Efficacy of Mepolizumab in patients with previous Omalizumab treatment failure: real life observation

Several severe asthmatic patients, correctly treated with Omalizumab, display a poor response to the drug. Empirically, if these subjects meet the prescription criteria also for anti-IL-5 treatment, a switch can be attempted. Our aim is to evaluate, in real-life, the effects of switching to Mepolizumab in patients where Omalizumab failed. This was a retrospective, chart-based analysis of patients treated with Omalizumab, who did not respond, and therefore switched to Mepolizumab. All the enrolled patients fulfilled indications for both drugs. Omalizumab was discontinued due to poor efficacy (no reduction in exacerbations, persisting need for systemic steroids, unsatisfactory control of symptoms). Clinical and biological data were collected before Omalizumab, at Omalizumab stop (pre-Mepolizumab) and after 1 year of Mepolizumab. 27 patients (female 52%, range 21-81 years) underwent the drug switch. No significant change, in the considered parameters, was seen during the Omalizumab treatment. On the contrary, after Mepolizumab, the exacerbation rate decreased by 81% (p< .0001), with a parallel reduction of hospitalizations (82%; p= .044). The oral steroid intake fell by 81% with a mean reduction from 16.9±11.6 mg to 1.7±4.4 mg of prednisone. Forced Expiratory Volume 1-second increased by 24% (p= .022), with a mean gain of 350 mL. The ACT increased by 39%; (p< .0001). No adverse event was observed. In selected severe asthmatic patients, not adequately controlled by Omalizumab, despite a correct prescription, a switch to Mepolizumab, if criteria are fulfilled, maybe successful, and the switch seems to be justified, at least on empirical basis.