Efficacy and Safety of Tacrolimus in Myasthenia Gravis: A Systematic Review and Meta-analysis

AIMS: This study was designed to determine whether treatments with tacrolimus would provide benefit for patients with myasthenia gravis (MG). MATERIALS AND METHODS: The databases of Medline, EMBASE, the Cochrane Library, and four Chinese databases were searched for eligible studies. Weighted mean differences and standardized mean differences (SMD) with corresponding 95% confidence intervals (CIs) were used to summarize the primary outcome, namely, steroid-sparing effect of tacrolimus in maintaining minimal manifestations, and the secondary outcome, namely, the effect of tacrolimus in reducing the severity of MG, respectively. RESULTS: After systematic retrieval, 13 researches with two randomized controlled trials (RCTs) and 11 prospective open-label single-arm clinical trials were included in the study. For the primary outcome of two RCTs, one RCT which was followed up for 1 year showed a positive effect and the other RCT which was associated with treatment duration of 28 weeks showed a negative result. For the secondary outcome, meta-analyses of other 11 trials showed a benefit effect, overall. For the quantitative MG (QMG) score, there were significant differences with high heterogeneity (SMD: 2.93; 95% CI: 1.14–4.73; I(2) = 86%). In contrast, for MG activities of daily living (MGADL) score, it was reduced by tacrolimus with significant SMD and less heterogeneity (SMD: 0.59; 95% CI: 0.33–0.85; I(2) = 7%). Adverse effects were mentioned as mild. DISCUSSION: The opposite results of two RCTs showed that tacrolimus with enough treatment duration might have positive steroid-sparing effect. The most possible cause of heterogeneity in the outcome of QMG score between trials was the baseline severity of MG. CONCLUSION: The above finding suggests that there might be a potential beneficial role with no serious side effects of tacrolimus, and additional better RCTs including larger sample sizes and long-term study are needed to confirm or refute the results.