Outcome of patients with active ankylosing spondylitis after two years of therapy with etanercept: Clinical and magnetic resonance imaging data

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Abstract
Objective To examine the long‐term outcome of patients with active ankylosing spondylitis (AS) clinically and by magnetic resonance imaging (MRI) after continuous treatment with the tumor necrosis factor (TNF) receptor fusion protein etanercept over 2 years. Methods Overall, 26 patients with active AS were treated with etanercept 25 mg twice daily subcutaneously, twice weekly with no concomitant disease‐modifying antirheumatic drugs (DMARDs) or steroids. The clinical response was assessed by standardized parameters. Inflammatory spinal lesions were quantified by the ASspiMRI‐a rating gadolinium‐enhanced (T1‐weighted gadolinium diethylenetriaminepentaacetic acid) and STIR MRI sequences. The primary outcome was a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) improvement ≥50% after 2 years of etanercept therapy compared with the baseline value of the study. Results Overall, 21 (70%) of 30 patients completed year 2. In the intent‐to‐treat analysis, 54% of the patients showed a 50% improvement according to the BASDAI and a 40% improvement according to the Assessment in Ankylosing Spondylitis (ASAS) criteria. In the completer analysis, 9 (43%) of 21 patients were in partial remission according to ASAS criteria. Mean ± SD BASDAI scores, which were elevated at baseline (6.3 ± 1.6), remained low: 2.7 ± 2.4 after 2 years compared with 2.6 ± 2.2 at week 54. In accordance, all other clinical parameters showed sustained improvement during year 2. The majority of patients had no disease activity flares. MRI evaluation showed a 75% improvement of active spinal lesions, but minor spinal inflammation was still present in 64% of the patients after 2 years. There were 2 serious adverse events leading to discontinuation of etanercept. Conclusion The clinical efficacy and safety of etanercept in patients with active AS without simultaneous administration of DMARDs or steroids over 2 years of continuous treatment is confirmed. Spinal inflammation as depicted by MRI decreased significantly, but a few patients still had some spinal inflammation even after long‐term anti–TNF therapy.