Numerically greater rates of ACR50 were sustained through Week 24.1 The full Week 24 findings are being presented at the 2026 ACR Convergence in Orlando, Florida, November 6–11.1 Data reported in this press release are based on the dataset included in the ACR abstract.1
"ACR50 is the new standard in PsA, reflecting considerable joint improvements and is known to be associated with clinically meaningful reductions in disease activity and subsequent improvements in quality of life," said Joseph F. Merola, MD-MMSc, Rheumatologist, Dermatologist, President of the Psoriasis and Psoriatic Arthritis Multicenter Advancement Network, Co-President of the Group for Research in Psoriasis and Psoriatic Arthritis and President of the Rheumatologic Dermatology Society. "In the BE BOLD head-to-head trial, bimekizumab demonstrated rapid and greater ACR50 responses that were sustained to six months, in addition to delivering high rates of complete skin clearance, both of which are especially important for those living with psoriatic arthritis."
Overall safety treatment-emergent adverse events (TEAEs) were comparable between treatments in BE BOLD, with the exception of increased rates of mild-to-moderate localized Candida infections in the BIMZELX arm.1 BE BOLD was not powered to compare safety.1
"Head-to-head trials designed to mirror clinical practice are the gold standard for comparative clinical research. The BE BOLD results help redefine treatment expectations for people living with psoriatic arthritis, reinforcing our belief that patients and clinicians can aim higher when setting treatment goals," said Donatello Crocetta, Chief Medical Officer, UCB. "This data is part of UCB's wider evidence portfolio at ACR, showing treatment with bimekizumab enables rapid and sustained clinically meaningful improvements in this chronic inflammatory disease."
The full Week 24 results from BE BOLD will be presented at ACR in an oral presentation at 10:15 a.m. ET on Tuesday, November 10. The data from BE BOLD form part of UCB's broader presence at the 2026 ACR Convergence, where a total of 18 abstracts will be presented across the UCB immunology portfolio assets in PsA, axial spondyloarthritis, rheumatoid arthritis, and systemic lupus erythematosus.
BE BOLD Week 24 results
- Week 16 data for BE BOLD, assessing BIMZELX, the first and only medicine approved to selectively inhibit both interleukin 17A (IL-17A) and interleukin 17F (IL-17F),2,3 versus the interleukin 23 inhibitor risankizumab4 in adults living with active PsA, was first presented at the EULAR 2026 annual congress.5 BIMZELX met the primary endpoint for BE BOLD of superiority in ACR50 at Week 16, achieved by 49.1% receiving BIMZELX vs 38.0% receiving risankizumab (a difference of 11.1%), with statistical significance (p=0.0058).1†
- At Week 24, ACR50 was achieved in 54.9% of those receiving BIMZELX and 43.8% receiving risankizumab.1*† Higher ACR50 responses were observed with BIMZELX at every study point, and as early as Week 4 (nominal p<0.0001)1*†
- The first ranked secondary endpoint (MDA at Week 16) was 3.4 percentage points higher with BIMZELX (p=0.3921; sequential testing stopped at this point, and subsequent ranked secondary endpoints were descriptive only), with higher rates sustained to Week 241†
- Numerically greater responses without statistical significance for BIMZELX observed across secondary endpoints, encompassing joint, skin,‡ and overall disease activity, sustained to Week 241†
- At Week 4, PASI100 was achieved in 12.5% of those receiving BIMZELX and 3.4% receiving risankizumab (nominal p<0.01).1*†‡ At Week 16, PASI100 was achieved in 53.4% of those receiving BIMZELX and 46.6% receiving risankizumab, without nominal significance.1*†‡ Rates of PASI100 for BIMZELX and risankizumab were comparable at Week 20 and Week 24 (59.7% and 59.1%, without nominal significance, at Week 24)*†‡
- Including all data to the cut-off, 161/277 (58.1%) BIMZELX-treated and 152/275 (55.3%) risankizumab-treated patients had ≥1 TEAE.1
- No new safety signals were identified in the study at Week 24.1 Discontinuation rates due to TEAEs and serious/severe TEAEs were low in both treatment groups.1 Fewer patients reported serious TEAEs on BIMZELX (5 [1.8%]) than on risankizumab (9 [3.3%]).1 One death occurred in a risankizumab-treated patient, deemed unrelated to treatment by the investigator1
- Candida infections were more frequent in BIMZELX-treated patients (2.9%) than in risankizumab-treated patients (0.7%), as anticipated by the mechanism of action; all were mild or moderate, none were serious, systemic, or led to study discontinuation1
- ACR50: A 50% or greater improvement from baseline in American College of Rheumatology response criteria, including at least a 50% improvement in tender and swollen joint counts as well as 50% or greater improvement in three of five additional criteria (physician global, patient global, patient pain, function, and C-reactive protein (CRP)/erythrocyte sedimentation rate).6 This represents a stringent efficacy outcome in psoriatic arthritis7,8
