POS0043 COMPLEMENT IN RADIOGRAPHIC AXSPA – BIOMARKERS OF RADIOGRAPHIC PROGRESSION? POST HOC ANALYSIS FROM CONSUL, A LONGITUDINAL MULTI-CENTER RANDOMIZED CONTROLLED TRIAL COHORT OF AXSPA-PATIENTS WITH A HIGH RISK OF STRUCTURAL PROGRESSION INITIATING TREATMENT WITH TNF-I

Background The biological processes involved in the development of structural changes associated with radiographic axial spondyloarthritis (r-axSpA) remain largely unraveled. Still, high disease activity, elevated C-reactive protein (CRP), and existing syndesmophytes are progression. complement system is an inflammation-generating part innate immune system. Animal models have shown inhibition activation to diminish axSpA [1]. Objectives This project aimed investigate serum levels proteins their correlations spinal progression over a two years follow-up period longitudinal cohort patients active r-axSpA, risk progression, recruited from randomized controlled trial CONSUL. Methods All had r-axSpA factors for (BASDAI ≥4, CRP and/ or ≥1 syndesmophyte(s)). Serum samples were collected at baseline ( n = 96) after 108 weeks 89) TNF-I therapy analyzed by immunoassays lectin pathway (L-ficolin, M-ficolin, H-ficolin, CL-L1, MBL, MASP-1, MASP-2, MASP-3, MAp44) product C3dg. X-rays performed read blinded clinical data chronology three independent expert readers. New bone formation was defined as growth syndesmophyte(s) and/or new determined 3-reader-agreement. Results Patient characteristics Table 1. In total, 19 developed week 108. Baseline C3dg formation, whereas MASP-3 decreased (all p <0.05). predicted univariate logistic regression analysis, did not. remained significant multivariate analysis. L-ficolin Conclusion this study, measured MASP-1 prior therapy, Furthermore, formation. These findings support involvement r-axSpA. Reference [1]Yang C et al. Sci Rep. 2016. demographics investigated patient population CONSUL RCT Age, median (IQR) 37 (31-45) Male, (%) 70 (73) HLA-B27 positive, 80 (83) Previous bDMARD treatment, 21 (22) Symptom duration years, 12 (6.0-20) Smoking, 36 (38) mSASSS, 5.0 (0.3-18) Syndesmophytes, 1.8 (0-6.3) Presence syndesmophyte(s)δ, 47 (49) CRP, 9.2 (3.2-19) Elevated (>5 mg/L), 64 (67) ASDAS-CRP, 3.6 (3.1-4.1) BASDAI, 6.2 (5.2-6.8) δDetermined 3 readers data. Figure ) according b formation: -values indicate comparisons between groups t-test. Bars IQR (MASP-1, C3dg), mean sd (L-ficolin). Acknowledgements: NIL. Disclosure Interests Clara Elbæk Mistegaard: None declared, Anne Troldborg: Gitte Loft Speakers bureau: AbbVie, MSD, Novartis, Pfizer, UCB, Consultant of: Grant/research from: Steffen Thiel: Burkhard Muche: Valeria Rios Rodriguez: Murat Torgutalp: Mikhail Protopopov: Joachim Listing: Sieper: Denis Poddubnyy: Fabian Proft AMGEN, BMS, Celgene, Janssen, Roche, Lilly, UCB.