XL844

XL844 is a potent small molecule inhibitor of the checkpoint kinases Chk1 and Chk2 (serine/threonine-protein kinase Chk1 and serine/threonine-protein kinase Chk2). These kinases are key regulators of cell cycle arrest in response to DNA damage. By inhibiting these targets, XL844 disrupts DNA repair mechanisms and can sensitize cancer cells to DNA-damaging agents such as radiation or chemotherapy. Preclinical studies have shown that XL844 enhances radiosensitivity in human cancer cells by promoting mitotic catastrophe and inhibiting DNA repair. The drug was initially developed by Exelixis for the treatment of solid tumors and hematologic malignancies but development was discontinued after early-phase clinical trials[1][2][3][5].