SCH900776 S-isomer

SCH900776 is a potent, selective and orally bioavailable inhibitor of checkpoint kinase Chk1 (IC50 = 3 nM), highly selective against Chk2 (IC50 = 1500 nM) and cyclin-dependent kinase CDK2 (IC50 = 160 nM). SCH900776 exposure phenocopies short interfering RNA-mediated CHK1 ablation and interacts synergistically with DNA antimetabolite agents in vitro and in vivo to selectively induce dsDNA breaks and cell death in tumor cell backgrounds. Chk1 inhibitor SCH 900776 abrogates cytarabine-induced S-phase arrest and enhances cytarabine cytotoxicity in acute leukemia cell lines and leukemic blasts in vitro.