A Cdk12 and Cdk13 inhibitor, binds to Cdk12 and Cdk13 (Kds = 98 and 4.9 nM, respectively), inhibits Cdk12- and Cdk13-dependent phosphorylation of RNA polymerase II in MDA-MB-231 cells (EC50 = 105.5 nM), inhibits the proliferation of MDA-MB-231, MDA-MB-468, Hs 578T, and MDA-MB-436 breast cancer cells (EC50s = 15.5, 22.1, 19.9, and 24.9 nM, respectively), induces the DNA damage response and apoptosis in MDA-MB-231 from 30-90 nM, reduces tumor volume and decreases the number of mice with tumors greater than 1,000 mm3 in a PDX model of breast cancer at 20 mg/kg
