Post‒marketing Surveillance of Mepolizumab Use in Patients with Eosinophilic Granulomatosis with Polyangiitis in Japan：Interim Analysis

Objectives：This post‒marketing surveillance study assessed the real‒world safety of mepolizumab in Japanese patients with eosinophilic granulomatosis with polyangiitis （EGPA）. 　　Methods：This ongoing all‒case study（GSK ID：208505）commenced in May 2018；here we report a 48‒week interim analysis using data up to March 23, 2020. Patient data were collected for the 4 weeks preceding and up to 48 weeks following mepolizumab initiation for the treatment of EGPA. Patients with data at Week 12 were included；Week 48 data were included where available. Adverse events（AEs）and serious AEs following mepolizumab initiation were identified using case report forms. In particular, important remispotential risks for mepolizumab identified by the Japanese Risk Management Plan were assessed. 　　Results：Of the 321 included patients, 58.6％（n＝188）were female and 60.1％（n＝193）were ＜65 years of age；72.3％（n＝232）of patients had a disease duration ≦5 years and 60.7％（n＝195）had a disease severity grading of III（range I‒V）. AEs were reported in 24.0％（n＝77）of patients and were serious in 12.8％（n＝41）of patients. The most common AEs were infections, reported in 7.5％（n＝24）of patients；3.4％（n＝11）of patients had serious infections and infestations. Hypersensitivity reactions were reported in 5.3％（n＝17）of patients and 2.2％（n＝7）of patients had serious hypersensitivity reactions. No malignancy was observed. Mepolizumab was discontinued in three patients with AEs；three deaths were reported（thalamus haemorrhage, capillary leak syndrome, pneumonia aspiration）. 　　Conclusions：This interim analysis of the post‒marketing surveillance study in Japan showed mepolizumab was well‒tolerated in patients with EGPA.