[18F]FDG PET/CT assessments at 2-4 weeks after initiation of combination therapy with triple oral antirheumatic drugs predict clinical outcome in patients with early rheumatoid arthritis

532 Objectives This study evaluated the potential of functional imaging to monitor disease activity and the efficacy of treatment in disease-modifying antirheumatic drug (DMARD)-naive patients with early rheumatoid arthritis (RA). Methods Seventeen RA patients with active disease, initiating combination therapy with hydroxychloroquine, sulfasalazine, methotrexate and low dose prednisolone, were studied. Clinical disease activity was assessed at screening, baseline and after 2, 4, 8, and 12 weeks of the therapy. 2-[18F]-fluoro-2-deoxy-D-glucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) and gadolinium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid magnetic resonance imaging (MRI) were performed at baseline and at weeks 2 and 4. Results Based on [18F]FDG PET/CT evaluation, 76% of the patients had reductions in maximum standardized uptake values from baseline to week 2 (reduction 22±13%) and 81% from baseline to week 4 (reduction 29±13%), respectively. The percent decrease in PET measures from baseline to week 2 predicted clinical outcome as measured by disease activity scoring (DAS-28) at week 12. In addition, changes in C-reactive protein (CRP) and erythrocyte sedimentation rate levels were positively associated with changes in PET. Interestingly, the PET measures at baseline showed correlation with CRP and tender joint count measured at week 12. None of the MRI measures up to week 4 correlated with clinical outcome measures in this patient population. Conclusions [18F]FDG PET/CT but not MRI findings at weeks 2 and 4 predicts treatment efficacy and clinical outcome in patients with early RA treated with triple combination oral DMARD therapy. Future studies utilizing [18F]FDG PET/CT may aid in predicting therapeutic response using novel drug treatments. Research Support Grant from Hoffmann-La Roche Inc