1.NounA protein drug that binds to and blocks the action of tumor necrosis factor and is administered by injection to treat various inflammatory diseases (such as rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis). It is a dimeric protein consisting of the ligand-binding portion of a human receptor for tumor necrosis factor linked to the basal, heavy chain, portion of IgG which determines the immune response to bound antigen. It is produced by recombinant DNA technology using hamster ovary cells and is marketed under the trademark Enbrel.