6. To assess the clinical efficacy and tolerability of sipuleucel -T plus CYT107 compared with sipuleucel -T alone Adverse events will be graded and reported using the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events (CTCAE) Version 4.0. Clinical efficacy will be assess differences in (1) overall survival, (2) PSA kinetics (3) progression free survival and, (4) circulating tumor cells (CTC). Progression free survival will be assessed by RECIST criteria for measureable disease by bone scans and radiographic criteria for non -measurable bony metastasis.