Two new blood tests that detect a variant of the androgen receptor — a protein that binds male hormones called androgens — may help to predict those advanced prostate cancer patients who would not benefit from anti-androgen therapies, new research suggests. The tests, which are called “liquid biopsies,” may help guide care toward more effective treatments. The research, “The PROPHECY trial: Multicenter prospective trial of circulating tumor cell (CTC) AR-V7 detection in men with mCRPC receiving abiraterone (A) or enzalutamide (E),” was recently presented at the 2018 American Society of Clinical Oncology (ASCO) annual meeting in Chicago. A variation of the androgen receptor, called AR-V7, has been linked to poor responses to drugs like Zytiga (enzalutamide) and Xtandi (abiraterone) in patients with castration-resistant prostate cancer. This happens because the medicines target a domain of the receptor that is missing in the AR-V7 version. (Castration resistant means the disease progresses despite androgen depletion therapy.) Researchers have developed tests that detect AR-V7 in tumor circulating cells — cells that shed from the tumor or metastasis into circulation – but whether these could be used to predict the effectiveness of Zytiga and Xtandi in metastatic castration-resistant prostate cancer is unclear.