Targeting immune checkpoints such as programmed cell death protein 1(PD-1)and pro-grammed death ligand-1(PD-L1)have been approved for treating melanoma,gastric cancer(GC)and bladder cancer with clinical benefit.Nevertheless,many patients failed to respond to anti-PD-1/PD-L1 treatment,so it is necessary to seek an alternative strategy for traditional PD-1/PD-L1 targeting immu-notherapy.Here with the data from The Cancer Genome Atlas(TCGA)and our in-house tissue library,PD-L1 expression was found to be positively correlated with the expression of ubiquitin-specific proces-sing protease 7(USP7)in GC.Furthermore,USP7 directly interacted with PD-L1 in order to stabilize it,while abrogation of USP7 attenuated PD-L1/PD-1 interaction and sensitized cancer cells to T cell killing in vitro and in vivo.Besides,USP7 inhibitor suppressed GC cells proliferation by stabilizing P53 in vitro and in vivo.Collectively,our findings indicate that in addition to inhibiting cancer cells proliferation,USP7 inhibitor can also downregulate PD-L1 expression to enhance anti-tumor immune response simul-taneously.Hence,these data posit USP7 inhibitor as an anti-proliferation agent as well as a novel ther-apeutic agent in PD-L1/PD-1 blockade strategy that can promote the immune response of the tumor.