CD274 and neoplasm: Sintilimab is a human immunoglobulin G4 (IgG4) monoclonal antibody that specifically binds to the PD-1 molecule on the surface of T cells, consequently blocking the tumor immune tolerance-inducing PD-1/programmed death-ligand 1 (PD-L1) pathway, re-activating the anti-tumor activities of lymphocytes, and inhibiting tumors.