Abstract 1761: A rapid and accurate nucleic acid amplification and detection method for KRAS mutation testing in colorectal cancer specimens

Abstract

Abstract Colorectal cancer (CRC) is one of the most common type of cancers both men and women in worldwide. Fortunately, overall death rates of CRC have been decreasing for the last two decades due to the improvement of screening test assays that detect early-stage cancer and pre-cancerous polyps. Nevertheless, the most common treatment for CRC is surgery, because it may completely eliminate the cancer region. In case of the cancer with systemic metastasis, chemotherapy is required before or after surgery for primary or metastatic lesions. Among the regimens for the chemotherapy, both monoclonal antibodies (Cetuximab and Pantitumumab) against the epidermal growth factor receptor have been shown to improve survival for only patients with lack of RAS mutations. Thus, the KRAS gene mutations (codons 12 and 13) in CRC patients have been extensively studied as a strong negative predictive biomarker to indicate whether a CRC patient responds to the treatment. Therefore, testing the KRAS mutational status of tumor samples is becoming an essential tool for managing patients with CRCs. Although a myriad of nucleic acid testing methods have been developed to analyze the mutation status in the key regions of the KRAS gene of CRC, several obstacles still remain related to low sensitivity, time consuming, and required large instruments including thermal cyclers. Here, we present a novel nucleic acid amplification and detection method for KRAS mutations (G12D and G13D) testing that enable rapid and accurate detection. This method is based on combination of isothermal DNA amplification method and bio-photonic silicon sensor that can be detected the mutations in a label-free and real-time manner. The proposed method can detect the mutant cell present at 1% in a mixture of wild type cells, while both PCR and sequencing can detect the mutations in a sample containing approximately 30% of mutant cells. We used 60 tissue samples from CRC patients (22 samples with G12D mutations, 23 samples with G13D mutation, and 15 samples with no mutation) to compare the clinical utility of three methods including PCR, Sanger sequencing and the proposed method. The proposed method with both G12D and G13D showed a value of 100% and 100% for sensitivity and specificity, respectively. One the other hand, the sensitivity and specificity of PCR (90.5% and 100%) and sequencing (95% and 100%) were lower than that of the proposed method. Therefore, the proposed method was found to be a rapid (< 30 min), highly sensitive and specific method for KRAS mutation testing. We believe that this rapid and accurate method will enable proper treatment for CRC patients. Note: This abstract was not presented at the meeting. Citation Format: Yong Shin, Choong Eun Jin, Seung-Seop Yeom, Seok-Byung Lim. A rapid and accurate nucleic acid amplification and detection method for KRAS mutation testing in colorectal cancer specimens [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1761. doi:10.1158/1538-7445.AM2017-1761