ACR 2026: Dapirolizumab Pegol Associated with Greater Treatment Response Rates Versus Placebo in SLE Using Novel Treatment Response Measure

• Dapirolizumab pegol (DZP) associated with higher response rates using the novel Treatment Response Measure for Systemic Lupus Erythematosus (TRM-SLE): A post-hoc analysis applying TRM-SLE to the DZP Phase 3 PHOENYCS GO data for the first time found greater proportions of patients receiving DZP plus standard of care (SOC) versus placebo plus SOC achieved a clinically meaningful response in at least half or all active organ domains through Week 48
• Sustained low disease activity and remission: In a separate presentation at ACR 2026, post-hoc analyses of PHOENYCS GO showed greater rates of sustained low disease activity and remission across Weeks 40, 44 and 48 with DZP plus SOC versus placebo plus SOC

BRUSSELS and CAMBRIDGE, Mass., Nov. 09, 2026 (GLOBE NEWSWIRE) -- UCB (Euronext Brussels: UCB) and Biogen Inc. (Nasdaq: BIIB) today announced further data characterizing the clinical profile of dapirolizumab pegol (DZP), an investigational biologic for people living with systemic lupus erythematosus (SLE). The data are being presented across five posters at ACR Convergence 2026, the annual meeting of the American College of Rheumatology, in Orlando, Florida, November 6-11.

In a post-hoc analysis of the DZP Phase 3 PHOENYCS GO study using the Treatment Response Measure for Systemic Lupus Erythematosus (TRM-SLE), a novel clinical outcome assessment, DZP plus standard of care (SOC) was associated with greater proportions of patients achieving a clinically meaningful response through Week 48 in at least half (TRM-SLE-50) or all (TRM-SLE-100) of their active organ domains, mainly joints and skin, versus placebo plus SOC (Poster 1296).¹

“In SLE, patients can improve in ways that matter to them, such as less joint pain or clearer skin, yet fail to register as a treatment responder based on today's trial measures,” said Professor Eric F. Morand, Centre for Inflammatory Diseases, Monash University, Melbourne, Australia, and co-author of the analysis. “TRM-SLE is designed to provide a simple, patient-centric and clinically intuitive assessment. Applying it to Phase 3 data for the first time is an important step toward a potential future primary outcome measure for clinical studies, one that mirrors how both patients and clinicians judge response.”

Difficulty measuring clinically meaningful response to treatment has hindered progress in clinical trials for SLE and impeded the approval of potential new therapies.² To address this, a global taskforce led by Monash University, with clinicians, patient representatives, industry partners and regulatory experts, developed the TRM-SLE as a novel clinical outcome assessment that measures clinically meaningful treatment effects across select organ domains in SLE trials.^2,3  

In PHOENYCS GO, DZP plus SOC met the primary endpoint of BICLA response at Week 48 versus placebo plus SOC, with results also favoring DZP for SRI-4 response (60% [125/208] vs 41% [44/107]), a secondary outcome not controlled for multiplicity.⁴ In the TRM-SLE analysis, DZP plus SOC through Week 48 was associated with a greater proportion of patients achieving TRM-SLE-50 (61.2% vs 43.2%) and TRM-SLE-100 (52.5% vs 36.8%) compared with placebo plus SOC, representing clinically meaningful improvements in at least half or all of their active organ domains, respectively. At baseline, patients primarily fulfilled the arthritis (joint) and mucocutaneous (skin) TRM-SLE domains.¹

The authors concluded that TRM-SLE distinguished response rates between the treatment arms and offers a potentially practical way to determine response to therapy in patients with SLE, while noting that further validation of the measure is needed.¹ TRM-SLE was applied here as a post-hoc analysis rather than as a pre-specified endpoint or as part of any regulatory submission.

“Progress in SLE depends not only on new medicines, but on how we recognize and measure meaningful outcomes,” said Donatello Crocetta, Chief Medical Officer and Head of Global Medical Affairs at UCB. “UCB and Biogen are pleased to support the taskforce behind TRM-SLE, and applying this framework to our Phase 3 data, alongside our analyses of sustained low disease activity and remission, reflects our commitment to advancing the science of meaningful and sustained treatment outcomes in SLE. By helping refine how treatment response is evaluated, we hope to support better evidence generation, contribute to evolving standards in SLE trials and, ultimately, better outcomes for people living with this condition.”

Sustaining Low Disease Activity and Remission in Patients with SLE
In a separate presentation, post-hoc analyses of PHOENYCS GO examined sustained attainment of low disease activity and remission with DZP plus SOC, endpoints of recognized prognostic importance in SLE. Across the final three study visits (Weeks 40, 44 and 48), greater proportions of patients receiving DZP plus SOC versus placebo plus SOC were found to achieve sustained LLDAS (24.0% [50/208] vs 10.3% [11/107]; nominal p=0.0012), sustained LLDAS-5, which requires a glucocorticoid dose of ≤5 mg/day prednisone equivalent (19.2% [40/208] vs 5.6% [6/107]; nominal p=0.0002), and sustained DORIS (11.5% [24/208] vs 4.7% [5/107]; nominal p=0.0253) (Poster 2196).⁵

“Our understanding of SLE has evolved, and so must the way we research potential treatments. Following the science means using additional measurement tools to fully understand how our treatments could potentially benefit people living with SLE. We are excited that this first application of TRM-SLE to Phase 3 trial data adds to the evidence reflecting the potential of dapirolizumab pegol. We are committed to deepening our understanding of the disease, advancing the science and ultimately helping improve outcomes for people living with SLE,” said Diana Gallagher, MD, Head of the Immune-Mediated and Neurodegeneration Development Unit at Biogen.

