Update on optimal use of omalizumab in management of asthma

Abstract

Omalizumab is a humanized monoclonal anti-IgE antibody recently approved for the treatment of severe allergic asthma. This drug inhibits allergic responses by binding to serum IgE, thus preventing interaction with cellular IgE receptors. Omalizumab is also capable of downregulating the expression of high affinity IgE receptors on inflammatory cells, as well as the numbers of eosinophils in both blood and induced sputum. The clinical effects of omalizumab include improvements in respiratory symptoms and quality of life, paralleled by a reduction of asthma exacerbations, emergency room visits, and use of systemic corticosteroids and rescue bronchodilators. Omalizumab is relatively well-tolerated, and only rarely induces anaphylactic reactions. Therefore, this drug represents a valid option as add-on therapy for patients with severe persistent allergic asthma inadequately controlled by high doses of standard inhaled treatments.

Keywords: anti-IgE; omalizumab; severe asthma.

Figure 1

Mechanism of action of omalizumab. Omalizumab binds to IgE, thus forming immune complexes that reduce levels of circulating free IgE and prevent their interactions with high-affinity IgE receptors (FcɛRI) expressed by dendritic cells, mast cells, basophils, and eosinophils. As a consequence, IgE-dependent antigen presentation, mast cell/basophil degranulation, and eosinophil infiltration are inhibited. Anti-IgE therapy with omalizumab also results in decreased FcɛRI expression. All these effects are responsible for a reduction of allergic airway inflammation, as well as of related asthma symptoms and exacerbations.