Abstract Rationale Despite the availability of biologic therapies targeting type 2 (T2) inflammation, a subgroup of patients with severe asthma continue to experience persistent symptoms, frequent exacerbations, and high disease burden. Switching between biologics has become an increasingly common clinical strategy, yet real-world evidence remains limited, particularly regarding ambitious endpoints such as clinical remission. We aimed to assess the clinical benefit of biologic initiation versus switching, and to evaluate strict remission as a meaningful outcome in real-life practice. Methods We conducted a single-center, retrospective study of 97 patients with severe asthma treated with biologics at CHU Humani in Charleroi, Belgium. Patients were divided into two cohorts: biologic initiation (n = 52) and biologic switch (n = 45, last switch analyzed). Outcomes were assessed at baseline and after 12 months and included forced expiratory volume in 1 second (FEV1, % predicted, pre-bronchodilator), Asthma Control Test (ACT) score, fractional exhaled nitric oxide (FeNO), annual exacerbation rate requiring oral corticosteroids (OCS), and blood eosinophil count. Strict clinical remission was defined as ACT ≥ 20, no OCS-requiring exacerbations, and FEV1 ≥ 80% predicted. Paired comparisons were performed using the Wilcoxon test. Results In the combined cohort (n = 97), significant improvements were observed after 12 months: FEV1 increased by 9.4% (n = 90, p 0.01), ACT score improved by 6.8 points (n = 87, p 0.01), and the annual exacerbation rate decreased by 2.3 (n = 96, p 0.01). FeNO decreased by 13.5 ppb (n = 56, p = 0.020) and blood eosinophils decreased by 235/µL (n = 87, p 0.01). Complete clinical remission was achieved in 19.6% of patients after initiation, 18.4% after switch, and 19% overall. Additionally, 52.4% of patients met both ACT ≥ 20 and absence of OCS-requiring exacerbations at 12 months. Conclusion Both initiation of biologic therapy and switching among non-responders were associated with substantial clinical benefit in severe asthma, including improved FEV1, symptom control, and reduced exacerbations, with concordant decreases in type 2 inflammatory markers (eosinophils and FeNO). Strict remission, although achievable in approximately one in five patients, remains highly dependent on definition and data completeness. Biologic switching should be individualized, and prospective multicenter studies with standardized outcome measures are warranted to refine predictors of response and validate remission as a practical therapeutic goal. This abstract is funded by: None
Clemens et al. (Fri,) studied this question.