Abstract
BACKGROUND: Severe asthma (SA) is a heterogeneous disease composed of various clinical phenotypes, and criteria for selecting the most appropriate biological agent remain unclear. Therefore, when optimal control cannot be achieved with the initial biological therapy, switching between biological drugs is often performed. METHODS: This real-world study evaluated patients with severe asthma who initiated omalizumab treatment. Based on their treatment response, patients were divided into two groups: those who continued omalizumab and those who switched to mepolizumab or benralizumab. Clinical data were evaluated before biological treatment, after omalizumab therapy, and following the second biological therapy. Additionally, factors influencing the decision to switch and the effectiveness of the switch were analyzed. RESULTS: Of the total 51 patients, 45.1% (n = 23) switched to a second biological agent due to inadequate response to the initial treatment. In the "Switch" group, baseline forced expiratory volume in one second (FEV₁) levels were significantly lower, while blood eosinophil counts (BEC) and exacerbation frequency were higher (p < 0.05). Although limited clinical improvement was observed after omalizumab treatment, significant improvements in asthma control test (ACT) scores, FEV₁, BEC, exacerbations, and hospitalizations were noted following the second biological therapy (p < 0.001). Low baseline FEV₁, high BEC, and frequent exacerbations were the main predictors of the decision to switch. CONCLUSIONS: In severe asthma patients who do not achieve adequate control with omalizumab, switching to interleukin-5 (IL-5) targeted biological therapies may provide clinically significant improvements. Baseline clinical parameters can serve as useful predictors for the need to change biological treatment.