A head-to-head phase 3b comparison of bimekizumab with risankizumab in active psoriatic arthritis: Written recap

In this Managed Healthcare Executive Between the Lines video program, Philip Mease, M.D., and Saakshi Khattri, M.D., discussed 16-week results from the BE BOLD trial, the first head-to-head phase 3b study comparing bimekizumab, an IL-17A and IL-17F inhibitor, sold under the brand name Bimzelx, with risankizumab, an IL-23 inhibitor, sold under the brand name Skyrizi, in adults with active psoriatic arthritis (PsA). The two rheumatologists covered the clinical and economic burden of PsA, how biologic use is shifting earlier in the treatment sequence, the trial’s design and efficacy and safety findings, and what the results could mean for payers and formulary decisions. Mease is the director of rheumatology research at Swedish Medical Center, Providence St. Joseph Health, in Seattle, and clinical professor at the University of Washington School of Medicine. Khattri is the director of the Center for Connective Tissue Diseases at the Icahn School of Medicine at Mount Sinai in New York.

The burden of psoriatic arthritis and the treatment landscape

Mease opened by asking Khattri to describe the clinical and economic burden of PsA. Khattri pointed to the direct costs of medical appointments and systemic therapies, particularly biologics, as well as the indirect costs of lost productivity when active disease keeps patients from daily activities and work. “It’s a very complicated disease to have where there’s a medical economic burden, loss of productivity, but also just a poor quality of life with active disease,” she said, adding that the toll is difficult to quantify because it varies by how active a person’s disease is and whether systemic therapy is controlling it. She said that head-to-head comparisons of biologic mechanisms of action remain uncommon in rheumatology, which is part of why she considers BE BOLD an important study for clinicians choosing systemic therapy for patients with active PsA.

Mease noted that psoriasis affects just over 3% of the U.S. population and that PsA develops in roughly 30% of people with psoriasis, making it a common condition overall. He described PsA as a “double whammy,” combining visible and uncomfortable skin disease with joint disease, spine involvement, and enthesitis, inflammation of the tendons and ligaments, that together create a multidomain burden on patients, families, and workplaces. Asked about the FDA-approved options for managing PsA, Khattri said clinicians now have more than a dozen systemic therapies to choose from, including oral small molecules that block PDE4, JAK inhibitors, and a more recently approved TYK2 blocker, along with injectable or infused biologics spanning TNF, IL-12/IL-23, IL-23, and IL-17 inhibitor classes. Within the IL-17 class, she noted, an IL-17A and IL-17F inhibitor was approved for PsA a little over a year earlier. Khattri said treatment choices depend on which disease domains a patient has and what the data show for each drug in those domains. She expects head-to-head data, such as that from the BE BOLD trial, to factor into those decisions in the future.

Real-world usage of biologics in psoriatic arthritis

Mease asked how often Khattri turns to biologics or targeted synthetic disease-modifying drugs as first-line systemic therapy. She said that practicing in New York City affords more flexibility than the conventional stepwise approach she learned during her fellowship, when conventional synthetic disease-modifying antirheumatic drugs such as methotrexate typically preceded a biologic. “I’ve been fortunate practicing in New York City that I’m able to get them biologics as first line if they need it,” she said of patients with active PsA. Mease said he sees similar access in Seattle, justified by the fact that methotrexate is often difficult to dose adequately and poorly tolerated because of side effects such as nausea. He noted that the American College of Rheumatology’s most recent guidelines now endorse using a biologic ahead of methotrexate. Khattri added that when insurers push back on biologics as first-line PsA therapy, she can sometimes secure approval for them as a treatment for the patient’s dermatological condition instead, since methotrexate is not typically used to treat psoriasis. She called this a practical “workaround” when the system is not aligned with biologic-first treatment.

Mease then walked through the design of BE BOLD, a multicenter, ongoing phase 3b trial presented at the European Alliance of Associations for Rheumatology meeting in June 2026, which was held in London. The study enrolled 553 adults with active PsA who were either biologic-naive or had an inadequate response to, or intolerance of, one prior TNF inhibitor. Patients on background methotrexate, sulfasalazine, or leflunomide were allowed to continue those therapies. Participants were randomly assigned one-to-one to bimekizumab or risankizumab, dosed according to the FDA and European Medicines Agency labeling. Approximately 10% of patients in the bimekizumab arm received a modestly higher initial dose appropriate for patients with moderate to severe psoriasis. The primary end point was American College of Rheumatology 50% (ACR50) response at week 16. Secondary end points included minimal disease activity (MDA), a composite threshold requiring patients to meet at least five of seven favorable criteria; simultaneous ACR50 and Psoriasis Area and Severity Index (PASI) 100 response; ACR50 at an early week-4 time point; PASI 100 alone; Disease Activity Index for Psoriatic Arthritis (DAPSA) low disease activity or remission; and safety outcomes.

