Omalizumab, sold under the brand name Xolair, is an injectable medication to treat severe persistent allergic forms of asthma, nasal polyps, urticaria (hives), and immunoglobulin E-mediated food allergy. Omalizumab is a recombinant DNA-derived humanized IgG1 monoclonal antibody which specifically binds to free human immunoglobulin E (IgE) in the blood and interstitial fluid and to the membrane-bound form of IgE (mIgE) on the surface of mIgE-expressing B lymphocytes. Its primary adverse effect is anaphylaxis. In 1987 Tanox filed its first patent application on the anti-IgE drug candidates. It took until 2003, in the United States until omalizumab was approved, in Europe until 2005 for moderate to severe persistent asthma, severe chronic rhinosinusitis with nasal polyps. In February 2024, the FDA approved it also to treat severe food allergy.

Reference
Wiki: Ige responsiveness