UCB SA has reported 24-week data from the Phase 3b BE BOLD trial showing that BIMZELX, or bimekizumab, maintained numerically higher ACR50 joint responses than AbbVie Inc.’s SKYRIZI, or risankizumab, in adults with active psoriatic arthritis. At Week 24, 54.9% of patients receiving BIMZELX achieved ACR50 compared with 43.8% receiving SKYRIZI, extending the separation first seen at Week 16.
The crucial statistical detail is that BIMZELX had already demonstrated formal superiority on the prespecified primary endpoint at Week 16, when ACR50 responses reached 49.1% versus 38.0% with SKYRIZI, with a p-value of 0.0058. However, the trial’s hierarchical testing sequence stopped when the first ranked secondary endpoint, minimal disease activity at Week 16, failed to achieve statistical superiority. That means the later Week 24 ACR50 comparison and most additional secondary outcomes should be interpreted as supportive or exploratory rather than as a new series of formally confirmed superiority claims.
That distinction matters because the commercial stakes are unusually high. SKYRIZI generated US$5.776 billion in worldwide revenue for AbbVie in the third quarter of 2026 across its approved indications, while UCB has raised BIMZELX peak annual sales guidance above €7 billion. BE BOLD therefore places one of UCB’s most important growth assets directly against one of the pharmaceutical industry’s largest immunology franchises.
What did the BE BOLD head-to-head trial actually show for BIMZELX versus SKYRIZI?
BE BOLD enrolled 553 adults with active psoriatic arthritis who were either biologic disease-modifying antirheumatic drug-naïve or had experienced inadequate response or intolerance to one previous tumour necrosis factor inhibitor. Patients were randomised 1:1 to BIMZELX or SKYRIZI using approved dosing regimens, creating a direct comparative study rather than the cross-trial comparisons that often dominate discussions of competing biologics.
The primary endpoint was ACR50 at Week 16, meaning at least a 50% improvement in American College of Rheumatology response criteria. BIMZELX achieved ACR50 in 49.1% of patients compared with 38.0% receiving SKYRIZI, establishing both non-inferiority and superiority for the prespecified primary endpoint.
The difference remained visible at Week 24. ACR50 was achieved by 54.9% of BIMZELX-treated patients and 43.8% receiving SKYRIZI, an absolute separation of 11.1 percentage points. The ACR abstract reported a nominal p-value of 0.0059 for that comparison.
BIMZELX also showed numerically higher ACR50 responses at every measured time point from Week 4 through Week 24. The speed of response may be clinically relevant in symptomatic inflammatory disease, although the formal interpretation of later endpoints is constrained by the trial’s statistical hierarchy.
Why did the statistical testing hierarchy stop even though BIMZELX won the primary endpoint?
Clinical trials commonly use hierarchical testing to control the risk of false-positive conclusions when numerous endpoints are analysed. Under this structure, secondary endpoints are tested in a predetermined order, and formal statistical testing may stop when one endpoint fails to cross its required significance threshold.
In BE BOLD, the first ranked secondary endpoint was minimal disease activity at Week 16. BIMZELX produced a numerically higher rate than SKYRIZI, but the difference was only 3.4 percentage points and generated a p-value of 0.3921. Because that endpoint did not achieve statistical significance, sequential testing stopped.
The consequence is important for interpreting UCB’s wider efficacy story. Subsequent comparisons can still provide clinically useful information, but they no longer carry the same confirmatory statistical status as the Week 16 ACR50 primary endpoint.
This is particularly relevant when looking at the Week 24 data. The 54.9% versus 43.8% ACR50 result is consistent with the primary endpoint and strengthens the impression of sustained separation, but it should not be portrayed as an independently confirmed second superiority endpoint.
Does BIMZELX also outperform SKYRIZI on skin clearance?
The skin results are more mixed than the joint response numbers. Among patients with psoriasis affecting at least 3% of body surface area at baseline, complete skin clearance measured by PASI100 was achieved earlier by a higher proportion of BIMZELX-treated patients.
At Week 4, PASI100 was achieved in 12.5% of BIMZELX-treated patients compared with 3.4% receiving SKYRIZI. By Week 16, complete clearance was seen in 53.4% versus 46.6%, although the difference was not nominally statistically significant.
By Week 24, the rates had converged almost completely, with PASI100 achieved by 59.7% of patients receiving BIMZELX and 59.1% receiving SKYRIZI. The later result therefore does not support a claim that BIMZELX provides superior complete skin clearance at six months.
The more defensible interpretation is that BIMZELX appeared to produce faster early skin clearance in this subgroup while SKYRIZI largely caught up over time. For clinicians managing psoriatic arthritis with significant skin involvement, speed of response may still matter, but sustained comparative efficacy is likely to carry greater weight in long-term treatment decisions.
Why is a direct BIMZELX versus SKYRIZI comparison commercially important?
The study matters because both medicines target major inflammatory pathways but through different mechanisms. BIMZELX selectively inhibits interleukin-17A and interleukin-17F, while SKYRIZI targets the p19 subunit of interleukin-23.
Both are already approved for active psoriatic arthritis, so BE BOLD is not testing whether either medicine works compared with placebo. It asks a more commercially consequential question: whether one established biologic can deliver meaningfully stronger disease control than another established competitor.
