Treatment Patterns and Outcomes of Anti-MuSK Antibody-Positive Myasthenia Gravis: A Retrospective Single-Center Study

Abstract

Background: There is limited knowledge regarding the real-world treatment status of muscle-specific tyrosine kinase antibody-positive myasthenia gravis (MuSK-MG) patients in clinical practice. The aim of this study was to analyze the overall treatment patterns and outcomes of MuSK-MG in Korea. Methods: In this single-center cohort study, we retrospectively included patients diagnosed with MuSK-MG. We analyzed their demographic features, clinical characteristics, treatment patterns focusing on corticosteroids (CSs), non-steroidal immunosuppressants (NSISs), and rituximab, and treatment outcomes. Specifically, we investigated the achievement of minimal manifestation status with a prednisolone dose 5 mg/day or below (MM-5). Results: The study included 30 patients with MuSK-MG, predominantly female (93.3%). The average age at time of diagnosis was 43.9 +/- 16.0 years, with the onset age of 42.3 +/- 16.2 years. All patients initially received CSs, and 24 patients (80%) were treated with NSISs. Tacrolimus was the most frequently prescribed NSIS, used in 70.8% of cases, followed by azathioprine (62.5%). All 10 patients who received rituximab therapy showed clinical improvement, with 5 patients (50%) achieving MM-5. Conclusion: This study summarized the treatment patterns and outcomes of patients with MuSK-MG in real-world clinical settings. As patients who received rituximab demonstrated a favorable prognosis, early administration of rituximab may be an effective treatment strategy for MuSK-MG, potentially reducing the adverse effects associated with long-term use of CSs and NSISs. Rituximab should be considered early in MuSK-MG patients who show insufficient response to initial immunosuppressive treatment.