Bimekizumab Tops Risankizumab in PsA Head-to-Head Trial

At the 2026 European Alliance of Associations for Rheumatology (EULAR) Annual Meeting, UCB presented 16-week findings from the phase 3 BE BOLD (NCT06624228) trial showing that bimekizumab achieved superior joint responses compared with risankizumab in adults with active psoriatic arthritis (PsA). The head-to-head study evaluated the IL-17A and IL-17F inhibitor bimekizumab Bimzelx; UCB) against the IL-23 inhibitor risankizumab (Skyrizi; AbbVie), representing the first direct comparison between these therapeutic pathways in PsA.¹

The study met its primary endpoint of American College of Rheumatology 50% improvement criteria (ACR50) at week 16. ACR50 responses were achieved in 49.1% of patients treated with bimekizumab compared with 38.4% of those receiving risankizumab, a statistically significant difference (p=0.0078).

According to UCB, bimekizumab is the first biologic therapy to demonstrate statistically significant superiority in ACR50 outcomes in a head-to-head PsA trial.

“Delivering high-level clinical responses is crucial for people with psoriatic arthritis. Achieving ACR50 level responses in clinical trials indicates joint improvements that correlate closely with clinically meaningful reductions in disease activity, inflammation control and consequent improvements in quality of life,” said Iain McInnes, MD, PhD, professor at the University of Glasgow, College of Medical Veterinary and Life Sciences, Glasgow, UK. “The new BE BOLD data, showing bimekizumab achieved superiority vs risankizumab in ACR50 at week 16 in a direct head-to-head trial design, can support clinicians in making early informed decisions for treating this chronic inflammatory disease.”

Clinical Significance of Early Joint Responses

Psoriatic arthritis is a heterogeneous immune-mediated condition involving peripheral arthritis, enthesitis, dactylitis, axial disease, and cutaneous psoriasis. As biologic options expand, treatment selection increasingly depends on efficacy across both joint and skin manifestations.²

Secondary Endpoints Numerically Favored Bimekizumab

Although the trial achieved its primary endpoint, the first-ranked secondary endpoint—minimal disease activity (MDA) at week 16—did not reach statistical significance within the predefined testing hierarchy. MDA was achieved by 43.0% of patients receiving bimekizumab and 39.9% of those receiving risankizumab (p=0.4408).

Because hierarchical testing stopped after this endpoint, subsequent ranked secondary outcomes were considered descriptive only.

Several additional measures numerically favored bimekizumab. Simultaneous achievement of ACR50 and complete skin clearance (PASI100) at week 16 occurred in 33.5% of bimekizumab-treated patients compared with 24.4% of risankizumab-treated patients. Investigators also reported earlier onset of joint response with bimekizumab, with ACR50 responses observed at week 4 in 19.9% of patients versus 7.2% in the risankizumab arm.

Exploratory analyses showed PASI100 responses at week 16 in 53.4% of patients receiving bimekizumab and 46.6% of those receiving risankizumab. Additionally, low disease activity or remission according to the Disease Activity Index for Psoriatic Arthritis (DAPSA) was achieved in 65.3% and 54.7% of patients, respectively.

Safety Profiles Remained Comparable

Safety findings were generally consistent with the established profiles of both therapies. Treatment-emergent adverse events (TEAEs) occurred in 57.0% of patients treated with bimekizumab and 52.0% of those receiving risankizumab.

Serious TEAEs were reported in 1.8% of bimekizumab-treated patients and 2.9% of risankizumab-treated patients. Severe TEAEs occurred in 1.8% of patients in both treatment groups. Discontinuation rates due to adverse events were low and identical between study arms.

Candida infections occurred more frequently among patients receiving bimekizumab, consistent with the mechanism of IL-17 inhibition. Investigators stated that all Candida infections were mild or moderate, with no serious or systemic cases reported and no discontinuations related to these events. No cases of suicidal ideation or behavior were observed during the study period.

Trial Design and Broader Implications

The BE BOLD trial enrolled adults with active PsA and used non-responder imputation analyses. Patients in the bimekizumab group received either 160 mg every 4 weeks or 320 mg every 4 weeks followed by every 8 weeks depending on psoriasis severity. Patients assigned to risankizumab received 150 mg at baseline, week 4, and week 16.

According to UCB, BE BOLD is the fourth head-to-head study in the bimekizumab clinical development program to demonstrate superiority over another biologic therapy, although previous comparative trials focused on plaque psoriasis rather than PsA.

As comparative effectiveness data become increasingly important in psoriatic disease management, findings from studies such as BE BOLD may help inform treatment decisions involving efficacy across joint and skin domains, onset of response, and tolerability profiles.

References

1. BIMZELX[®](bimekizumab) demonstrates superior efficacy over SKYRIZI[®] (risankizumab) in psoriatic arthritis: BE BOLD week 16 data. News release. UCB. Published May 19, 2026. Accessed May 19, 2026. https://www.ucb.com/newsroom/press-releases/article/bimzelxrbimekizumab-demonstrates-superior-efficacy-over-skyrizir-risankizumab-in-psoriatic-arthritis-be-bold-week-16-data
2. Azuaga AB, Ramírez J, Cañete JD. Psoriatic arthritis: pathogenesis and targeted therapies. Int J Mol Sci. 2023;24(5):4901. Published 2023 Mar 3. doi:10.3390/ijms24054901