Khattri said the study population closely resembled participants in other PsA trials, with double-digit swollen and tender joint counts, enthesitis in about half of patients, an even male-to-female ratio, and an average body mass index of 29. She contrasted that with her own practice, where she more often sees oligoarticular patients with single-digit joint counts, but said a trial enrolling more active disease still offers useful reassurance for less severely affected patients. On the choice of ACR50 as the primary end point, Khattri said it represents a meaningfully higher bar than the ACR20 response rheumatologists have historically used to set patient expectations, and a better one for patients. She also welcomed the inclusion of an early ACR50 assessment at week 4, saying patients frequently ask how soon they can expect to see a response, and an early signal helps encourage adherence while they wait for the primary week-16 outcome.

BE BOLD efficacy and safety data: Comparing bimekizumab and risankizumab on joint-centric end points

Mease presented the results: 49.1% of patients treated with bimekizumab achieved ACR50 at week 16 compared with 38.4% of those on risankizumab, a statistically significant difference. MDA was numerically higher with bimekizumab, 43% versus 39.9%, but did not reach statistical significance. Mease noted that MDA can be harder to differentiate when both comparator drugs are highly effective because it sets a high combined threshold across skin, enthesitis and joint domains. Combined ACR50 and PASI 100 response showed a nominal P value of 0.08. The early ACR50 assessment at week 4 showed a clear separation favoring bimekizumab, which Mease attributed to the faster onset of action associated with the IL-17A and IL-17F mechanism, while PASI 100 skin clearance was similar between the two drugs, reflecting strong skin benefit with both mechanisms. DAPSA low disease activity or remission, a primarily joint-centric measure, was achieved by 65.3% in the bimekizumab arm compared with 54.7% in the risankizumab arm. “This, again, reflects the joint-centric superiority of bimekizumab,” commented Mease.

On safety, Mease said the two drugs performed similarly and were consistent with each medication’s individual clinical trial history, without a signal for serious infection, malignancy, or major adverse cardiovascular events. A small percentage of patients in the bimekizumab arm developed mild oral candidiasis, or thrush, which was easily treated and did not tend to recur, and there was a single case of inflammatory bowel disease in the bimekizumab arm. Rates of severe adverse events were low and essentially identical between the two arms.

Real-world safety experience and clinical takeaways from the BE BOLD trial

Asked about her own experience, Khattri echoed the trial’s safety findings, saying she has not seen a signal for major infections, major adverse cardiovascular events or malignancy in practice. She said she counsels patients starting bimekizumab about the risk of oral, mucocutaneous yeast infections, taking care to clarify that this differs from genital yeast infections, a distinction she said patients often assume incorrectly. The thrush cases she sees are mild to moderate and straightforward to treat with nystatin or oral fluconazole, and the incidence tends to decline with continued treatment. “I haven’t had to stop or discontinue bimekizumab in any of my patients,” she said.

Asked for her main takeaways from the 16-week data, Khattri said bimekizumab met its primary ACR50 end point and demonstrated superiority over an IL-23 inhibitor in patients with active PsA, giving clinicians another head-to-head data point to weigh alongside the many other systemic options available. She said the trial has made her more inclined to offer bimekizumab as a first-line option for patients with active PsA. Mease agreed that head-to-head data make it easier to have direct, evidence-based conversations with patients about treatment choices.

Payer implications and final takeaways from the BE BOLD trial

Discussing BE BOLD’s limitations, Khattri said her main critique was that several ranked secondary end points did not reach statistical significance once the testing hierarchy was broken, which would have made an even more compelling case for bimekizumab’s superiority had they done so. Otherwise, she described the trial as robust and reflective of the patients with active PsA she has seen in practice. Mease noted roughly 30% of patients with PsA have axial inflammation involving the sacroiliac joints or spine, which can be disabling but is difficult to measure in phase 3 trials because it requires serial MRI scans and does not occur in every patient. He noted that bimekizumab has shown efficacy in axial spondyloarthritis, a related condition, while comparable spine data for risankizumab are not yet available. Mease said he hopes future trials will collect more axial data. Khattri said she hopes more of her rheumatology colleagues will become aware of BE BOLD so they can discuss the head-to-head comparison with patients as a first-line systemic option.

Asked about the study’s relevance for payers, Khattri said she was reluctant to let coverage decisions drive treatment choices for her patients with active PsA, while acknowledging that payers often do influence which systemic therapies are available. She said she hopes payers will weigh the head-to-head superiority data when making coverage decisions but was clear that she does not want payers to dictate systemic therapy choices for patients with active PsA. Mease said he favors treatment decisions grounded in efficacy and safety evidence presented to patients, with the goal of matching the right drug to the right patient.

On how she weighs safety against efficacy when counseling patients, Khattri said the discussion depends on each patient’s individual risk tolerance. She said nothing in bimekizumab’s safety profile, apart from the thrush risk stemming from its dual IL-17A and IL-17F blockade, keeps her from offering it as a first-line option. Some patients decide the thrush risk isn’t worth it for them, a decision she supports through shared decision-making. The one clear exception, she said, is active inflammatory bowel disease or a history of it.

Both physicians said they wanted to see more head-to-head trials of treatments for PsA that have differing mechanisms of action. Khattri said dermatology has embraced head-to-head trials more readily than rheumatology, and doing so has given dermatologists clearer evidence for choosing among an expanding array of systemic options.