The androgen receptor (AR) is the primary driver of prostate cancer as it activates downstream signals for cell growth, invasion, and survival. Androgen deprivation therapy (ADT) is a frontline treatment for prostate cancer patients but most patients develop mechanisms of resistance to AR-targeted therapy and progress to a lethal state. It has recently been recognized that expression of AR splice variants is one of the key mechanisms conferring resistance to ADT. The goal of this project is to develop a sensitive and specific detection method to quantify simultaneously the expression of AR wild type (AR-wt) and splice variants in circulating tumor cells (CTCs) -isolated from PC patients’ peripheral blood- using multiplex RT-qPCR.