That type of evidence can influence treatment sequencing, formulary positioning and physician preference, particularly when therapies operate in a crowded market with multiple effective options. Direct comparative trials can therefore carry commercial value beyond their immediate clinical findings.
For UCB, the trial also supports a broader effort to position BIMZELX around deep response rather than merely adequate disease control. ACR50 is a more demanding endpoint than ACR20, and demonstrating superiority on that measure provides a stronger differentiation argument than showing small differences on less stringent response thresholds.
AbbVie, however, retains enormous commercial scale. SKYRIZI generated US$5.776 billion in global revenue during the third quarter of 2026 and US$15.764 billion during the first nine months of the year across psoriasis, psoriatic arthritis and inflammatory bowel disease indications. The franchise grew 22.7% year over year in the third quarter.
That means UCB is challenging a drug with deeply established prescribing, reimbursement and commercial infrastructure rather than an emerging competitor.
How large has BIMZELX become within UCB’s growth strategy?
BIMZELX has rapidly become central to UCB’s financial outlook. The medicine generated approximately €1.52 billion in sales during the first half of 2026, supported by expansion across psoriasis, psoriatic arthritis, axial spondyloarthritis and hidradenitis suppurativa.
UCB has increased its peak annual sales ambition for BIMZELX to more than €7 billion, reflecting management’s confidence in the product’s commercial trajectory. That forecast remains a company expectation rather than guaranteed revenue, but it illustrates how much strategic weight UCB is placing on continued market-share gains.
The company also raised its 2026 financial guidance in October, citing stronger BIMZELX performance in the United States, robust patient demand and favourable net pricing dynamics. Revenue growth is now expected in the low twenties percentage range at constant exchange rates, while adjusted earnings before interest, tax, depreciation and amortisation growth is expected in the low-to-mid forties.
BIMZELX’s ability to demonstrate superiority against major branded competitors therefore matters well beyond clinical prestige. Each convincing head-to-head result can potentially support physician adoption and strengthen the commercial narrative behind UCB’s aggressive peak-sales expectations.
What does the BE BOLD safety comparison show?
Treatment-emergent adverse events occurred in 58.1% of patients receiving BIMZELX and 55.3% receiving SKYRIZI using all data available at the study cut-off. Serious treatment-emergent adverse events were reported in 1.8% and 3.3% of patients, respectively.
The study was not powered to establish comparative safety superiority, so those percentages should not be used to conclude that one treatment is safer overall. The numbers provide descriptive context rather than a definitive ranking.
Candida infections were more frequent with BIMZELX, occurring in 2.9% of patients compared with 0.7% receiving SKYRIZI. UCB reported that the infections were mild or moderate, none were systemic or serious and none led to treatment discontinuation.
That pattern is biologically consistent with IL-17 pathway inhibition and is already reflected in BIMZELX’s established safety profile. The United States prescribing information also includes warnings relating to infections, liver enzyme abnormalities and inflammatory bowel disease, making patient selection and monitoring important in routine use.
One death occurred in a SKYRIZI-treated patient during the study and was considered unrelated to treatment by the investigator. The available data do not support attributing that event to risankizumab.
Can one head-to-head win materially threaten AbbVie’s SKYRIZI franchise?
Not by itself. Psoriatic arthritis represents only one part of SKYRIZI’s commercial footprint, which also includes major positions in plaque psoriasis, Crohn’s disease and ulcerative colitis. AbbVie has built the medicine into one of its principal post-Humira growth engines.
BE BOLD nevertheless provides UCB with something commercially useful that many competitors lack: a randomised head-to-head superiority result against SKYRIZI on a meaningful joint endpoint. That is stronger evidence than comparing response rates from unrelated trials.
The limitation is breadth. BIMZELX did not establish formal superiority across the full sequence of secondary outcomes, and the skin-clearance advantage narrowed substantially by Week 24. The trial therefore supports a focused claim around ACR50 joint response rather than a broad conclusion that BIMZELX is clinically superior across every important domain of psoriatic arthritis.
Treatment choice will also depend on comorbidities, previous therapy, dosing preferences, payer access, safety considerations and the degree of skin versus musculoskeletal disease. No single response endpoint can determine optimal therapy for every patient.
What does the market reaction say about expectations around UCB?
UCB shares traded at approximately €294.70 on 9 November, rising about 1.3% during the session and sitting close to the upper end of their 52-week trading range. The stock had gained roughly 5% over five trading days and approximately 45% over one month.
That sharp one-month move reflects a broader sequence of positive developments, including stronger commercial performance and UCB’s October guidance increase, rather than the BE BOLD update alone. It would therefore be inappropriate to attribute the share-price appreciation specifically to the latest psoriatic arthritis data.
The market backdrop nevertheless shows that expectations around BIMZELX are already elevated. A company guiding towards more than €7 billion in peak sales must continue converting clinical differentiation into patient starts, reimbursement access and sustained retention across multiple indications.
The BE BOLD results support that ambition, but they also demonstrate why statistical detail matters. UCB has a legitimate superiority result against SKYRIZI on ACR50 at Week 16 and a sustained numerical advantage at Week 24. It does not have a blanket superiority result across the entire psoriatic arthritis efficacy profile.
For a medicine attempting to challenge one of AbbVie’s largest franchises, that distinction does not diminish the value of the trial. It defines exactly where BIMZELX has generated its strongest comparative evidence and where UCB will still need additional data to broaden the competitive argument.
