Abstract
Despite recent advances in immunotherapy with immune checkpoint inhibitors, many patients with non-small cell lung cancer (NSCLC) fail to respond or develop resistance after an initial response. In situ vaccination (ISV) with engineered viruses has emerged as a promising antigen-agnostic strategy that can both condition the tumor microenvironment and augment antitumor T-cell responses to overcome immune resistance. We engineered a live attenuated viral vaccine, hyper-IFN-sensitive (HIS) virus, by conducting a genome-wide functional screening and introducing eight IFN-sensitive mutations in the influenza genome to enhance host IFN response. Compared with wild-type influenza, HIS replication was attenuated in immunocompetent hosts, enhancing its potential as a safe option for cancer therapy. HIS ISV elicited robust yet transient type I IFN responses in murine NSCLCs, leading to an enrichment of polyfunctional effector Th1 CD4+ T cells and cytotoxic CD8+ T cells into the tumor. HIS ISV demonstrated enhanced antitumor efficacy compared with wild-type in multiple syngeneic murine models of NSCLC with distinct driver mutations and varying mutational burden. This efficacy was dependent on host type 1 IFN responses and T lymphocytes. HIS ISV overcame resistance to anti-PD-1 in LKB1-deficient murine NSCLC, resulting in improved overall survival and systemic tumor-specific immunity. These studies provide compelling evidence to support further clinical evaluation of HIS as an "off-the-shelf" ISV strategy for patients with NSCLC refractory to immune checkpoint inhibitors.