Birinapant is a SMAC (synthetic small molecule and peptidomimetic of second mitochondrial-derived activator of caspases) mimetic and IAP (Inhibitor of Apoptosis Protein) antagonist with potential antineoplastic activity. Birinapant binds to and inhibits the activity of IAPs, such as X chromosome-linked IAP (XIAP) and cellular IAPs 1 and 2. Since IAPs shield cancer cells from the apoptosis process, this agent may restore and promote the induction of apoptosis through apoptotic signaling pathways in cancer cells.