The Phase 3 PHOENYCS GO study was published in The Lancet in May 2026, reporting statistically significant and clinically meaningful improvement in disease activity with DZP plus SOC versus placebo plus SOC at Week 48, as measured by BICLA response (50% [103/208] vs 35% [37/107]; p=0.011).⁴ In the study, DZP showed a generally favorable safety profile, with safety findings consistent with previous DZP studies.^4,6 Treatment-emergent adverse events were more common with DZP plus SOC versus placebo plus SOC, while serious treatment-emergent adverse events were less frequent in the DZP plus SOC arm, and discontinuations due to treatment-emergent adverse events were low in both groups.⁴

Additional Information

• TRM-SLE: Treatment Response Measure for Systemic Lupus Erythematosus (TRM-SLE), a novel clinical outcome assessment developed by a global taskforce with regulatory input. It assesses response in each patient's active organ domains, drawn from six: arthritis, mucocutaneous, nephropathy, serositis, hemolytic anemia and thrombocytopenia.^1,3
• TRM-SLE-50/100: clinically meaningful improvement in at least half (TRM-SLE-50) or all (TRM-SLE-100) of a patient's active TRM-SLE domains.¹
• BICLA: British Isles Lupus Assessment Group (BILAG)-based Composite Lupus Assessment (BICLA), the primary endpoint of PHOENYCS GO. A BICLA response requires improvement in all organ systems active at baseline without worsening in others, no worsening in Systemic Lupus Erythematosus Disease Activity Index-2000 (SLEDAI-2K) total score, and no significant deterioration in Physician Global Assessment (PGA).⁴
• SRI-4: SLE Responder Index-4 (SRI-4), a composite measure based primarily on improvement in SLEDAI-2K score.⁴
• LLDAS / LLDAS-5: Lupus Low Disease Activity State (LLDAS). LLDAS-5 is LLDAS with a glucocorticoid dose of ≤5 mg/day prednisone equivalent.⁵
• DORIS: Definitions of Remission in SLE (DORIS).⁵
• Sustained LLDAS, LLDAS-5 and DORIS: achieved at each of the final three study visits (Weeks 40, 44 and 48).⁵

About Dapirolizumab Pegol
Dapirolizumab pegol is a novel investigational humanized Fc-free polyethylene glycol (PEG)-conjugated antigen-binding (Fab’) fragment.⁶ Dapirolizumab pegol inhibits CD40L signaling, which has been shown to reduce B-cell activation and autoantibody production, mitigate type 1 interferon (IFN) secretion and attenuate T-cell and antigen-presenting cell (APC) activation.⁶ Dapirolizumab pegol is presently in Phase 3 clinical development for the treatment of systemic lupus erythematosus (SLE) under a collaboration between UCB and Biogen.^7,8

Dapirolizumab pegol is an investigational biologic currently in clinical development. The safety and efficacy have not been established, and it is not approved by any health authority worldwide.

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).

About Biogen
Founded in 1978, Biogen is a leading biotechnology company that pioneers innovative science to deliver new medicines to transform patients’ lives and to create value for shareholders and our communities. We apply deep understanding of human biology and leverage different modalities to advance first-in-class treatments or therapies that deliver superior outcomes. Our approach is to take bold risks, balanced with return on investment to deliver long-term growth.

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References:

1. Aranow C, Kalunian KC, Arnaud L, et al. Treatment response measure for systemic lupus erythematosus (TRM-SLE): application to a phase 3 trial of dapirolizumab pegol. Arthritis Rheumatol. 2026;78(suppl 9):Abstract 1296.
2. Connelly K, Eades LE, Koelmeyer RL, et al. Towards a novel clinical outcome assessment for systemic lupus erythematosus: first outcomes of an international taskforce. Nat Rev Rheumatol. 2023;19(9):592–602. doi:10.1038/s41584-023-00993-7.
3. Connelly K, Koelmeyer R, Ayton D, et al. Domains for inclusion in a novel Treatment Response Measure for Systemic Lupus Erythematosus (TRM-SLE): results of a modified Delphi study. Lupus Sci Med. 2025;12(1):e001484. doi:10.1136/lupus-2024-001484.
4. Clowse MEB, Isenberg DA, Merrill JT, et al. Efficacy and safety of the CD40 ligand inhibitor dapirolizumab pegol in systemic lupus erythematosus (PHOENYCS GO): a randomised, double-blind, placebo-controlled, phase 3 trial. Lancet. Published online May 29, 2026. doi:10.1016/S0140-6736(26)00691-4.
5. Morand EF, Carter LM, Dall'Era M, et al. Dapirolizumab pegol treatment resulted in sustained attainment of low disease activity and remission in patients with systemic lupus erythematosus: 48-week results from a phase 3 trial. Arthritis Rheumatol. 2026;78(suppl 9):Abstract 2196.
6. Furie RA, Bruce IN, Dörner T, et al. Phase 2, randomized, placebo-controlled trial of dapirolizumab pegol in patients with moderate-to-severe active systemic lupus erythematosus. Rheumatology (Oxford). 2021;60(11):5397–407.
7. ClinicalTrials.gov. NCT04294667. https://clinicaltrials.gov/study/NCT04294667. Accessed November 6, 2026.
8. ClinicalTrials.gov. NCT06617325. https://clinicaltrials.gov/study/NCT06617325. Accessed November 6, 2026.