IMMU-48. Ruxolitinib enhances viroimmunotherapy of gliomas: targeting JAK-guided immunosuppressive pathways

Abstract Treating glioblastoma remains a therapeutic challenge in oncology. Viroimmunotherapy is emerging as a promising new treatment approach. Our laboratory developed an oncolytic adenovirus, termed Delta-24-RGD, which has been tested in clinical trials for recurrent glioblastoma patients with encouraging results (NCT00805376, NCT02798406). These clinical studies, together with preclinical data, showed that the efficacy of Delta-24-RGD was due to direct tumor cell oncolysis and indirect activation of anti-tumor immunity. To further leverage this immune component, our group generated Delta-24-RGDOX, an armed version of Delta-24-RGD that expresses the T-cell activator OX40 ligand (OX40-L). Here, we aim to further improve the efficacy of Delta-24-RGDOX by targeting factors that maintain the immunosuppressive characteristic of gliomas. RNA sequencing of glioma-bearing mice treated with Delta-24-RGDOX revealed interferon gamma (IFNγ) as the top upstream regulator. In addition, we observed upregulation of the tryptophan metabolism and immunoregulator IDO1-AhR network in these treated tumors. We performed gene expression analysis on 38 tumor biopsies from the Delta-24-RGD and Pembrolizumab clinical trial (NCT02798406), identifying a significant positive correlation between IFNγ and IDO1 (a main regulator of AhR activation), identifying this axis as clinically relevant. The IFNγ signaling converges through the JAK family, which induces the activation STATs and the subsequent engagement of inflammatory programs. In vitro studies demonstrated that Delta-24-RGDOX treatment of glioma cells increased STATs and IDO1 expression, resulting in AhR nuclear translocation and transcriptional activation. Of clinical interest, the IFNγ-induced IDO1 expression was completely abrogated by concomitant treatment with Ruxolitinib, a clinically approved JAK inhibitor. Using syngeneic glioma models, we showed that combination therapy with Delta-24-RGDOX and Ruxolitinib yielded better survival outcomes compared to monotherapy controls. In summary, this study illustrates the feasibility of combining virotherapy with drugs targeting immunosuppressive pathways in gliomas and provides a strong rationale for translating this strategy into the clinical setting.