CCT-251921 is primarily used in research and development, particularly in the field of oncology. It serves as a potent and selective inhibitor of the protein kinase WEE1, which plays a critical role in regulating the cell cycle. By inhibiting WEE1, CCT-251921 disrupts the DNA damage response in cancer cells, making them more susceptible to DNA-damaging agents or radiation therapy. This mechanism is being explored to enhance the efficacy of existing cancer treatments, especially in cases where tumors have developed resistance to conventional therapies. Additionally, it is utilized in preclinical studies to better understand the role of WEE1 in cell cycle control and its potential as a therapeutic target in various cancers.