Riviciclib is a potent inhibitor of cyclin-dependent kinase (CDK)(CDK9-cyclinT1, CDK4-cyclin D1, and CDK1-cyclinB with IC50s of 20 nM, 63 nM, and 79 nM, respectively),with antitumor activity on cisplatin-resistant cells.
CDK4 6-IN-5 is a highly effective inhibitor of CDK4 and CDK6, with Ki values of 0.2 and 4.4 nM for CDK4 Cyclin D1 and CDK6 CyclinD3, respectively (WO2019207463A1, example A93).