Biologic therapies for severe asthma with persistent type 2 inflammation

Asthma is a chronic inflammatory airways disease with reversible airflow obstruction, characterised in the majority by type 2 airway inflammation. Type 2 inflammation results in secretion of interleukin-4, -5 and -13 in the airways, recruitment of inflammatory cells (especially eosinophils and mast cells), and airway changes such as mucus hypersecretion and increased airway reactivity. Approximately 5 to 10% of people with asthma, despite optimal therapy and adherence to treatment with inhaled corticosteroids and long-acting beta₂ agonists, are unable to obtain good symptom control and continue to experience exacerbations requiring oral corticosteroids; this is known as 'severe asthma'. In many cases, this is associated with persistent type 2 inflammation, indicated by the persistent elevation of blood eosinophils or fractional exhaled nitric oxide. In people with severe asthma and persistent type 2 inflammation, biologic (monoclonal antibody) therapy is indicated. Biologic therapies currently available in Australia for asthma are benralizumab, dupilumab, mepolizumab and omalizumab. They are administered subcutaneously and are generally well tolerated. Biologic asthma therapies are very effective in improving symptoms, and reducing the rate of exacerbations and use of oral corticosteroids, in people with severe asthma and persistent type 2 inflammation. Inhaled corticosteroid treatment should be continued in people using a biologic therapy.