Ligelizumab (also known as QGE031) is an investigational, humanized monoclonal antibody that targets immunoglobulin E (IgE) with higher affinity than the clinically established antibody omalizumab. It binds to the Cε3 domain of IgE, the same region that interacts with the high-affinity IgE receptor (FcεRI) on mast cells and basophils. By doing so, ligelizumab prevents IgE from binding to FcεRI, thereby inhibiting the allergen-induced cross-linking and activation of these cells that leads to the release of histamine and other inflammatory mediators. It is being developed for the treatment of moderate-to-severe allergic asthma, chronic spontaneous urticaria (CSU), and other IgE-mediated allergic conditions.