Abstract 3782: Genetic analysis using a novel high-purity enrichment system for circulating tumor cells independent of epithelial cell antigen

Abstract

Abstract Background Genetic analysis of circulating tumor cells (CTCs) is useful as a liquid biopsy. However, there are 3 challenging issues in processing of CTC samples for clinical use of the analysis: [1] numerous residual blood cells in processed samples, [2] loss of CTCs that do not express epithelial markers, and [3] very laborious process. Here, we developed a novel system capable of overcoming all of these problems. Methods Our CTC analysis system is composed of 3 steps: [1] filtering of whole blood followed by immunostaining and magnetic labeling of cells trapped on the filter, [2] depletion of white blood cells (WBCs) in the cells recovered from the filter by magnetic separation, and [3] trapping the resultant cells at an observation chamber in a microfluidic enrichment device using dielectrophoresis, followed by recovering them as a concentrated sample after fluorescence microscope observation. SNV and CNV analysis was conducted using the collected concentrated sample, and the system performance was substantiated. Genetic mutations of the cells in the collected sample were detected by the Quenching Probe method. On the other hand for CNV analysis, cells in the collected concentrated sample were immobilized on slide glass and analysis of gene amplification conducted by FISH. Results With SNV analysis, our system successfully detected EGFR, KRAS or PIK3CA mutations of cancer cell lines spiked in 8 mL of whole blood (Table). The detection sensitivity of our method was 1 cell/mL, and both the cancer cells and their genetic mutations were detected within 9 hours of starting the processing of whole blood. Additionally, with CNV analysis, HER2 gene amplification was confirmed with cell lines spiked in 8 mL of blood. This detection result was obtained within 48 hours. Conclusion Our system would be useful for the analysis of gene mutations in a wide range of CTC types independent of certain epithelial antigens, such as CK and EpCAM, and can be used for various genetic analyses. Table Results of spiking test for SNV analysisSpiked cell linesExpected count[cells/8ml]No. of detected spiked cells [cells]No. of detected remained WBCs [cells]Detected genotypesNCI-H197512979EGFR L858RNCI-H16508225EGFR exon19 deletionSW6208648KRAS codon12, 13SNU-1124154KRAS codon12, 13MCF-777341PIK3CA G1633A Citation Format: Hidenori Takagi, Masahiro Kozuka, Hiroshi Ito, Soo Hyeon Kim, Mitsuharu Hirai, Teruo Fujii. Genetic analysis using a novel high-purity enrichment system for circulating tumor cells independent of epithelial cell antigen [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 3782. doi:10.1158/1538-7445.AM2017-3782