Presence of CD133‐positive circulating tumor cells predicts worse progression‐free survival in patients with metastatic castration‐sensitive prostate cancer

Objective To investigate the clinical significance of the expression of the stemness marker CD133 in circulating tumor cells of newly diagnosed metastatic castration‐sensitive prostate cancer patients. Methods For this study, 104 metastatic castration‐sensitive prostate cancer patients treated at the Fudan University Shanghai Cancer Center from September 2015 to February 2017 were considered. After enrollment, the patients received androgen deprivation therapy (bicalutamide + goserelin). Circulating tumor cells were isolated and identified using the CanPatrol system, which can identify not only traditional epithelial markers but also mesenchymal markers in cells that have undergone epithelial mesenchymal transition. CD133 was used to characterize the circulating tumor cells. The primary endpoint of this research was to evaluate progression to castration resistance. Results Among the 104 patients enrolled, 89 patients were circulating tumor cell positive at baseline, and the median circulating tumor cell count was four. The median follow‐up was 24 months, and at the end of follow‐up, the proportion of patients who progressed to castration‐resistant prostate cancer in the CTC+CD133+ group was 93.3%, which was significantly higher than that of the circulating tumor cell negative group (73.3%) and the CTC+CD133− group (75.0%), with P = 0.043. After follow‐up, progression‐free survival for CTC+CD133+, CTC+CD133−, and circulating tumor cell patients was 10.0, 13.0, and 14.0 months, respectively, with P = 0.022. Univariate and multivariate analyses also confirmed that the characterization of circulating tumor cells using CD133 can independently predict progression‐free survival in metastatic castration‐sensitive prostate cancer patients after receiving androgen deprivation therapy (P = 0.042; hazard ratio 1.396). Conclusion Baseline CTC+CD133+ was a poor independent prognostic factor for metastatic castration‐sensitive prostate cancer patients to progress to castration‐resistant prostate cancer after receiving androgen deprivation therapy.