Mepolizumab add-on therapy in a real world cohort of patients with severe eosinophilic asthma: response rate, effectiveness, and safety

Introduction: Severe eosinophilic asthma is an incapacitating disease. Mepolizumab, a humanized anti-interleukin-5 monoclonal antibody, proved to be effective as an add-on therapy in patients with severe eosinophilic asthma. However, only data from randomized controlled trials are available and real world data are lacking. Methods: A retrospective observational longitudinal study was conducted in a real world cohort of patients with severe eosinophilic asthma treated with mepolizumab. The primary objective was to determine response rate, based on a global evaluation of treatment effectiveness by the treating pulmonologist. Secondary objectives were to assess exacerbation frequency, systemic maintenance glucocorticoid usage, Asthma Control Questionnaire (ACQ), lung function, and adverse events. Results: Seventy-eight patients were included. Treatment with mepolizumab was considered beneficial and was therefore continued in 75.6% of patients 12 months from the initiation of mepolizumab. The most common reason for drop-out was insufficient response. Secondary objectives: 12 months from the initiation of mepolizumab there was a decrease of 3.2 (CI 2.5–4.1; p < 0.001) severe asthma exacerbations per year, a decrease of ACQ of 0.80 points (CI 0.49–1.12; p < 0.001), and an increase of 3.7 (CI 0.3–7.2; p = 0.034) percent of predicted FEV1 compared to baseline. At baseline 51.3% of patients were treated with systemic glucocorticoid maintenance therapy, compared to 15.4% (p < 0.001) of patients 12 months from the initiation of mepolizumab. No serious adverse events considered to be related to mepolizumab were reported. Conclusion: This study confirms that mepolizumab add-on therapy is effective and safe in a real world cohort of patients with severe eosinophilic asthma