AZ20 is primarily used in research settings as a selective inhibitor of the ATR (ataxia telangiectasia and Rad3-related) kinase, a key protein involved in the DNA damage response pathway. Its main application lies in oncology research, where it helps scientists study mechanisms of DNA repair and cell cycle regulation. By inhibiting ATR, AZ20 enhances the sensitivity of cancer cells to DNA-damaging agents such as chemotherapy and radiation, making it a valuable tool for exploring combination therapies. It is also used to investigate synthetic lethality, particularly in cancers with defects in other DNA repair pathways like those involving BRCA mutations. Due to its role in disrupting cancer cell survival under replication stress, AZ20 supports the development of targeted anti-cancer treatments and helps validate ATR as a therapeutic target.