PD-1-IN-20 is the less active enantiomer of PD-1-IN-1.

PD-1/PD-L1-IN-20 is a small molecule inhibitor of PD-1/PD-L1 protein-protein interaction. PD-1/PD-L1-IN-20 blocks the PD-1/PD-L1 interaction (IC50: 5.29 nM). PD-1/PD-L1-IN-20 can be used to study cancer, infectious diseases and autoimmune diseases.

TPP-1, a peptide inhibitor, targets the interaction between programmed cell death protein 1 (PD-1) and its ligand (PD-L1), binding specifically to PD-L1 with a dissociation constant (Kd) of 94.67 nM. At a concentration of 20 µM, TPP-1 effectively counteracts the PD-L1-induced suppression of IFN-γ production in anti-CD3-stimulated isolated human CD4+ T cells. Furthermore, TPP-1 demonstrates significant efficacy in reducing tumor volume in a mouse xenograft model of HL-60 leukemia. This model involved HL-60 cells co-cultured with anti-CD3-activated isolated human CD4+ T cells, with TPP-1 administration at a dosage of 4 mg/kg showing notable antitumor activity.