Exogenous non-coding dsDNA-dependent trans-activation of phagocytes augments anti-tumor immunity.

Stimulator of interferon genes (STING)-dependent signaling is requisite for effective anti-microbial and anti-tumor activity. STING signaling is commonly defective in cancer cells, which enables tumor cells to evade the immunosurveillance system. We evaluate here whether intrinsic STING signaling in such tumor cells could be reconstituted by creating recombinant herpes simplex viruses (rHSVs) that express components of the STING signaling pathway. We observe that rHSVs expressing STING and/or cGAS replicate inefficiently yet retain in vivo anti-tumor activity, independent of oncolytic activity requisite on the trans-activation of extrinsic STING signaling in phagocytes by engulfed microbial dsDNA species. Accordingly, the in vivo effects of virotherapy could be simulated by nanoparticles incorporating non-coding dsDNA species, which comparably elicit the trans-activation of phagocytes and augment the efficacy of established cancer treatments including checkpoint inhibition and radiation therapy. Our results help elucidate mechanisms of virotherapeutic anti-tumor activity as well as provide alternate strategies to treat cancer.

Targeting IGF2-IGF1R Signaling to Reprogram the Tumor Microenvironment for Enhanced Viro-Immunotherapy.

BACKGROUND: The FDA approval of oncolytic herpes simplex-1 virus (oHSV) therapy underscores its therapeutic promise and safety as a cancer immunotherapy. Despite this promise, the current efficacy of oHSV is significantly limited to a small subset of patients largely due to the resistance in tumor and tumor microenvironment (TME). METHODS: RNA sequencing (RNA-Seq) was used to identify molecular targets of oHSV resistance. Intracranial human and murine glioma or breast cancer brain metastasis (BCBM) tumor-bearing mouse models were employed to elucidate the mechanism underlying oHSV therapy-induced resistance. RESULTS: Transcriptome analysis identified IGF2 as one of the top secreted proteins following oHSV treatment. Moreover, IGF2 expression was significantly upregulated in 10 out of 14 recurrent GBM patients after treatment with oHSV, rQNestin34.5v.2 (71.4%) (p=0.0020) (ClinicalTrials.gov, NCT03152318). Depletion of IGF2 substantially enhanced oHSV-mediated tumor cell killing in vitro and improved survival of mice bearing BCBM tumors in vivo. To mitigate the oHSV-induced IGF2 in the TME, we constructed a novel oHSV, oHSV-D11mt, secreting a modified IGF2R domain 11 (IGF2RD11mt) that acts as IGF2 decoy receptor. Selective blocking of IGF2 by IGF2RD11mt significantly increased cytotoxicity, reduced oHSV-induced neutrophils/PMN-MDSCs infiltration, and reduced secretion of immune suppressive/proangiogenic cytokines, while increased CD8+cytotoxic T lymphocytes (CTLs) infiltration, leading to enhanced survival in GBM or BCBM tumor-bearing mice. CONCLUSION: This is the first study reporting that oHSV-induced secreted IGF2 exerts a critical role in resistance to oHSV therapy, which can be overcome by oHSV-D11mt as a promising therapeutic advance for enhanced viro-immunotherapy.