JAK inhibition enhances virotherapy in gliomas by modulating interferon-driven resistance

Background: Treating glioblastoma remains a therapeutic challenge in oncology. 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). Here, we aim to further improve the efficacy of Delta-24-RGD by targeting factors that maintain the immunosuppressive characteristics of gliomas. Methods: We performed bulk RNA-sequencing of murine gliomas treated with Delta-24-RGD or control (PBS) and analyzed the upstream regulators using Ingenuity Pathway Analysis. A correlation plot of IFNgamma and IDO1 transcript levels from 38 glioblastoma patient samples was obtained from the Delta-24-RGD plus Pembrolizumab clinical trial (NCT02798406) and analyzed in R Studio. Western blots, qPCR, and ELISA in glioma cells validated the IFNgamma-induced IDO1 expression. To study macrophage polarization, bone marrow-derived macrophages (BMDMs) were stimulated with IFNgamma or IL-4 in the presence or absence of JAK inhibitors, and gene expression of immunosuppressive markers was assessed by qPCR. Therapeutic efficacy in vivo was assessed by quantifying brain-infiltrating leukocytes using flow cytometry and evaluating tumor growth and survival. Results: RNA sequencing revealed IFNgamma as the top upstream regulator in murine tumors treated with an oncolytic virus. In addition, we observed upregulation of the tryptophan metabolism and immunoregulator IDO1 network in these treated tumors. We found a significant and positive correlation between IFNgamma and IDO1 in glioblastoma tumor biopsies from the clinical trial. In vitro studies demonstrated that IFNgamma treatment of glioma cells increased JAKs/STATs phosphorylation levels, IDO1 expression, and the Kyn/Trp metabolite ratio, which were abrogated by concomitant treatment with JAK inhibitors. Additionally, we observed that the JAK inhibitors reduced the expression of anti-inflammatory genes (Retnla, Arg1, Ido1, and Cd274) in polarized BMDMs. In syngeneic glioma models, we demonstrated that combination therapy with Delta-24-RGD and Baricitinib (a JAK inhibitor) yielded better tumor control when compared to monotherapy controls. Moreover, we observed that combination therapy reprograms the myeloid compartment of the tumor microenvironment towards an immunostimulatory phenotype. Conclusions: Our study highlights the dual role of IFNgamma in gliomas treated with oncolytic virotherapy: while it promotes antitumor immunity, it also induces immunosuppressive pathways such as IDO1 activation and tryptophan metabolism. These findings underscore the complexity of immune regulation in the tumor microenvironment and support the therapeutic potential of JAK inhibition in combination with oncolytic viruses for cancer treatment.