[How I treat… severe «T2-high» asthma].

Severe asthma refers to uncontrolled asthma despite optimal inhaled treatment combining high-dose inhaled corticosteroids and a long-acting β2 agonist. This condition is characterized by significant clinical and pathophysiological heterogeneity, particularly in terms of inflammation. Understanding the role of type 2 inflammation ("T2-high") has led to the development of biologic therapies targeting cytokines or their receptors, such as interleukin 5 (IL-5), IL-4/IL-13, thymic stromal lymphopoietin (TSLP) and immunoglobulin E (IgE), the impact of which varies depending on the asthma phenotype. Phenotyping is based on the identification of biomarkers such as fractional exhaled nitric oxide, blood eosinophilia and serum IgE levels. Biotherapies have demonstrated a significant reduction in exacerbations, as well as improved symptom control and quality of life. Six molecules are available on the market. The choice of treatment is based primarily on the biomarker profile and associated comorbidities.