[1]Pardoll DM. The blockade of immune checkpoints in cancer immunotherapy\[J\]. Nat Rev Cancer, 2012, 12(4):252-264.[2]Hamid O, Robert C, Daud A, et al. Safety and tumor responses with lambrolizumab (antiPD1) in melanoma \[J\]. N Engl J Med, 2013, 369(2):134-144.[3]Brahmer JR,Tykodi SS,Chow LQ,et al.Safety and activity of antiPDL1 antibody in patients with advanced cancer \[J\]. N Engl J Med, 2012, 366(26) : 2455-2465.[4]Topalian SL, Hodi FS, Brahmer JR, et al. Safety, activity, and immune correlates of antiPD1 antibody in cancer \[J\]. N Engl J Med, 2012, 366(26):2443-2454.[5]Kleffel S, Posch C, Barthel SR, et al. Melanoma cellintrinsic PD1 receptor functions promote tumor growth \[J\]. Cell,2015,162(6):1242-1256.[6]Yuan J, Zhang J, Zhu Y, et al. Programmed deathligand1 expression in advanced gastric cancer detected with RNA in situ hybridization and its clinical significance \[J\].Oncotarget, 2016,7(26):39671-39679.[7]Bger C, Behrens HM, Mathiak M, et al. PDL1 is an independent prognostic predictor in gastric cancer of Western patients\[J\]. Oncotarget, 2016,7(17):24269-24283.[8]Derks S, Liao X, Chiaravalli AM, et al. Abundant PDL1 expression in EpsteinBarr virusinfected gastric cancers \[J\]. Oncotarget, 2016,7(22):32925-32932.[9]Tumeh PC, Harview CL, Yearley JH, et al. PD1 blockade induces responses by inhibiting adaptive immune resisitance \[J\].Nature, 2014,515(7528):568-571.[10]Schatton T, Schutte U, Frank NY,et al. Modulation of Tcell activation by malignant melanoma initiating cells \[J\].Cancer Res,2010,70(2):697-708.[11]Chen L, Deng H, Lu M, et al. B7H1 expression associates with tumor invasion and predicts patient′s survival in human esophageal cancer \[J\].Int J Clin Exp Pathol,2014, 7(9):6015-6023.[12]Kataoka K, Shiraishi Y, Takeda Y,et al. Aberrant PDL1 expression through 3′UTR disruption in multiple cancers\[J\].Nature,2016, 534(7607):402-406.