Safety and Efficacy of Mepolizumab in Hypereosinophilic Syndrome: An Open-Label Extension Study
Gerald J. Gleich, Florence Roufosse, Geoffrey Chupp, Stanislas Faguer, Bastian Walz, Andreas Reiter, Steven W. Yancey, Jane H. Bentley, Jonathan Steinfeld, Gabriel Ricardo García, Pablo Pascale, Luis Wehbe, Daniël Blockmans, Florence Roufosse, Martti Antila, Daniela Blanco, Andreia Luisa Francisco Pez, Stanislas Faguer, Jean‐Emmanuel Kahn, Guillaume Lefèvre, A. Néel, Peter Kern, Andreas Reiter, Bastian Walz, Tobias Welte, Fabrizio Pane, Alessandro M. Vannucchi, Ruth Cerino-Javier, Dante Daniel Hernández-Colín, Héctor Glenn Valdéz-López, Izabela Kupryś‐Lipińska, Jacek Musiał, Enikő Mihály, Viola Maria Popov, Vladimir Ivanov, Nikolay Tsyba, María C. Cid, María Laura Fox, Guillermo Sanz Santillana, Andrew J. Wardlaw, Praveen Akuthota, Joseph H. Butterfield, Geoffrey Chupp, Gerald J. Gleich, Devi Jhaveri, Marc E. Rothenberg
Abstract
BackgroundA double-blind, placebo-controlled, phase III study (200622) showed that mepolizumab reduces disease flares for patients with uncontrolled FIP1-like-1-platelet-derived growth factor receptor α–negative hypereosinophilic syndrome (HES) and two or more flares in the previous year.ObjectiveTo further characterize the safety, clinical benefit, and pharmacodynamics of mepolizumab.MethodsEligible patients from both treatment arms of the double-blind study could enter an open-label extension study (205203; NCT03306043) to receive 4-weekly mepolizumab (300 mg subcutaneously) plus background therapy for 20 weeks. Primary end points were safety-based; other end points included flare rates and changes from baseline in mean daily oral corticosteroid (OCS) dose and blood eosinophil count.ResultsOf 104 patients who completed the double-blind study, 98% (previous placebo, n = 52; previous mepolizumab, n = 50) enrolled in the open-label extension. Overall, 66 of patients reported adverse events (AEs) (65%), 15 reported treatment-related AEs (15%), and nine reported serious AEs (9%). No events were fatal. The annualized flare rate (95% confidence interval) in the previous placebo and previous mepolizumab groups was 0.37 (0.16-0.86) and 0.14 (0.04-0.49) events/y, respectively. Of 72 patients receiving OCS during weeks 0 to 4, 20 (28%; previous placebo, n = 14; previous mepolizumab, n = 6) achieved 50% or greater reductions in mean daily dose during weeks 16 to 20. At week 20, blood eosinophil count was reduced by 89% in patients previously receiving placebo and remained reduced for those previously receiving mepolizumab.ConclusionsExtended mepolizumab treatment was associated with a positive benefit–risk profile. Continued control of disease flares and blood eosinophil counts, plus reductions in OCS use, were observed with mepolizumab in patients with FIP1-like-1-platelet-derived growth factor receptor α–negative HES. A double-blind, placebo-controlled, phase III study (200622) showed that mepolizumab reduces disease flares for patients with uncontrolled FIP1-like-1-platelet-derived growth factor receptor α–negative hypereosinophilic syndrome (HES) and two or more flares in the previous year. To further characterize the safety, clinical benefit, and pharmacodynamics of mepolizumab. Eligible patients from both treatment arms of the double-blind study could enter an open-label extension study (205203; NCT03306043) to receive 4-weekly mepolizumab (300 mg subcutaneously) plus background therapy for 20 weeks. Primary end points were safety-based; other end points included flare rates and changes from baseline in mean daily oral corticosteroid (OCS) dose and blood eosinophil count. Of 104 patients who completed the double-blind study, 98% (previous placebo, n = 52; previous mepolizumab, n = 50) enrolled in the open-label extension. Overall, 66 of patients reported adverse events (AEs) (65%), 15 reported treatment-related AEs (15%), and nine reported serious AEs (9%). No events were fatal. The annualized flare rate (95% confidence interval) in the previous placebo and previous mepolizumab groups was 0.37 (0.16-0.86) and 0.14 (0.04-0.49) events/y, respectively. Of 72 patients receiving OCS during weeks 0 to 4, 20 (28%; previous placebo, n = 14; previous mepolizumab, n = 6) achieved 50% or greater reductions in mean daily dose during weeks 16 to 20. At week 20, blood eosinophil count was reduced by 89% in patients previously receiving placebo and remained reduced for those previously receiving mepolizumab. Extended mepolizumab treatment was associated with a positive benefit–risk profile. Continued control of disease flares and blood eosinophil counts, plus reductions in OCS use, were observed with mepolizumab in patients with FIP1-like-1-platelet-derived growth factor receptor α–negative HES.