Bimekizumab Proves To Be A Highly Effective Therapy For Psoriatic Arthritis Patients
Psoriatic arthritis (PsA) is a chronic inflammatory disease affecting joints, skin, nails, and other tissues. Because it is long-term and can vary significantly between patients, ongoing treatment is needed. Biologic therapies like TNF inhibitors (TNFi) are often combined with methotrexate (MTX), although there is limited evidence supporting the added benefit of this combination in PsA. Some studies show that using MTX with TNFi can help patients stay on treatment longer, but the overall effectiveness remains to be determined, especially for patients with different symptoms. This study looks at the safety and efficacy of bimekizumab, a newer treatment that targets two inflammatory proteins, in patients with PsA, both with and without MTX, over 52 weeks.
A BACKGROUND ON PSORIATIC ARTHRITIS AND ITS TREATMENT
Psoriatic arthritis (PsA) is a chronic and progressive inflammatory disease that affects various tissues, including the joints, skin, nails, and entheses. Due to its heterogeneous nature, PsA can present with a range of symptoms, such as involvement of peripheral and axial joints. Managing this disease requires long-term treatment, and over time, several therapeutic options have been developed to control its symptoms and slow disease progression. Among these, first-line biologic therapies, particularly tumor necrosis factor inhibitors (TNFi), are frequently used in combination with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) such as methotrexate (MTX) [1,2]. However, the role of MTX in PsA treatment remains controversial due to a lack of substantial randomized controlled trial evidence specific to this condition [3,4].
Although MTX is recommended in PsA treatment guidelines, much of the supporting evidence comes from studies in other autoimmune diseases, such as rheumatoid arthritis and psoriasis, where MTX is effective [5,6]. Several studies have examined the effect of combining MTX with TNFi in PsA, but the results are inconsistent. Some research suggests that adding MTX may help prolong the time before TNFi discontinuation. At the same time, other studies show no significant difference in efficacy between TNFi alone and in combination with MTX [5,7]. Moreover, while some data indicate that TNFi-MTX combination therapy may increase remission rates, the overall evidence supporting the added benefit of MTX is limited, particularly in patients with PsA involving skin or axial symptoms [8,9].
As the availability of biologic DMARDs (bDMARDs) continues to grow, understanding the impact of combining MTX with these targeted therapies is crucial for optimizing treatment outcomes in PsA. Bimekizumab, a novel humanized monoclonal antibody, inhibits interleukin (IL)-17A and IL-17F, two key cytokines involved in inflammation. Previous studies have demonstrated the safety and efficacy of bimekizumab in patients with PsA who are naïve to bDMARDs or who have had an inadequate response to TNFi (TNFi-IR) [10,11]. Despite these findings, conclusive data remains on whether adding MTX to bDMARD therapy improves clinical outcomes in PsA, particularly for peripheral and skin-related disease manifestations.
This study aims to evaluate the clinical efficacy and safety of subcutaneous bimekizumab treatment in both bDMARD-naïve and TNFi-IR patients with PsA. The study also investigates the impact of concomitant MTX use on treatment outcomes over 52 weeks, providing new insights into the role of MTX when combined with targeted biologic therapies for PsA [12,13].
THE STUDY METHOD
This study included three main clinical trials: BE OPTIMAL, BE COMPLETE, and the BE VITAL open-label extension (OLE). All studies evaluated the efficacy and safety of subcutaneous bimekizumab administered at 160 mg every four weeks in patients diagnosed with psoriatic arthritis (PsA). BE OPTIMAL was a 52-week, multicenter, randomized, double-anonymized, placebo-controlled trial focusing on bDMARD-naïve patients. It consisted of a 16-week placebo-controlled phase followed by a 36-week active treatment period, during which patients initially assigned to placebo switched to bimekizumab at Week 16. Additionally, an adalimumab reference arm was included to compare the benefit/risk profile of bimekizumab with a standard treatment; however, this arm was not statistically powered for comparison. Patients were randomized in a 3:2:1 ratio to receive either bimekizumab, placebo, or adalimumab.
BE COMPLETE was designed as a 16-week, randomized, double-anonymized, placebo-controlled trial for patients with active PsA who had previously experienced an inadequate response to one or two TNFi. Patients were randomly assigned in a 2:1 ratio to receive bimekizumab or placebo. Those who completed Week 16 and met eligibility criteria were invited to participate in the BE VITAL OLE study, which offered bimekizumab to all participants, including those who initially received a placebo. The studies were conducted according to ethical standards, with approval from institutional review boards, and all participants provided written informed consent.
