Efficacy and safety of tacrolimus in myasthenia gravis: A systematic review and meta-analysis

This study was designed to determine whether treatments with tacrolimus would provide benefit for patients with myasthenia gravis (MG).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.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; I2 = 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; I2 = 7%). Adverse effects were mentioned as mild.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.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.