Concordantly, a study of the role of Treg cells (reviewed in [80,81]) in canine bladder cancer showed that CCR4 blockade-induced Treg depletion can inhibit tumor growth [82], and studies of immune checkpoint molecules (reviewed in [83,84]) found that high-grade bladder cancer expresses higher levels of PD-1 and PD-L1 compared to low-grade bladder cancer [85] and the inhibition of CTLA-4 alone or in combination with the inhibition of PD-1 prevents the growth of mouse bladder cancer [86]. This evidence concerns the gene CCR4 and urinary bladder cancer.