sanger sequencing. The EGFR StripAssay analysis identified 7 (11.8%) of 59 FFPE samples to carry an EGFR mutation, of which 4 (57.1%) and 3 (42.8%) samples were positive for exon 19 and 21 mutations, respectively. Of note, no sample was identified with EGFR exon 18 or 20 mutation. All mutations were confirmed by DNA sequencing. Using 50 ng of template DNA, the EGFR StripAssay demonstrated a detection limit of 1% mutant sequence in a background of normal DNA. The EGFR StripAssay is a fast and robust platform for the sensitive detection of EGFR mutation in FFPE DNA. Therefore, this assay could be considered as an alternative protocol to Sanger sequencing for EGFR mutation testing on limited-quantity samples.