Modification of extracellular matrix enhances oncolytic adenovirus immunotherapy in glioblastoma.

Purpose Extracellular matrix (ECM) component hyaluronan (HA) facilitates malignant phenotypes of glioblastoma (GBM), however, whether HA impacts response to GBM immunotherapies is not known. Herein, we investigated whether degradation of HA enhances oncolytic virus immunotherapy for GBM. Experimental design Presence of HA was examined in patient and murine GBM. Hyaluronidase-expressing oncolytic adenovirus ICOVIR17, and its parental virus ICOVIR15 without transgene, were tested whether they increased animal survival and modulated the immune tumor microenvironment (TME) in orthotopic GBM. HA regulation of NF-kB signaling was examined in virus-infected murine macrophages. We combined ICOVIR17 with PD-1 checkpoint blockade and assessed efficacy and determined mechanistic contributions of tumor-infiltrating myeloid and T cells. Results Treatment of murine orthotopic GBM with ICOVIR17 increased tumor-infiltrating CD8+ T cells and macrophages, and upregulated PD-L1 on GBM cells and macrophages, leading to prolonged animal survival, compared to control virus ICOVIR15. High-molecular weight HA inhibits adenovirus-induced NF-kB signaling in macrophages in vitro, linking HA degradation to macrophage activation. Combining ICOVIR17 with anti-PD-1 antibody further extended the survival of GBM-bearing mice, achieving long-term remission in some animals. Mechanistically, CD4+, CD8+ T cells and macrophages all contributed to the combination therapy that induced tumor-associated pro-inflammatory macrophages and tumor-specific T cell cytotoxicity locally and systemically. Conclusions Our studies are the first to show that immune-modulatory ICOVIR17 has a dual role of mediating degradation of HA within GBM-ECM and subsequently modifying the immune landscape of the TME, and offers a mechanistic combination immunotherapy with PD-L1/PD-1 blockade that remodels innate and adaptive immune cells.