Liu, Tao

Abstract Background: The limited efficacy of oncolytic virotherapy (OV) in gastrointestinal malignancies has been attributed to an immunologically inert tumor microenvironment. While cisplatin is widely used as a cytotoxic agent, its immunomodulatory effects remain incompletely defined. We hypothesized that cisplatin may reprogram the tumor immune landscape to enable more effective OV-mediated anti-tumor responses. Methods: We evaluated the effects of cisplatin in combination with two distinct oncolytic platforms, vesicular stomatitis virus (VSV) and adenovirus (AdV), across both in vitro and in vivo colorectal cancer models. In vivo efficacy was assessed using MC38 subcutaneous and peritoneal metastatic models, with analysis of tumor growth, survival, and toxicity. Immune profiling was performed using single-cell RNA sequencing (scRNA-seq), flow cytometry, and bulk RNA sequencing to interrogate changes in CD8+ T cell states and functional programs. Guided by these preclinical findings, a clinical trial combining XELOX, PD-1 blockade, and OV therapy was initiated (ChiCTR2500107607). Results: Cisplatin markedly enhanced OV-mediated anti-tumor efficacy across models, resulting in sustained tumor control and improved survival in both subcutaneous and peritoneal disease settings. This effect was conserved across viral platforms, indicating a virus-agnostic interaction. Mechanistically, cisplatin induced a robust interferon (IFN)–dominant transcriptional program, characterized by upregulation of interferon-stimulated genes, including IRF7, IRF9, and ISG15. Single-cell analysis revealed that combination therapy reshaped the CD8+ T cell compartment, promoting the expansion of a population with transcriptional and functional features of central memory T cells (Tcm), alongside reduced exhaustion signatures. These changes were accompanied by enhanced cytokine signaling pathways associated with T cell maintenance and function, including IL-2, IL-7, and IL-15. In vitro, the combination of cisplatin and OV increased tumor cell death and interferon-γ production, supporting a model in which cytotoxic and immunostimulatory effects are mechanistically linked. A phase I clinical trial has been initiated. In gastric cancer, patients with retroperitoneal metastases are being treated with OV in combination with PD-1 blockade (ongoing). In colorectal cancer, the strategy is being evaluated in the neoadjuvant setting with an rectal preservation approach. Conclusions: Our findings identify a previously unrecognized role for cisplatin in priming an interferon-driven immune program that promotes Tcm differentiation and function, thereby enabling durable responses to oncolytic virotherapy. This work provides a mechanistic rationale for leveraging chemotherapy-induced immune reprogramming to enhance viro-immunotherapy and supports the clinical translation of this strategy in gastrointestinal malignancies. Citation Format: Joseph Brandon. Parker, Zhongyi Dong, Tao Liu, Qisen Guo, Haoyu Zhang, Bo Ni, Long Bai, Yiwen Chen, Jiasheng Zong, Xiang Xia, Jiaojiao Zheng, Hoang Tran Pham, Aya Elalfy, Demarcus Ingram, Ahmed Abdel-Hakeem, Muhammad Ali, Shannon Hartzell, Zizhen Zhang, Vivienne Yang. Cisplatin primes an interferon-driven CD8+ central memory T cell program to enable oncolytic virotherapy in gastrointestinal cancer malignancies [abstract]. In: Proceedings of AACR Drug Discovery and Development (AACR D3) Conference; 2026 Jul 21-24; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(14_Suppl):Abstract nr B024.