[Clinical study of etanercept for treating ankylosing spondylitis]

To evaluate the efficacy and safety of etanercept, a tumor necrosis factor (TNF)-alpha inhibitor, in the treatment of ankylosing spondylitis (AS), and investigate its effect on serum levels of matrix metalloproteinase-3 (MMP-3).

Forty-eight patients with AS received etanercept 25 mg twice a week for a treatment course of 12 weeks. The patients' symptoms, signs, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) levels and side effects were observed before and after the treatment. The serum levels of MMP-3 was determined using enzyme-linked immunosorbent assay (ELISA).

All the patients completed the treatment. The degree of spinal pain and pain at night, the duration of morning stiffness, the finger-to-floor distance, BASDAI and BASFI were significantly improved after the treatment (P<0.05). Etanercept treatment resulted in a significant reduction in serum MMP-3 level in the AS patients to 31.22-/+10.26 ng/ml as compared with the level before treatment (46.17-/+25.74 ng/ml, P<0.05). The reduction of serum MMP-3 was positively correlated to decrement of ESR and CRP (r=0.397 and 0.474, respectively, P<0.05). The most common adverse events of etanercept included injection site reaction and upper respiratory infection.

Etanercept treatment has obvious therapeutic effects on AS without serious adverse effects. MMP-3 may be a potentially useful indicator to assess the effect of anti-TNF-alpha treatment in AS patients.