Activation of the STAT5 signaling pathway up‐regulates antiapoptotic protein Bcl2 and drives proliferation of autoreactive conventional CD4 T cells (Tcons). In systemic lupus erythematosus (SLE), an increased T cell Bcl2 content and perturbed homeostasis of CD45RA−FOXP3hi activated regulatory T cells (aTregs) were described. We assessed Tcon/Treg subsets and phosphorylation of STAT5 (pSTAT5) in blood T cells from patients with SLE by using conventional and imaging flow cytometry. Forty‐one patients with SLE, 33 healthy controls, and 29 patients with rheumatoid arthritis were included. Long‐term monitoring was performed in 39 patients with SLE, which were followed longitudinally for up to 1000 d. Significantly increased Bcl2 protein content in T cells from patients with SLE was associated with IL‐7–dependent STAT5 activation, expressed as increased basal levels and nuclear localization of pSTAT5. pSTAT5 levels were significantly increased in the FOXP3 low‐expressing CD4+ T cell subsets but not in the aTreg subset, which was significantly decreased in patients with SLE. In contrast to aTreg, SLE Tcon displayed significantly increased pSTAT5 and Bcl2 levels. Moreover, the percentage of Tcon‐expressing proliferation marker Ki‐67 was significantly increased in patients with SLE and was positively correlated with CD4 T cell pSTAT5 levels. Finally, a subgroup of patients characterized by an increased Tcon–pSTAT5/aTreg–pSTAT5 ratio experienced a more aggressive‐relapsing disease course and displayed higher time‐adjusted cumulative CD4 T cell pSTAT5 levels during follow‐up, which were positively correlated with time‐adjusted cumulative disease activity. Our results indicate that imbalanced STAT5 phosphorylation, which is related to Bcl2 and Ki‐67 expression, may confer survival and proliferative advantage to Tcon over aTreg and could represent a possible marker of SLE disease severity.

O1 Efficacy and safety of Canakinumab in patients with periodic fever syndromes (colchicine-resistant fmf, hids/mkd and traps): results from a phase 3, pivotal, umbrella trial F. De Benedetti, J. Anton, M. Gattorno, H. Lachmann, I. Kone-Paut, S. Ozen, J. Frenkel, A. Simon, A. Zeft, E. Ben-Chetrit, H.M. Hoffman, Y. Joubert, K. Lheritier, A. Speziale, J. Guido IRCCS Ospedale Pediatrico Bambino Gesú, Rome, Italy; Hospital Sant Joan de Déu, Barcelona, Spain; Pediatric Rheumatology, G. Gaslini Institute, Genoa, Italy; UK National Amyloidosis Centre, University College London Medical School, London, United Kingdom; Hôpital Kremlin Bicetre, University of Paris SUD, Paris, France; 6 Department of Pediatrics, Hacettepe University, Ankara, Turkey; University Medical Center Utrecht, Utrecht, Netherlands; Radboud University Medical Centre, Nijmegen, Netherlands; Pediatrics Rheumatology, Cleveland Clinic, Cleveland, USA; Rheumatology Unit, Hadassah—Hebrew University Medical Center, Jerusalem, Israel; University of California, San Diego, La Jolla, USA; Novartis Pharma AG, Basel, Switzerland Presenting author: F. De Benedetti Pediatric Rheumatology 2017, 15(Suppl 1):O1

P381 Transient periosteal hyperostosis with dysproteinemia (Goldbloom syndrome): two cases report Riccardo Papa, Alessandro Consolaro, Francesca Minoia, Roberta Caorsi, Gianmichele Magnano, Marco Gattorno, Angelo Ravelli, Paolo Picco Pediatria II, Reumatologia, Istituto Giannina Gaslini, Genoa, Italy; Radiologia, Istituto Giannina Gaslini, Genoa, Italy Presenting author: Riccardo Papa Pediatric Rheumatology 2017, 15(Suppl 1):P381

BackgroundsThe purpose of the study was to evaluate the clinical and magnetic resonance imaging (MRI) outcome of cervical spine arthritis in children with juvenile idiopathic arthritis (JIA), who received anti-TNFα early in the course of cervical spine arthritis.MethodsMedical charts and imaging of JIA patients with cervical spine involvement were reviewed in this retrospective study. Data, including age at disease onset, JIA type, disease activity, treatment and clinical outcome were collected. Initial and followup MRI examinations of cervical spine were performed according to the hospital protocol to evaluate the presence of inflammation and potential chronic/late changes.ResultsFifteen JIA patients with MRI proved cervical spine inflammation (11 girls, 4 boys, median age 6.3y) were included in the study: 9 had polyarthritis, 3 extended oligoarthritis, 2 persistent oligoarthritis and 1 juvenile psoriatic arthritis. All children were initially treated with high-dose steroids and methotrexate. In addition, 11 patients were treated with anti-TNFα drug within 3 months, and 3 patients within 7 months of cervical spine involvement confirmed by MRI. Mean observation time was 2.9y, mean duration of anti-TNFα treatment was 2.2y. Last MRI showed no active inflammation in 12/15 children, allowing to stop biological treatment in 3 patients, and in 3/15 significant reduction of inflammation. Mild chronic changes were found on MRI in 3 children.ConclusionsEarly treatment with anti-TNFα drugs resulted in significantly reduced inflammation or complete remission of cervical spine arthritis proved by MRI, and prevented the development of serious chronic/late changes. Repeated MRI examinations are suggested in the follow-up of JIA patients with cervical spine arthritis.