Two runners, the clear winner crossing the lineBE BOLD goes head-to-head
BE BOLD was a multicentre, randomized, double-blind, active comparator–controlled, parallel-group phase IIIb trial. A total of 553 patients with active PsA were randomized 1:1 to receive subcutaneous bimekizumab (n=277; mean age, 51.1 years; male, 50.9 percent) or risankizumab (n=276; mean age, 50.7 years; male, 51.4 percent) for 24 weeks. [McInnes IB, et al, EULAR 2026, abstract LB0001]
The primary endpoint was ACR50 at week 16 (noninferiority and superiority). “This is the first study to test head-to-head superiority on a joint-focused outcome in PsA, which is why I think it’s so incredibly exciting,” said Dr Joseph Merola of UT Southwestern Medical Center, US, who presented the data at the European Alliance of Associations for Rheumatology Annual Congress (EULAR) 2026.
Eligible patients were either biologic disease-modifying antirheumatic drug (bDMARD)–naïve, or had an inadequate response to or intolerance to a maximum of one prior tumour necrosis factor inhibitor. In the bimekizumab group, patients with no or mild psoriasis received bimekizumab 160 mg Q4W through week 24; those with moderate or severe psoriasis received 320 mg Q4W until week 16, followed by Q8W until week 24. In the risankizumab group, patients received risankizumab 150 mg at baseline and week 4, then Q12W until week 24, regardless of baseline psoriasis severity. Concomitant stable doses of conventional synthetic DMARDs were allowed.
BE BOLD met its primary endpoint. “Dual inhibition of interleukin [IL]-17A and IL-17F with bimekizumab was superior to IL-3 inhibition with risankizumab for the primary endpoint of ACR50 at week 16 [49.1 vs 38.0 percent; difference (Δ), +11.1 percent; p=0.0058] in patients with active PsA,” said Merola.
“This is the first head-to-head study in PsA to demonstrate superiority for a joint-focused primary endpoint,” pointed out Merola. “[Before BE BOLD,] we haven’t had such high-quality data to date in this space.”
Joint response as early as week 4
“There was an early, rapid response [as demonstrated by early separation of the curves] between the two groups,” noted Merola.
The difference in ACR50 between the two groups was apparent at week 4 (19.9 vs 7.2 percent; Δ, 12.7 percent; pnominal<0.0001) and persisted through week 24 (54.9 vs 43.8 percent; Δ, 11.1 percent; pnominal=0.0059).
“This is relevant to us insofar as we often make clinical decisions as early as 12 weeks, when we discuss adding or changing therapy,” Merola commented.
“We have long discussed how time matters to patients — not only for symptom relief, but also [to prevent irreversible] functional damage over time,” he added. “These findings could guide treatment decisions and inform clinical recommendations for PsA management.”
BE BOLD pushes for ACR50
While most PsA trials rely on ACR20 (a ≥20 percent improvement in ACR response criteria) as the primary endpoint, this generally does not represent an optimal clinical improvement. [Curr Rheumatol Rep 2017;19:21]
Notably, BE BOLD adopted a more stringent primary endpoint of ACR50, which requires ≥50 percent improvement in tender and swollen joint counts, and in three of five additional criteria, including physician and patient global assessments, pain, functional status, and inflammatory markers. [www.ncbi.nlm.nih.gov/books/NBK549711; McInnes IB, et al, EULAR 2026, abstract LB0001]
Disease activity, complete skin clearance
“A numerically higher proportion of bimekizumab-treated patients achieved secondary outcomes encompassing joint, skin and overall disease activity than risankizumab-treated patients over 24 weeks,” Merola highlighted.
Minimal disease activity (MDA) response at weeks 4, 16 and 24 was achieved in 13.7, 43.3 and 49.1 percent of patients in the bimekizumab group and in 6.5, 39.9 and 42.4 percent of those in the risankizumab group, respectively.
Disease Activity Index for Psoriatic Arthritis Low disease Activity or Remission (DAPSA LDA + REM), defined as a DAPSA score ≤14, was achieved in a higher proportion of patients in the bimekizumab vs risankizumab group from week 4 (29.6 vs 21.7 percent) to week 24 (68.2 vs 62.3 percent).
In patients with ≥3 percent body surface area involvement at baseline, bimekizumab produced a higher rate of complete skin clearance (Psoriasis Area and Severity Index 100 [PASI100]) at week 4 (12.5 vs 3.4 percent; pnominal=0.0037) vs risankizumab, with comparable responses at week 16 (53.4 vs 46.6 percent) and week 24 (59.7 vs 59.1 percent).
Additionally, bimekizumab showed numerically higher rates of simultaneous ACR50 and PASI100 achievement at week 16 (33.5 vs 24.4 percent) and week 24 (39.2 vs 34.1 percent) vs risankizumab.
Comparable safety profiles
“Overall safety profiles were comparable between the two groups, with no new safety signals identified,” Merola reported. Although Candida infections were more frequent with bimekizumab, they were all mild or moderate in severity.
Rates of treatment-emergent adverse events (TEAEs) and serious TEAEs were 58.1 percent and 1.8 percent with bimekizumab, and 55.3 percent and 3.3 percent with risankizumab, respectively. Severe TEAEs occurred in 1.8 percent of patients in both groups.
“Rates of serious infections, inflammatory bowel disease, malignancy, neutropenia, hypersensitivity, and hepatic or cardiovascular events were low across both groups,” Merola noted. “No cases of suicidal ideation and behaviour, anaphylaxis, or active tuberculosis were reported.”
Superiority across psoriatic diseases
Unlike other bDMARDs that block a single cytokine, bimekizumab specifically inhibits both IL-17A and IL-17F – the two primary cytokines driving the inflammatory pathways in psoriatic diseases.
Other clinical trials of bimekizumab have been promising, demonstrating superior efficacy in plaque psoriasis in BE SURE (vs adalimumab), BE RADIANT (vs secukinumab) and BE VIVID (vs ustekinumab). [N Engl J Med 2021;385:130-141; N Engl J Med 2021;385:142-152; Lancet 2021;397:487-498]
“BE BOLD represents the fourth head-to-head study demonstrating bimekizumab’s superiority across psoriatic diseases,” highlighted Merola.