Jackson, David J.

Abstract Rationale: The 1-year double-blind period of the MANDARA trial (NCT04157348) demonstrated non-inferiority of benralizumab to mepolizumab for achieving remission, in adults with relapsing/refractory eosinophilic granulomatosis with polyangiitis (EGPA). Here, we report the 2-year combined double-blind and ongoing open-label extension (OLE) data. Methods: On completion of the double-blind period (n=136/140) comparing benralizumab 1x30mg versus mepolizumab 3x100mg subcutaneously every 4 weeks, patients were invited to enter the OLE where they continued benralizumab (benra/benra) or switched from mepolizumab to benralizumab (mepo/benra). Endpoints included remission (Birmingham Vasculitis Activity Score=0 and oral glucocorticoid [OGC[ dose ≤4 mg/day), OGC use, relapse, blood eosinophil count (bEOS), Asthma Control Questionnaire (ACQ-6), pre-bronchodilator forced expiratory volume in 1 second (pre-BD FEV1), and safety. Results: In total, 128 patients entered the OLE (n=66 benra/benra, n=62 mepo/benra; mean age 52.8 years; 60.2% female), and 119 completed OLE Year 1. Baseline characteristics of those entering the OLE were similar to the double-blind period. At Week 104, over 60% in both groups (41 [62.1%] benra/benra and 42 [67.7%] mepo/benra patients) achieved remission. During the OLE, 51 (77.3%) benra/benra and 42 (67.7%) mepo/benra patients had no relapses. The percentage of benra/benra patients who discontinued OGCs was similar at Weeks 49-52 (27 [40.9%]) and Weeks 101-104 (29 [43.9%]), while the percentage increased for mepo/benra patients between Weeks 49-52 (16 [25.8%]) and Weeks 101-104 (27 [43.5%]; Figure). The median (IQR) OGC dose at Weeks 101-104 was 0.5 (0,5) in benra/benra and 1.36 (0,5) mg/day in mepo/benra patients. The median (IQR) bEOS in benra/benra patients was 20 (10,40) cells/µL at both Weeks 52 and 100; bEOS were depleted in mepo/benra patients from 70 (40,90) cells/µL to 20 (10,50) cells/µL by 4 weeks after switching. Mean (SD) ACQ-6 scores were 0.64 (0.78) in benra/benra patients and 0.60 (0.76) in mepo/benra patients at Week 104 compared with 1.39 (1.18) and 1.11 (0.95) at baseline. Mean (SD) pre-BD FEV1 was 2.59 (0.90) L versus 2.62 (0.84) L in benra/benra versus mepo/benra patients at Week 52, and 2.61 (0.90) versus 2.63 (0.81) L, at Week 100. Safety of mepolizumab and benralizumab was consistent with their known profiles. Conclusions: In patients with EGPA receiving benralizumab, remission rates, OGC discontinuation, and bEOS depletion were durable over 104 weeks with low relapse rates, and without loss of asthma control or lung function decline. Additional bEOS depletion and OGC sparing was observed in patients switching from mepolizumab to benralizumab.

The enigmatic eosinophil has emerged as an exciting component of the immune system, involved in a plethora of homeostatic and inflammatory responses. Substantial progress has been achieved through experimental systems manipulating eosinophils in vivo, initially in mice and more recently in humans. Researchers using eosinophil knockout mice have identified a contributory role for eosinophils in basal and inflammatory processes and protective immunity. Primarily fueled by the purported proinflammatory role of eosinophils in eosinophil-associated diseases, a series of anti-eosinophil therapeutics have emerged as a new class of drugs. These agents, which dramatically deplete eosinophils, provide a valuable opportunity to characterize the consequences of eosinophil knockout humans. Herein, we comparatively describe mouse and human eosinophil knockouts. We put forth the view that human eosinophils negatively contribute to a variety of diseases and, unlike mouse eosinophils, do not yet have an identified role in physiological health; thus, clarifying all roles of eosinophils remains an ongoing pursuit.