UCB (Euronext Brussels: UCB) and Biogen Inc. (NASDAQ:BIIB) today announced data, comprising two posters and three abstracts, at the European Alliance of Associations for Rheumatology (EULAR) 2026 Congress, demonstrating the clinical profile of dapirolizumab pegol (DZP), an investigational biologic in patients with systemic lupus erythematosus (SLE).

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease affecting multiple organs, including skin, joints and kidneys, often requiring long-term treatment to control disease activity.1 Patients with SLE frequently experience flares, transient worsening of disease activity that can lead to permanent organ damage, increased morbidity, and even early mortality.2 Many patients rely on steroid-based therapy to manage flares; however, prolonged steroid use is associated with significant cumulative toxicity, making steroid tapering while maintaining disease control a key goal in SLE management.3,4

"Achieving and maintaining durable disease control while reducing glucocorticoid exposure is one of the central challenges in managing SLE," said Megan E. B. Clowse, M.D., MPH, Chief of the Division of Rheumatology and Immunology, Duke University, and primary author of the PHOENYCS GO primary results. "The Phase 3 PHOENYCS GO data showed patients receiving dapirolizumab pegol were more likely to maintain disease control while tapering steroids – an important finding given strong evidence that cumulative steroid exposure and uncontrolled disease activity are major drivers of organ damage accrual, morbidity and mortality in SLE."

Post hoc analyses displayed in one of the posters from the PHOENYCS GO program showed that, in patients with baseline glucocorticoid dose >7.5 mg/day prednisone equivalent, treatment with DZP plus standard of care was associated with a higher proportion of patients achieving control of disease activity while enabling glucocorticoid tapering to ≤7.5 mg/day through Week 48, compared with placebo plus standard of care.5 Importantly, these findings suggest that higher proportions of patients receiving DZP plus standard of care versus placebo plus standard of care achieved sustained glucocorticoid tapering while also achieving BICLA response, achieving SRI-4 response, or remaining free from moderate or severe BILAG-2004 flares through Week 48.5

"At UCB, our mission is to help improve the lives of people living with serious inflammatory diseases by advancing therapies that address unmet needs," said Donatello Crocetta, Chief Medical Officer and Head of Global Medical Affairs at UCB. "These data showed the potential of dapirolizumab pegol to reduce long-term glucocorticoid use while maintaining disease control, an important goal for people living with SLE and the clinicians who care for them."

Additional EULAR 2026 presentations highlighted the breadth of data from the PHOENYCS GO program, including:

  • Improvements in key immunological markers, including reduced anti-dsDNA antibodies and increased complement proteins C3 and C4 in patients with abnormal levels at baseline (Poster POS1364).6
  • Lower rates of moderate or moderate/severe BILAG-2004 flares with DZP plus standard of care versus placebo plus standard of care through Week 48, using alternative definitions of flares to increase measurement sensitivity (Abstract AB1163).7
  • Insights into how symptoms and flares are assessed in SLE, including fatigue as a burdensome patient-reported symptom that can be difficult to capture in clinical trials (Abstracts AB1184 and AB1125).8,9

     

Together, these findings support the importance of tools that can measure patient experience and help inform more meaningful assessment of disease impact in both clinical practice and research.8,9

"Systemic lupus erythematosus is a biologically complex disease, and these EULAR data further characterize dapirolizumab pegol's impact across clinical, biological and patient-reported outcomes," said Diana Gallagher, MD, Head of Immunology, MS and Alzheimer's Development Units at Biogen. "Delivering this data reflects the strength of the UCB and Biogen collaboration and our shared commitment to advancing evidence that may help address the complex and multifaceted needs of people living with SLE."

The EULAR data follow the recent publication of the Phase 3 PHOENYCS GO study in The Lancet, reporting clinically meaningful improvements in disease activity with dapirolizumab pegol at Week 48.10 In the Phase 3 PHOENYCS GO study, DZP demonstrated a generally favorable safety profile, with safety findings consistent with previous DZP studies.10,11 Treatment-emergent adverse events were more common with DZP plus standard of care versus placebo plus standard of care, while serious treatment-emergent adverse events were less frequent in the DZP plus standard of care arm, and discontinuations due to treatment-emergent adverse events were low in both groups.