Pidilizumab (formerly CT-011) is a monoclonal antibody being developed by Medivation for the treatment of cancer and infectious diseases. Pidilizumab was originally thought to bind to the PD-1 immune checkpoint molecule, however, recent evidence suggests that Delta-like 1 (DLL1) is its primary binding target while binding to PD-1 is secondary and restricted to non-glycosylated and hypoglycosylated forms of this molecule. Pidilizumab causes in the attenuation of apoptotic processes in lymphocytes, primarily effector/memory T cells.