Motolimod is an agonist of toll-like receptor 8 (TLR8). It increases the production of TNF-α and IL-12 in human peripheral blood mononuclear cells (PBMCs; EC50s = 140 and 120 nM, respectively), monocytes, and myeloid dendritic cells. Motolimod also increases IFN-γ production in natural killer (NK) cells and increases cytolysis in K562 NK cell-sensitive leukemia cells when used at concentrations of 167 and 500 nM for 48 hours. It increases plasma levels of a group of human cytokines, including IL-6, IL-12p70, TNF-α, MCP-1, and MIP-1β, in NOD-scid IL2rynull (NSG) mice reconstituted with human immune system (NSG-HIS) when administered at doses of 1.5 and 15 mg/m2. Motolimod, when used in combination with pegylated liposomal doxorubicin (PLD), reduces tumor growth and increases tumor infiltration of monocytes and T cells in an ovarian cancer NSG-HIS mouse model.
