CCR8 (C-C motif chemokine receptor 8) is a chemokine receptor that plays a significant role in immune cell trafficking and is highly expressed on regulatory T cells (Tregs) in the tumor microenvironment. In the context of cancer, CCR8 is specifically highly expressed on Tregs within the tumor tissue, but is minimally expressed in peripheral blood and normal tissues, making it a specific biomarker for Tregs at the tumor site. Its signaling pathway is involved in the regulation of various solid tumors, such as gastric cancer, breast cancer, and colorectal cancer, among others. Therefore, CCR8 is considered a highly potential target for tumor immunotherapy.