Abstract A089: Detection of circulating tumor cells (CTC) by microfluidic technology based on lateral magnetophoresis and CTC-based multigene profiling analysis in prostate cancer patient
Authors: Cho Hyungseok , Han Ki-Ho , Chung Jae-Seung 
Published: September 2020

Introduction By using the circulating tumor cells (CTCs), we can get useful genomic information that enable monitoring of patient’s prognosis or selecting of appropriate treatment over time by repeat biopsy. Despite their usefulness, current CTC separation techniques are limited in terms of their ability to separate high recovery and purity CTCs from peripheral blood. We aimed to separate CTCs from prostate cancer patients using microfluidic technique that based on disposable lateral magnetophoretic microseparator (named ‘assembly-disposable CTC-μChip’) and assess the gene expression that are specific for prostate cancer using mRNA from isolated CTCs measured by droplet digital PCR (ddPCR) method. Patients and Methods Total 54 samples of 45 patients who underwent treatment for prostate cancer between 06/2018 and 03/2019 were prospectively enrolled for CTC collection. Approximately 10 ml of whole blood was drawn from prostate cancer patients; Group A, 12 samples (22.2%) with localized stage II-III cancer, Group B, 5 samples (9.3%) with stage IV, Group C, 6 samples (11.1%) with metastatic hormone-sensitive prostate cancer (mHSPC) and Group D, 31 samples (57.4%) with metastatic castration-resistant prostate cancer (mCRPC). CTCs were positively isolated by using Assembly-disposable CTC-μChip. CTCs from 5 mL of blood were used for counting to identify isolated CTC numbers with immunofluorescence detection procedure. CTCs from the remaining 5 mL of blood were used for gene analysis by ddPCR. For the gene expression analysis, selected 13 patient’s samples were examined for 6 prostate cancer-related genes, such as androgen receptor (AR), androgen receptor splice variant 7 (AR-V7), prostate specific membrane antigen (PSMA), prostate specific antigen (PSA), cytokeratin-19 (CK-19) and epithelial cell adhesion molecule (EpCAM). Results We identified the average of 3, 16, 14 and 26 CTCs per 1ml in group A, B, C and D, respectively (P&lt; 0.01). Background contaminated white blood cells are indispensably isolated with CTCs that counted on average 2245.4 cells, thereby CTC purity rate was 2.56 %. The gene positive rate of AR, AR-V7, PSA, PSMA, KRT-19, and EpCAM were 2.3 % (12/13), 15.4 % (2/13), 38.5 % (5/13), 69.2 % (9/13), and 100 % (13/13), respectively. Especially, the copy number of PSA, PSAM and CK-19 increased in proportion as the clinical stage increased. All samples showed EpCAM positive, whereas AR-V7 was rare events, with only in 2 out 5 patients positive with mCRPC, but not in other stages. Conclusions This study demonstrates that assembly-disposable CTC-μChip is a suitable for CTC isolation from prostate cancer patients. Our data also showed that CTC-based multigene profiling can be analyzed using ddPCR, making it a clinically relevant biomarker. Interrogating tumor expression via CTCs isolation may allow for enhancing precision-based treatment.

Citation Format: Hyungseok Cho, Ki-Ho Han, Jae-Seung Chung. Detection of circulating tumor cells (CTC) by microfluidic technology based on lateral magnetophoresis and CTC-based multigene profiling analysis in prostate cancer patient [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr A089.