Activation of HIV-specific CD8+ T-cells from HIV+ donors by vesatolimod.

BACKGROUND: Vesatolimod (VES; GS-9620) is a Toll-like receptor 7 (TLR7) agonist that directly activates human plasmacytoid dendritic cells (pDCs) and B lymphocytes resulting in direct and indirect production of cytokines and immune activation. VES is being evaluated in HIV-1-infected people as part of an HIV remission strategy. Here we investigated the potential of VES to trigger indirect activation of HIV-specific CD8+ T-cells using immune cell cultures derived from HIV+ donors. METHODS: Peripheral blood mononuclear cell (PBMC) cultures derived from HIV+ donors virologically suppressed on stable antiretroviral therapy (n=31) were isolated and treated with VES or vehicle for 24 h. Cells were stained with surface and intracellular fluorescent conjugated antibodies and HIV-specific pentamers, and analysed by flow cytometry. RESULTS: Treatment of PBMCs with VES resulted in all 31 donors demonstrating a concentration dependent increase in CD8+ T-cell activation (CD69+) of up to 88%. Of these donors, 20 of 31 donors displayed a concentration-dependent increase in HIV-specific CD8+ T-cell activation due to VES with a maximum of 20.8%. Intracellular staining was performed in a subset of donors (n=14), 5 of which displayed VES-induced activation of functional HIV-specific CD8+ T-cells as assessed by CD107a and/or tumour necrosis factor (TNF)-α upregulation. CONCLUSIONS: This study demonstrates that VES treatment can induce the activation of functional HIV-specific CD8+ T-cells in donor derived PBMCs. These data support the potential use of VES to activate functional HIV-specific CD8+ T-cells as part of an HIV remission strategy.

Identification and optimization of pteridinone Toll-like receptor 7 (TLR7) agonists for the oral treatment of viral hepatitis.

Pteridinone-based Toll-like receptor 7 (TLR7) agonists were identified as potent and selective alternatives to the previously reported adenine-based agonists, leading to the discovery of GS-9620. Analogues were optimized for the immunomodulatory activity and selectivity versus other TLRs, based on differential induction of key cytokines including interferon α (IFN-α) and tumor necrosis factor α (TNF-α). In addition, physicochemical properties were adjusted to achieve desirable in vivo pharmacokinetic and pharmacodynamic properties. GS-9620 is currently in clinical evaluation for the treatment of chronic hepatitis B (HBV) infection.