Sipuleucel-T Combined With Bipolar Androgen Therapy in Men With mCRPC

The primary endpoint is the immune response to PA2024 as measured by ELISPOT by week 26. This immunological endpoint was chosen as the primary based on the data showing the Sipuleucel-T immune parameters correlating with overall survival from the pooled analysis phase III trials of Sipuleucel-T (Sheikh NA et al. Cancer Immunol Immunother 2013). Secondary endpoints include other immune parameters related to the Sipuleucel-T, including (1) APC cumulative activation (CD54 upregulation), (2) APC number and (3) total nucleated cells (TNC) count, which also have correlated with survival outcomes and clinical endpoints, and (4) T cell proliferation response to PA2024 and PAP, (5) ex vivo cytokine profile and (6) humoral response to PA2024 and PAP, clinical endpoints including: (7) PSA50 response rate (PSA50 RR), (8) objective response rate (ORR), (9) radiographic progression-free survival (rPFS), and (10) overall survival (OS), (11) safety and tolerability. We hypothesize that BAT potentiates the anti-tumor immune response and enhances clinical outcomes when given before and concurrently with Sipuleucel-T. Secondarily, we also hypothesize that the clinical activity of BAT will increase with concurrent Sipuleucel-T, as measured by PSA50 response rate and objective response rate compared to historical controls. Participants will start with testosterone injection every 4 weeks. The first dose of standard of care Sipuleucel-T will be prepared and infused after two doses of testosterone and will continue every 2 weeks for a total of 3 infusions at a standard schedule. The testosterone injection will continue once every 4 weeks until treatment discontinuation criteria are met. The participants will be assessed with HPE, and PSA every 4 weeks, and radiographic assessment per PCWG3 every 12 weeks. DEPO-Testosterone (testosterone cypionate) IM injection will continue until disease progression, unacceptable toxicity, or withdrawal of consent to treatment. In the event of suspected/radiographic disease progression, tumor biopsy may be performed as a standard of care to confirm progression.