1117 Inhalable extracellular vesicle delivery of IL-12 mRNA to treat lung cancer and promote systemic immunity

<h3>Background</h3> Lung carcinoma is one of the most common cancers and has one of the lowest survival rates in the world. Cytokines such as interleukin-12 (IL-12) have demonstrated considerable potential as robust tumour suppressors. However, their applications are limited due to off-target toxicity. <h3>Methods</h3> In this study, we develop inhalable extracellular vesicles loaded with IL-12 mRNA to address lung cancer and bolster systemic immunity in lung tumor-bearing mouse models. IL-12 mRNA is loaded into human embryonic kidney cell-derived exosomes (HEK-Exo) through electroporation, yielding IL-12 mRNA-loaded exosomes (IL-12-Exo). The local gene translation, immune response, tumor rechallenge, and synergistic application have been explored. Additionally, the preliminary long-term toxicity is assessed on non-human primates and mice. <h3>Results</h3> Inhalation and preferential uptake by cancer cells results in targeted delivery and fewer systemic side effects. The IL-12 messenger RNA generates interferon-γ production in both innate and adaptive immune-cell populations. This activation consequently incites an intense activation state in the tumor microenvironment and augments its immunogenicity. The increased immune response results in the expansion of tumor cytotoxic immune effector cells, the formation of immune memory, improved antigen presentation and tumor-specific T cell priming. The strategy is demonstrated against primary neoplastic lesions and provides profound protection against subsequent tumor rechallenge. Therapeutic benefits in combination with the checkpoint inhibitor and the long-term safety indicate the translational potential of IL12-Exo therapy. <h3>Conclusions</h3> This novel therapy shows the potential for locally delivered cytokine-based immunotherapies to address orthotopic and metastatic lung tumors (figure 1). For future clinical study, this therapy may be suited well to patients with refractory non-small cell lung cancer and those with cancers from other organs metastatic to the lung.