Biologic switching in allergic bronchopulmonary aspergillosis: a scoping review of published clinical experience.

Background: Allergic bronchopulmonary aspergillosis (ABPA) is a type 2 (T2) inflammatory pulmonary disorder with limited long-term treatment options. Although biologic therapies targeting T2 inflammation are increasingly used off-label in ABPA, clinical responses are heterogeneous, and some patients require switching between biologic agents. Evidence on biologic switching in ABPA, however, has not been systematically summarized. Methods: We conducted a scoping review following PRISMA-ScR guidelines. PubMed, Embase, and Web of Science were searched from inception to 30 July 2025. Eligible studies included ABPA patients treated with biologics who underwent at least one documented biologic switch. Data on patient characteristics, biologic agents, reasons for switching, switching patterns, and reported clinical outcomes were extracted and summarized. Results: Thirty-one publications were included, comprising 2 retrospective observational studies, 3 case series, and 26 case reports or letters, describing 73 patients with ABPA and 108 biologic switching events. Omalizumab was the most commonly used first-line biologic. The most frequent initial switching pathway was from omalizumab to anti-interleukin (IL)-5/IL-5 receptor agents, while subsequent switching from anti-IL-5/IL-5 receptor therapy to dupilumab was commonly reported. Inadequate clinical response and adverse events were the leading reasons for switching. Across studies, biologic switching was frequently associated with reported clinical improvement, although outcome definitions and follow-up durations varied substantially. Conclusions: Biologic switching is a commonly reported strategy in ABPA management, particularly in patients with inadequate response or intolerance to initial therapy. However, available evidence is largely descriptive and case-based, precluding conclusions regarding comparative efficacy or optimal sequencing. Prospective studies are needed to guide biologic selection and switching in ABPA.