On the basis of the above observations that the “immune-excluded” phenotype of gastric cancer is characterized by high expression of TGF-β1, the efficacy of siTGF-β1-αPDL1-PEG-PCL-NPs against GC could be enhanced by down-regulating suppressive cytokines, such as TGF-β1, within the tumor microenvironment, therefore increasing CD8+ T cell infiltration in the tumor parenchyma and converting the immune-exclude phenotype into the immune-inflamed phenotype. This evidence concerns the gene TGFB1 and gastric cancer.