KU-60019 is a potent and selective inhibitor of the ATM (ataxia telangiectasia mutated) kinase, a key protein involved in the DNA damage response pathway. It is primarily used in research settings to study DNA repair mechanisms and cellular responses to genotoxic stress. By inhibiting ATM, KU-60019 enhances the sensitivity of cancer cells to ionizing radiation and certain chemotherapeutic agents, making it a valuable tool in oncology research, particularly in exploring strategies for radiosensitization and chemosensitization. It has shown promise in preclinical studies involving cancers with defects in DNA repair pathways, where suppression of ATM activity can lead to increased cancer cell death. Its application is mainly focused on understanding tumor resistance mechanisms and developing combination therapies that improve the efficacy of existing cancer treatments.