Wobble-enhanced ARMS Method for Detection of KRAS and BRAF Mutations

Monoclonal antibodies targeting the epidermal growth factor receptor have expanded the range of treatment options for patients with metastatic colorectal cancer. However, somatic mutations in the KRAS and BRAF genes have proven to be molecular predictors of resistance to treatment with anti-epidermal growth factor receptor therapy in these patients. Thus, we have developed a sensitive mutation assay, wobble-enhanced amplification refractory mutation system, for detecting the 8 most commonly reported mutations of clinical importance in the KRAS and BRAF genes; KRAS g.34G > C (p.G12R), g.34G > A (p.G12S), g.34G > T (p.G12C), g.35G > A (p.G12D), g.35G > C (p.G12A), g.35G > T (p.G12V), g.38G > A (p. G13D), and BRAF g.1799T > A (p.V600E). A total of 28 candidate setups were designed based on bioinformatics and primer/probe design. Eight candidate setups were thus selected using a synthetic oligonucleotide model. The setups were further validated through several experiments using formalin-fixed paraffin-embedded tissue and cell lines. The results confirm that the wobble-enhanced amplification refractory mutation system method is quick, cost effective, and sensitive. The method is optimized to handle a typical template input of 1 to 20 ng DNA per polymerase chain reaction and can be implemented in any laboratory with ease with a real-time polymerase chain reaction instrument capable of handling TaqMan techonology. The steps used to develop this method can be implemented to design assays for other mutations located in KRAS, BRAF, or other candidate genes.