 Patients with metastatic, asymptomatic or minimally symptomatic CRPC that has progressed despite androgen deprivation therapy will be eligible for the study. After informed consent eligible patients will be scheduled to receive sipuleucel-T three infusions two weeks apart with normal-protein diet vs. low-protein diet. Each cycle will be every 14 days. Diet intervention will commence 1 week prior to the first apheresis Day -7 and will continue until 10 days after the last infusion of sipuleucel-T Day 42 Fig. 2. 