circCCAR1 is taken up by CD8+ T cells causing enhanced PD‐1 expression and results 121 in CD8+ T cell exhaustion, thereby rendering the cells resistant to nivolumab (Opdivo).[92] Increased expression of the m6A reader YTHDF1 is implicated in tumor immunity against immune checkpoint inhibitors in melanoma and CRC. This evidence concerns the gene CD8A and colorectal carcinoma.