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.
Keywords: TAMA; TAMG; corticosteroid; eculizumab; refractory.
Eculizumab in thymoma-associated myasthenia gravis Patients with unresectable thymomas tend to have more severe symptoms at a younger age, a higher frequency of myasthenic crisis (MC), longer respiratory support duration, and increased mortality compared to those without thymomas. Only a few case reports have explored the therapeutic efficacy of eculizumab in thymoma-associated myasthenia gravis (TAMG), which is a subtype of myasthenia gravis (MG) that is associated with anti-acetylcholine receptor antibodies. Using a multicenter, observational cohort of patients with generalized myasthenia gravis from China, we enrolled patients with TAMG who were refractory to immunotherapies and then switched to eculizumab. Our study revealed a significant improvement in the Myasthenia Gravis Activities of Daily Living (MG-ADL) score in patients with TAMG (7.4 points) by week 12. Moreover, this study demonstrated the efficacy and safety of eculizumab in the TAMG cohort, with most patients experiencing clinical improvement within 2 weeks and an average reduction in steroid dosage of approximately one-third in the first month. Further, we believe that this article will be of interest to the readership of your journal because it provides evidence-based findings that indicate that eculizumab has emerged as a viable treatment option not only for TAMG but also for thymoma-associated multiorgan autoimmunity (TAMA).
© The Author(s), 2024.