Bimekizumab in Chinese Patients with Active Non-Radiographic Axial Spondyloarthritis: 52-Week Results from the Phase 3 BE MOBILE 1 Study

INTRODUCTION: Bimekizumab, a humanised monoclonal IgG1 antibody that selectively inhibits interleukin (IL)-17F in addition to IL-17A, was efficacious and well tolerated to 52 weeks in patients with non-radiographic axial spondyloarthritis (nr-axSpA) in the global phase 3 multicentre study BE MOBILE 1. In this pre-specified analysis, we examine in more detail the efficacy and safety of bimekizumab in the Chinese subpopulation of patients with nr-axSpA from BE MOBILE 1. METHODS: BE MOBILE 1 comprised a 16-week double-blind, placebo-controlled period and 36-week maintenance period. Patients with nr-axSpA were randomised to receive subcutaneous bimekizumab 160 mg every 4 weeks or placebo to week 16; thereafter, all patients received bimekizumab. Here we report efficacy and safety outcomes to week 52 for the Chinese subpopulation. No formal statistical comparisons were made; results should be interpreted as nominal. RESULTS: Overall, 36/274 patients in BE MOBILE 1 were enrolled in China (bimekizumab-randomised 18; placebo-randomised 18); 32 completed week 52. A greater proportion of bimekizumab- vs placebo-randomised patients achieved Assessment of SpondyloArthritis international Society (ASAS) ≥ 40% response (38.9% vs 22.2%), ASAS partial remission (33.3% vs 11.1%), and Axial Spondyloarthritis Disease Activity Score < 2.1 (77.7% vs 49.7%) at week 16. By week 52, improvements were comparable between bimekizumab-randomised and placebo-randomised patients who had switched to bimekizumab. Similar trends were observed for objective signs of inflammation, spinal pain, physical function, health-related quality of life, and peripheral manifestations. To week 52, treatment-emergent adverse events (TEAEs) occurred in 33 bimekizumab-treated patients (91.7%), with upper respiratory tract infection the most frequent (10 patients [27.8%]). Four patients (11.1%) had serious TEAEs; four had fungal infections (11.1%; all Tinea). No patients experienced adjudicated inflammatory bowel disease or uveitis. CONCLUSIONS: In patients with nr-axSpA from China, bimekizumab showed rapid and sustained efficacy improvements to week 52 and was well tolerated, consistent with the global patient population. Graphical Abstract is available for this article. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT03928704.