The Alliance for Clinical Trials in Oncology is conducting a Phase III clinical trial of enzalutamide (Xtandi®) with or without abiraterone acetate (Zytiga®) and prednisone in men with hormone-refractory, metastatic prostate cancer with the hope of improving overall survival. Details of this trial can be found at the U.S. National Institutes of Health (NIH) clinical trials website, ClinicalTrials.gov. Enzalutamide works by disrupting a tumor cells’ ability to use testosterone by blocking the cell’s testosterone receptors and prevents the production of androgens within the cell itself. Zytiga® inhibits two distinct steps in the production of testosterone from cholesterol even in tumor cells by blocking a cell membrane enzyme called CYP17A1. Both drugs have been approved by the Food and Drug Administration for treatment of men with metastatic, hormone-refractory prostate cancer. For further information on these two agents, see the January 3rd, 2012 website blog.