Bimekizumab Maintains Strong Efficacy Across Five Years in Ankylosing Spondylitis
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Five-year extension data for bimekizumab (Bimzelx) show that nearly 50% of patients with ankylosing spondylitis maintained an ASAS40 response even under conservative analysis, with no new safety signals and a notably low rate of uveitis. Researchers called the durability of results at this time point surprising and encouraging.
Abstract
Five-year long-term extension data for bimekizumab in patients with radiographic axial spondyloarthritis (ankylosing spondylitis) were presented at a major rheumatology congress in March 2025. Bimekizumab is a monoclonal IgG1 antibody that selectively inhibits both IL-17A and IL-17F.
At week 256 (approximately 5 years), 49.7% of patients achieved ASAS40 under non-responder imputation. ASDAS low disease activity was achieved in 41.6% of patients. No new safety signals were identified over the extended follow-up period. The rate of anterior uveitis events was very low, which is clinically significant given the approximately 40% lifetime risk of uveitis in this population. These data support the sustained long-term efficacy and safety of bimekizumab without evidence of diminishing response over time.