Abstract Detection of mutations in EGFR in non-small cell lung cancer is important for the clinical decision-making process of molecularly targeted therapies, including Iressa®, Tarceva®, and Tagrisso®. In this study we developed an assay allowing the detection of EGFR gene mutations being conducted in the routine diagnostic procedure and its analytic and clinical performance were evaluated using different types of specimens. The EGFR mutation assay in this study allows for detecting EGFR exon 19 deletion (Del), exon 20 insertion (Ins), and mutation in T790M, L858R, S768I and L861Q of rare amounts in a normal genetic background. Enhancement of detection sensitivity was achieved with the developed mutant enrichment method which combines mutation-specific primers and 3'-phosphorylation oligonucleotides as blockers for inhibiting wild-type gene from DNA amplification. Analytic performance for each mutant was assessed using the control plasmids containing the mutant genes of known amounts as well as the genomic DNA extracted from mutant cell lines and Horizon FFPE samples. The assay performance were also evaluated using clinical samples in parallel with the FDA-approval companion diagnostic product therascreen® EGFR RGQ PCR Kit . The sensitivity of the assay evaluated using control plasmids for Del, T790M , L858R, S768I, L861Q mutation and Ins was 5%, 0.5%, 1%, 0.5%, 0.1% and 0.5% respectively, and was 1%, 0.5%, 0.5%, 0.5%, 0.1% and 0.5% respectively when applying on HDx reference standards. Diagnostic results for the 116 clinical samples for identifying mutations of del, T790M, L858R, S768I, L861Q and Ins was 92.2%, 100%, 99.1%, 100%, 97.4% and 100% respectively concordance with the therascreen® EGFR RGQ PCR Kit, including 17 cases of multiple mutations. The overall diagnostic results for all mutations evaluated with PPA (positive percent agreement), NPA (negative percentage agreement) and OPA (overall percentage agreement) were 83.3%, 98.2% and 90.5%, respectively. The three samples firstly diagnostic as false positive were retested and confirmed to be Exon 19 del by DNA sequencing. The assay demonstrated good sensitivity when compared with commercial product. More clinical studies are being performed to establish relationship between drug efficacy and different mutation combinations. Citation Format: Hung-Chi Chien. Highly-sensitive detection of EGFR mutation in non-small cell lung cancer using mutant-enrichment method [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 759. doi:10.1158/1538-7445.AM2017-759
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