P199 Mepolizumab improves and sustains asthma control and lung function in patients with severe asthma independent of baseline blood eosinophil count in the real world: results from REALITI-A at 2 years

<h3>Introduction and Objectives</h3> Preliminary 1-year analyses from the real-world REALITI-A study demonstrated mepolizumab improvements in asthma control and lung function, a key outcome measurement, with mepolizumab treatment across blood eosinophil count (BEC) levels, in patients with severe asthma. However, additional real-world evidence on the sustained effect of mepolizumab across BEC ranges is required. <h3>Methods</h3> REALITI-A was a 2-year, international, observational, prospective, single-arm study enrolling patients (≥18 years) with severe asthma, newly prescribed mepolizumab (100 mg subcutaneously). Changes from baseline in asthma control (Asthma Control Questionnaire-5 [ACQ-5] scores, minimal clinically important difference: 0.5) and lung function (forced expiratory volume in 1 second [FEV₁]) were assessed for baseline BEC subgroups (&lt;150, ≥150−&lt;300, ≥300−&lt;500, ≥500 cells/µL) at 1-year and 2-years post-mepolizumab exposure. <h3>Results</h3> 822 treated patients were included. ACQ-5 scores decreased from baseline to 2-years post-mepolizumab exposure across all BEC subgroups (figure 1; mean change from baseline [95% CI]: &lt;150 cells/µL, -1.40 [-3.27, 0.47]; ≥150−&lt;300 cells/µL, -1.76 [-2.34, -1.19]; ≥300−&lt;500 cells/µL, -1.74 [-2.15, -1.33]; ≥500 cells/µL, -1.88 [-2.23, -1.53]). Improvements in ACQ-5 were sustained from 1-year post-exposure reductions (mean change from baseline at 1-year [95% CI]: -1.06 [-1.68, -0.44]; -1.19 [-1.81, -0.57]; -1.37 [-1.84, -0.90]; -1.65 [-2.01, -1.28], respectively). Lung function (FEV₁) improved from baseline to Month 21–24 post-mepolizumab exposure for the BEC ≥300 cells/µL subgroups (figure 1; mean change from baseline [95% CI]: ≥300−&lt;500 cells/µL, 261.5 [111.1, 411.9]) and ≥500 cells/µL, 275.6 [160.5, 390.6]), sustained from changes in FEV₁ at Month 9–12 post-exposure (mean change from baseline [95% CI]: 130.1 [-3.4, -263.7] and 239.4 [141.7, 337.2], respectively). Improvements in lung function were less consistent in the BEC groups &lt;300 cells/µL. <h3>Conclusions</h3> This analysis confirms treatment with mepolizumab in a real-life setting improves asthma control independent of baseline BEC, while lung function shows greater improvement with increased BEC; improvements observed at 1 year are maintained at 2 years.