1445: Patient Characteristics, and Physician-Reported Treatment Effectiveness and Treatment Satisfaction with Bimekizumab for Axial Spondyloarthritis in the United States: Interim Analysis from a Real-World Study

Background/Purpose: Axial spondyloarthritis (axSpA) is a chronic inflammatory condition affecting the sacroiliac joints and spine.¹ Bimekizumab (BKZ) is a monoclonal IgG1 antibody that selectively inhibits interleukin (IL)-17F in addition to IL-17A and has demonstrated long-term clinical efficacy and safety in patients (pts) with axSpA across the full disease spectrum (non-radiographic [nr-]axSpA and radiographic [r-]axSpA).^2,3 BKZ was approved for axSpA treatment in the US in September 2024.⁴

This first presentation of BKZ real-world clinical data from the US describes physician-reported pt characteristics, including treatment history and disease severity, of pts with axSpA initiating BKZ in routine clinical practice in the US, and physician-reported effectiveness of BKZ treatment and satisfaction with disease control.

Methods: Interim data were drawn from the Adelphi Real World BKZ axSpA Plus Disease Specific Programme™, an ongoing cross-sectional survey in Canada, France, Germany, Italy, Japan, Spain, the UK and the US. Physician questionnaires on pts with PsA or axSpA undergoing BKZ treatment began in July 2024, staggered by country based on BKZ reimbursement; completion expected September 2025. Interim data from the US axSpA population are reported (data cut April 22 2025).

Physicians completed a questionnaire per patient at most recent visit including current and retrospective questions (answered as perceived by physicians and/or by medical records). We present pt characteristics at BKZ initiation, physician-reported overall disease severity (mild, moderate or severe; as perceived by physicians) at BKZ initiation and most recent visit, and physician satisfaction with disease control, at most recent visit (stratified by BKZ treatment duration [TD]: < 3, 3–6 or >6 months).

Pts with mild axSpA at BKZ initiation were excluded and no TD-related inclusion criteria were imposed. All analyses are descriptive; observed data reported.

Results: At interim data cut, 10 physicians provided data for 43 BKZ-treated pts with axSpA and available TD information (Table).

Between BKZ initiation and most recent visit, physicians reported overall disease severity improvements with BKZ for all TDs including < 3 months, suggesting rapid treatment response. By the most recent visit, most pts had mild overall disease severity and none had severe disease severity (Figure 1), demonstrating sustained improvements in disease control. At the most recent visit, physicians were satisfied/very satisfied with treatment for almost all pts across TD groups (Figure 2).

Conclusion: In real-world settings, physician-reported disease severity improved over time in BKZ-treated pts with axSpA regardless of TD. Physicians were satisfied/very satisfied with almost all pts’ disease control on BKZ treatment across all TD groups. These results from routine clinical practice complement the rapid and sustained effectiveness of BKZ in pts with axSpA previously observed in phase 3 trials.

References: 1. Navarro-Compán V. Lancet 2025;405:159–72; 2. Deodhar A. RMD Open 2025;11:e005081; 3. Baraliakos X. Rheumatology 2025;keaf009; 4. FDA. 2024. https://www.accessdata.fda.gov/drugsatfda_docs/label/2024/761151s009lbl.pdf.