Abstract
Anti-melanoma differentiation-associated protein 5 (MDA5) antibody-positive dermatomyositis (MDA5-DM) is frequently complicated with rapidly progressive-interstitial lung disease (RP-ILD). The prognosis of MDA5-DM with RP-ILD is mostly poor despite intensive treatment with a combination of high-dose glucocorticoids and single conventional immunosuppressants. It was reported that the triple therapy (high-dose glucocorticoids, cyclophosphamide and tacrolimus) was more effective than a combination of high-dose glucocorticoids and stepwise addition of immunosuppressants. In addition, the efficacy of tofacitinib 10 mg/day for MDA5-DM with RP-ILD refractory to the triple therapy was suggested. However, the effect of those therapies was evaluated only in comparison to the historical control. Moreover, more importantly, there are still refractory patients even if treated with those therapies. In this case series, we report six MDA5-DM cases with RP-ILD in which the dose of tofacitinib was increased from 10 mg to 20 mg/day due to poor response to the triple therapy, followed by tofacitinib 10 mg/day. Four of six patients improved after dose escalation of tofacitinib, while two non-responders died. All six patients developed at least one infection including five cases of cytomegalovirus reactivation, one pulmonary aspergillosis, one herpes zoster and one herpes simplex keratitis. These cases suggest that the dose escalation of tofacitinib can be an option for MDA5-DM patients refractory to 10 mg/day of tofacitinib and other immunosuppressants although the risk of infection is a concern. The risk-benefit balance of the dose escalation of tofacitinib should be carefully assessed in each case.