Mizoribine Provided Effective Maintenance Therapy Following Cyclophosphamide Pulses in Two Cases of Systemic Sclerosis with Interstitial Lung Disease

Abstract

Intersitial lung disease, a common complication of systemic sclerosis, often has a poor prognosis. Recent studies have shown the effectiveness of cyclophosphamide for preventing deterioration of lung function in patients with systemic sclerosis-associated interstitial lung disease. However, these beneficial physiological effects, which are evident after 12 months of therapy, are no longer apparent at 24 months. Therefore, other potentially immunosuppressive agents with sufficiently low toxicity are needed as maintenance therapies. Myzoribine, which selectively inhibits inosine monophosphate dehydrogenase, is an immunosuppressive agent newly developed in Japan that exerts beneficial therapeutic effects on lupus nephritis and rheumatoid arthritis. In the present study, two patients with systemic sclerosis-associated interstitial lung disease were treated with 150 mg of mizoribine once a day after intravenous cyclophosphamide treatment. In both cases, lung function further improved without any adverse reactions, suggesting that mizoribine can possibly provide effective maintenance therapy following intravenous cyclophosphamide treatment.