CDK4 6-IN-3 is a brain-penetrant CDK4CDK6 inhibitor (Kis: <0.3 nM and 2.2 nM) used for the treatment of glioblastoma. It inhibits CDK1 with a Ki of 110 nM.
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 Cyclin D3, respectively (WO2019207463A1, example A93).
PD 0332991, an unsymmetrical indolocarbazole compound, is cell-permeable and exhibits antiproliferative effects by functioning as a potent, selective, reversible, and ATP-competitive inhibitor of Cdk4 D1 (IC 50 = 76 nM). Although it can inhibit other Cdks, such as Cdk2 E and Cdk1 B, effectiveness requires higher concentrations (IC 50 = 520 nM and 2.1 µM, respectively) and demonstrates minimal activity against CaMKII, PKA, or GSK-3β (IC 50 ≥ 12.4 µM). PD 0332991 efficiently inhibits tumor cell growth in HCT-116 and NCI-H460 cell lines with an IC 50 < 3.0 µM, primarily through blocking Rb phosphorylation and inducing G1 cell cycle arrest.
CDK4 6-IN-7, a highly potent and selective orally active inhibitor of CDK4 6, demonstrates impressive inhibition activity with IC50 values of 1.58 nM and 4.09 nM respectively. This compound is particularly valuable for breast cancer research [1].