Objective. The aim was to assess the efficacy of rituximab for the cutaneous manifestations of adult DM and JDM.
Methods. Patients with refractory adult DM (n = 72) and JDM (n = 48) were treated with rituximab in a randomized placebo-phase-controlled trial [either rituximab early drug (week 0/1) or rituximab late arms (week 8/9), such that all subjects received study drug]. Stable concomitant therapy was allowed. Cutaneous disease activity was assessed using the Myositis Disease Activity Assessment Tool, which grades cutaneous disease activity on a visual analog scale. A myositis damage assessment tool, termed the Myositis Damage Index, was used to assess cutaneous damage. Improvement post-rituximab was evaluated in individual rashes as well as in cutaneous disease activity and damage scores. The χ2 test, Student’s paired t-test and Wilcoxon test were used for analysis.
Results. There were significant improvements in cutaneous disease activity from baseline to the end of the trial after rituximab administration in both adult DM and JDM subsets. The cutaneous visual analog scale activity improved in adult DM (3.22–1.72, P = 0.0002) and JDM (3.26–1.56, P <0.0001), with erythroderma, erythematous rashes without secondary changes of ulceration or necrosis, heliotrope, Gottron sign and papules improving most significantly. Adult DM subjects receiving rituximab earlier in the trial demonstrated a trend for faster cutaneous response (20% relative improvement from baseline) compared with those receiving B cell depletion later (P = 0.052).
Conclusion. Refractory skin rashes in adult DM and JDM showed improvement after the addition of rituximab to the standard therapy in a clinical trial.