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Test Code: NEGFR
Description: The presence of mutations in the EGFR gene has been shown to predict response to small molecule tyrosine kinase inhibitors (TKIs) targeting EGFR in non-small cell lung cancer. The most prevalent EGFR mutations are in-frame deletions in exon 19 and the p.Leu858Arg (p.L858R) point mutation in exon 21 in the EGFR kinase domain. These two classes of mutation together account for 80-90% of EGFR mutations in non-small cell lung cancer. Less common activating mutations include those affecting p.Gly719 and p.Leu861 and in-frame insertions in exon 20. Exon 19 deletions, p.Leu858Arg, and mutations affecting p.Leu861 and p.Gly719 predict sensitivity to TKIs, while most exon 20 insertions are associated with decreased sensitivity. The p.Thr790Met (p.T790M) mutation is associated with resistance to TKIs, and is found in ~50% of lung cancer patients who acquire resistance to first-line therapy with TKIs as well as rarely in patients at initial presentation.

Our assay was developed to identify exon 19 deletions, exon 20 insertions, and point mutations affecting positions c.2155, c.2156, c.2369, c.2573, and c.2582 (p.Gly719, p.Thr790, p.Leu858, and p.Leu861, respectively) in EGFR (NCBI accession NM_005228.3) using a PCR-based technique. The EGFR exon 19 deletion and exon 20 insertion assay consists of PCR amplification followed by capillary electrophoresis fragment analysis. Point mutations are detected using multiplex PCR followed by single nucleotide mutation detection using SNaPshot methodology (dideoxy single-base extension of oligonucleotide primers).

Reference: Dias-Santagata D, et al (2010) Rapid targeted mutational analysis of human tumours: a clinical platform to guide personalized cancer medicine. EMBO Mol Med 2: 146-158


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