Eculizumab in thymoma-associated myasthenia gravis: a real-world cohort study
Lei Jin, Dingxian He, Quantao Zeng, Song Tan, Jian‐Quan Shi, Ying Liu, Zhang‐Yu Zou, Jie Song, Chong Yan, Xiao Huan, Yuan Wang, Lei Yang, Jianying Xi, Zongtai Wu, Ziqi Liu, Jianming Zheng, Chongbo Zhao, Xianglin Chu, Sushan Luo
Abstract
Background: Thymoma-associated myasthenia gravis (TAMG) is a subtype of myasthenia gravis (MG) that is associated with more severe symptoms and a relatively poor prognosis. Eculizumab, an inhibitor to target human C5 component of the complement cascade, is considered a treatment option for refractory generalized MG (gMG). Objectives: To explore the safety and efficacy of eculizumab in patients with TAMG. Design: This is an observational multicenter real-world cohort study to assess TAMG who were treated with eculizumab from June 2023 to June 2024. Data sources and methods: Clinical features associated with thymoma-associated multi-organ autoimmunity (TAMA), Myasthenia Gravis Activities of Daily Living (MG-ADL) score, and the incidence of treatment-emergent adverse events (TEAEs) were prospectively collected. Results: Overall, 42 patients with gMG were treated with eculizumab at 5 research centers, of whom 22 patients with TAMG were finally included. This cohort had a mean age of 51.5 ± 12.1 years and an average disease duration of 4.0 ± 4.3 years. Regarding thymomas, the World Health Organization (WHO) histological classification was primarily B2 and B3 (63.7%), and Masaoka staging was predominantly IV (45.5%). Nine participants (40.9%) switched from efgartigimod to eculizumab aiming at a better clinical improvement and reducing steroid use. By week 12, the MG-ADL score decreased to 4.8 ± 4.7 (baseline: 11.7 ± 6.0), and the corticosteroid dose reduced to 23.2 ± 26.5 mg (baseline: 41.8 ± 63.9 mg). Two patients with TAMA showed significant improvement in skin lesions and thrombocytopenia. Two TEAEs were recorded including COVID-19 and herpes labialis infection. Four patients (18.2%) died of respiratory or circulatory failure owing to thymoma metastasis. Conclusion: This real-world study demonstrates the efficacy of eculizumab in achieving symptom control and corticosteroid reduction for TAMG. It may also be a therapeutic option for refractory TAMG and TAMA. Trial registration: NCT04535843.