Talizumab (TNX 901) is a humanized IgG1 monoclonal antibody that specifically targets circulating immunoglobulin E (IgE). it binds to free IgE not already bound by the high-affinity IgE receptors (FcεRI) present on mast cells and basophils, which leads to the marked downregulation of these receptors and additionally inhibits allergen-specific T-cell activation by interfering with antigen processing and presentation activities.