Sipuleucel-T and Low-protein Diet in Patients With Metastatic Castrate-resistant Prostate Cancer

Primary Objective To assess the feasibility of low-protein diet intervention in patients with metastatic CRPC receiving immunotherapy with sipuleucel-T. Change in blood urea nitrogen (BUN) and urine urea nitrogen (UUN) from baseline to 6 weeks will be measured to assess adherence of following the diet intervention. The expected changes (mean, standard deviation) in BUN are 5.5 ± 2.6 mg/dL with 10% protein diet arm and 2.5 ± 2.6 mg/dL with 20% protein diet arm (please see section 12.5.7). Secondary Objectives 1. To assess whether low-protein diet intervention augments the immune response to sipuleucel-T in men with metastatic CRPC. 2. To assess the safety and tolerability of the combination of sipuleucel-T and low-protein diet intervention. 3. To obtain preliminary evidence of clinical efficacy of the combination of sipuleucel-T and low-protein diet compared to sipuleucel-T and control-diet, including objective response rate (partial + complete response), progression-free survival (PFS) and overall survival (OS), and changes in prostate-specific antigen (PSA).