CPI-455 is a specific KDM5 inhibitor, elevating global levels of H3K4 trimethylation (H3K4me3) and decreased the number of DTPs in multiple cancer cell line models treated with standard chemotherapy or targeted agents.
CPI-455 has improved potency against KDM5A while demonstrating ~200-fold selectivity for KDM5A over KDM4C. CPI-455 inhibits KDM5A, KDM5B and KDM5C to similar extents but showed substantially weaker potency toward KDM4C and KDM7B (~200- and 770-fold, respectively) and no measurable inhibition of KDM2B, KDM3B or KDM6A. CPI-455-mediated KDM5 inhibition results in a dose-dependent increase in global H3K4me3 in HeLa cells. CPI-455 specifically alters H3K4 methylation in cells and binds at the demethylase active site.