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KRAS Gene Mutation Analysis DESCRIPTION The v-Ki-ras2 Kirsten rat sarcoma (KRAS) gene encodes a small GTPase that functions in a signal transduction cascade downstream of the epidermal growth factor receptor (EGFR). KRAS somatic mutations have been identified in 30-40% of colorectal cancers and 10-30% of non-small cell lung cancers. The most common mutations reported are in KRAS codons 12 and 13. Several studies have demonstrated that tumors carrying any of these mutant forms of the KRAS gene are less likely to respond to EGFR inhibitors. Clinical guidelines now recommend KRAS testing before starting anti-EGFR therapy. The KRAS Gene Mutation Analysis assay is able to differentiate between the following 7 most common mutations and the wild-type form of KRAS codons 12 and 13: Gene Mutation KRAS KRAS KRAS KRAS 12GGT>AGT 12GGT>GAT 12GGT>GTT 12GGT>TGT Amino Acid Change G12S G12D G12V G12C Gene KRAS KRAS KRAS Mutation 12GGT>GCT 12GGT>CGT 13GGC>GAC Amino Acid Change G12A G12R G13D SPECIFICATIONS IG Labs Test Code 118 Turnaround Time 24-48 hours PCR/Probe Targets Mutations within codons 12 and 13 of the v-Ki-ras2 Kirsten rat sarcoma (KRAS) gene and an endogenous control. Specimen Formalin-fixed, paraffin-embedded blocks/slides 2-3 10-micron sections Storage: Ambient (4°C preferred) Sections must be freshly prepared or less than 3 months old. Causes for Rejection DNA quality can be compromised due to nucleic acid fragmentation, and/or modification by chemical reactions between formaldehyde and nucleic acids which include crosslinking with proteins or other biomolecules. Specimens with endogenous control Ct values greater than 30 cycles will be deemed as Quantity/Quality Not Sufficient (QNS) and are noted as such. Limit of Detection 2% mutant content (Validated in Formalin-fixed paraffin embedded cell line studies) Detection Range Reaction Ct Value Endogenous Control 20 - 30 KRAS Detection Above Baseline < 35 cycles Samples with a 35 Ct value are approaching the lower limits of detection for the assay. Method Quantitative Real-Time Polymerase Chain Reaction (qPCR) CPT Codes 81275, 81403 References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Allegra C.J., et al. J Clin Oncol (2009), 27:2091-2096. Amado R.G., et al. J Clin Oncol (2008), 26:1626-1634. Baldus, S.E., et al. Clin Cancer Res (2010), 16:790-799. Eberhard D.A., et al. J Clin Oncol (2005), 23:5900-9. Jackman D.M., et al. Clin Cancer Res (2009), 15:5267-5273. Lievre A., et al. Cancer Res (2006), 66: 3992-3995. Massarelli E., et al. Clin Cancer Res. (2007), 13:2890-2896. Pao W., et al. PLosMed. (2005), 2:e17. ASCO Provisional Clinical Opinion. J Clin Oncol (2009), 27. College of American Pathologists Perspective on Emerging Technologies – KRAS Mutation Testing for Colorectal Cancer (CRC), September 2009. 11. National Comprehensive Cancer Network - NCCN Clinical Practice Guidelines in Oncology November 2008.