Phase 1 study of a SARS-CoV-2 vaccine adjuvanted via controlled biodistribution of mRNA encoding spike protein and IL-12p70 - Project Summary mRNA-lipid nanoparticle (LNP)-based vaccines are an exciting platform that made advances in combating the pandemic viruses. However, currently licensed mRNA-LNP vaccines approaches are limited in their ability to induce long lived antibody durability, degree of protection varies by age, and levels of cell mediated immunity (CMI) are suboptimal. mRNA vaccine self-adjuvantation is lower in aged individuals, with impaired immune activation upon exposure, inducing insufficient immunity with consequential impaired protection. To try to advance solutions, our published and unpublished work focus on two major novel mRNA vaccine innovations. One is a multi-organ protection (MOP) mRNA sequence homologous to tissue-specific micro-RNAs and enable tissue- specific mRNA translation, constraining expression to the site of injection. Secondly, a biological mRNA-encoded molecular adjuvant precisely guides immunity through inducing the potent and Th1-polarizing analyte, IL-12p70. Based on promising SARS-CoV-2 spike-trimer specific humoral and CMI, in young and aged murine models, and protection from viral challenge in non-human primates (NHPs), the goal of this U01 IICT application is to evaluate a mRNA encoding molecular adjuvant, delivered alongside MOP technology, in the context of a SARS-CoV-2 vaccine. Spike-MOP (CTx892) and IL-12-MOP (CTx672) are first-in-human evaluations, so to assess safety and tolerability, we would first perform dose escalations for CTx892 (stage 1A) and CTx 672 (stage 1B). Based on tolerability, doses less than maximal tolerated CTx892 are chosen to expand sample size for subsequent immunogenicity and mechanism studies. In stage 2, two different doses of CTx 892 will be paired with an escalating CTx672 (IL-12-MOP, e.g., 0.1, 1 µg) dose to assess adjuvanticity along with local and systemic safety and tolerability. Additionally, humoral immunity will be quantified with Spike-specific total IgG (titer and pre-immunization fold- change), IgG1 and IgG3 (Th1 markers), and IgG4 (Th2 marker), with surrogate virus, pseudo- virus, and true viral neutralization. Cellular immunity will include innate assessment in the days after, and adaptive CD4, CD8, and B cell immunity in the weeks, post-immunization. Further readouts include dried blood spots in the hours post-injection to assess proteomic kinetics. In Stage 3, biopsies of lymph node at ~14 days post-immunization and bone marrow at 6 months post-immunization will enable in-depth immunophenotyping and quantification of long-lived plasma cell (LLPC) responses. Durability of humoral and cellular immunity will be probed with a 6-month follow-up sampling of peripheral blood, IL-12-sustained humoral and cellular immunity.
