BE BOLD and the Case for IL-17 Inhibition in Psoriatic Arthritis, With David Cotter, MD, PhD

Bimekizumab (Bimzelx), a dual IL-17A/F inhibitor, achieved superior ACR50 response over the IL-23 inhibitor risankizumab (Skyrizi) in active psoriatic arthritis (PsA) in the phase 3b BE BOLD trial (NCT06624228), according to David Cotter, MD, PhD, a board-certified dermatologist at Las Vegas Dermatology and assistant clinical professor at the Kirk Kerkorian School of Medicine at the University of Nevada, Las Vegas.

In an interview with HCPLive, Cotter discussed where IL-17 blockade fits for patients with psoriasis, emerging PsA, or both.

Sixteen-week results were presented at the 2026 European Alliance of Associations for Rheumatology (EULAR) Annual Meeting in London, United Kingdom, held June 3 to 6, making bimekizumab the first approved biologic to show statistically significant ACR50 superiority in a head-to-head PsA trial.1 BE BOLD randomized 553 adults with active PsA 1:1 to either agent.

At week 16, 49.1% of patients receiving bimekizumab achieved ACR50 vs 38.4% with risankizumab (P = .0078).1 Separation appeared by week 4, at 19.9% vs 7.2%. The first ranked secondary end point, minimal disease activity at week 16, was numerically higher with bimekizumab but not statistically significant (43.0% vs 39.9%; P = .4408).1

“What that means clinically is so much deeper than just a 10% delta. If I pick 10 patients and I put them on bimekizumab, 5 out of 10 are going to hit an ACR50. If I put 10 on risankizumab, 4 out of 10 are going to hit an ACR50,” Cotter said.

Cotter cautioned against overinterpreting skin end points, since 248 of 277 patients in the bimekizumab arm received the PsA dose of 160 mg every 4 weeks rather than the 320 mg dose used in psoriasis. In an exploratory analysis of patients with psoriasis covering at least 3% of body surface area, PASI 100 at week 16 reached 53.4% with bimekizumab and 46.6% with risankizumab, a difference which was not statistically significant.1 He called for subgroup analyses of patients receiving psoriasis dosing.

On safety, Cotter said he does not typically start an IL-17 inhibitor in patients with a personal or strong family history of inflammatory bowel disease. He also counsels patients on suicidality language in IL-17 labeling, a boxed warning for brodalumab (Siliq) and a label warning for bimekizumab, without letting it sideline otherwise appropriate candidates. Early biologic treatment in a patient newly diagnosed with psoriasis may help prevent permanent joint damage decades later, he added.

References

1. BIMZELX (bimekizumab) demonstrates superior efficacy over SKYRIZI (risankizumab) in psoriatic arthritis. News release. UCB. May 19, 2026. Accessed October 12, 2026. https://www.ucb.com/sites/default/files/press_files/9f04679e4da0ce8a.pdf