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 25 mg 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 (p < 0.05, r = 0.40) at baseline. At 6 months of etanercept treatment, 10 patients entered remission (DAS28-ESR < 2.6) whereas the other 35 patients did not (DAS28-ESR > 2.6). 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.