SAT0386 Free DKK-1 Serum Levels Are Unchanged in Spondyloarthritis Patients Treated by Anti-TNF – Data from The Sparse Study
Authors: C. Miceli-Richard, B. Combe, F. Berenbaum, T. Schaeverbeke, N. Koppiker, I. Logeart, A. Dubanchet, M. Dougados
Journal: Annals of the Rheumatic Diseases (2016)

<h3>Background</h3> DKK-1 and SOST are two inhibitory proteins of the Wnt signaling pathway which lead to decreased bone formation by osteoblasts and osteocytes, respectively. Due to the limited data assessing free DKK-1 and SOST in SpA patients under anti-TNF treatment, a post-hoc examination of the SPARSE study was designed in order to answer these question. <h3>Objectives</h3> To assess free DKK-1 and SOST serum levels at Baseline and 24 weeks after etanercept or placebo treatment in patients from the SPARSE study. <h3>Methods</h3> In the SPARSE study, patients were randomized to receive either etanercept (N=42) or placebo (n=48) in case of active AxSpA disease (defined by mini BASDAI &gt;40) despite optimal NSAIDs intake. The 90 patients from the SPARSE study were quantified for free DKK-1 and SOST serum levels, at Baseline and at Week 8 (w8) corresponding to the end of the placebo controlled period. DKK-1 and SOST serum levels were assessed by the use of a classic sandwich ELISA test (Biomedica, Vienna) and results were provided in pmol/L. Changes in DKK-1 and SOST serum levels were adjusted for disease activity, CRP levels, NSAIDs intake, X-ray status and treatment groups. <h3>Results</h3> LS Mean (±SE) serum DKK-1 at Baseline was not significantly different between treatment groups (ETN: 36.2 ± 1.97; PBO: 37.1 ± 1.84; p=0.72). At Baseline, DKK-1 was not associated with any of the patients9 or disease characteristics: ASDAS-CRP (r=0.096; 95% CI [-0.122, 0.305]); CRP (r=0.002; 95% CI [-0.210, 0.214]); X-ray status (LS Mean (SE): negative 37.4 (±2.38) versus positive 36.3 (± 1.77); p=0.71). There were no significant differences between treatment groups in the change from Baseline to w8 in the DKK-1 serum levels (p=0.97). We also considered patients with (N=67) or w/o NSAIDs intake (n=19) within the week preceding w8 serum level assessment and found no significant difference (p=0.99). We further assessed DKK-1 serum levels at Baseline according to their Baseline CRP (&lt;6mg/L; ≥6mg/L), X-ray status (Positive; Negative), or NSAIDs intake (Yes; No) within the week preceding w8, and found no significant differences. These analyses were repeated for SOST serum levels at Baseline and with the exception of patients with Negative X-ray status at Baseline having significantly lower values than those patients with Positive X-ray status (p=0.047), no significant differences were observed in terms of the Baseline disease characteristics; Similarly there were no differences between treatment groups in the change from Baseline to w8 SOST serum levels. <h3>Conclusions</h3> This post-hoc examination of patients randomized in the SPARSE study suggest that etanercept does not significantly change DKK-1 or SOST serum levels within the 8 first weeks of treatment. Disease activity, CRP, NSAIDs intake and X-ray status were not significantly associated with DKK-1 serum levels. These results should be considered in the context of previous studies suggesting that DKK-1 was dysfunctional in SpA patients (1). Taken together, these results suggest that DKK-1 should not be considered as a valuable bone remodeling marker in SpA, unlike in rheumatoid arthritis. <h3>References</h3> Daoussis, D., et al. Arthritis Rheum, 62, 150–8 <h3>Disclosure of Interest</h3> C. Miceli-Richard: None declared, B. Combe: None declared, F. Berenbaum: None declared, T. Schaeverbeke: None declared, N. Koppiker Employee of: Pfizer, I. Logeart Employee of: Pfizer, A. Dubanchet Employee of: Pfizer, M. Dougados: None declared