CHIR-124

CHIR-124 is a quinolone-based inhibitor of Checkpoint kinase-1 (Chk1). It potently and selectively inhibits Chk1 in vitro with an IC₅₀ of 0.3 nM. It interacts synergistically with topoisomerase poisons (e.g., camptothecin) in inhibiting the growth of several p53-mutant solid tumor cell lines. CHIR-124 potentiates the growth inhibitory effects of irinotecan by abrogating the G2-M checkpoint and increasing tumor apoptosis in a breast cancer xenograft model.