Bimekizumab outperforms risankizumab in the first head-to-head trial in PsA

In the BE-BOLD-trial (NCT06624228), the first randomised head-to-head comparison of 2 widely used biologics in psoriatic arthritis (PsA), bimekizumab achieved a significantly higher American College of Rheumatology 50% (ACR50) response than risankizumab at week 16. This advantage was maintained for an additional 8 weeks of treatment in this phase 3b study.

Direct comparative evidence remains scarce in PsA, a gap that prompted this study, as Prof. Joseph Merola (University of Texas Southwestern, TX, USA) pointed out [1]. Risankizumab blocks interleukin (IL)-23, whereas bimekizumab inhibits both IL-17A and IL-17F. Both pro-inflammatory cytokines play a central role in disease activity.

A total of 553 patients were randomised, and approximately 90% completed the study. Around 1 in 5 had shown an inadequate response to tumour necrosis factor (TNF) inhibitors. Because only about 11% of participants (60 of 553) had mild-to-moderate psoriasis at baseline, most received the PsA dosing regimen of bimekizumab (160 mg every 4 weeks) rather than the higher psoriasis regimen (320 mg every 4 weeks through week 16, then every 8 weeks).

The primary endpoint was ACR50, defined as at least a 50% improvement according to the American College of Rheumatology response criteria. “ACR50 represents a very meaningful endpoint in PsA,” Prof. Merola emphasised.

Baseline characteristics were well balanced between the treatment groups; only about a 11% of patients had moderate-to-severe psoriasis (29 of 277 receiving bimekizumab and 31 of 276 receiving risankizumab). At week 16, 49.1% of patients receiving bimekizumab reached ACR50 compared with 38.0% of those receiving risankizumab (P=0.0058), and the separation between the treatment arms was maintained through week 24.

Secondary endpoints, including minimal disease activity, numerically favoured bimekizumab but did not reach statistical significance.

Prof. Merola characterised the safety profile as “reassuring and free of new signals,” noting that the comparison produced what he termed “a welcome lack of surprises.” Overall safety findings were broadly comparable between the 2 agents, with 1 expected difference: Candida infections occurred more frequently with bimekizumab, consistent with its mechanism of action, although cases were mild to moderate. The trial is ongoing, and Prof. Merola indicated that additional data will be reported.

These findings position dual IL-17A/F inhibition with bimekizumab ahead of IL-23 blockade with risankizumab for achieving ACR50 in patients with PsA over 24 weeks, at the cost of a predictable and manageable increase in mild-to-moderate Candida infections.

Merola J, et al. Bimekizumab efficacy & safety versus risankizumab in patients with active psoriatic arthritis: 16-week results from a head-to-head, multicentre, randomised, phase 3b study (BE BOLD) LB0001, EULAR 2026, 3–6 June, London, United Kingdom.