XCL1/Glypican-3 Fusion Gene Immunization Generates Potent Antitumor Cellular Immunity and Enhances Anti-PD-1 Efficacy

摘要

Cancer vaccines can amplify existing antitumor responses or prime naive T cells to elicit effector T-cell functions in patients through immunization. Antigen-specific CD8(+) T cells are crucial for the rejection of established tumors. We constructed XCL1-GPC3 fusion molecules as a liver cancer vaccine by linking the XCL1 chemokine to glypican-3 (GPC3), which is overexpressed in hepatocellular carcinoma(HCC). Cells expressingXCL1-GPC3 chemoattracted murine XCR1(+)CD8a(+) dendritic cells (DC) and human XCR1(+)CD141(+) DCs in vitro and promoted their IL12 production. After subcutaneous mXcl1-GPC3 plasmid injection, mXCL1-GPC3 was mainly detected inCD8a(+) DCsofmouse draining lymph nodes. XCL1-GPC3-targeted DCs enhanced antigen-specific CD8(+) T-cell proliferation and induced the de novo generation of GPC3-specific CD8(+) T cells, which abolished GPC3-expressing tumor cells in mouse and humansystems. Weimmunized amurine autochthonous liver cancer model, with a hepatitis B background, with the mXcl1GPC3 plasmid starting at 6 weeks, when malignant hepatocyte clusters formed, or at 14 weeks, when liver tumor nodules developed, after diethylnitrosamine administration. mXcl1-GPC3-immunized mice displayed significantly inhibited tumor formation and growth compared with GPC3-immunized mice. After mXcl1-GPC3 immunization, mouse livers showed elevated production of IFN gamma, granzyme B, IL18, CCL5, CXCL19, and Xcl1 and increased infiltration of GPC3-specific CD8(+) T cells, activated natural killer (NK) cells, and NKT cells. The antitumor effects of these immune cells were further enhanced by the administration of anti-PD-1. Anti-HCC effects induced by hXCL1-GPC3 were confirmed in an HCC-PDX model from 3 patients. Thus, XCL1-GPC3 might be a promising cancer vaccine to compensate for the deficiency of the checkpoint blockades in HCC immunotherapy.