In vitro activity: Atuveciclib (formerly known as BAY-1143572) is novel, potent, oral and highly selective PTEFb/CDK9 inhibitor. It inhibits CDK9/CycT1 with an IC50 of 13 nM and is more than 100-fold more selective for CDK9 over CDK2. It also inhibits GSK3 kinase with IC50 values of 45 nM and 87 nM for GSK3α and GSK3β respectively. Atuveciclib is currently in Phase I clinical trial. In comparison with BAY 1143572, BAY-1143572 S-Enantiomer reveals very similar in vitro properties, well within the limits of measurement accuracy; however, with multiple batches of BAY-1143572 S-Enantiomer there is a trend toward a slightly lower activity against CDK9 in the biochemical assay (IC50 CDK9/CycT1: 16 nM) and antiproliferative activity against HeLa cells (IC50: 1100 nM).

Kinase Assay: Atuveciclib (formerly known as BAY-1143572) is novel, potent, oral and highly selective PTEFb/CDK9 inhibitor. It inhibits CDK9/CycT1 with an IC50 of 13 nM and is more than 100-fold more selective for CDK9 over CDK2. It also inhibits GSK3 kinase with IC50 values of 45 nM and 87 nM for GSK3α and GSK3β respectively.

Cell Assay: BAY 1143572 demonstrates antiproliferative activity against HeLa cells (IC50 = 920 nM) and MOLM-13 cells (IC50 = 310 nM). It also demonstrates improved Caco-2 permeability and a decreased efflux ratio (PappA→B: 35 nm/s, ER: 6) relative to lead compound BAY‐958 (PappA→B: 22 nm/s, ER: 15).