As summarized in Table 1, prostate cancer cells recruit various immunosuppressive populations—including Tregs, MDSCs, and TAMs—while also upregulating soluble factors such as indoleamine-2,3-dioxygenase (IDO) and transforming growth factor (TGF)-β, together creating a profoundly “cold” TME that limits robust antitumor immunity [25,31]. Here, TGFB1 is linked to prostate cancer.