Certolizumab Pegol Efficacy in Patients With Non-Radiographic Axial Spondyloarthritis Stratified by Baseline MRI and C-Reactive Protein Status: An Analysis From the C-axSpAnd Study

Objective: Tumor necrosis factor inhibitors (TNFi) are an effective treatment for non-radiographic axial spondyloarthritis (nr-axSpA). To be eligible, however, many authorities require patients with nr-axSpA to show active sacroiliitis on magnetic resonance imaging (MRI) and/or an elevated C-reactive protein (CRP) level, possibly resulting in a perception that patients with nr-axSpA without both factors have only low responses to TNFi treatment. We evaluated clinical responses to certolizumab pegol (CZP) in patients with nr-axSpA stratified by baseline MRI/CRP status. Methods: C-axSpAnd was a phase 3, multicenter study on CZP in adult patients with active nr-axSpA and objective signs of inflammation. This analysis assessed efficacy of CZP over the 52-week randomized, double-blind, placebo-controlled period in patients stratified into subgroups based on the presence of active sacroiliitis on MRI and CRP level at baseline. Results: CZP-treated patients across all MRI/CRP subgroups achieved clinical responses greater than placebo. Across outcome measures, CZP-treated MRI+/CRP+ patients demonstrated the greatest clinical responses, but substantial improvements were also observed in CZP-treated MRI+/CRP− and MRI−/CRP+ patients. Ankylosing Spondylitis Disease Activity Score Major Improvement response rates at week 52 among CZP-treated patients (75.6% MRI+/CRP+; 47.5% MRI−/CRP+; and 29.7% MRI+/CRP−) were higher than rates in placebo groups (range: 3.9%-12.5%). Assessment of SpondyloArthritis international Society 40% response, Bath Ankylosing Spondylitis Disease Activity Index, and Bath Ankylosing Spondyloarthritis Functional Index had similar response patterns, although differences between the CZP-treated MRI/CRP subgroups were smaller. Clinical responses among CZP-treated patients were also observed in additional subgroups, including those with low Spondyloarthritis Research Consortium of Canada MRI sacroiliac joint inflammation scores and those with normal baseline CRP levels. Conclusion: Our findings indicate that CZP treatment benefits patients with nr-axSpA across MRI+/CRP+, MRI−/CRP+, and MRI+/CRP− subgroups.