RT Journal Article SR Electronic T1 Abatacept in the treatment of adult dermatomyositis and polymyositis: a randomised, phase IIb treatment delayed-start trial JF Annals of the Rheumatic Diseases JO Ann Rheum Dis FD BMJ Publishing Group Ltd and European League Against Rheumatism SP annrheumdis-2017-211751 DO 10.1136/annrheumdis-2017-211751 A1 Anna Tjärnlund A1 Quan Tang A1 Cecilia Wick A1 Maryam Dastmalchi A1 Herman Mann A1 Jana Tomasová Studýnková A1 Radka Chura A1 Nicola J Gullick A1 Rosaria Salerno A1 Johan Rönnelid A1 Helene Alexanderson A1 Eva Lindroos A1 Rohit Aggarwal A1 Patrick Gordon A1 Jiri Vencovsky A1 Ingrid E Lundberg YR 2017 UL http://ard.bmj.com/content/early/2017/10/09/annrheumdis-2017-211751.abstract AB Objectives To study the effects of abatacept on disease activity and on muscle biopsy features of adult patients with dermatomyositis (DM) or polymyositis (PM).Methods Twenty patients with DM (n=9) or PM (n=11) with refractory disease were enrolled in a randomised treatment delayed-start trial to receive either immediate active treatment with intravenous abatacept or a 3 month delayed-start. The primary endpoint was number of responders, defined by the International Myositis Assessment and Clinical Studies Group definition of improvement (DOI), after 6 months of treatment. Secondary endpoints included number of responders in the early treatment arm compared with the delayed treatment arm at 3 months. Repeated muscle biopsies were investigated for cellular markers and cytokines.Results 8/19 patients included in the analyses achieved the DOI at 6 months. At 3 months of study, five (50%) patients were responders after active treatment but only one (11%) patient in the delayed treatment arm. Eight adverse events (AEs) were regarded as related to the drug, four mild and four moderate, and three serious AEs, none related to the drug. There was a significant increase in regulatory T cells (Tregs), whereas other markers were unchanged in repeated muscle biopsies.Conclusions In this pilot study, treatment of patients with DM and PM with abatacept resulted in lower disease activity in nearly half of the patients. In patients with repeat muscle biopsies, an increased frequency of Foxp3+ Tregs suggests a positive effect of treatment in muscle tissue.