Omalizumab

Omalizumab which is sold under the brand name Xolair is a medication originally designed to reduce sensitivity to allergens and is used for treating chronic idiopathic urticaria, and allergic asthma. Omalizumab acts as a mast cell stabilizer, so it is also a potential treatment for mast cell disorders.

Theory
Omalizumab is classed as a monoclonal antibody that binds to free immunoglobulin E (IgE) in the blood and interstitial fluid and to membrane-bound form of IgE (mIgE) on the surface of mIgE-expressing B cells. It inhibits the binding of IgE to FcεRI on mast cells and basophils by binding to an antigenic epitope on IgE that overlaps with the site to which FcεRI binds. In this sense, it is a potent mast cell stabilizer.

Evidence
In a study of 55 French patients with mast cell disorders treated with omalizumab, 43 patients achieved a "best response" and 76.7% of the responding patients achieved a persistent response (three months or longer.) Median time to first response was 2 months and median time to best response was 6 months. One severe adverse event occurred, with researchers suggesting this recommends initiating treatment in hospital, but otherwise found the safety profile acceptable.

Learn more

 * 2019, A new therapy to calm down mast cells - American Academy of Allergy, Asthma & Immunology
 * Omalizumab - drugs.com