PD1-PDL1-IN 2 (ZE132) is a potent and selective PD-1/PD-L1 inhibitor, which has robust anti-tumour activity in vivo. PD1-PDL1-IN 2 promotes cytotoxic T-cell tumour infiltration and induces IL-2 expression. In addition, PD1-PDL1-IN 2 elicits strong inhibitory effects on the mRNA expression of TGF-β.