Evaluating changes in circulating tumor cell count in prostate cancer patients during androgen deprivation plus chemotherapy by using AxonDx enumeration device.

266Background: Circulating tumor cell (CTC) counts have clinical utility as a prognostic marker in cancer. For prostate cancer (PCa), CTC counts ≥5 CTC/7.5 ml using the FDA-approved CellSearch system convey a negative prognosis with respect to overall survival, but the significance of changes in CTC count during treatment is not fully understood. To determine whether longitudinal CTC counts can be used as a prognostic and/or predictive marker of clinical outcome in PCa patients undergoing androgen deprivation therapy (ADT) plus chemotherapy, we used the AxonDx nCyte non-enrichment-based CTC detection and enumeration system to evaluate CTC counts at baseline, during, and after therapy in 18 patients for up to 11 months. Methods: Whole blood was drawn from PCa patients on clinical trials for ADT plus chemotherapy at PSA evaluation (±radiographic reevaluation) into vacutainers containing K3-EDTA and processed within 6 hr. PBMC containing nucleated cells harvested from 6 ml of whole blood were fixed, permeabi...