AIM:
To investigate if tissue turnover biomarkers were efficacy biomarkers in ankylosing spondylitis and if the biomarkers at baseline predicted a good outcome (BASDAI50).

PATIENTS & METHODS:
Twenty-two etanercept treated ankylosing spondylitis patients were investigated for inflammation (CRP, ESR, CRPM) and tissue turnover (C1M, C2M, C3M) during the first year of treatment. Biomarkers profiles and treatment response were investigated.

RESULTS:
ESR, CRP, BASDAI and C1M were decreased with treatment (p ≤ 0.04). C1M and CRP segregated patients into two populations predicting treatment efficacy.

CONCLUSION:
C1M and CRP were efficacy biomarkers and baseline biomarkers could select who benefited (by biomarkers) from treatment. C1M was not superior to CRP, but the biomarkers evaluate different pathologic events, indicating that C1M and CRP identify different events.

KEYWORDS:
ankylosing spondylitis; extracellular matrix turnover; protein fingerprint biomarkers; segregation of patients at baseline; structural benefit assessed by serological biomarkers; treatment efficacy of etanercept