Early clinical response associates with long-term outcomes with ixekizumab in radiographic axial spondyloarthritis

Background The Assessment of SpondyloArthritis international Society-European Alliance of Associations for Rheumatology recommendations for axial spondyloarthritis (axSpA) management include patient assessment for biological disease-modifying antirheumatic drug (bDMARD) treatment response after at least 12 weeks of treatment. The current treat-to-target strategy for axSpA is to achieve inactive disease (ID; Axial Spondyloarthritis Disease Activity Score (ASDAS) <1.3) or at least low disease activity (LDA; 1.3≤ASDAS<2.1). To investigate the association between treatment response at week 12 and/or week 24 and attainment of the ASDAS<2.1 treat-to-target recommendation at week 52 in bDMARD-naïve patients with radiographic (r-)axSpA treated with ixekizumab (IXE). Methods This post hoc analysis included patients randomly assigned to IXE 80 mg every 4 weeks from COAST-V (NCT02696785), a phase 3 trial in bDMARD-naïve patients with r-axSpA. The proportion of patients who achieved ASDAS<2.1 at week 52 was measured among those who attained or not clinically important improvement (CII, ΔASDAS≥1.1) response, and among those with ID, LDA and high or very high disease activity at week 12 and/or week 24. Non-response was assumed for missing data. Results Amongst 81 patients, 47 (58.0%) achieved ASDAS CII at week 12, with 70.2% (n=33) achieving ASDAS<2.1 at week 52. At week 24, 52 (64.2%) patients achieved ASDAS CII, with 71.2% (n=37) achieving ASDAS<2.1 at week 52. Of the 24 patients who did not achieve ASDAS CII at either week 12 or week 24, 5 (20.8%) achieved ASDAS<2.1 at week 52. Conclusion This analysis reinforces the current recommendation that continuing treatment in those achieving ASDAS CII at week 12 and/or week 24 increases the likelihood of obtaining ID/LDA at week 52. Trial registration number NCT02696785.