The severity of asthma can be graded from mild intermittent disease, with little impact on everyday life, through to severe disease with permanent symptoms and serious limitation of normal activities.
Patients with severe asthma can be broadly classified as eosinophilic (Th2-high) or non-eosinophilic (Th2-low) phenotypes; subpopulations with distinct pathologies, clinical characteristics and treatment management strategies. Despite numerous drugs now being marketed for the treatment of severe asthma (i.e. monoclonal antibody therapies targeting interleukin (IL)-5 and IL-4/IL-13 cytokine pathways), an unmet need persists for many patients. This includes severe non-eosinophilic asthmatics, for whom no targeted therapies are currently available, as well as severe eosinophilic asthmatics with sub-optimal response to anti-interleukin therapies.