Long-term remission of nephrotic syndrome with etanercept for concomitant juvenile idiopathic arthritis

Etanercept is a tumor necrosis factor (TNF)-α inhibitor that has been applied beneficially for juvenile idiopathic arthritis (JIA). We experienced long-term remission of nephrotic syndrome (NS) in a boy treated with etanercept, which was initially used for concomitant JIA. He developed NS at age 3 years 7 months and had mostly been treated with cyclosporine because of steroid dependency and frequent relapses. Cyclosporine was halted at 10 years 7 months because of nephrotoxicity, and he was subsequently treated with mizoribine. However, he had three relapses in the first year and developed JIA at 11 years 7 months. He was treated with sulfasalazine, methotrexate, and prednisolone, but his arthritis persisted. Etanercept was started at 12 years 3 months. Thereafter, his arthritis went into complete remission. Surprisingly, he has remained relapse-free for both NS and JIA for more than 3 years with etanercept and mizoribine. It is difficult to know whether the NS remission after initiating etanercept was coincidental. However, there are many reports of increased TNF-α or soluble TNF-α receptor in NS relapse. To date, there are two reports of the efficacy of TNF-α inhibitors against NS. It is possible that TNF-α inhibitors may have potential as therapeutic agents for NS.