Abstract 1578: NanoVelcro CTC Purification Systems for expressional analysis of circulating tumor cells from prostate cancer patients
Authors: Jan Yu Jen , Chen Jie-Fu , You Sungyong , Yoon Junhee , Yao Nu , Cheng Shirley , Freeman Michael R. , Tseng Hsian-Rong , Posadas Edwin M. 
Published: August 2018

Background: Circulating tumor cells (CTCs) are blood borne tumor cells shed from all present disease sites, including primary and metastatic tumors. Researchers have been exploring the use of CTCs to identify important transcriptomic features such as androgen receptor splicing variants in prostate cancer (PCa). Newer transcriptomic profiles such as the prostate cancer classification system (PCS) have been developed that may be useful clinically. Over the past decade, we have been developing the NanoVelcro CTC purification system which includes 3 different stimuli-responsive strategies (temperature-dependent, glycan-stimulated, click chemistry-mediated) to capture and release viable CTCs with intact RNA. The purified CTCs can then be subjected to transcriptomic analysis such as quantitative PCR (qPCR), Droplet Digital PCR (ddPCR) and NanoString's nCounter system. In this study, we benchmarked the efficiency of these platforms for purification of CTCs from blood specimens and the feasibility for detection of PCa-related RNA signatures from purified CTCs.

Methods: NanoVelcro CTC purification system is combined with qPCR and ddPCR platform to detect PCa-specific RNA targets such as full length AR (AR-FL), AR splicing variant 7 (AR-V7), KLK3 (prostate-specific antigen, PSA), FOLH1 (prostate-specific membrane antigen, PSMA), and long-noncoding RNA SChLAP1 (second chromosome locus associated with prostate-1) in purified CTCs from patients' blood samples. We also developed a modified PCS panel of 30 genes adapted to the nCounter platform and tested purified CTCs from PCa patient blood samples and performed differential expression analysis for PCa disease profiling.

Results: PCa-related RNA signals were detected in 16/17 CTC(+) PCa patients, including 3 of 4 non-metastatic patients. We also tested the gene expressions of the modified PCS panel using 32 patient blood samples. Upon performing clustering of samples based on the RNA signatures, we found the differential expression of CTC-target genes grouped patients in a manner which strongly related to drug response and clinical status.

Conclusions: With the evolution of our NanoVelcro CTC purification system, we have shown the capability of purifying CTCs with high efficiency, while retaining cell viability and molecular integrity, allowing for detection of PCa-specific RNA signatures from CTCs. Our non-invasive, blood-based assay will be useful for detecting and continuous monitoring molecular alterations related to disease evolvement, addressing an unmet need for prostate cancer clinical care.

Citation Format: Yu Jen Jan, Jie-Fu Chen, Sungyong You, Junhee Yoon, Nu Yao, Shirley Cheng, Michael R. Freeman, Hsian-Rong Tseng, Edwin M. Posadas. NanoVelcro CTC Purification Systems for expressional analysis of circulating tumor cells from prostate cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1578.