PD-1/PD-L1-IN-9 hydrochloride is a potent and orally active inhibitor of PD-1/PD-L1 interaction, with an IC50 of 3.8 nM. PD-1/PD-L1-IN-9 hydrochloride can enhance the killing activity of tumor cells by immune cells. PD-1/PD-L1-IN-9 hydrochloride also exhibits significant in vivo antitumor activity in a CT26 mouse model.
