KRAS and BRAF

KRAS and BRAF testing can be used for metastatic colorectal cancer prognosis and therapy evaluation.  The tests can aid in the identification of patients eligible for treatment with cetuximab (Erbitux®) or panitumumab (Vectibix®)

KRAS Gene Mutation Detection

Mutations in the KRAS gene have been documented in a variety of cancers, including 35% to 45% of colorectal cancers.  Recent studies have shown that the normal form of the KRAS gene is associated with response to anti-EGFR monoclonal antibody based therapies. Recent guidelines from the American Society of Clinical Oncology (ASCO) and the National Comprehensive Cancer Network (NCCN) have recommended testing to determine KRAS mutation status in stage IV colon cancers.

Specimen:  Formalin-fixed, paraffin-embedded (FFPE) tissue. Send five precut unstained slides from paraffin block in 10-μM sections and an H&E reference slide or formalin-fixed, paraffin-embedded tissue block containing ≥50% tumor.

Volume:  Five precut, unstained slides from paraffin block in 10-μM sections and one H&E reference slide or formalin-fixed, paraffin-embedded tissue block containing ≥50% tumor

Use:  Mutations in the K-ras oncogene are frequently found in human cancers. They are common in pancreatic cancer, colorectal cancer, lung adenocarcinoma, gallbladder cancer, bile duct cancer, and thyroid cancer. These mutations may indicate prognosis and drug response, and many new cancer therapies are being targeted to the K-ras pathway. This assay detects seven K-ras mutations in codons 12 and 13, allowing determination of whether there is a correlation between K-ras mutation status and drug response.

Limitations:  The provided tumor tissue should be composed of ≥50% tumor cells for accurate test interpretation. Preparation of DNA from tissue samples is dependent on the quality of the specimen provided. Inadequate DNA extraction may occur in a significant number of paraffin-embedded samples. The methods used in this assay are highly selective and, depending on the total amount of DNA present, can detect approximately 1% of mutant in a background of wild-type genomic DNA. The assay has a limit of detection of between five and ten copies.

Methodology:  Amplification refractory mutation system (ARMS) and real-time polymerase chain reaction (PCR) using Scorpions™ technology
 

BRAF Gene Mutation Detection

Mutation status of the BRAF gene has recently been shown to provide prognostic and potentially predictive information for patients considered for anti-EGFR monoclonal antibody therapies. Individuals with tumor samples that contain the normal variants of the KRAS and BRAF genes have an increased response to such therapies. In addition, BRAF mutations have been demonstrated in a variety of other tumor types (melanoma, thyroid etc.) and have been shown to be prognostic for these and other cancers.

A recent study (Di Nicolantonio et al, Journal of Clinical Oncology 2008;35:5705) indicated that BRAF tumor genotype provides prognostic and predictive information for patients considered for anti-EGFR antibody therapies.  In this study, all patients who responded to such therapies had both normal KRAS and BRAF genes. 

Specimen:  Formalin-fixed, paraffin-embedded (FFPE) tissue. Please send four precut unstained slides from paraffin block in 5-μM sections and an H&E reference slide or formalin-fixed, paraffin-embedded tissue block containing ≥50% tumor.

Volume:  Four unstained slides and one H&E stained at 5 μM or formalin-fixed paraffin-embedded tissue block

Use:  Somatic mutations in the BRAF oncogene are frequently found in human cancers.

Limitations:  The provided tumor tissue should be composed of ≥50% tumor cells for accurate test interpretation. Preparation of DNA from tissue samples is dependent on the quality of the provided specimen. Inadequate DNA extraction may occur in a significant number of paraffin-embedded samples.The methods used in this assay are highly selective and, depending on the total amount of DNA present, can detect approximately 1% of mutants in a background of wild-type genomic DNA. The assays have limits of detection of between 5 and 10 copies.This procedure may be considered by Medicare and other carriers as investigational and, therefore, may not be payable as a covered benefit for patients.

Methodology:  Amplification refractory mutation system (ARMS) and real-time polymerase chain reaction (PCR) using Scorpions™ technology

Additional Information:  These mutations are common in melanomas, colorectal cancer, lung cancer, ovary cancer, and thyroid gland cancer. Over 90% of mutations are the V600E (1799T>A) mutation. Recent studies have shown that metastatic colorectal cancer patients with this BRAF mutation do not have a strong response to anti-EGFR therapies such as cetuximab and panitumumab. This assay will detect the V600E mutation in the BRAF gene, allowing identification of patients who are likely to benefit from such treatment.
 

If you would like additional information about KRAS or BRAF testing, please ask your local sales rep or e-mail sales@uslabs.net.