Decrement of serum cartilage oligomeric matrix protein (COMP) in rheumatoid arthritis (RA) patients achieving remission after 6 months of etanercept treatment: Comparison with CRP, IgM-RF, MMP-3 and anti-CCP Ab.

OBJECTIVE: The aim of this study was to evaluate whether serum COMP can estimate the therapeutic response of RA after 6 months of treatment with etanercept. METHODS: Forty-five RA patients receiving 25mg of etanercept twice a week for 6 months were registered in this prospective observational study. Clinical response to the therapy was evaluated by DAS 28. Laboratory variables- COMP, CRP, ESR, IgM-RF, MMP-3, and anti-CCP Ab -were assessed at baseline and after 6 months of treatment. We assessed the correlations between serum COMP and other variables and whether serum COMP is associated with DAS28 remission. RESULTS: Serum COMP correlated with DAS28-ESR (p2.6). The decrement of serum COMP at 6 months was significant in the remission group (N=10) but not in the non-remission group (N=35). On the other hand, CRP, ESR and MMP-3 decreased at 6 months regardless of remission status. IgM-RF titer as well as anti-CCP Ab titer did not differ at 6 months. CONCLUSIONS: Serum COMP at baseline reflects clinical disease activity of RA. Serum COMP is a valuable serologic marker to identify the subset of RA patients achieving remission during treatment with etanercept