Bimekizumab Demonstrates Superiority Over Risankizumab in Psoriatic Arthritis Trial

UCB, a Belgium-based biopharmaceutical company, reported positive topline results on March 11, 2026 from a head-to-head clinical trial (BE BOLD) showing that the company’s bimekizumab (brand name Bimzelx) demonstrated statistically significant superiority over risankizumab (brand name Skyrizi, AbbVie) in adults with active psoriatic arthritis (PsA).¹

The head-to-head study compared the dual interleukin-17A (IL-17A) and IL-17F inhibitor bimekizumab with the IL-23 inhibitor risankizumab. The study met its primary endpoint of superiority in achieving an American College of Rheumatology 50% improvement response (ACR50) at Week 16.¹

The randomized, double-blind trial represents the first study in PsA to demonstrate superiority of a licensed biologic therapy over an IL-23 inhibitor using the stringent ACR50 disease activity endpoint.² The findings add comparative evidence to an increasingly competitive immunology market in which multiple cytokine-targeting strategies are being evaluated to optimize treatment outcomes in psoriatic disease.³

How did bimekizumab perform in the trial?

The BE BOLD trial enrolled 553 adults with active PsA who were either biologic naïve or had previously received one tumor necrosis factor inhibitor with inadequate response or intolerance.

Participants were randomized in a double-blind design to receive either bimekizumab or risankizumab. The primary endpoint assessed the proportion of patients achieving ACR50 response at Week 16, a stringent measure that requires at least 50% improvement in tender and swollen joint counts along with improvement in additional disease activity measures.

According to the topline results, bimekizumab achieved statistically significant superiority over risankizumab in meeting this endpoint. Treatment was reported to be generally well tolerated through the Week 16 analysis, with no new safety signals identified.¹

“Our landmark BE BOLD study provides the first head-to-head evidence of superiority versus an IL-23 inhibitor in psoriatic arthritis,” said Emmanuel Caeymaex, executive vice president, head of Patient Evidence, UCB, in a company press release.¹ “These topline results reinforce bimekizumab’s potential to deliver clinically meaningful improvements using the stringent ACR50 measure of disease activity, indicating more complete control of joint inflammation,”

“BE BOLD represents the fourth head-to-head study demonstrating bimekizumab superiority, supporting physicians to make informed treatment decisions and advancing our ambitions to raise the standard of care for people living with psoriatic disease,” Caeymaex added.

What does the result suggest about cytokine targeting strategies in psoriatic arthritis?

Bimekizumab is a monoclonal immunoglobulin G1 antibody designed to selectively inhibit both IL-17A and IL-17F, cytokines that play key roles in inflammatory signaling pathways associated with psoriatic disease. Its dual inhibition strategy differs from IL-23–targeting therapies such as risankizumab, which act upstream in the inflammatory cascade. Comparative studies like BE BOLD may help clarify whether direct cytokine blockade at the IL-17 level produces greater control of joint inflammation in some patients with psoriatic arthritis.

The study findings also expand the growing head-to-head dataset within the bimekizumab clinical program. BE BOLD represents not only the fourth comparative trial demonstrating superiority of the therapy across psoriatic disease indications but also the first head-to-head study conducted specifically in PsA, according to the company.

PsA is a chronic inflammatory disease affecting both joints and skin, with approximately 30% of individuals with psoriasis eventually developing joint involvement.⁴ Without effective disease control, ongoing inflammation can lead to progressive joint damage, disability, and reduced quality of life.⁵

UCB indicated that full results from the BE BOLD study will be presented at a forthcoming international scientific congress.

As biologic treatment options expand across multiple cytokine targets, including IL-17, IL-23, and tumor necrosis factor pathways, direct comparative studies are increasingly being used to guide treatment selection and inform evolving standards of care in immune-mediated inflammatory diseases.⁶

References

1. UCB. BIMZELX (bimekizumab) superior to SKYRIZI (risankizumab) in BE BOLD: first head-to-head study in active psoriatic arthritis (PsA) to demonstrate superiority in ACR50. Press Relesae. March 11, 2026.
2. UCB Pharma. A Study to Evaluate the Efficacy and Safety of Bimekizumab in Adult Study Participants With Active Psoriatic Arthritis. ClinicalTrials.gov. Last updated March 9, 2026. Accessed March 11, 2026. https://clinicaltrials.gov/study/NCT06624228
3. Dimopoulou V, Nitsa M, Koutsianas C. Emerging Targets in Psoriatic Arthritis: Dual IL-17A/F and Selective TYK2 Inhibition in a Clinical Perspective. Mediterr J Rheumatol. 2026;37(Suppl 1):68-76. doi: 10.31138/mjr.101025.erh
4. National Psoriasis Foundation. About Psoriatic Arthritis. Accessed March 11, 2026. https://www.psoriasis.org/about-psoriatic-arthritis/
5. Lee S, Mendelsohn A, Sarnes E. The burden of psoriatic arthritis: a literature review from a global health systems perspective. P T. 2010;35(12):680-689. https://pubmed.ncbi.nlm.nih.gov/21197266/
6. Stisen ZR, Nielsen SM, Skougaard M, et al. Tolerability and comparative effectiveness of TNF, IL-17 and IL-23(p19) inhibitors in psoriatic arthritis: a target trial emulation study. Rheumatology (Oxford). 2024;63(6):1543-1551. doi: 10.1093/rheumatology/kead488