|Tislelizumab (BGB-A317) is a humanized IgG4 monoclonal antibody targeting the PD-1 immune checkpoint . It contains an alternative hinge region compared to other IgG4 anti-PD-1 antibodies, and subsequently does not induce the crosslinking between PD-1 and FcγRI that is observed for existing agents and which is believed to negatively impact on anti-PD-1 antibody-mediated anti-cancer activity. This modified profile is predicted to enhance tislelizumab's clinical efficacy . Like other anti-PD-1 antibodies tislelizumab acts to prevent the binding of the ligands PD-L1 and PD-L2 to PD-1. Tislelizumab is an immuno-oncology drug candidate being developed by Beigene Ltd (see their patent US8735553B1 ).