Effectiveness and clinical characteristics of biologic switching in severe asthma patients with inadequate response to initial biologic therapy: a systematic review

Bronchial asthma (hereafter referred to as asthma) is a common chronic inflammatory airway disease affecting more than 300 million people worldwide. Although most patients achieve control with conventional or biologic therapies, a subset of patients with severe asthma has an inadequate response to biologic treatment. This systematic review aimed to evaluate the effectiveness of biologic switching in these patients and to describe the estimated prevalence of smoking, nasal polyps, chronic rhinosinusitis, allergic rhinitis, atopic dermatitis, and atopy. PubMed, Embase, Web of Science, Cochrane Library, and CNKI were searched from inception to April 10, 2026. An update was performed on July 27, 2026, to capture studies published between April 10, 2026, and July 27, 2026. Studies including patients with severe asthma who switched biologics due to an inadequate initial response were eligible. Methodological quality was assessed using MINORS. Meta-analysis was not feasible for treatment efficacy outcomes because of substantial heterogeneity. However, random-effects single-arm meta-analyses were performed for baseline prevalence outcomes. Twenty-one studies involving 956 patients were included. The estimated prevalence of current or former smoking was 35%. Prevalence estimates were 53% for chronic rhinosinusitis, 47% for nasal polyps, 32% for allergic rhinitis, 10% for atopic dermatitis, and 83% for atopy (defined by positive skin prick test and/or specific IgE). Most studies reported improvement in one or more clinical outcomes after switching to an alternative biologic. However, given that all included studies were of uncontrolled observational designs, the findings of this study are descriptive in nature and do not provide a basis for inferring a causal relationship between specific comorbidities and the need for biologic switching. Available observational evidence suggests that switching to alternative biologics may be associated with improvement in multiple clinical outcomes in patients with severe asthma who exhibit an inadequate response to initial biologic therapy. Upper airway comorbidities were common in biologic switchers with insufficient initial response, but their descriptive findings lack predictive value and warrant comparative validation. This systematic review was registered retrospectively with PROSPERO (CRD420261376157) on April 22, 2026.