M. Dougados ^1,*, D. van der Heijde ², J. Sieper ³, J. Braun ⁴, W. P. Maksymowych ⁵, G. Citera ⁶, R. Pedersen ⁷, R. Bonin ⁷, J. Bukowski ⁷, A. S. Koenig ⁷, B. Vlahos ⁷, D. Alvarez ⁷

¹Paris-Descartes Univ., Cochin Hospital, Paris, France, ²Leiden Univ. Med. Center, Leiden, Netherlands, ³Charité - Universitätsmedizin Berlin, Berlin, ⁴Rheumazentrum Ruhrgebiet, Herne, Germany, ⁵Univ. of Alberta, Edmonton, Canada, ⁶Instituto de Rehabilitación Psicofísica, Buenos Aires, Argentina, ⁷Pfizer Inc, Collegeville, PA, United States

Abstract

Background Anti-TNF agents are currently recommended for the treatment of NSAID-resistant ankylosing spondylitis, but limited data are available on their efficacy in axial spondyloarthritis (axSpA), particularly non-radiographic axSpA (nr-axSpA).
Objectives To compare the efficacy of etanercept (ETN) vs placebo (PBO) after 12 weeks of double-blind treatment in patients with nr-axSpA who had an insufficient response to NSAIDs.
Methods Enrolled patients satisfied ASAS criteria for axSpA,without fulfilling modified NY criteria for ankylosing spondylitis (determined by central reading), had symptom duration of 3 months-5 years and a BASDAI score ≥4 despite current NSAID use, and had failed ≥2 NSAIDs (including current one). Patients were randomized to ETN 50 mg weekly or PBO and continued to receive background NSAID. Randomization was stratified by sacroiliitis (positive/negative on MRI by central reading according to ASAS criteria) and by geographic region. The primary endpoint was ASAS40 at week 12 (mITT). In addition to clinical assessments, MRI of the spine and sacroiliac (SI) joints was performed at baseline and week 12 and analyzed using the SPARCC scoring method (average of two independent central readers).
Results At baseline, the mean age of patients was 32 years (range, 18-49 years); 61% were male; and mean disease duration was 2.4 years (range, 4 months-5 years). A total of 80.9%, 42.8%, and 87.9% were MRI+, had elevated CRP (CRP+), or were MRI+ and/or CRP+, respectively; 71.2% and 11.2% were HLA-B27+ or had psoriasis. Significantly more patients in the ETN group vs PBO group achieved ASAS40 (32.4% vs 15.7%; P=0.006) and most other clinical endpoints at week 12 (table); ETN was associated with significant improvements vs placebo in disease activity/function and inflammation on MRI.

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