Nivolumab acts by blocking a negative regulator of T-cell activation and response, thus allowing the immune system to attack the tumor. This is an example of immune checkpoint blockade.
PD-1 is a protein on the surface of activated T cells. If another molecule, called programmed cell death 1 ligand 1 or programmed cell death 1 ligand 2 (PD-L1 or PD-L2), binds to PD-1, the T cell becomes inactive. This is one way that the body regulates the immune system, to avoid an overreaction. Many cancer cells make PD-L1, which inhibits T cells from attacking the tumor. Nivolumab blocks PD-L1 from binding to PD-1, allowing the T cell to work. PD-L1 is expressed on 40–50% of melanomas and has limited expression otherwise in most visceral organs with the exception of respiratory epithelium and placental tissue.
CG0063 is a chimeric antibody containing the variable domain of Nivolumab and a rabbit IgG constant domain. Thus, it can be used to investigate PD-1 expression in human tumors as illuminated by Nivolumab reactivity and detection via anti- rabbit IgG secondary.
A chimera betweeen rabbit IgG and the varibale domians of Nivolumab.