Omalizumab to Treat Eosinophilic Gastroenteritis

Eosinophilic gastroenteritis (EG) is characterized by eosinophilic infiltration of the bowel wall, gastrointestinal symptoms, and in more than 50% of patients, peripheral eosinophilia. Approximately one half of EG patients have multiple food allergies and/or elevated immunoglobulin E (IgE), suggesting an allergic etiology. The purpose of this study is to evaluate the safety and efficacy of humanized monoclonal anti-IgE antibody, omalizumab (Xolair (Registered Trademark)), in eosinophilic gastroenteritis. Omalizumab is approved for use in asthma and is dosed subcutaneously based on serum total IgE level and body weight, with a maximum dose of 375 mg every 2 weeks. Subjects with EG, and either food hypersensitivity or environmental allergies will be admitted to the Clinical Center. All subjects will undergo a thorough clinical evaluation, including endoscopy. The primary endpoints will be the evaluation of safety of omalizumab and its efficacy in reducing peripheral blood absolute eosinophil count. In addition, the following secondary endpoints will be studied: symptom scores, study drug pharmacodynamics, and tissue eosinophilia. Blood cells and serum will be collected and evaluated in the laboratory to address issues related to the immunopathogenesis and treatment of EG. This study will provide a better understanding of inflammatory and allergy mediators in the pathogenesis of EG and may provide a potential therapy for EG. Following subcutaneous administration of the initial dose of omalizumab (maximum 375 mg), subjects will be followed as inpatients for a minimum of 24 hours to monitor for adverse effects. Subsequent doses will be administered biweekly for a total of 8 doses.