Long-term efficacy and safety of tacrolimus in young children with myasthenia gravis

This study was performed to evaluate the efficacy and long-term safety of tacrolimus for young children with myasthenia gravis (MG).Children with corticosteroids (CSs)-ineffective, CSs-dependent or CSs-intolerable MG treated with tacrolimus for at least one year were recruited. The Myasthenia Gravis Foundation of America (MGFA) clinical classification and MGFA post-intervention status (MGFA-PIS) were used to evaluate before tacrolimus administration and at the last visit, respectively. MG Activities of Daily Living (MG-ADL) score and the dose of prednisone were recorded. Patients were divided into responders and poor responders based on changes in MG-ADL score to investigate the factors that affected tacrolimus efficacy. Unfavorable events were recorded.Twenty-one patients with MG were enrolled. The median age of starting tacrolimus was 8.7 (range 2.2-15.1) years old. At the last visit, 15 patients (71.4%) achieved minimal manifestation (MM) or better status. The symptoms evaluated by MG-ADL improved significantly one month after initiating tacrolimus (p＜0.05) and the dose of prednisone decreased significantly three months later (p＜0.05), and it continued to improve throughout the study. Thirteen patients (61.9%) were ultimately weaned off prednisone. Compared with 16 responders, 5 poor responders had lower MG-ADL scores. MG-ADL score was the only clinical factor of tacrolimus efficacy. Intraocular pressure and transient urine microprotein were present in one patient.A course of tacrolimus of more than one year was effective and well-tolerated in young children with MG, and tacrolimus improved MG symptoms and reduced the dose and adverse events of oral prednisone.