ABT-263 is primarily used in cancer research due to its ability to induce apoptosis in tumor cells. It functions as a potent inhibitor of Bcl-2 family proteins, which are often overexpressed in various cancers and contribute to resistance against cell death. By blocking these proteins, ABT-263 promotes the activation of pro-apoptotic factors, leading to programmed cell death in malignant cells. It has shown promising activity in hematological malignancies such as chronic lymphocytic leukemia, small lymphocytic lymphoma, and acute myeloid leukemia. Researchers use ABT-263 in preclinical studies to evaluate combination therapies, especially with agents like chemotherapy or targeted drugs, to enhance tumor cell killing and overcome treatment resistance. Due to its mechanism, ABT-263 is also explored in studies involving minimal residual disease and cancer stem cells, where evasion of apoptosis is a key survival strategy. Its application remains largely experimental, serving as a tool compound in oncology drug development and mechanistic studies.