VE-822 is a potent and selective inhibitor of the ataxia telangiectasia and Rad3-related (ATR) kinase, a key protein in the DNA damage response pathway. It is primarily used in cancer research to enhance the effectiveness of DNA-damaging agents such as chemotherapy and radiation. By inhibiting ATR, VE-822 prevents cancer cells from repairing DNA damage, leading to increased cell death, especially in tumors with defective DNA repair mechanisms. It shows promising synergistic effects when combined with agents like cisplatin or ionizing radiation, making it a valuable tool in developing targeted cancer therapies. Its application is particularly explored in preclinical studies involving solid tumors and cancers with high replication stress.