Patients were required to have a documented diagnosis of adult-onset PsA for at least six months before screening, with active disease defined by a baseline tender joint count of 3 or more and a swollen joint count of 3 or more, along with at least one active psoriatic lesion or a history of psoriasis. In BE OPTIMAL, patients with prior exposure to any biologics for PsA or psoriasis were excluded, while BE COMPLETE focused on patients with a documented inadequate response to TNFi. MTX use was permitted in both studies, with a maximum dose of 25 mg/week or the highest tolerated dose, provided patients had started treatment at least 12 weeks before baseline and maintained a stable dose for at least 8 weeks before randomization.
Efficacy and safety assessments were conducted throughout the studies, with outcomes categorized based on patient randomization group and MTX treatment at baseline. Key efficacy outcomes included improvement in the American College of Rheumatology response criteria, changes in the Psoriasis Area and Severity Index, and minimal and meager disease activity measures. Safety outcomes were evaluated up to Week 52 and included treatment-emergent adverse events, serious adverse events, and discontinuations due to adverse effects, among other safety-related topics.
ANALYSIS
The statistical analysis for the studies was primarily based on post hoc evaluations of patient responses and changes from baseline values (Week 0) in both the BE OPTIMAL and BE COMPLETE trials. The analysis was structured to report data for the randomized sets, comparing outcomes side by side across each treatment arm and considering whether patients were receiving concomitant methotrexate (MTX) at baseline. Since this analysis was post hoc, no formal statistical comparisons were made between groups. Efficacy data were presented with 95% confidence intervals (CIs) in tables and figures where applicable.
The analysis employed various imputation methods to handle missing data. Non-responder imputation was utilized for dichotomous outcomes, while multiple imputation was used for continuous outcomes to estimate missing values. Specifically, for the Disease Activity Index for Psoriatic Arthritis (DAPSA), the worst-category imputation was applied, assigning missing data to the most severe category. Additionally, patients who did not enroll in the BE VITAL OLE study were still included in the BE COMPLETE analysis up to Week 16, categorized as non-responders for response variables, and their subsequent data were imputed using multiple imputations for continuous variables.
Safety data were reported for all randomized patients who received at least one dose of bimekizumab. Exposure-adjusted incidence rates (EAIRs) per 100 patient-years (PY) were calculated for safety events, providing a standardized way to report the frequency of adverse events associated with the treatment. This comprehensive approach to statistical analysis ensured a thorough evaluation of both efficacy and safety outcomes for treating psoriatic arthritis.
RESULTS
- Patient Disposition and Baseline Characteristics
- Patient Demographics:
- The studies BE OPTIMAL and BE COMPLETE evaluated bimekizumab in patients with psoriatic arthritis (PsA). In BE OPTIMAL, 712 patients were randomized to either bimekizumab or placebo, with 415 (58.3%) receiving methotrexate (MTX) and 297 (41.7%) not receiving it. By Week 52, 90.6% (645 patients) completed the study, showing high retention rates across both groups.
- In BE COMPLETE, 400 patients were involved, with 170 (42.5%) on MTX and 230 (57.5%) not. Overall, 97.0% (388 patients) completed Week 16, and 86.8% (347 patients) completed Week 52.
- Baseline Characteristics:
- Both studies showed consistent baseline characteristics between +MTX and −MTX groups, with slight differences in high-sensitivity C-reactive protein (hs-CRP) and swollen joint counts (SJC). The average MTX dose among patients ranged from 16.7 mg to 19.0 mg.
- Efficacy
- Overall Improvements:
- Bimekizumab significantly improved PsA symptoms, with sustained efficacy from Week 16 to Week 52 across all measured domains.
- ACR50 Response (American College of Rheumatology 50% Improvement):
- The ACR50 response, indicating a 50% improvement in arthritis symptoms, was achieved by 54.4% of +MTX and 54.7% of −MTX patients in BE OPTIMAL. In BE COMPLETE, rates were 56.3% for +MTX and 48.0% for −MTX. Patients switching from placebo to bimekizumab at Week 16 also showed marked improvements.
- Complete Skin Clearance (PASI100 – Psoriasis Area Severity Index 100% Improvement):
- For those with significant skin involvement, 61.1% of +MTX and 60.4% of −MTX patients achieved complete skin clearance (PASI100) in BE OPTIMAL. In BE COMPLETE, the rates were 68.8% for +MTX and 63.5% for −MTX.
- Minimal Disease Activity (MDA) Response:
- The MDA response, reflecting low disease activity, was also sustained from Week 16 to Week 52, with similar response rates across both studies.
