Immune Checkpoint Inhibitors (ICIs)—Ipilimumab are monoclonal antibodies targeting cytotoxic T-lymphocyte antigen 4 (CTLA-4), belonging to a class of immune checkpoint inhibitors (ICIs) used in cancer therapy for conditions such as metastatic melanoma, ovarian cancer, renal cell carcinoma, and prostate cancer. This evidence concerns the gene CTLA4 and prostate cancer.