NCIt definition : A recombinant immunoglobulin G4 (IgG4) kappa monoclonal antibody directed against
the negative immunoregulatory human cell receptor programmed cell death protein 1
(PD-1; PDCD1; CD279), with potential immune checkpoint inhibitory and antineoplastic
activities. Upon administration, anti-PD-1 monoclonal antibody 609A targets, binds
to and inhibits PD-1 and its downstream signaling pathways. This may restore immune
function through the activation of T-cells and T-cell-mediated immune responses against
tumor cells. PD-1, a transmembrane protein in the immunoglobulin superfamily (IgSF)
expressed on T-cells, functions as an immune checkpoint that negatively regulates
T-cell activation and effector function when activated by its ligands programmed cell
death-1 ligand 1 (PD-L1) or 2 (PD-L2); it plays an important role in tumor evasion
from host immunity.;