III. Safety
- Overall Safety Data:
- The incidence of treatment-emergent adverse events (TEAEs) was similar between the +MTX and −MTX groups. In BE OPTIMAL, 79.3% of +MTX patients experienced TEAEs, compared to 78.8% in the −MTX group. In BE COMPLETE, the rates were lower (62.5% for +MTX and 62.7% for −MTX).
- Serious and Drug-related Adverse Events:
- Serious and drug-related adverse events occurred at comparable rates in both groups, with some instances of elevated liver enzymes being more common in the MTX group.
- Candida Infections:
- The incidence of Candida infections was similar across groups, indicating no significant safety concerns related to fungal infections.
- Mortality:
- Two deaths were reported during the studies, neither linked to the study medication. One was due to a motorcycle accident, and the other involved a patient with a prior cardiac history.
DISCUSSION
The study highlights the consistent and sustained clinical efficacy of bimekizumab for patients with active psoriatic arthritis (PsA) over 52 weeks, regardless of their treatment history with biologic disease-modifying antirheumatic drugs (bDMARDs) or tumor necrosis factor inhibitors (TNFi). The results indicate that both bDMARD-naïve and TNFi-IR patients demonstrated significant improvements across joint, skin, and composite outcomes, emphasizing the treatment’s effectiveness even in traditionally challenging patient populations. Given that TNFi-IR patients often experience reduced response rates and more rapid cycling through therapies, these findings hold substantial clinical relevance [25,26].
A notable aspect of bimekizumab’s efficacy is its unique dual inhibition of IL-17A and IL-17F, which contributes significantly to its therapeutic effects. This mechanism operates independently of concomitant methotrexate (MTX) treatment, suggesting that MTX may not be necessary to maintain efficacy in patients receiving bimekizumab. The consistent results across different patient backgrounds and treatment combinations can aid clinicians in making informed treatment choices, especially considering the challenges posed by TNFi-IR patients [27,28].
Regarding safety, the overall profile of bimekizumab remains consistent with previous reports, with similar rates of treatment-emergent adverse events (TEAEs) observed between studies. Notably, the incidence of fungal infections did not differ based on MTX use, reinforcing that MTX does not influence bimekizumab’s safety outcomes. However, while the rates of liver enzyme elevations were slightly higher in the +MTX group, the studies could not evaluate statistical significance, necessitating a cautious interpretation of these findings [16,17,29].
The implications of these findings extend beyond mere treatment efficacy; they address the burden of concomitant medications and the potential reduction in MTX-associated adverse events. By clarifying the role of MTX in bimekizumab treatment, this research may facilitate more individualized patient care and shared decision-making between healthcare providers and patients. The focus on enhancing patient quality of life while minimizing adverse effects represents a significant advancement in managing PsA, particularly for those with challenging treatment histories [30,32,33].
In conclusion, the data suggest that bimekizumab can effectively manage PsA without the obligatory use of MTX, simplifying treatment regimens and potentially alleviating some of the burdens associated with traditional therapies. Future studies will be crucial in further elucidating the roles of IL-17F and MTX, aiming to optimize therapeutic strategies that improve patient outcomes while minimizing adverse events and enhancing overall quality of life [34,35].
STUDY LIMITATIONS
- Post Hoc Analysis
- The study was conducted as a post hoc analysis, limiting the findings’ robustness.
- The analysis was not powered to precisely evaluate the benefits of methotrexate (MTX) in combination with bimekizumab.
- Confidence Intervals
- Efficacy data are presented with 95% confidence intervals (CIs), providing a range of possible outcomes but not confirming definitive results.
- Safety Analysis Limitations
- Safety results were derived from descriptive analyses, preventing the detection of significant differences in safety events between treatment arms or MTX groups.
- Sample Size Constraints
- When stratified by MTX, the placebo treatment group in the BE COMPLETE trial had a smaller sample size, particularly affecting endpoints related to enthesitis and dactylitis.
- Future Data Reporting
- Eligible patients from the BE OPTIMAL and BE COMPLETE studies could enroll in the OLE BE VITAL study after specified time points, with longer-term data (2-year analysis) to be reported in future publications.
CONCLUSION
In conclusion, treatment with bimekizumab demonstrated consistent and sustained clinical efficacy over 52 weeks in patients with active psoriatic arthritis (PsA), including both those who were biologic disease-modifying antirheumatic drug (bDMARD)-naïve and those who had an inadequate response to tumor necrosis factor inhibitors (TNFi-IR). Notably, the efficacy of bimekizumab was observed irrespective of concomitant administration of methotrexate (MTX). Results were comparable across the BE OPTIMAL and BE COMPLETE study populations, highlighting the robustness of the findings. Additionally, bimekizumab was well tolerated among patients with PsA in the MTX and non-MTX groups.
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