Pharmacologic Treatment of Type 2-High Severe Asthma

Abstract

Asthma is a common and heterogeneous disease whose treatment has considerably changed over the last decades. While inhaled therapies based on inhaled corticosteroids and long acting β2 agonists are effective in controlling asthma in the majority of patients, about 5% of asthmatics poorly respond to inhaled steroids or inhaled steroids/long acting β2 agonists combinations. These patients are affected by “severe asthma”, which is associated with need of oral corticosteroids, progression of the disease, increased use of healthcare services, deterioration of quality of life, and a significant economic burden on society. Asthma is no longer considered a single disease, but a respiratory syndrome with complex biological network of distinct and interrelating inflammatory and remodeling pathways (endotypes) that are associated with different clinical manifestations (phenotypes) both in the lungs (asthma) and other organs (e.g. nose and skin). Severe asthma endotypes may be broadly regarded as Type 2-high and Type 2-low, a model that has become central to asthma management with the development of novel treatments for the Type 2-high endotypes. The hallmark feature of Type 2-high asthma is eosinophilic inflammation, often associated with increased serum IgE, increased exhaled nitric oxide (FeNO) and blood eosinophilia. The discovery of the main key drivers of Type 2-high inflammation (IgE, cytokines such as interleukin IL-5, -4 and -13) enabled the development of new biological agents directed towards specific molecular targets. These advances have shifted the existing paradigm “one drug fits all” to “patient-tailored” novel therapies. The monoclonal antibodies direct to IgE (omalizumab), IL-5 and IL-5 receptor (mepolizumab, benralizumab, reslizumab), and to the α chain of the IL-4 and IL-13 combined receptor (dupilumab), and more recently, to the thymic stromal lymphopoietin (tezepelumab) have been shown in both clinical trials and real-life studies to control symptoms, reduce asthma exacerbations and improve lung function in severe asthmatics not controlled by full inhalation therapies. More recently, the Single Inhaler Triple Therapy (SITT) containing inhaled steroids, long acting β2 agonists and muscarinic antagonists has been developed, slightly improving the effectiveness/safety of the inhalation therapy. This report aims to review available therapeutic opportunities for patients with severe asthma focusing on patients with Type 2-high severe asthma and how to position these new therapeutic alternatives in clinical practice.