LY2603618 is a selective inhibitor of checkpoint kinase 1 (CHK1), a key protein involved in the DNA damage response pathway. It is primarily investigated for its potential in cancer therapy, especially in combination with DNA-damaging agents such as chemotherapy or radiation. By inhibiting CHK1, LY2603618 prevents cancer cells from repairing DNA damage, leading to increased cell death and enhanced efficacy of cytotoxic treatments. This compound has shown promise in preclinical studies involving tumors with high replication stress or defects in other DNA repair pathways, such as those with p53 mutations. Its application is focused on improving outcomes in solid tumors and hematologic malignancies by exploiting synthetic lethality and overcoming treatment resistance.