Work

Pembrolizumab-associated myasthenia gravis in thymic tumors: A single-center case series and comparative analysis

Year: 2026

Type: article

Abstract: BackgroundMyasthenia gravis (MG) is commonly associated with thymic tumors and may be triggered or worsened by immune checkpoint inhibitors (ICIs). Although pembrolizumab (PEM) has shown efficacy in relapsed/refractory thymic tumors, its relationship with MG in thymic tumor patients is unclear.MethodsWe retrospectively reviewed patients with thymic tumors treated with PEM at a tertiary center (2016-2021) to assess the prevalence, timing, and clinical features of new-onset or exacerbated MG, along with immune-related adverse events (irAEs). Outcomes were compared with 714 thymic tumor patients not treated with ICIs (1993-2021), stratified by tumor type.ResultsAmong 60 PEM-treated patients (mean age 50.4 years; 33% female), six (10%) developed new-onset (3/60) or relapsed (3/60) generalized MG which worsened after PEM administration. MG occurred in 42% of thymoma (5/12) versus 2% of thymic carcinoma patients (1/43; p = 0.001). All MG cases had other irAEs, most frequently myositis (n = 5) and myocarditis/cardiomyopathy (n = 3). Despite improvement of MG with immunotherapy, three patients died from tumor progression or irAEs. Compared with non-PEM-treated thymoma patients, MG incidence was numerically higher but not statistically significant.ConclusionPEM-treated thymic tumor patients may develop or experience worsening MG, typically with severe symptoms and concurrent irAEs that affect prognosis. While a direct causal link between PEM and MG remains uncertain, careful monitoring is warranted.

Source: Journal of Neuromuscular Diseases

DOI: 10.1177/22143602261486591