This article is dedicated to the main characteristics of severe bronchial asthma (SBA) and its heterogeneity. In particular, it describes T2 asthma and the role of the main cytokines involved in T2 inflammation. It focuses on the role of IL-4 and IL-13 in the pathogenesis of asthma and other T2-associated diseases, as key cytokines in the initiation and maintenance of T2 inflammation. The article presents the results of experimental studies proving that the activation of IL-4/IL-13 can cause significant hyperresponsiveness of the human airway smooth muscles and the combined blockade of the activity of these cytokines using a human monoclonal antibody against the common IL-4/13 receptor-subunit-dupilumab-determines the clinical efficacy not only in relation to exacerbations and control of asthma symptoms, but also an improvement of the lung function and a reduction in bronchial hyperresponsiveness. When type 2 helper cells (Th2) interact with antigen-presenting cells, IL-4 and IL-13 are simultaneously released, therefore, blocking IL-4Ris more effective than blocking each of the ligands separately, which explains the high efficacy of dupilumab not only in T2 asthma, but also other T2-associated diseases: atopic dermatitis and chronic rhinosinusitis with nasal polyps. In addition to asthma and atopic dermatitis, a new indication for dupilumab, chronic rhinosinusitis with nasal polyps, has recently been approved.
 According to the recommendations of the European Academy of Allergy and Clinical Immunology (EAACI) for the biological therapy of SBA 2020, dupilumab is recommended as an add-on maintenance therapy in adults and children aged 1217 years old with uncontrolled severe T2 asthma, including asthma with the allergic and eosinophilic phenotype, as well as mixed (when there are signs of both phenotypes) and steroid-dependent asthma. At the same time, dupilumab is well tolerated.