CCR8 and melanoma: Preclinical studies in mice modelling colon (BC38, CT26), melanoma (B16F10), breast (EMT6) and urothelial (MB49) cancer revealed that tumor Treg cells expressed high levels of CCR8 whose targeting in monotherapies with mouse CCR8-specific antibodies resulted in significant inhibition of tumor growth, equivalent to what has been seen with anti-PD-1 blocking antibodies [55,56,57,58,59].