A recent study conducted across five research centers in Shanghai, China, has revealed promising results for the use of eculizumab in treating thymoma-associated myasthenia gravis. The study, published in Therapeutic Advances in Neurological Disorders, indicates that eculizumab significantly reduces the severity of symptoms and the need for corticosteroids in patients with this subtype of myasthenia gravis.
The real-world analysis included 22 patients diagnosed with generalized myasthenia gravis who also had thymomas. These patients, treated between June 2023 and June 2024, experienced notable improvements in their Myasthenia Gravis Activities of Daily Living (MG-ADL) scores and a reduction in corticosteroid usage by the 12th week of eculizumab treatment.
Study Details and Patient Characteristics
The study included patients aged 18 years or older with a history of thymomas and seropositivity for anti-AChR antibodies. Participants had to receive at least four eculizumab infusions to complete the induction phase and be vaccinated against Neisseria meningitidis or receive antibiotic prophylaxis. The average age of the patients was 51.5 years, and 54.5% were female. At baseline, the mean AChR antibody level was 15.3 nmol/L, the mean disease duration was 4.0 years, the MG-ADL score was 11.7, and the steroid dose was 41.8 mg. A majority (19 out of 22) had undergone thymectomies.
Efficacy of Eculizumab
Most patients initiated eculizumab treatment due to a myasthenic crisis (27.3%), an impending myasthenic crisis (22.7%), or an acute disease exacerbation (13.6%). By the final follow-up, 81.8% of patients showed clinically meaningful improvements, with initial improvements observed within an average of 1.7 weeks of starting eculizumab. Mean MG-ADL scores progressively declined by 5.3, 6.1, and 7.4 points at 4, 8, and 12 weeks, respectively. Overall, 77% of patients with thymoma-associated myasthenia gravis were classified as ADL responders.
Compared to baseline, the mean oral corticosteroid dose decreased by 44.5% to 23.2 mg by week 12 of eculizumab treatment.
Safety Profile
The safety profile of eculizumab was favorable, with only two patients experiencing treatment-emergent adverse events: one case of COVID-19 and one case of rash/herpes labialis. There were no cases of meningococcal infection or treatment discontinuations. Four patients died, but two had initially improved on eculizumab before succumbing to respiratory or circulatory failure secondary to metastasis.
Subanalysis of Efgartigimod Use
A subanalysis of patients who received efgartigimod before eculizumab showed promising results, with an ending MG-ADL score of 0 in some patients or at least an improved status in others. The cohort's overall MG-ADL baseline score was reduced from 11.6 to 3.4, and their average corticosteroid dose dropped from 31.7 mg to 11.3 mg by week 12.
Implications and Future Directions
The study investigators suggest that the advent of new biologic treatments offers opportunities to explore target-specific immunotherapies in myasthenia gravis, with eculizumab being one such option. They recommend conducting larger randomized controlled trials to confirm eculizumab's efficacy in thymoma-associated myasthenia gravis.