- MDA: Minimal Disease Activity (MDA), a dichotomous endpoint (i.e., either it is reached or it is not) demonstrating minimum inflammatory disease. The MDA score comprises seven relevant disease-related domains (tender/swollen joint count, skin, physical function, pain, enthesis, general patient-based evaluation), such that achieving five of the seven indicates MDA.9 A participant in BE BOLD was considered as having MDA if five or more of the following seven criteria were fulfilled:10
- Tender joint count ≤1
- Swollen joint count ≤1
- PASI ≤1 or BSA ≤3 (less than or equal to 3% body surface area affected)
- PtAAP VAS ≤15 (Patient's Assessment of Arthritis Pain score ≤15: 0=no pain; 100=most severe pain)
- PGA-PsA VAS ≤20 (Physician's Global Assessment in Psoriatic Arthritis score ≤20: 0=very good, asymptomatic, no limitation of normal activities; 100=very poor, very severe symptoms which were intolerable, inability to carry out all normal activities)
- HAQ-DI ≤0.5 (Health Assessment Questionnaire-Disability Index score ≤0.5: degree of difficulty experienced in eight domains of daily living activities [20 questions], total score [0–3] computed from item scores, with lower scores meaning less disability)
- Tender enthesial points ≤1
- PASI100: 100% improvement from baseline in Psoriasis Area and Severity Index (PASI), indicating complete skin clearance11
About psoriatic arthritis
Psoriatic arthritis (PsA) is a serious, highly heterogeneous, chronic, systemic inflammatory condition affecting both the joints and skin with a prevalence of 0.02 percent to 0.25 percent of the population.12 Of people living with psoriasis, approximately 30 percent progress to also develop psoriatic arthritis.13 It manifests as joint pain and stiffness, skin plaques, swollen toes and fingers (dactylitis) and inflammation of the sites where tendons or ligaments insert into the bone (enthesitis).13 The burden on those living with PsA extends beyond physical discomfort to reduced quality of life, with comorbidities including hypertension, cardiovascular disease, anxiety, and depression.14 In PsA, uncontrolled active disease can lead to long-term structural damage.
About the BE BOLD trial
BE BOLD is a multicenter, randomized, double-blind, risankizumab-controlled, parallel-group Phase 3b study designed to evaluate the efficacy and safety of BIMZELX in adult study participants (n=553) with active psoriatic arthritis (PsA).1,10 The study includes adults with active PsA who are naïve to biologic treatments or who had previous exposure to one tumor necrosis factor-inhibitor (TNFi) with an inadequate or intolerant response.10
The primary endpoint in BE BOLD is ACR50 at Week 16.10 The study has a double-blinded methodology until Week 24.16 In the study, participants were randomized 1:1 to receive either BIMZELX or risankizumab.10
About BIMZELX® (bimekizumab-bkzx) in the U.S.
BIMZELX is a humanized monoclonal IgG1 antibody that is designed to selectively inhibit both interleukin 17A (IL-17A) and interleukin 17F (IL-17F), two key cytokines driving inflammatory processes.3 Elevated levels of IL-17A and IL-17F are found in lesional psoriatic skin.3
The approved indications for BIMZELX in the U.S. are:
- Plaque psoriasis: BIMZELX is indicated for the treatment of moderate-to-severe plaque psoriasis in adults who are candidates for systemic therapy or phototherapy
- Psoriatic arthritis: BIMZELX is indicated for the treatment of adult patients with active psoriatic arthritis
- Non-radiographic axial spondyloarthritis: BIMZELX is indicated for the treatment of adult patients with active non-radiographic axial spondyloarthritis with objective signs of inflammation
- Ankylosing spondylitis: BIMZELX is indicated for the treatment of adult patients with active ankylosing spondylitis
- Hidradenitis suppurativa: BIMZELX is indicated for the treatment of adults with moderate-to-severe hidradenitis suppurativa
Most Common Adverse Reactions
Most common (≥1%) adverse reactions in plaque psoriasis and hidradenitis suppurativa include upper respiratory tract infections, oral candidiasis, headache, injection site reactions, tinea infections, gastroenteritis, herpes simplex infections, acne, folliculitis, other candida infections, and fatigue.
Most common (≥2%) adverse reactions in psoriatic arthritis include upper respiratory tract infections, oral candidiasis, headache, diarrhea, and urinary tract infections.
Most common (≥2%) adverse reactions in non-radiographic axial spondyloarthritis include upper respiratory tract infections, oral candidiasis, headache, diarrhea, cough, fatigue, musculoskeletal pain, myalgia, tonsillitis, transaminase increase, and urinary tract infections.
Most common (≥2%) adverse reactions in ankylosing spondylitis include upper respiratory tract infections, oral candidiasis, headache, diarrhea, injection site pain, rash, and vulvovaginal mycotic infection.
About UCB
UCB is a global biopharmaceutical company inspired by the needs of people living with severe diseases and driven by science to make a meaningful difference in their lives. We combine our understanding of disease biology, scientific innovation and patient insights to develop differentiated medicines and solutions, with a focus on neurology, immunology and other areas of unmet medical need. Founded in Belgium in 1928, UCB has more than 10,000 employees in approximately 40 countries and generated revenue of €7.7 billion in 2025. UCB is listed on Euronext Brussels (symbol: UCB).
