Ixekizumab for Active Radiographic Axial Spondyloarthritis in Chinese Patients: 16- and 52-Week Results from a Phase III, Randomized, Double-Blind, Placebo-Controlled Study

Introduction Ixekizumab, an interleukin-17A inhibitor, was efficacious and well tolerated for the treatment of active radiographic axial spondyloarthritis (r-axSpA) in international clinical studies. This phase III study aimed to determine the efficacy and safety of ixekizumab for treating Chinese patients with active r-axSpA. Methods Adults with active r-axSpA naïve to biologic disease-modifying antirheumatic drugs (bDMARDs), or with an inadequate response/intolerance to one tumor necrosis factor inhibitor, were randomized (1:1), double-blind, to receive ixekizumab 80 mg every 4 weeks (IXEQ4W; starting dose 160 mg), or placebo, for 16 weeks. Patients receiving placebo were then switched to IXEQ4W, and those receiving IXEQ4W continued, until week 52. The primary endpoint was the proportion of bDMARD-naïve patients achieving an Assessment of SpondyloArthritis International Society 40 (ASAS40) response at week 16. Results In total, 147 patients were randomized to receive placebo ( n = 73) or IXEQ4W ( n = 74). At week 16, more bDMARD-naive patients achieved ASAS40 in the IXEQ4W group ( n = 66; 40.9%) than the placebo group ( n = 64, 7.8%; p < 0.001). In the overall study population, ASAS40 was also achieved by more patients in the IXEQ4W group (37.8%) than the placebo group (8.2%; p < 0.001) at week 16, with a significant difference observed as early as week 1. There were significant improvements in all key secondary endpoints at week 16 with IXEQ4W versus placebo. Efficacy was sustained at week 52 in patients who continued IXEQ4W and there were also clinical improvements from weeks 16 to 52 in patients switched to IXEQ4W. The safety profile of ixekizumab was consistent with that described previously. Infections and injection-site reactions were the most frequently reported events of special interest. Conclusions IXEQ4W was associated with rapid and significant improvements in the signs and symptoms of active r-axSpA in Chinese patients at week 16 that were sustained at week 52, with no new safety signals. Trial registration number ClinicalTrials.gov identifier: NCT04285229.