mRNA vaccines encoding influenza virus hemagglutinin (HA) elicits immunity in mice from influenza A virus challenge

Influenza viruses cause epidemics and can cause pandemics with substantial morbidity with some mortality every year. Seasonal influenza vaccines have incomplete effectiveness and elicit a narrow antibody response that often does not protect against mutations occurring in influenza viruses. Thus, various vaccine approaches have been investigated to improve safety and efficacy. Here, we evaluate an mRNA influenza vaccine encoding hemagglutinin (HA) proteins in a BALB/c mouse model. The results show that mRNA vaccination elicits neutralizing and serum antibodies to each influenza virus strain contained in the current quadrivalent vaccine that is designed to protect against four different influenza viruses including two influenza A viruses (IAV) and two influenza B (IBV), as well as several antigenically distinct influenza virus strains in both hemagglutination inhibition assay (HAI) and virus neutralization assays. The quadrivalent mRNA vaccines had antibody titers comparable to the antibodies elicited by the monovalent vaccines to each tested virus regardless of dosage following an mRNA booster vaccine. Mice vaccinated with mRNA encoding an H1 HA had decreased weight loss and decreased lung viral titers compared to mice not vaccinated with an mRNA encoding an H1 HA. Overall, this study demonstrates the efficacy of mRNA-based seasonal influenza vaccines are their potential to replace both the currently available split-inactivated, and live-attenuated seasonal influenza vaccines.

Intravenous administration of IL-12 encoding self-replicating RNA-lipid nanoparticle complex leads to safe and effective antitumor responses

Interleukin 12 (IL-12) is a potent immunostimulatory cytokine mainly produced by antigen-presenting cells (e.g., dendritic cells, macrophages) and plays an important role in innate and adaptive immunity against cancers. Therapies that can synergistically modulate innate immunity and stimulate adaptive anti-tumor responses are of great interest for cancer immunotherapy. Here we investigated the lipid nanoparticle-encapsulated self-replicating RNA (srRNA) encoding IL-12 (referred to as JCXH-211) for the treatment of cancers. Both local (intratumoral) and systemic (intravenous) administration of JCXH-211 in tumor-bearing mice induced a high-level expression of IL-12 in tumor tissues, leading to modulation of tumor microenvironment and systemic activation of antitumor immunity. Particularly, JCXH-211 can inhibit the tumor-infiltration of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs). When combined with anti-PD1 antibody, it was able to enhance the recruitment of T cells and NK cells into tumors. In multiple mouse solid tumor models, intravenous injection of JCXH-211 not only eradicated large preestablished tumors, but also induced protective immune memory that prevented the growth of rechallenged tumors. Finally, intravenous injection of JCXH-211 did not cause noticeable systemic toxicity in tumor-bearing mice and non-human primates. Thus, our study demonstrated the feasibility of intravenous administration of JCXH-211 for the treatment of advanced cancers.