AZD-5991 is primarily investigated for its potential in cancer therapy, particularly in targeting hematologic malignancies. It functions as a selective inhibitor of MCL-1, a protein that plays a crucial role in the survival of cancer cells by preventing apoptosis. By inhibiting MCL-1, AZD-5991 promotes programmed cell death in cancer cells, making it a promising candidate for treating cancers that are dependent on MCL-1 for survival, such as certain types of leukemia and lymphoma. Its application is currently in the research and development phase, with studies focusing on its efficacy, safety, and potential use in combination with other anticancer agents to enhance therapeutic outcomes.