Abstract 2751: Automatic DNA extraction system can improve the EGFR point mutation detection rate of liquid biopsy

The usefulness of liquid biopsy to detect mutations from cancer patients has been well recognized today. However, because the mutation detection rates from plasma DNA were relatively lower than those of tissue re-biopsy, its clinical utility has not been confirmed yet. As previously we reported, we have developed fully automatic high-sensitive point mutation detecting system named mutation-biased PCR and quenched probe (MBP-QP) system for liquid biopsy. Recently, the importance of pre-analytical procedures for plasma DNA anazysis has been highlighted. In this study, we examined whether the automatic DNA extraction system can improve the mutation detection rate in our MBP-QP system. Sixty-one plasma samples were obtained from advanced non-small cell lung cancer patients, and plasma DNA extraction was performed from 200μl plasma by manually (200-M), and 200μl (200-A), 1000μl (1000-A) plasma by automatically. We used silica membrane spin column system for manual DNA extraction, and magnet beads system for automatic DNA extraction procedure. The median DNA concentrations quantified by quantitative real-time PCR of 200-M, 200-A, 1000-A were 4.92, 6.00, 20.1 ng/mL plasma, respectively. In terms of the epidermal growth factor receptor (EGFR) L858R point mutation detection, the sensitivity of 200-M, 200-A, 1000-A were 36.6%, 58.5%, 77.5%, that of the specificity were 93.3%, 100%, 96.7%, and the concordance rates were 60.6%, 76.1%, 85.7%, respectively. The size distribution of automatically extracted plasma DNA represented two peaks characteristics at 170 bp and 5 kb. In this study, we indicate the automatic DNA extraction can improve mutation detection rates in plasma DNA. Citation Format: Chiho Nakashima, Akemi Sato, Tomonori Abe, Tomomi Nakamura, Kazutoshi Komiya, Eisaburo Sueoka, Shinya Kimura, Naoko Sueoka-Aragane, Junichi Kato, Mitsuharu Hirai. Automatic DNA extraction system can improve the EGFR point mutation detection rate of liquid biopsy [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 2751. doi:10.1158/1538-7445.AM2017-2751