KRAS and BRAF provide information to aid physicians in the treatment of CRC patients⁷.
Guiding Colorectal Cancer Treatment
Asuragen's KRAS and BRAF tests are molecular tools for Colorectal Cancer (CRC) run on formalin-fixed paraffin embedded (FFPE) tissue. These Laboratory Developed Tests (LDTs) interrogate mutations within the KRAS and BRAF genes, respectively.
The American Society of Clinical Oncology (ASCO) recommends all patients with metastatic colorectal cancer, for whom treatment with EGFR antagonists is being considered, be specifically tested to determine their KRAS mutational status at codons 12 and 13¹∙².
BRAF is a downstream molecule from KRAS in a signaling pathway involved in cell cycling. Mutations in the BRAF gene, such as V600E, are also observed in CRC and are responsible for an additional 12-15% of patients who fail to respond to anti-EGFR treatment³.
Clinical Significance
RAS genes are the most common targets for somatic gain-of-function mutations in human cancers. Specific activating RAS mutations occur in approximately 30% of human cancers including, colorectal cancer (CRC), non-small cell lung cancer (NSCLC), pancreatic cancer, and others⁴.
Mutations in the KRAS gene, present in about 40% of CRC patients, are associated with poor prognosis and lack of response to anti-epidermal growth factor receptor (anti-EGFR) therapy⁵. In July 2009, the Food and Drug Administration (FDA) approved labeling changes to two EGFR antagonists, cetuximab and panitumumab, stating that these agents are not recommended for the treatment of CRC harboring those KRAS mutations. Thus, determination of KRAS mutation status in patients is critical when evaluating their eligibility for anti-EGFR therapy.
Data from the CRYSTAL trial suggest that BRAF mutations are also indicative of poor prognosis⁶. The National Comprehensive Cancer Network (NCCN) Colon Cancer Guideline Update 2010 (link to NCCN) states that testing for BRAF mutations should occur when KRAS testing indicates wild type⁷.
Note: KRAS and BRAF LDTs are intended to be used and interpreted in conjunction with all other available clinical and laboratory information when evaluating anti-EGFR treatment options for CRC patients.
Markers and Options
Testing Options: KRAS and BRAF are available in several configurations (see above) and were optimized for maximum coverage and sensitivity. The KRAS 7 Mutation panel allows for detection of the seven clinically relevant KRAS mutations in codons 12 and 13. The KRAS 12 Mutation panel configuration enables detection of additional five rare KRAS mutations in codon 13.
Specimen Requirements
• FFPE tissue or cell block.
• A minimum one 10 µm unstained FFPE slide with a tissue surface area equal or greater than 1cm², containing ≥40% abnormal area content and one H&E stained slide for pathology assessment.
• FFPE clinical blocks containing ≥40% abnormal area (additional charges will apply for generation of H&E slide and pathology review).
• For specimens with <40% abnormal area content, Asuragen’s pathologist will determine if the specimen abnormal area content can be enriched to the required 40%.
Note: These laboratory developed tests are analytically validated for use with CRC formalin-fixed paraffin-embedded (FFPE) tissue specimens that contain at least 40% tumor area, or that can be enriched to that tumor content in the course of a histological specimen review. These tests have not been validated on other specimen types or other human malignancies.
Billing and Turnaround Time
Asuragen bills third parties (private insurance and Medicare), patients, and hospitals.
Note: Asuragen does not accept Medicaid. Asuragen cannot accept samples from New York or Florida at this time.
For additional billing information, please contact Clinical Laboratory Support: Phone: 888-772-8018 Email: ClinicalLabSupport@asuragen.com
Results can be expected within 8-10 business days from the date the sample is received
1. Allegra, C. J., Jessup, J. M., Somerfield, M. R., Hamilton, S. R., Hammond, E. H., Hayes, D. F., McAllister, P. K., Morton, R. F., and Schilsky, R. L. American Society of Clinical Oncology provisional clinical opinion: testing for KRAS gene mutations in patients with metastatic colorectal carcinoma to predict response to anti-epidermal growth factor receptor monoclonal antibody therapy. J Clin Oncol 2009; 27: 2091-2096.
2. Javle, M. and Hsueh, C. T. Updates in Gastrointestinal Oncology - insights from the 2008 44th annual meeting of the American Society of Clinical Oncology. J Hematol Oncol 2009; 2: 9.
3. Mao, C., Liao, R. Y., Qiu, L. X., Wang, X. W., Ding, H., and Chen, Q. BRAF V600E mutation and resistance to anti-EGFR monoclonal antibodies in patients with metastatic colorectal cancer: a meta-analysis. Mol Biol Rep, 2010.
4. Forbes, S. A., Bindal, N., Bamford, S., Cole, C., Kok, C. Y., Beare, D., Jia, M., Shepherd, R., Leung, K., Menzies, A., Teague, J. W., Campbell, P. J., Stratton, M. R., and Futreal, P. A. COSMIC: mining complete cancer genomes in the Catalogue of Somatic Mutations in Cancer. Nucleic Acids Res 2011; 39: D945-950.
5. Siddiqui, A. D. and Piperdi, B. KRAS mutation in colon cancer: a marker of resistance to EGFR-I therapy. Ann Surg Oncol 2010; 17: 1168-1176.
6. Van Cutsem, E., Kohne, C. H., Hitre, E., Zaluski, J., Chang Chien, C. R., Makhson, A., D'Haens, G., Pinter, T., Lim, R., Bodoky, G., Roh, J. K., Folprecht, G., Ruff, P., Stroh, C., Tejpar, S., Schlichting, M., Nippgen, J., and Rougier, P. Cetuximab and chemotherapy as initial treatment for metastatic colorectal cancer. N Engl J Med 2009; 360: 1408-1417.
7. Colon Cancer. Clinical Practice Guidelines in Oncology (NCCN Guidelines) National Comprehensive Cancer Network, 2011.