Adavosertib (AZD1775) is a small molecule inhibitor targeting the Wee1 kinase, a key regulator of the G2/M cell cycle checkpoint. It is a potent and selective ATP-competitive inhibitor with a molecular formula of C₂₃H₂₃N₅O₃S and a molecular weight of 449.53 g/mol. The compound is a key component in the development of targeted cancer therapies. Its primary application is as an investigational anti-cancer agent (API). By inhibiting Wee1, adavosertib abrogates the DNA damage checkpoint, forcing cancer cells with compromised DNA repair mechanisms (e.g., p53-deficient cells) into premature mitosis, leading to mitotic catastrophe and cell death. It is being evaluated in clinical trials, both as a monotherapy and in combination with DNA-damaging chemotherapeutics or radiation, for various solid tumors including ovarian, breast, and glioblastoma. Furthermore, adavosertib serves as a critical chemical probe and a validated target protein ligand in chemical biology and drug discovery. It is specifically utilized in the field of targeted protein degradation (TPD) as a high-quality warhead for the development of proteolysis-targeting chimeras (PROTACs) aimed at degrading Wee1 kinase, offering a potential alternative therapeutic modality to inhibition.