Bimekizumab-Treated Patients with Axial Spondyloarthritis Maintained Stringent Clinical Responses Over 3 Years: Phase 3 and Open-Label Extension Results

Objective To assess the effect of bimekizumab, a dual inhibitor of IL-17F and IL-17A, on maintenance of stringent clinical response outcomes to three years in patients with axial spondyloarthritis (axSpA) from two phase 3 studies and their open-label extension (OLE). Methods Achievement of stringent clinical outcomes (Assessment of SpondyloArthritis international Society ≥40% improvement/partial remission [ASAS40/PR]), disease activity outcomes (Axial Spondyloarthritis Disease Activity Score low disease activity/inactive disease [ASDAS LDA/ID], Bath Ankylosing Spondylitis Disease Activity Index [BASDAI] <2), no/minimal or mild pain/fatigue (BASDAI Q1/Q2 <2/<4, respectively) and resolution of enthesitis (Maastricht Ankylosing Spondylitis Enthesitis Score [MASES]=0) are reported pooled across BE MOBILE 1 (non-radiographic [nr]-axSpA) and 2 (radiographic [r]-axSpA), to Week 164 for bimekizumab-randomised patients who achieved each outcome at Week 16. Data are descriptive, reported as non-responder imputation (NRI), modified NRI (mNRI), multiple imputation (MI) or observed case (OC). Results Of 349 bimekizumab-randomised patients, at Week 16, 45.8% achieved ASAS40, 24.6% ASAS PR, 43.6% ASDAS LDA, 16.6% ASDAS ID (NRI). The majority sustained achievement of these outcomes at Week 164 (80.4%/66.3%/78.8%/61.0%, respectively; mNRI/MI). Similar trends were observed for pain/fatigue reduction and resolution of enthesitis. Respectively, 36.2% and 38.0% who achieved ASDAS LDA and BASDAI <2 at Week 16 maintained their response at every visit to Week 164 (as observed). Conclusion In this exploratory analysis, across the full axSpA disease spectrum, the majority of patients who achieved stringent clinical outcomes with bimekizumab treatment at Week 16 maintained their response over three years, supporting deep and sustained efficacy with long-term bimekizumab treatment.