Vaccines may improve TTP in combination therapy. Preliminary data from an interim analysis of an ongoing trial of flutamide alone (n=17) vs. Flutamide + PSA-TRICOM (n=18) in patients with nonmetastatic CRPC (NCT00450463) suggest that adding vaccine to ADT + flutamide may delay disease progression. ([23]) 1.2.5.1 Enzalutamide does not Diminish Immune Cell Numbers or Function in Preclinical Models Enzalutamide has been evaluated preclinically by Dr. James Hodge of the Laboratory of Tumor Immunology and Biology (LTIB) at the NCI. The first objective was to determine the 16 Short Title: Enzalutamide Vaccine in mCRPC Version Date: 03/29/2022 appropriate dose to use in evaluation of the Male C57BL/6 mice. Doses at 1, 10, 50 and 100 mg/day were evaluated and the 10 mg/day dose was found to be most appropriate given that it achieved a serum concentration of 20 ug/ml, consistent with serum levels in humans. Therefore, that was the dose evaluated in Male C57BL/6 mice. (Figure 6A) It was confirmed that enzalutamide at 10 mg/day had a significant decrease in the weight of the genitourinary organs of Male C57BL/6 mice after 14 days of dosing, demonstrating the physiologic effects of enzalutamide at 10 mg/day dose level. (Figure 6B) Figure 6. Enzalutamide mediates a reduction in genitourinary (GU) weight. (A). Concentration of Enzalutamide in plasma of mice on Enzalutamide daily diet. Male C57BL/6 mice (n=3) were treated with Enzalutamide at different calculated target daily doses (0, 1, 10, 50, and 100mg) for 14 days. On day 15, blood was collected and Enzalutamide concentration in the plasma was determined. (B). Exposure to Enzalutamide causes reduction of GU weight. Male C57BL/6 mice (n=7) were not treated (open circles) or treated with Enzalutamide (closed circles) for 14 days. On day 15, mice were sacrificed and their GU and were harvested and weighed. All experiments were done three times with similar results.