The cyclin‐dependent kinase inhibitor AT7519 is a human RORγt agonist

Abstract AT7519, which inhibits multiple cyclin‐dependent kinases, has been extensively investigated in various types of cancer cells. Previous studies have demonstrated the ability of this molecule to suppress the expression of the nuclear receptor retinoic acid–related orphan receptor gamma (RORγ) and several genes involved in hepatocellular carcinoma progression. In this study, we identified a distinct agonistic effect of AT7519 on RORγt, an isoform expressed by various immune cells, including T helper 17 lymphocytes. These immune cells play pivotal roles in shaping the tumor microenvironment and promoting the anticancer response of the immune system. After exposure to AT7519 during differentiation, primary human CD4 + T cells presented increased expression of IL17A/F , IFNG and GZMB and decreased expression of PDCD1 and CTLA4 . These findings elucidate a previously unrecognized facet of AT7519 activity and suggest the potential incorporation of this molecule into immune therapies to augment the effectiveness of diverse anticancer strategies involving anti–programmed cell death protein 1 (anti–PD‐1) and anti–cytotoxic T‐lymphocyte antigen 4 (anti– CTLA4 ) regimens.