194 OMALIZUMAB (XOLAIR) FOR CHRONIC URTICARIA. Issue 1 (1st January 2007) - Scofield, R. H.
Abstract : Background: Chronic urticaria is a difficult medical problem for which a definite cause is frequently not identified. In addition, treatment is difficult and often poorly effective. A patient with chronic urticaria and elevated IgE prompted a trial of omalizumab. This drug is a humanized monoclonal antibody that binds circulating IgE and prevents degranulation of mast cells by IgE. Methods: Case report, or n-of-1 trial. Results: A 25-year-old woman with a lifelong history of poorly controlled asthma gave a 1-year history of urticaria occurring conitnually every day. An extensive workup had revealed no infectious or allergic cause. No malignancy was identified initially or in follow-up. Protein level and activity assays of C1 esterase inhibitor were normal. Serum immunoglobulin levels were normal except for serum IgE, which was about twice the upper end of normal on multiple occasions. The patient was begun on omalizumab 300 mg subcutaneous every 2 weeks. Within a few hours of the first dose, the urticaria disappeared. The third dose was held when the patient had streptococcal pharyngitis. Urticaria recurred 20 days after the last dose and promptly resolved with an additional dose. After 3 months, the dosage was reduced to 150 mg subcutaneous every 2 weeks with continued efficacy. Conclusions: Omalizumab, a humanized anti-IgE monoclonal antibody, was approved by the FDA for treatment of refractory asthma in 2003. This drug blocks IgE-mediated degranulation of mast cells and proved useful in this patient with chronic urticaria associated with elevated IgE.