A small-molecule Toll-like receptor 8 (TLR8) agonist with potential immunostimulating and antineoplastic activities. Motolimod binds to TLR8, present in cutaneous dendritic cells, monocytes/macrophages, and mast cells, which may result in the activation of the central transcription factor nuclear factor-B, the secretion of proinflammatory cytokines and other mediators, and a Th1-weighted antitumoral cellular immune response. Primarily localized to endosomal membranes intracellularly, TLR8, like other TLRs, recognizes pathogen-associated molecular patterns (PAMPs) and plays a key role in the innate immune system.