UCB Launches Study Comparing BIMZELX® and SKYRIZI® for Active Psoriatic Arthritis

UCB, a prominent global biopharmaceutical company, has recently announced the initiation of a significant Phase 3b study named BE BOLD. This study is set to compare the effectiveness of BIMZELX® (bimekizumab-bkzx), an interleukin (IL)-17A and IL-17F inhibitor, with SKYRIZI® (risankizumab), an IL-23 inhibitor, in treating adults suffering from active psoriatic arthritis (PsA). This marks the first head-to-head study in PsA that aims to demonstrate the superiority of an IL-17A and IL-17F inhibitor over an IL-23 inhibitor.

Dr. Philip J. Mease, Director of Rheumatology Research at Providence Swedish Medical Center, emphasized the importance of such evidence-based clinical studies. He stated, "The conduct of head-to-head clinical studies in psoriatic arthritis is crucial as they provide valuable scientific evidence, helping healthcare professionals and patients make informed treatment decisions." Notably, this is the first Phase 3b head-to-head study in PsA using the primary endpoint of ACR50 at Week 16, promising a robust assessment of bimekizumab versus risankizumab on inflamed joints—a primary concern for PsA patients.

Fiona du Monceau, Executive Vice President and Head of Patient Evidence at UCB, highlighted the company's history of head-to-head Phase 3/3b studies in moderate-to-severe plaque psoriasis. Previous studies demonstrated the superiority of bimekizumab over widely-used biologics like secukinumab, ustekinumab, and adalimumab. She noted, "BE BOLD represents the fourth head-to-head study in the bimekizumab clinical trial program, but the first in psoriatic arthritis and against an IL-23 inhibitor. This study underscores our belief in the potential of bimekizumab for people living with psoriatic disease, and we anticipate sharing the top-line results in 2026."

The BE BOLD study is a multicenter, randomized, double-blind, risankizumab-controlled, parallel-group trial designed to assess the efficacy and safety of BIMZELX in approximately 550 adults with active psoriatic arthritis. Participants will include those who are biologic treatment-naïve or have had inadequate or intolerant responses to one tumor necrosis factor-inhibitor (TNFi). The study will primarily evaluate the American College of Rheumatology 50 (ACR50), which signifies a 50 percent or greater improvement in PsA signs and symptoms, at Week 16. Additional secondary endpoints include minimal disease activity at Week 16 and a composite endpoint of ACR50 and PASI100 (complete skin clearance) at Week 16.

Psoriatic arthritis (PsA) is a severe, chronic, and systemic inflammatory condition affecting both joints and skin, with a prevalence ranging from 0.02 percent to 0.25 percent in the general population and 6 percent to 41 percent among psoriasis patients. Symptoms of PsA include joint pain, skin plaques, dactylitis (swollen toes and fingers), enthesitis (inflammation at tendon or ligament insertion points), and axial involvement.

Bimekizumab, marketed as BIMZELX, is a humanized monoclonal IgG1 antibody designed to selectively inhibit both IL-17A and IL-17F, key cytokines driving inflammatory processes. Elevated levels of these cytokines are found in psoriatic skin lesions. In the U.S., BIMZELX is approved for treating moderate-to-severe plaque psoriasis, active psoriatic arthritis, non-radiographic axial spondyloarthritis with objective signs of inflammation, and active ankylosing spondylitis.

The study is positioned as a critical step forward in the treatment of PsA, offering hope for more effective therapeutic options. UCB’s ongoing efforts in conducting rigorous clinical trials like BE BOLD reflect its commitment to advancing medical knowledge and improving patient outcomes. The results of this study, expected in 2026, are eagerly anticipated by the medical community and patients alike, as they could significantly influence future clinical practices and treatment strategies for psoriatic arthritis.