Notes: PD-1/PD-L1 inhibitor 3 is a macrocyclic peptide inhibitor of the protein-protein interaction between programmed cell death protein 1 (PD-1) and PD-1 ligand (PD-L1).{66107} It inhibits the PD-1/PD-L1 interaction in a time-resolved FRET (TR-FRET) assay (IC50 = 9 nM).