Abstract 6652: Advanced glioblastoma immunotherapy: Attenuated herpes oncolytic virus armed with anti-PD-1 antibody and IL-12

Abstract Background: Glioblastoma (GBM), the most common and deadly primary brain tumor in adults, has limited treatment options with poor outcomes. The urgent need for innovative treatments has spurred research into immunotherapy and oncolytic virus therapy as promising alternatives. Herein, we have developed a new generation oncolytic herpes simplex virus (oHSV) armed with IL-12 and anti-PD-1 antibody to provide a synergistic anti-GBM efficacy for immune-oncolytic therapy. Methods: MVR-C5252, a novel oHSV, was created by genetic engineering, which included the removal of a 15-kb internal repeat (IR) region and both copies of the γ34.5 genes, along with the insertion of two exogenous genes encoding the anti-PD-1 antibody and IL-12. MVR-C5252 was characterized and assessed for its anti-GBM activities through a series of experiments as follows: 1) Safety assessments, including evaluations of neurotoxicity and latency-reactivation characteristics, were conducted in Balb/C mice. 2) Anti-tumor activities were evaluated in cell cultures, subcutaneous and orthotopic xenograft mouse models, and immunocompetent mouse models. 3) Mechanistic studies were performed to uncover the mode of action of MVR-C5252, with a specific focus on its ability to induce cell death in GBM cells and activate the immune response in vivo. Results: 1) In vitro studies showed that MVR-C5252 is highly replication attenuated but with higher cell-killing activity in GBM cells compared to the first generation oHSV, R3616, which has γ34.5 deletions only. 2) Mechanistic studies showed that MVR-C5252 infection increased cell death by reducing CNTNRα expression, which typically prevents caspase 3 activation and has an anti-apoptotic effect in glioma cells. 3) Intracranial injection of MVR-C5252 revealed a remarkable safety profile, with over an 800-fold reduction in virulence compared to wild-type HSV-1. Furthermore, the mouse trigeminal ganglion (TG) infection model suggested that MVR-C5252 was unable to establish latency or reactivate in the TG. 4) In vivo subcutaneous and orthotopic xenograft mouse models showed that compared to the R3616 group, enhanced anti-tumor activity and extended survival were observed in the MVR-C5252 group. Additionally, in the syngeneic mice model, MVR-C5252 exhibited superior anti-tumor activity and immune activation over the backbone virus. Conclusions: With the unique combination of safety, potent anti-tumor activity, and immune-stimulatory properties, MVR-C5252 makes it a big potential candidate to address the pressing need for effective treatment strategies of GBM. Citation Format: Lei Wang, Xusha Zhou, Xiaoqing Chen, Yuanyuan Liu, Yanxin Zheng, Runbin Yan, Yonghong Liu, Jing Zhao, Grace Guoying Zhou. Advanced glioblastoma immunotherapy: Attenuated herpes oncolytic virus armed with anti-PD-1 antibody and IL-12 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6652.