Optimization of an innate immune stimulating adjuvant for an HIV DNA vaccine

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DESCRIPTION: There is a growing consensus that protection against HIV infection will require BOTH antiviral antibody responses as well as polyfunctional CD4+ and CD8+ T cells with potent lytic activity. To stimulate the breadth, potency, and rate of response required, Profectus Biosciences intends to utilize its platform technologies based on electroporation of DNA vaccines combined with genetic adjuvants. As a step in that direction, a recent phase 1 clinical trial, HVTN-080, showed that electroporation in combination with our IL-12 adjuvant can double the CD4+ and CD8+ T cell response rate in vaccinees over electroporation alone1. Even with this success, we recognize that a truly effective HIV vaccine will require a regimen that can consistently provide high magnitude, long-lived responses at rates >95% with as few booster immunizations as possible. We believe that adjuvants are a key to developing such a vaccine. Under a previous phase I SBIR, we identified a new class of genetic adjuvants that exploit the RIG-1 signaling cascades and trigger potent anti-viral innate immune responses. These innate responses integrate with TLR evoked innate responses and DAMPs/alarmins to evoke potent anti-viral adaptive immune responses. We demonstrated that these new adjuvants have comparable activity to the "gold standard" genetic adjuvant IL-12. Unfortunately, the performance of these adjuvants fell short of reaching our milestone for progression to phase II, which was superiority over IL-12. We have subsequently discovered that type I interferons produced by these new adjuvants severely attenuate vaccine antigen expression from our DNA vaccine plasmid that is driven by a CMV promoter. Under this follow-on phase I SBIR, we will identify a lead interferon insensitive promoter to drive our vaccine antigen and adjuvant expression and test this promoter in mouse studies with our lead RIG-1 pathway activating adjuvant comparing its activity to IL-12. We fully anticipate that our lead RIG-1 pathway activating adjuvant driven from an interferon insensitive promoter will yield the results that we originally anticipated for this adjuvant and will therefore meet or exceed our milestone for proceeding to phase II. Under phase II, we will combine this lead RIG-1 pathway activating adjuvant with our other adjuvants in macaques to evoke potent antiviral innate and adaptive immune responses of the type believed best suited to prevent/combat HIV infections.