Introduction: Ixekizumab, an interleukin-17A antibody, has shown efficacy in non-radiographic axial spondyloarthritis (nr-axSpA). The objectives of this analysis were (a) to measure improvement in ixekizumab-treated patients in Assessment of Spondyloarthritis International Society (ASAS) response domains and other patient-reported outcomes (PROs) and (b) to determine how ASAS responses were associated with changes in patient global disease activity (PtGA), spinal pain, function, stiffness, fatigue, and spinal pain at night.
Methods: COAST-X was a phase 3, 52-week multicenter, randomized, controlled trial investigating the efficacy and safety of 80-mg ixekizumab every 2 weeks (Q2W) and every 4 weeks (Q4W) in patients with active nr-axSpA. Changes from baseline in PROs were analyzed via mixed-effects models for repeated measures. Association analyses for ASAS responses used analysis of covariance with Scheffé's method.
Results: Patients treated with ixekizumab Q2W and Q4W reported significantly greater improvements in PtGA, spinal pain, function, and stiffness at week 1, when these measures were first assessed, compared with placebo (p < 0.05). ASAS40 responders, in comparison to ASAS20 non-responders, had the highest correlations with improvements in all response domains (PtGA, spinal pain, function, and stiffness) as well as fatigue and spinal pain at night (p < 0.001). ASAS40 responses were associated with 3.5- to 48.0-fold greater improvements in these PROs, with the highest values for PtGA and function, compared to ASAS20 non-achievement.
Conclusions: As early as week 1, patients with nr-axSpA treated with ixekizumab reported significant improvements in PtGA, spinal pain, function, and stiffness compared with those taking placebo. ASAS40 responders reported significantly greater improvements in all ASAS response domains (PtGA, spinal pain, function, and stiffness) as well as fatigue and spinal pain at night than ASAS20 non-responders. Improvements in PtGA and function appear to be major drivers in achieving ASAS40 response in patients with nr-axSpA.
Trial registration: NCT02757352.
Keywords: Assessment of Spondyloarthritis International Society (ASAS) response; Biological therapy; Ixekizumab; Non-radiographic axial spondyloarthritis; Patient-reported outcomes.