Tilomisole (also known as Wy-18,251) is a benzimidazole derivative patented by American Home Products Corp. as an antineoplastic agent with immunomodulating and antimetastatic activity. Tilomisole significantly enhanced the blastogenic response of cancer patients' lymphocytes in vitro. Tilomisole significantly increases macrophage phagocytosis against 51chromium labeled opsonized chicken red blood cells. In preclinical models, Tilomisole administration significantly increases peripheral blood lymphocytes in rats and demonstrates marked anti-inflammatory activity. The acute anti-inflammatory of Tilomisole.) was similar to aspirin, but in contrast to aspirin, Tilomisole failed to demonstrate antipyretic activity. Tilomisole also inhibited chronic inflammatory responses in the adjuvant- and collagen-induced arthritis models. Unfortunately, in clinical trials, Tilomisole failed to demonstrate significant antitumor responses.