Detection and Phenotyping of Circulating Tumor Cells in High-Risk Localized Prostate Cancer

Circulating tumor cells (CTCs) have established prognostic value in the setting of metastatic castration-resistant prostate cancer. However, their utility in the setting of localized prostate cancer is largely unknown. In the current study, a novel method was used to quantify and characterize CTCs in patients with high-risk localized prostate cancer (HRLPC). Background: In this study, we aimed to determine the feasibility of identifying CTCs in patients with HRLPC, using a modified isolation procedure using the Cell Search (Veridex) platform, and to assess the expression of stem cell and epithelial-mesenchymal transition (EMT) markers on the CTCs. Patients and Methods: Thirty-five patients with HRLPC who had chosen prostatectomy for definitive management were prospectively identified. After obtaining consent, four 30-mL blood draws were performed, 2 before surgery and 2 after surgery. The CTC-containing fraction was Ficoll-purified and transferred to a Cell Save (Veridex) tube containing dilution buffer before standard enumeration using the Cell Search system. Loss of E-cadherin expression, a marker of EMT, and CD133, a putative prostate cancer stem cell marker, were characterized using the open channel of the Cell Search platform. CTC fragments were also enumerated: Results: Using the modified methodology, CTCs were detectable in 49% of patients before surgery. Although no correlation between CTC count and biochemical recurrence (BR) was observed, the percentages of CD133 and E-cadherin positive CTC fragments were associated with BR at 1 year. Conclusion: Our results suggest that further research into the development of CTCs as prognostic biomarkers in HRLPC is warranted.