AB0054 Relationship between Calprotectin Serum Level, Disease Activity, Matrix Metalloproteinase-3 Concentration and Response to Etanercept Therapy in RA Patients
Authors: A. Pchelintseva, A. Zhornyak, N. Ionichenok, E. Panasyuk, M. Cherkasova, L. Denisov
Journal: Annals of the Rheumatic Diseases (2014)

<h3>Background</h3> Calprotectin (CP) is potentially more sensitive biomarker of disease activity in rheumatoid arthritis (RA) than conventional acute-phase reactants because it directly reflects inflammation in the synovium rather than systemic inflammation. <h3>Objectives</h3> to evaluate relationship between serum CP levels, disease activity, matrix metalloproteinase-3 (MMP-3) concentration and response to Etanercept (ETN) therapy in RA patients. <h3>Methods</h3> 84 patients with moderate-to-severe RA despite stable doses of cDMARDs received ETN 50 mg weekly for 24 weeks. The mean age was 52±13,3 years; 85% (n=71) were females; the median disease duration was 9,3±8,3 years; RF+ and ACCP + were 81% (n=68) and 83% (n=70), extraarticular manifestations were found in 18% (n=15); 62% (n=52) used MTX, 26% (n=22)-LEF, 11% (n=9)-other DMARDs, 38% (n=32) -corticosteroids ≤10 mg/day. 60% (n=50) had used another biologics prior to start of ETN. Baseline disease characteristics (Me [Q<sub>25–75</sub>]): patient disease activity, VAS, mm: 63 [49-75]; TJC: 12 [9-16]; SJC: 9 [7-12]; CRP, mg/l: 23,7 [8,25-46,8]; ESR, mm/h: 46 [29-67]; RF, IU/ml: 122,5 [17,45-313,15]; ACCP, U/ml: 181,2 [43,6-300]; DAS28 6,35 [5,72-6,81]; CP, μg/ml 5,34 [2,12-10,98]; MMP-3, ng/ml 1,01 [0,64-1,67].Response was defined as achievement of good/moderate response according EULAR at weeks 12, 25. Serum CP and MMP-3 levels were evaluated with ELISA at weeks 0, 12, 25. Serum samples from 21 healthy subjects served as control. <h3>Results</h3> There wasn9t significant difference in median CP level between patients with RA compared to healthy controls (5,34 vs 4,17, <i>p</i>=0,26) at baseline, possibly due to small size of control group. Highly significant correlations were found in RA patients between CP baseline level and ESR, CRP, MMP-3 and DAS28 at week 0: CRP (<i>r</i>=0,69,<i>p</i>&lt;0,0001), ESR (r=0,41,<i>p</i>&lt;0,0001), MMP-3 (r=0,47,p&lt;0,0001), DAS28 (<i>r=0,37</i>,p&lt;0,0001). The similar data were determined at weeks 12 and 25. We didn9t find strong correlations between CP level and clinical parameters of disease activity. CP serum level decreased after 6 months of ETN treatment (p&lt;0,0001). ROC analysis provided an AUC<sub>roc</sub> of 0.8±0,06 (95%CI 0,68-0,91) for the differentiation of RA patients and healthy control. A cut-off value of 0,67 μg/ml resulted in sensitivity and specifity values of 73 and 86% respectively.There wasn9t found predictive value for CP baseline level and good/moderate EULAR response to ETN treatment (AUC<sub>roc</sub>=0,41±0,07; p=0,18; 95%CI 0,28-0,54). <h3>Conclusions</h3> CP level strongly correlates with laboratory parameters of joint inflammation and bone destruction (MMP-3) and significantly decreases in response to ETN treatment. There was not prognostic association between CP baseline level and response to ETN treatment. This result indicate that CP is a promising marker for assessment and monitoring of disease activity in RA patients. CP prognostic value is unclear, futher investigations are required to evaluate it. <h3>Disclosure of Interest</h3> None declared <h3>DOI</h3> 10.1136/annrheumdis-2014-eular.3484