Immunization with glypican-3 nanovaccine containing TLR7 agonist prevents the development of carcinogen-induced precancerous hepatic lesions to cancer in a murine model

Am J Transl Res. 2018 Jun 15;10(6):1736-1749. eCollection 2018.

Abstract

Background: Glypican-3 (GPC3) is one of the key tissue markers that could discriminate malignant precancerous lesions from benign hepatic lesions in cirrhotic patients. We aimed to develop a GPC3 cancer vaccine to induce specific T cells to intervene in hepatocellular carcinoma (HCC) development.

Methods: Synthesizing mannosylated liposomes (LPMan) as vaccine delivery system, incorporating one Toll-like receptor (TLR)-7/8 agonist CL097 as adjuvant, we prepared a GPC3 nanovaccine, LPMan-GPC3/CL097. We injected 25 mg/kg diethylnitrosamine intraperitoneally to induce autochthonous HCC in HBV-transgenic mice, which persistently express hepatitis B surface antigen in hepatocytes. Starting from week 8 after diethylnitrosamine injection when malignant hepatocytes generated, we immunized the mice subcutaneously every 2 weeks 4 times with LPMan-GPC3/CL097 containing 5 µg of GPC3 plus 5 µg of CL097.

Results: The vaccine efficiently targeted draining lymph nodes where naïve T cells reside and enhanced the expression of molecules involved in antigen presentation in migratory dendritic cells (DCs). Antigen was professionally processed in endoplasmic reticulum-Golgi system of DCs, subsequently priming both CD4+ and CD8+ T cells. The LPMan-GPC3/CL097 immunization generated significantly more GPC3-specific CD4+ IFNγ- and CD8+ IFNγ-producing T cells in mice spleens and livers, which specifically eliminated GPC3-expressing tumor cells. One week after last immunization (week 15 after diethylnitrosamine), 5/5 un-immunized, 5/5 sham (LPMan-CL097) and 1/5 LPMan-GPC3/CL097-immunized mice developed HCC. By week 20 after diethylnitrosamine, significantly less HCC developed in LPMan-GPC3/CL097-immunized mice than in sham-immunized mice (P<0.01).

Conclusions: LPMan-GPC3/CL097 immunization induced de novo generation of specific T cells against tumor-associated antigen GPC3 that could prevent HCC development in cirrhotic liver.

Keywords: Cancer vaccine; T cells; hepatocellular carcinoma; murine model; tumor-associated antigen.