CAR T Cell-Packaged Oncolytic Vaccinia Virus Displays Enhanced Antitumor Efficacy

Background: Oncolytic vaccinia virus is a promising cancer therapeutic modality. However, the effectiveness of oncolytic viruses is limited by several factors. Systemic or intratumoral delivery of vaccinia viruses with the subsequent quick clearance of the viruses from the tumor site and the body by the strong immune responses induced by the virus are among the key challenges. In this study, we explored CAR T cell-packaged oncolytic vaccinia virus as a combinational therapy strategy in order to overcome current limitations for oncolytic virotherapy. Materials and Methods: We generated human HER2-CAR T cells and infected the HER2-CAR T cells with a EphA2-CD3 T cell engager-armed oncolytic vaccinia virus and evaluated the virus infectivity and replication within the T cells by flow analysis and virus tittering. T cell activation and cytotoxicity were determined by ELISA and 51Cr release assay. Results: We demonstrated that oncolytic vaccinia virus infected human HER2-CAR T cells effectively and virus particle in the activated human T cells increased >1000 fold in 3 days. In addition, EphA2-CD3 T cell engager effectively activated HER2-CAR T cells in the presence of HER2dimEphA2high NSCLC A549 cell lines, indicated by the elevated expression level of IFNγ and IL2. Importantly, in vitro studies showed that HER2-CAR T cell-packaged EphA2-TEA-VV displayed enhanced cytotoxicity against HER2dimEphA2high NSCLC A549 cell lines compared to HER2-CAR T cells or EphA2-TEA-VV alone. Conclusion: HER2-CAR T cell-packaged EphA2-TEA-VV is a promising therapeutic candidate with the ability to overcome the virus’s high immunogenicity and tumor heterogeneity, resulting in enhanced antitumor effects.