Birinapant is a bivalent mimetic of the Diablo homolog known as second mitochondria-derived activator of caspase (Smac). It is an antagonist of cellular inhibitor of apoptosis 1 (cIAP1, or BIRC2), cIAP2 (BIRC3), and XIAP (BIRC4), binding each at nanomolar concentrations. Birinapant causes rapid cIAP1 degradation, caspase activation, PARP cleavage, and NF-κB activation in breast cancer cells. It shows in vivo antitumor activity, inducing apoptosis in several types of cancer xenografts in mice.
