AR and prostate cancer: CTC enumeration has been shown to be prognostic for OS in prostate cancer using Cell Search platform.16-18 The PROPHECY trial demonstrated that AR-V7 expression, either by gene expression and protein analysis, is prognostic for PFS and OS with ARSI treatment independent of enumeration.26 It is unknown if the number of CTCs present in each sample may affect the detection or level of gene expression for the genes in this panel.