S63845 is a potent and selective inhibitor of the anti-apoptotic protein MCL-1, which plays a critical role in the survival of cancer cells. Its primary application is in the field of oncology, particularly in the development of targeted cancer therapies. By inhibiting MCL-1, S63845 can induce apoptosis in cancer cells that rely on this protein for survival, making it a promising candidate for treating various types of cancers, including hematological malignancies and solid tumors. It is often studied in combination with other anticancer agents to enhance therapeutic efficacy and overcome drug resistance. Additionally, S63845 is used in preclinical research to better understand the role of MCL-1 in cancer biology and to identify potential biomarkers for patient stratification in clinical trials.