Available at: http://www.bt.cdc.gov/agent/smallpox/vaccination/mgmt-adv-reactions.asp]. 4 BIOSPECIMEN COLLECTION 4.1 CORRELATIVE STUDIES FOR RESEARCH 4.1.1 Parameters of Immune Response (Refer to 4.1.2 Immunologic Assays for detail): IFN-gamma ELISPOT assay for PSA-specific T lymphocytes CD4 T Cell Proliferation Antibodies to PSA and other tumor antigens Leukocyte CD3, CD4, CD8 subsets; CD4:CD8 ratio will be drawn at baseline and each cycle while the patient remains on trial. Immunologic profiles will be investigated to evaluate whether enhanced thymopoiesis might be present during vaccine administration; these immunologic profiles are to include enumeration of recent thymic emigrants by quantification of T-cell subsets by multiparameter flow cytometry. 33 Short Title: Enzalutamide Vaccine in mCRPC Version Date: 03/29/2022 The results of the HIV antibody test need to be available before treatment to determine eligibility. HLA class I expression (HLA typing) with A2 subtyping (obtain any time prior to first vaccine).