CD274 and cancer: In microsatellite high instability gastric cancer, the number of frameshift mutations in BRD3 is negatively correlated with CD274 expression.48 Apart from CD274, BETs also directly promote the expression of IDO1, an immune checkpoint that mediates metabolic immune escape in cancer through the production of L-kynurenine.126 Collectively, the evasion of immune surveillance by BETs covers multiple immunosuppressive mechanisms.