Abstract 3382: Detection of CTCs using a micro-channel combined fluid dynamics and electrophoresis in colorectal cancer

Abstract

Abstract Background: Circulating tumor cells (CTCs) are tumor cells that can be isolated from peripheral blood. Investigation of CTCs might allow comprehensive studies at the DNA, RNA, and protein. However, fewer CTCs generally can be collected from patients with colorectal cancer, limiting the possibility of clinical applications of CTC analysis despite the development of many different methods. We have developed a micro-channel device that integrates hydrodynamic filtration (HDF) capable of size separation and dielectrophoresis (DEP) capable of electrical property separation, using peripheral blood from colorectal cancer patients. Method: A separation test was performed using a whole peripheral blood sample obtained from colorectal cancer patients with KRASmutation in the tumor tissue. The sample blood was diluted 2-fold with PBS, and red blood cells and plasma were removed using HDF. After that, Leukocytes and CTCs were separated in the same channel by DEP. DNA was extracted from CTCs (port 1) and leucocyte fraction (port 2), and KRAS mutations were detected using droplet digital PCR. In order to evaluate the separated fractions, microwell slide was used for evaluation by nuclear staining, CD45 and EpCAM antibody staining. Results: 52 colorectal cancer patients were participated. The median age of patients was 71 years, 38 (73%) were male. Twenty-eight (53.9%) had colon cancers. Four stage III and 48 stage IV patients were included. The quality of DNA extracted from all patients were suitable for molecular genetic analysis. The DNA concentration of port 1 was significantly lower than that of port 2 (371 ng/mL vs 36667 ng/mL, P<0.001). Using droplet digital PCR, KRAS mutations were detected in the port 1 of 8 (15.4%) patients and in port 2 of 15 (28.8%) patients. In 35.5% of patients, KRAS mutations were detected in either port 1 or port 2. Conclusion: This device does not require pretreatment and is easy to extract CTCs. Since CTCs are contaminated with the leukocyte fraction, it is necessary to improve the accuracy of CTCs collection by adjusting the conditions of DEP. Citation Format: Ryo Ohta, Takeshi Yamada, Nobuhiko Taniai, Hiroshi Yoshida. Detection of CTCs using a micro-channel combined fluid dynamics and electrophoresis in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3382.