In this section, we reviewed immunotherapy for metastatic castration-resistant PCa (mCRPC), which is a promising area of research. Sipuleucel-T, a vaccine, showed some survival benefit but limited PSA decline. Other vaccines and immune checkpoint inhibitors are being tested with mixed results. CAR-T cell therapy, where T cells are engineered to target cancer cells, is also under investigation. More studies are needed to determine the best immunotherapies for PCa.