Tofacitinib for new-onset adult patients with anti-melanoma differentiation-associated 5 gene antibody positive dermatomyositis

Objective We aimed to investigate the efficacy and safety of tofacitinib in adult anti-melanoma differentiation-associated 5 gene (Anti-MDA5) antibody-positive dermatomyositis (DM) patients and evaluate the effects of tofacitinib on peripheral lymphocyte subsets.Methods An open-label study was conducted of 15 new-onset, untreated adult patients with anti-MDA5-positive DM for tofacitinib with a dose of 5mg twice per day. The primary outcome was defined by the total improvement score after treatment for 6 months, classified according to the 2016 American College of Rheumatology/ European League Against Rheumatism (ACR/EULAR) response criteria for adult DM and polymyositis. Secondary outcomes after 6 months treatment comprised the change in predicted forced vital capacity, the percentage of predicted carbon monoxide diffusion capacity, ferritin level and peripheral blood lymphocyte subsets measured by flow cytometry.Results Disease responses occurred in 10 patients (71.4%) after 6 months. The median total improvement score was 43.75 (41.875-59.375). Two patients achieved major improvement, seven achieved moderate and one minimal. The serum ferritin level (p = 0.008), DLCO% (p = 0.009) was improved and a marked increase in total lymphocyte cells (p = 0.045) and CD8+ T cells (p = 0.006) was measured after 6 months treatment compared to baseline.Conclusion Tofacitinib demonstrates efficacy for new-onset, untreated adult patients with anti-MDA5-positive DM and stimulates proliferation of peripheral lymphocyte subsets (especially total lymphocyte cells and CD8+ T cells) after 6 months treatment. Further studies are warranted to validate the current findings.