Real-life evaluation of the clinical, functional, and hematological effects of mepolizumab in patients with severe eosinophilic asthma: Results of a single-centre observational study

Mepolizumab is a humanized monoclonal antibody which targets interleukin-5 (IL-5) and is nowadays available in many countries for add-on biological therapy of severe eosinophilic asthma. Although the approval of mepolizumab use in clinical practice has been made possible by several successful pre-marketing controlled trials, so far only a very few studies have been performed in a real-life setting. Within such a context, our present observational investigation refers to 14 patients with refractory eosinophilic asthma, currently treated with mepolizumab at the Respiratory Unit of "Magna Griecia" University Hospital located in Catanzaro, Italy, whose anti-IL-5 treatment began between June 2017 and January 2018. These patients experienced a significant increase in asthma control test (ACT) score, that was evaluated at baseline (13.64 +/- 3.00), as well as after 4 weeks (18.86 +/- 3.15; p < 0.0001) and 24 weeks (20.07 +/- 1.94; p < 0.0001) of add-on therapy with mepolizumab. This relevant improvement in symptom control was paralleled by a dramatic fall of blood eosinophil numbers, counted at baseline (647.1 +/- 274.7 cells/mu l), and at the 4th (147.8 +/- 66.5 cells/mu l; p < 0.0001) and 24th week (98.6 +/- 40.3 cells/mu l; p < 0.0001) after starting add-on treatment with mepolizumab. These changes were associated with significant and stable increases in FEV1, which was recorded at baseline (1389 +/- 454.3 mL), as well as after 4 weeks (1711 +/- 482.3 mL; p < 0.001) and 24 weeks (1701 +/- 456.0 mL; p < 0.01). Moreover, in comparison to the 6 months preceding the beginning of treatment with mepolizumab, after 24 weeks of anti-IL-5 therapy significant decreases were detected with regard to exacerbation numbers (from 3.64 +/- 1.86 to 1.0 +/- 0.78; p < 0.001) and oral intake of prednisone (from 24.11 +/- 10.36 mg/day to 1.78 +/- 3.82 mg/day). Therefore, these preliminary data referring to our single-centre observational study corroborate, in a real-life environment, the efficacy of mepolizumab for treatment of patients with exacerbation-prone, corticosteroid-refractory, severe eosinophilic asthma.