A BIOMARKER RESPONSE IS NOT ASSOCIATED WITH LONG-TERM RADIOGRAPHIC PROGRESSION IN AS PATIENTS TREATED WITH INFLIXIMAB: A FOLLOW-UP EVALUATION OF THE ASSERT BIOMARKER STUDY

Background: TNF blockade is a milestone in the treatment of ankylosing spondylitis (AS). Similar to clinical indices, the levels of inflammatory biomarkers show significantly decreased levels under anti-TNF. Assessment of structural damage in AS is best evaluated on conventional radiographs. We have recently reported that increased baseline levels of osteoprotegerin (OPG) can to some extent distinguish between patients with a fast or a slow structural deterioration after two years under anti-TNF treatment. However, the relationship between a change of biomarkers and radiographic progression under such treatment is still unclear. Objectives: To determine the role of different biomarkers in predicting radiographic progression in AS patients under anti-TNF treatment Methods: Data of AS patients who participated in ASSERT were retrospectively analyzed. Complete data from radiographs and of the following biomarkers (measured by ELISA) were available at baseline and after 2 years: interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), transforming growth factor-b (TGFb) for inflammation and osteocalcin (OC), bone alkaline phosphatase (BAP), C-Telopeptide 1 (CTX-I), N-Telopeptide (NTX-I), OPG and cartilage oligomeric matrix protein (COMP) for bone turnover. Assessment of clinical markers for disease activity (BASDAI), function (BASFI), metrology (BASMI), laboratory parameters (CRP, ESR) and radiographs were available at baseline and after 2 yrs. Analyses were performed based on `severe radiographic progression' (SRP, increase of ≥3 mSASSS units/year) and/or the development of new syndesmophytes at the 2-year follow-up. Summary statistics were used for the baseline data, and linear and logistic regression to test for the association of serum markers with mSASSS scores, clinical indices and SRP or the development of new syndesmophytes. Results: Of the 148 patients available for analysis, 22 (15%) showed SRP and 28 (19%) had new syndesmophytes after 2 years. Two-week, 24-week and 52 week decreases of biomarkers for inflammation (IL-6 and VEGF) were remarkable under anti-TNF treatment, and all clinical indices decreased significantly, but in the same time radiographic changes showed further deterioration. Overall, we found no single correlation between a change in any of the biomarkers or clinical indices and a change in 2-year mSASSS, the 2-year development of syndesmophytes or 2-year SRP. Conclusions: Although baseline OPG may have some potential in predicting subsequent radiographic progression, anti-TNF-induced changes in biomarker levels and clinical indices are not associated at all with radiographic progression. These findings suggest that the process of inflammation and new bone formation may be at least partly separated. Disclosure of Interest: X. Baraliakos: None Declared, R. Landewe: None Declared, D. van der Heijde Grant/Research support from: Centocor, J. Listing: None Declared, D. Baker Employee of: Centocor, B. Hsu Employee of: Centocor, J. Braun Grant/Research support from: CentocorCitation: Annals of the Rheumatic Diseases, volume 70, supplement 3, year 2011, page 343Session: Spondylarthritis – treatment (Poster Presentations )