Current and Emerging Biologic Therapies for Severe Asthma

Severe asthma is a heterogeneous disorder characterized by persistent symptoms, frequent exacerbations, and corticosteroid dependence despite optimized therapy. Seven monoclonal antibodies are currently approved, targeting immunoglobulin E (IgE; omalizumab), interleukin (IL)-5 or IL-5 receptor α (mepolizumab, reslizumab, depemokimab, benralizumab), IL-4 receptor α (dupilumab), and the epithelial alarmin thymic stromal lymphopoietin (TSLP; tezepelumab). These therapies have demonstrated substantial reductions in exacerbation rates and oral corticosteroid use, along with improvements in lung function and patient-reported outcomes. Safety profiles are generally favorable across populations. Key predictors of response include blood eosinophil counts, fractional exhaled nitric oxide, and phenotype-specific biomarkers. Despite these advances, unmet needs remain. Current biologics only partially address type 2-low, neutrophilic, and mixed granulocytic phenotypes, as well as airway remodeling and persistent exacerbations in type 2-high patients. Emerging strategies aim to overcome these limitations by targeting upstream alarmins (TSLP and IL-33), dual or trispecific cytokine pathways, and IgE-producing B cells. Novel Fc-engineered and dual-receptor anti-IgE monoclonal antibodies enhance the magnitude and durability of IgE suppression. Multi-target constructs, including bispecific and trispecific agents, simultaneously block overlapping type 2 and non-type 2 pathways, which could improve outcomes in heterogeneous and refractory populations. Preclinical and early-phase clinical studies suggest that these approaches may provide disease-modifying effects and support biomarker-guided personalized therapy. This review summarizes the current landscape of approved biologics and the rationale for next-generation therapies in severe asthma. It highlights mechanistic insights, clinical efficacy, and future directions for precision-targeted treatment strategies.