D1.158 - Clinical and Functional Outcomes of Biological Therapy Switching in Severe Asthma: A Real-Life Retrospective Study

Severe asthma represents 5–10% of all asthma cases and is associated with high morbidity, frequent exacerbations and impaired quality of life. Targeted biological therapies such as omalizumab, mepolizumab and benralizumab have improved disease control in selected phenotypes; however, a subset of patients fails to achieve adequate response or loses effectiveness over time, necessitating switching between biological agents. Real-life data regarding outcomes after biological switching remain limited.

This retrospective single-center study included 19 patients with severe asthma who received biological therapy between 2015 and 2025 and underwent biological switching due to insufficient clinical response or medical necessity. Demographic characteristics, blood eosinophil and lymphocyte counts, spirometric parameters (FEV1, FVC, FEF25–75), annual exacerbation rates (hospitalization and/or ≥3 days of systemic corticosteroid use), and Asthma Control Test (ACT) scores were recorded before initial biological therapy, after first biological therapy, and after switching.

Mean age was 47.8 ± 13.4 years and mean body mass index was 36.9 ± 29.4 kg/m². The average age of asthma onset was determined to be 29.42 ± 12.46 years. The mean duration of initial biological therapy was 6.67 ± 7.61 months. Prior to the first biological therapy, the mean eosinophil count was 640 ± 572 cells/µL. (Table 1) After the first biological therapy, eosinophil counts and exacerbation rates significantly decreased (p=0.018 and p=0.003, respectively), and ACT scores improved (p=0.028), whereas spirometric parameters did not show significant changes. (Table 2) Following biological switching, significant improvements were observed in eosinophil counts (p=0.034), FEV1 (p=0.011), FEV1% (p=0.020), FVC (p=0.008), FEF25–75 (p=0.012), exacerbation rates (p=0.001) and ACT scores (p=0.001). Lymphocyte counts did not change significantly. (Table 3)

Switching biological therapy in patients with severe asthma who show inadequate response to initial treatment is associated with meaningful improvements in inflammatory markers, lung function, exacerbation frequency and disease control. Biological switching appears to be an effective real-life strategy in selected patients.