Short‐term effect of low‐dose rituximab on myasthenia gravis with muscle‐specific tyrosine kinase antibody
Yufan Zhou, Chong Yan, Xinyu Gu, Lei Zhou, Jun Lü, Wenhua Zhu, Xiao Huan, Sushan Luo, Huahua Zhong, Jie Lin, Jiahong Lu, Chongbo Zhao, Jianying Xi
Abstract
INTRODUCTION/AIMS: The study aims to investigate the short-term efficacy of low-dose rituximab and its effect on immunological biomarker levels in myasthenia gravis (MG) patients with antibodies against muscle-specific tyrosine kinase (MuSK-MG). METHODS: Twelve MuSK-MG patients were enrolled in this prospective, open-label, self-controlled pilot study. Clinical severity was evaluated at baseline and 6 mo after a single rituximab treatment (600 mg). B lymphocyte subtypes, MuSK antibody titers, together with levels of immunoglobulins, serum B-cell activating factor (BAFF), a proliferation-inducing ligand (APRIL), soluble CD40L, and four exosomal microRNAs were evaluated. A correlation matrix to reveal pairwise relationships among above variables was also generated. RESULTS: The single rituximab treatment significantly lowered the clinical severity scores and reduced daily dosage of prednisone (P = .032) at 6 mo. MuSK antibody titers decreased (P = .035) without significant changes in immunoglobulin levels. Serum BAFF level increased (P = .010), which negatively correlated with the percentages of B cells in lymphocytes as well as clinical severity. Additionally, serum exosomal miR-151a-3p showed a reduction of 28.1% (P = .031). DISCUSSION: We confirmed the clinical efficacy of low-dose rituximab in MuSK-MG, accompanied by a decrease in MuSK antibody titers and an increase in serum BAFF. Serum BAFF levels negatively correlated with B-cell counts as well as clinical severity.