Biologic Therapy in Severe Asthma: A Phenotype-Driven and Targeted Approach

Asthma is a highly heterogeneous respiratory disease that, in its severe forms, is characterized by persistent symptoms, frequent exacerbations, and a significant impact on patients' quality of life. Despite high-dose inhaled corticosteroids and long-acting bronchodilators, a subset of patients remains uncontrolled, necessitating advanced therapeutic strategies. The advent of biologic therapies has revolutionized the management of severe asthma, offering targeted interventions based on the underlying inflammatory endotypes, primarily T2-high and T2-low. However, selecting the most appropriate biologic remains challenging due to overlapping phenotypic features and the limited availability of validated biomarkers. This narrative review explores the clinical utility of key biomarkers, including blood eosinophils, fractional exhaled nitric oxide (FeNO), periostin, and total and specific IgE, in guiding biologic therapy. All the information provided is based on an extensive literature search conducted on PubMed. We also examine the clinical characteristics and comorbidities that influence therapeutic choices. Furthermore, we present a practical decision-making platform, including a clinical table matching phenotypes with biologic agents, such as omalizumab, mepolizumab, benralizumab, dupilumab, and tezepelumab. By integrating biomarker analysis with clinical assessment, based on current guidelines and our extensive real-life experience, we aim to offer a logical framework to help clinicians select the most suitable biologic treatment for patients with uncontrolled severe asthma. Future research should focus on identifying novel biomarkers, refining patient stratification, and evaluating long-term outcomes to further advance precision medicine in the management of severe asthma.