A pilot trial of rituximab in the treatment of patients with dermatomyositis

Background: Dermatomyositis is an autoimmune disease that is associated with muscle and skin inflammation. Using quantitative scales, we sought to evaluate the effects of rituximab therapy on muscle strength and skin disease in patients with dermatomyositis. Observations: An open-label trial of rituximab therapy was conducted in 8 adult patients with dermatomyositis. Patients received 2 infusions of rituximab (1 g each) 2 weeks apart without peri-infusional steroids. The primary outcome was partial remission at week 24 (pre-specified reduction in elevated creatine phosphokinase levels, muscle strength deficit (Manual Muscle Test), or skin disease (Dermatomyositis Skin Severity Index). After the first infusion of rituximab, all patients achieved sustained depletion of peripheral B cells. One patient withdrew at week 16 owing to a lack of treatment efficacy. Three patients (38%) achieved partial remission at week 24, in each case by improvement in muscle strength. Muscle enzyme levels and skin scores at week 24 were not significantly changed from those at baseline. Rituximab infusions were well tolerated, with no serious infectious complications. One patient died of metastatic cancer 9 months after his last infusion. Conclusion: Depletion of peripheral B cells had modest effects on muscle disease and limited effects on skin disease in our cohort of patients with dermatomyositis.