LCL161 is primarily used in cancer research as a smac mimetic that promotes apoptosis in tumor cells. It functions by inhibiting inhibitor of apoptosis proteins (IAPs), which are often overexpressed in various cancers and contribute to resistance against cell death. By blocking IAPs, LCL161 sensitizes cancer cells to apoptosis, especially when combined with other agents such as tumor necrosis factor-alpha (TNFα) or chemotherapy drugs. It has been investigated in clinical trials for its potential in treating solid tumors and hematologic malignancies. Its application is mainly in experimental and therapeutic development for oncology, particularly in strategies aimed at overcoming treatment resistance.