Emerging therapies for severe asthma

Asthma is a chronic inflammatory disease of the airways that affects over 300 million individuals worldwide [1]. The majority of adults with asthma have mild or moderate disease that can be controlled by inhaled corticosteroids either alone or in combination with inhaled long-acting ？2 agonist bronchodilators [1-3]. Questionnaire surveys however indicate that a considerable proportion of these patients [4], as well as most with severe asthma [5], or who are cigarette smokers [6,7] have poorly controlled asthma. Systematic evaluation can help identify patients with severe asthma from those with difficult-to-treat asthma due to poor adherence, untreated co-morbidities, dysfunctional breathing or psychological problems [8,9]. For patients with severe asthma, which accounts for 5% to 10% of cases [10], there is a need for improved therapies [10-12]. This mini-review focuses on biological agents, new inhaled long-acting bronchodilators and corticosteroids, arachidonic acid pathway blockers, bronchial thermoplasty plus a range of other anti-inflammatory agents that have been recently licensed or are at an advanced stage of development for patients with severe asthma (Figure 1). In addition, we briefly discuss the idea that the development of novel therapies for asthma is likely increasingly to involve the assessment of genotypic and/or phenotypic factors.The first and as yet only biological agent licensed for the treatment of asthma is omalizumab, a humanized monoclonal antibody that binds circulating IgE antibody, preventing it from binding to its specific high-affinity receptor on mast cells and basophils [13]. In patients with allergic asthma, omalizumab treatment improves symptoms and reduces exacerbations [14,15]. Clinical trials are also underway to assess the efficacy of omalizumab in non-allergic asthma and in combination with specific allergen immunotherapy, with the aim of reducing systemic allergic reactions [16]. The adverse effect profile of omalizumab is gen