Oncolytic virus OVV-03 enhances CAR-T cell therapy against glioblastoma via immune modulation and specific HER2 upregulation.

Glioblastoma (GBM) remains therapeutically challenging due to treatment resistance and immunosuppression. Oncolytic virotherapy offers a promising strategy. This study engineered OVV-03, a novel HER2-armed oncolytic vesicular stomatitis virus (VSV), and evaluated its efficacy against GBM. OVV-03 demonstrated potent infectivity and cytotoxicity in GBM cell lines and patient-derived cells, inducing caspase-dependent apoptosis and suppressing proliferation/clonogenicity. In murine GBM models, OVV-03 significantly suppressed tumor growth, improved survival, and enhanced CD8⁺ T cell infiltration. Single-cell RNA sequencing revealed OVV-03 remodels the tumor immune microenvironment by boosting cytotoxic T cell activity and inhibiting immunosuppressive pathways, notably PD-L1/PD-1 signaling. Mechanistically, OVV-03 downregulated PD-L1 by inhibiting the JNK-c-Fos/c-Jun axis, reversible by TNF-α stimulation. Critically, OVV-03 synergized with B7H3- or HER2-targeted CAR-T cells, inducing superior tumor regression and prolonged survival in orthotopic models. These findings demonstrate that OVV-03 exerts potent antitumor effects through direct oncolysis and immune activation, including PD-L1 modulation. Its synergistic combination with CAR-T cells highlights OVV-03 as a highly promising oncolytic immunovirotherapy platform for GBM.