Abstract 1064: Evaluation of ex vivo and in vivo biomarkers in different stages of prostatic cancer
Authors: Theil Gerit , Schietinger Carlotta 
Published: August 2018

Abstract
Clinical factors such as PSA and pathological factors such as Gleason grading and TNM staging are well known as prognostic markers in prostatic cancer. These tools are often insufficient for an accurate risk stratification of each patient. It is therefore essential for therapy monitoring to provide qualifed surrogate biomarkers for survival, the ability to characterize the changing biology of the tumor at the patients level, and qualified predictive biomarkers which can guide treatment selection based profiles derived from characterization. The detection of circulating tumor cells in the blood of patients with prostate cancer might therefore, in addition to their prognostic value, serve as liquid biopsy, complementing or replacing PSA determination in predicting and monitoring the response to different therapies. Here, we present data of a pilot study comparing different biomarkers. CTCs are the in vivo biomarker isolated by the CellCollector, which enables for the vivo isolation of CTCs from the peripheral blood. The multiplex assay was used for the determination of the ex vivo biomarkers the following analytes HER-2, IL-6, IL-8, Leptin, uPA and uPAR were measured in serum samples. We enrolled 34 PCa patients, 21 with localized (PCa-l) and 13 with metastasized prostate cancer (PCa-m). At multiple time points of treatment, CTCs and a Luminex assay were determined. The CellCollector was inserted in a cubital vein for 30 minutes. The interaction of target CTCs with the CellCollector was mediated by an antibody to the epithelial cell adhesion molecule The Luminex Assay is a bead-based principle which requires a small sample volume (≤ 50 µl) for the determination. The number of in vivo captured CTC in PCa-m patients varied from 0-820, a mean of 17.9 CTCs, median 5 and in PCa-l patients from 0-8 CTCs, a mean of 1.6 CTCs, median 0. The CTC count, the PSA level and the Gleason grading were significant different in our two groups. Apart from the leptin level showed levels of HER-2, IL-6, IL 8, uPA, uPAR no significant differences appeared in our groups. Interestingly, significant correlations between PSA and uPAR; HER-2 ; IL-8 ; uPA r; Leptin; IL-6 r= in metastasized prostate cancer patients were demponstrated. Unfortunately, the CTC numbers showed and included no correlation between the ex vivo Biomarkers. The overall survival for metastasized patients with &lt; 5 CTCs was significant better than for patients with ≥ 5 CTCs. Some personalized marker profiles of the patients show a correlation between the different ex vivo Biomarker and in vivo biomarkers. The in vivo captured CTCs seem to be a useful prognostic marker because of the significant better survival of patients with &lt;5 CTCs. Although there was no general validity, single patient analyses showed several, partly significant correlations between CTC count, PSA level and ex-vivo parameters. So these markers could be useful in individual risk stratification and therapy option decision-making.
Citation Format: Gerit Theil, Carlotta Schietinger. Evaluation of ex vivo and in vivo biomarkers in different stages of prostatic cancer [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 1064.