This can be due to multiple factors, including the immunosuppressive transforming growth factor-β–rich (TGF-β–rich) tumor microenvironment (TME) of prostate cancer, dysfunctional T cells, tumor loss of major histocompatibility complex (MHC) class I, and a dearth of tumor-associated antigens (3, 4). This evidence concerns the gene TGFB1 and prostate cancer.