GVGH aims to develop a broadly protective vaccine to reduce the incidence and severity of Strep A superficial infections and consequently reduction of associated antibiotic prescriptions and the global burden of associated autoimmune sequelae: ARF and RHD. To tackle that, GVGH is developing a Strep A vaccine composed of three recombinant proteins (SLO, SpyAD and SpyCEP) and one glycoconjugate (GAC conjugated to recombinant CRM), formulated on two different adjuvants: Alum and AS37, a proprietary GSK adjuvant.
While both formulations are based on aluminium hydroxide, AS37 contains a TLR7 agonist (LHD153R) that has shown to stimulate a more balance Th1/Th2 cell-dependent response to other vaccine candidates. In this study, we will show the pre-clinical added value of AS37 adjuvant to the GSK Strep A vaccine. Beyond inducing a Th1 cell-dependent response, showed by the increase IL-2, IFN and TNF production and a shift on IgG2/IgG1 and IgG3/IgG1 ratio, AS37 promoted a significant increment in IgG titers for most antigens in comparison to Alum following one single injection, which was translated into a stronger functionality in dedicated functional assays.
The Strep A vaccine formulated on Alum and AS37 were also tested in a repeated dose-toxicology study, showing the two vaccine formulations were well tolerated and immunogenic.
Moreover, GSK is currently at late stage of CMC manufacturing of this vaccine and all ethical approvals have been already obtained. Therefore, the GSK Strep A vaccine formulated on Alum and AS37 is close to progress to Phase 1 clinical studies in Australia.