Real life experience with omalizumab and mepolizumab in severe asthma : do patient baseline features preclude effectiveness comparison ?

Abstract

RCT have already established the benefits of biotherapies in severe refractory allergic asthma. Among those, omalizumab is a humanized monoclonal antibody that neutralizes circulating IgE antibodies, whereas mepolizumab recognizes and blocks interleukin-5 (IL-5). We conducted a retrospective real life study comparing baseline demographic, functional and immuno-inflammatory features of patients who benefited from omalizumab or mepolizumab between 2007 and 2017. We also examined changes in lung function, quality of life and asthma control in the two cohorts after 16 (omalizumab) and 18 months (mepolizumab). Asthmatics remaining uncontrolled with at least two exacerbations within the previous 12 months despite combination of high dose ICS/LABA benefited from omalizumab (n=147) or mepolizumab (n=81). Those receiving mepolizumab were older (55 vs 48 yrs) and had higher requirements in chronic oral corticosteroids (24%) than those receiving omalizumab (12%). Baseline FEV1, ACQ and AQLQ were similar between the two cohorts. Patients with mepolizumab had greater blood eosinophil counts but lower total serum IgE. At 16/18 months, there was significant improvement in FEV1 (%pred), ACQ and AQLQ in each group. Exacerbation rate was maintained below 1/patient/year in both groups despite reduction in OCS and ICS dose. We conclude that patients receiving mepolizumab were slightly older and more severely affected than those receiving omalizumab, and that both biotherapies bring significant clinical improvement in a real life setting. Direct size effect comparison between treatment groups must be cautious as baseline features are different between the two cohorts.