Abstract 5072: “Armed” oncolytic herpes simplex virus enables CD19 CAR-T for solid tumor cell treatment as a combination therapy

Abstract Background: Chimeric antigen receptor (CAR) T cell therapy has achieved unprecedented success in treating hematologic malignancies but still struggles in the context of solid tumors. The challenges of effective CAR-T cell therapy for solid tumors are multifaceted including 1) physical barriers that limit T cell infiltration; 2) tumor heterogeneity and antigen escape leading to resistance to therapy; 3) immunosuppressive tumor microenvironment (TME) dampening T cell function. As a novel modality for cancer therapy, oncolytic virus (OV) can be engineered to overcome the limitations of CAR-T therapy in solid tumor. Here we developed a new-generation of oncolytic herpes simplex virus (oHSV) to enable clinically approved CD19 CAR-T for solid tumor therapy. Methods: oHSV MVR-T7011 (T7011) was genetically engineered to drive ectopic expression of the extracellular domain of CD19, the blood tumor antigen, on solid tumor cell surface upon viral infection. In addition, multiple payloads, CCL5, IL-12, and anti-PD-1 antibody were introduced into T7011 to modulate the TME. Payload expression was detected both in vitro and in vivo. Co-culture studies were performed to test the cell-killing activity of CD19 CAR-T combined with T7011. Antitumor activities of T7011 administrated via intratumoral (IT) or intraperitoneal (IP) in combination with CD19 CAR-T cells were assessed in immunodeficient and immunocompetent mice. Results: The in vitro studies indicated that the expression of CD19 on tumor cell surface was detected as early as 4 hours post infection (hpi) and retained for at least 96 hours in the T7011-infected cells. In mouse study showed that the CD19 expression on tumor cells was detected as early as 8 hpi and lasted for 20 days when T7011 was injected via IT in immunodeficient mice. The payload of CCL5, IL-12, and anti-PD-1 antibody showed a similar expression pattern as CD19. Co-culture studies showed that T7011 infection enhanced cell-killing activity of CD19 CAR-T but the virus had no effect on viability and proliferation of CAR-T cell itself, which concludes that T7011 does not dampen the CAR-T function as its combination treatment. The in vivo efficacy studies demonstrated that IT and IP administration of T7011, rather than MVR-T3011 virus which lacks CD19, specifically promoted CD19 CAR-T anti-solid tumor activities in both immunodeficient and immunocompetent mice. Conclusions: The new-generation of HSV oncolytic virus T7011 expressing the targetable CD19 antigen on tumor surface enables the CD19 CAR-T for solid tumor cell treatment as a combination therapy. In addition, T7011 also carries multi-immunomodulators further to enhance antitumor efficacy by reinvigorating the infiltrated CAR-T cells and reversing the immunosuppressive TME. T7011 is expected to be a promising combinational therapy with CD19-specific CAR-T cells enabling effective cell therapy against multiple solid tumors. Citation Format: Yanxin Zheng, Yuanyuan Liu, Tianyi Deng, Yue Huang, Ziwen Liu, Borui Zhan, Xusha Zhou, Runbin Yan, Jiangtao Ren, Yun Xing, Guixing Wu, Yonghong Liu, Jing Zhao, Xiaoqing Chen, Grace Zhou. “Armed” oncolytic herpes simplex virus enables CD19 CAR-T for solid tumor cell treatment as a combination therapy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5072.