Abstract 4184: RNA-seq analyses reveal remodeling of tumor microenvironment and reversal of glioma resistance to oncolytic viruses by targeting immunometabolism

Abstract Viroimmunotherapy aims to infect cancer cells to elicit anti-tumor immune responses. In clinical trials, glioma treatment with oncolytic viruses induced durable clinical responses in a small fraction of patients. To improve the percentage of responders, it is necessary to reshape the tumor microenvironment that shields the tumor from the immune system of the patient. Thus, we engineered Delta-24-RGDOX (DNX-2440), an oncolytic adenovirus that carries the cDNA of the T-cell activator, OX40L. In this work, we observed that Delta-24-RGDOX triggered a dramatic reshaping of the tumor microenvironment dominated by strong changes in immune processes as indicated by RNA-sequencing via ingenuity pathway analyses in a murine glioblastoma model. Paradoxically, network analyses revealed that Delta-24-RGDOX also induced robust activation of the cytokine-driven immunosuppressive IDO-Kynurenine-AhR circuitry, indicating a potential mechanism of resistance of the cancer cells to oncolytic virotherapy. To reverse this immunosuppression, we combined Delta-24-RGDOX with clinically relevant IDO inhibitors to treat glioma bearing mice. Importantly, addition of the IDO inhibitor to Delta-24-RGDOX decreased the activation of the IDO network. IDO inhibition did not affect virus infection or replication in human or murine glioma cells. Flow cytometry assays revealed that the combination therapy increased the frequency of activated CD8+ T cells and decreased the presence of the immunosuppressive cell populations, MDSCs and Tregs. Gene set enrichment analyses confirmed the decrease of MDSCs and Tregs in the combination treated glioma-bearing mice compared to the virus alone. Functional co-culture studies showed that the combined therapy activated splenocytes against tumor antigens, and that this activation was reversed by kynurenine. Importantly, the combination treatment eradicated the tumors in a CD4-dependent manner and significantly prolonged the survival of glioma-bearing mice. Altogether, these studies indicate that the combination treatment promotes an adaptive immune response while decreasing immunosuppression caused by virus-induced IDO activation. Furthermore, our data identified the striking role of immunosuppressive pathways in the resistance of gliomas to oncolytic virotherapy. Specifically, the activity of the tumor microenvironment IDO circuitry was responsible, at least partially, for the remodeling of local immunosuppression after tumor infection. Combining molecular and immune-related therapies may improve outcomes in human gliomas treated with virotherapy. Citation Format: Teresa T. Nguyen, Dong Ho Shin, Sagar Sohoni, Sanjay K. Singh, Yisel Rivera-Molina, Hong Jiang, Xuejun Fan, Joy Gumin, Frederick F. Lang, Christopher Alvarez-Breckenridge, Marta M. Alonso, Filipa Godoy-Vitorino, Lijie Zhai, Erik Ladomersky, Kristen L. Lauing, Derek A. Wainwright, Juan Fueyo, Candelaria Gomez-Manzano. RNA-seq analyses reveal remodeling of tumor microenvironment and reversal of glioma resistance to oncolytic viruses by targeting immunometabolism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4184.