PVP-037.2 is a TLR7/8 agonist that acts as an adjuvant to enhance vaccine-induced TH1 immune responses and boost the production of antigen-specific antibodies IgG1 and IgG2c.

PVP-037.2, at concentrations ranging from 0.1 to 100 μM over a 24-hour period, induces the production of TNF and IL-1β in human aged peripheral blood mononuclear cells (PBMCs) in a concentration-dependent manner. Furthermore, PVP-037.2 exhibits TLR7/8-dependent immunomodulatory properties when administered at 100 μM for 20-24 hours.

Administered to adult C57BL/6J mice (weighing 20 to 30 g), PVP-037.2 (3 mg/kg, intravenous injection, measurements taken between 0-8 hours post-administration) exhibits high plasma clearance and negligible hemolytic activity. Furthermore, this compound (100 nmol per mouse, intravenous injection, single immunization) significantly enhances the adjuvant effect in mice vaccinated with the trivalent recombinant rHA influenza vaccine Flublok and the SARS-CoV-2 spike protein. Compared to its use alone, the PVP-037.2 O/W emulsion formulation (10 nmol per mouse, intravenous injection, IgG titers measured on day 42) substantially boosts the innate immune activation in wild-type C57BL/6J mice.