Targeting Th2 cells in asthmatic airways

Asthma represents a profound worldwide public health problem. The most effective anti-asthmatic drugs currently available include inhaled b 2 -agonists and glucocorticoids; these control asthma in about 90–95% of patients. However, the future therapies will need to focus on the 5–10% patients who do not respond well to these treatments and who account for ~50% of the health care costs of asthma [1, 2]. Strategies for the primary prevention of asthma remain in the realm of speculation and hypothesis [3] . Drug development for asthma has been directed at improving currently available drugs and finding new compounds that target the Th2-driven airway inflammatory response. Several new compounds have been developed to target specific components of the inflammatory process in asthma [e.g., anti-IgE antibodies (omalizumab), cytokines and/or chemokines antagonists, immunomodulators, antagonists of adhesion molecules], although they have not yet been proven to be particularly effective. In fact, only omalizumab has reached the market; it may be most cost-effective for patients with severe persistent asthma and frequent severe exacerbations requiring hospital care [3– 5] . In this chapter, we will review the role of current antiasthma drugs and future new chemical entities that can target Th2 cells in asthmatic airways. Some of these new Th2-oriented strategies may, in the future, not only control symptoms and modify the natural course of asthma, but also potentially prevent or cure the disease.