CDK12-IN-6, a pyrazolotriazine compound, is a powerful inhibitor of CDK12. Its inhibitory activity is significant with an IC50 value of 1.19 μM when tested at high ATP concentration (2 mM). Notably, CDK12-IN-6 does not exhibit any inhibitory effect on CDK2 Cyclin E (IC50 >20 μM) and CDK9 Cyclin T1 (IC50 >20 μM) when tested under the same high ATP conditions (2 mM) (WO2021116178A1).
CDK12-IN-4, a pyrazolotriazine compound, exhibits potent inhibition of CDK12 by achieving an IC50 value of 0.641 μM, utilizing high ATP levels (2 mM). Notably, CDK12-IN-4 does not impact CDK2 Cyclin E (IC50 > 20 μM) or CDK9 Cyclin T1 (IC50 > 20 μM) under the influence of high ATP (2 mM) levels (WO2021116178A1).
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.