Long-acting interleukin-7 improves the efficacy of oncolytic viral therapy in glioblastoma

Despite advances in immunotherapy, the prognosis for patients with glioblastoma (GBM) remains poor. The efficacy of GBM-targeted immunotherapies is limited by the paucity of functional T cells in the tumor microenvironment, a consequence of the local and systemic immunosuppression prevalent in patients with GBM. To overcome these challenges, here we develop a treatment strategy we term "expand and pull," which uses systemic administration of rhIL-7-hyFc, a long-acting recombinant human interleukin-7, to increase peripheral T cell abundance ("expand"), followed by intratumoral oncolytic virus treatment to recruit these cells to the tumor microenvironment ("pull"). We show that rhIL-7-hyFc improves the efficacy of multiple oncolytic viral therapies in syngeneic immuno-resistant mouse models of glioma. Combining rhIL-7-hyFc and Zika virus (ZIKV) increases systemic and intratumoral T cell abundance, improves cytotoxic T cell function, and delays expression of inhibitory checkpoint receptors, resulting in long-term tumor-free survival. We observe similar survival efficacy in experiments using a safer, genetically modified Δ10 3'-UTR ZIKV, as well as the clinically tested oncolytic adenovirus, Delta24-RGD. Collectively, our findings demonstrate that augmentation of both the systemic and local immune responses improves the utility of GBM-targeted immunotherapies.