Oncolytic virus–mediated GPC3 delivery overcomes antigen heterogeneity in hepatocellular carcinoma and enhances GPC3-directed immunotherapy

Background Hepatocellular carcinoma (HCC) remains a major cause of cancer-related mortality worldwide and is characterized by substantial molecular and immunologic heterogeneity that contributes to therapeutic resistance and poor clinical outcomes. Glypican-3 (GPC3) is an attractive immunotherapy target in HCC; however, its heterogeneous expression limits the effectiveness of GPC3-directed approaches. ECT204, a GPC3-directed ARTEMIS ® T-cell therapy, has shown improved safety compared with conventional CAR T cells but remains dependent on sufficient tumor-associated GPC3 expression. In this study, we investigated whether an oncolytic virus could be used to selectively deliver GPC3 to tumor cells to expand the applicability of GPC3-targeted immunotherapies. Methods We engineered the oncolytic vaccinia virus CF33-GPC3 to express GPC3 and evaluated its ability to sensitize GPC3-negative tumor cells to ECT204 in vitro and in vivo using GPC3-knockout HepG2 xenograft models. We also assessed the compatibility with other GPC3-targeted immunotherapies, including a bispecific T-cell engager (BiTE) and the monoclonal antibody codrituzumab. Results CF33-GPC3 efficiently induced surface expression of GPC3 in previously GPC3-negative tumor cells, resulting in activation of GPC3-directed ECT204 T cells and subsequent tumor cell killing. In vivo , combination therapy with CF33-GPC3 and ECT204, administered either intratumorally or intravenously, achieved significantly greater tumor control than either monotherapy alone. Moreover, OV-mediated GPC3 expression sensitized tumor cells to killing by GPC3-specific BiTE-redirected T cells and enhanced codrituzumab-mediated NK cell cytotoxicity. Conclusions These findings demonstrate that OV-mediated GPC3 delivery can overcome antigen heterogeneity in HCC and broaden the applicability of GPC3-directed immunotherapies.