Abstract 3474: Comparison of CTC capture efficiency of the CellCollector™ technology versus CellSearch® in prostate cancer patients at multiple time points
Authors: Theil Gerit , Haubold Kathrin , Fornara Paolo , Stresemann Antje , Schmitz Arndt , Krahn Thomas , Lücke Klaus 
Published: May 2015

Abstract
Castration-Resistant Prostate Cancer (CRPC) is the second most common cancer cause of cancer-related death in men. Since most prostate cancer patients have a biopsy performed only at the time of diagnosis, representative tumor tissue sample giving real time information about the disease status is generally missing. The detection of circulating tumor cells (CTCs) in the blood of patients with CRPC might therefore, in addition to their prognostic value, serve as liquid biopsy, complementing or replacing prostate-specific antigen (PSA) determination in predicting and monitoring the response to different therapies. However, capturing these rare cells from whole blood is still a major challenge that needs significant improvement. Here we present the results of a comparison study, in which we compared the CellCollector™, a unique in vivo approach for the isolation of CTCs, with the CellSearch® system, the current standard.
The study included 25 prostate cancer patients (15 with localized and 10 with metastasized prostate cancer (PCa-l and PCa-m)) and 29 subjects in the control group (24 men with benign prostate hypertrophy (BPH) and 5 women). At multiple time points of treatment, CTCs were enumerated (PCa-l: 42 applications; PCa-m: 29 applications). The CellCollector™, a medical wire coated with epithelial cell adhesion molecule (EpCAM) antibodies, was inserted in the cubital vein and incubated for 30 minutes. The captured CTCs were identified by immunofluorescence staining using cytokeratin (CK) and Hoechst positive as well as CD45 negative as criteria. For the CellSearch® measurements, a blood draw of 7.5 ml blood was performed. We found in 77.5 % (55/71) applications (PCa-l: 55.2 % (16/29); PCa-m: 88.1 % (37/42)) the cancer patient to be positive for CTCs using the CellCollector™. In contrast the CellSearch® system resulted only in 42.2 % (30/71) in the detection of CTCs (PCa-l: 17.2 % (5/29); PCa-m: 61.9 % (26/42)). The control groups showed in rare cases very low numbers of CK positive cells. In addition we found a correlation of the CTC levels detected by the CellCollector™ and the CellSearch® with the PSA level during treatment. In summary, our comparison study shows an improved sensitivity of the CellCollector™ compared to the current standard regarding the isolation of CTCs from prostate cancer patients and gives new insights in the value of CTCs for the monitoring of prostate cancer treatment.
Citation Format: Gerit Theil, Kathrin Haubold, Paolo Fornara, Antje Stresemann, Arndt Schmitz, Thomas Krahn, Klaus Lücke. Comparison of CTC capture efficiency of the CellCollector™ technology versus CellSearch® in prostate cancer patients at multiple time points. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3474. doi:10.1158/1538-7445.AM2014-3474