Purpose of review: Severe asthma is a heterogeneous syndrome. Classification of asthma into phenotypes and endotypes can improve understanding and treatment of the disease. Identification and utilization of biomarkers, particularly those linked to T2 inflammation, can help group patients into phenotypes, predict those who will respond to a specific therapy, and assess the response to treatment.

Recent findings: Biomarkers are present in sputum, exhaled breath, and blood of patients with asthma. These include sputum eosinophils and neutrophils, fractional excretion of nitric oxide, blood eosinophilia, IgE, and periostin. Many of these biomarkers are associated with eosinophilic inflammation propagated mainly by T2 cytokines such as IL-5 and IL-13, which are released from Th2 cells and Type 2 innate lymphoid cells. Biomarkers have been utilized in recent trials of novel biologic agents targeted at T2 inflammation and may contribute to the defining population who would respond to these therapies.

Summary: Despite advances in the identification and utilization of asthma biomarkers, further studies are needed to better clarify the role of biomarkers, individually or in combination, in the diagnosis and treatment of severe asthma. Future therapeutic trials should include the use of biomarkers in their design, which may lead to a more personalized approach to therapy and improved outcomes.