UCB and Biogen Inc. 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, an investigational biologic in patients with systemic lupus erythematosus. In additional results from the Phase 3 PHOENYCS GO study, dapirolizumab pegol plus standard of care was associated with sustained disease control at lower glucocorticoid doses through Week 48 compared with placebo plus standard of care, supporting reduced long-term steroid exposure. In other findings presented at EULAR 2026, improvements in immunological markers and reduced flare rates were observed, supporting the potential of dapirolizumab pegol to address the complex burden of 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. Patients with SLE frequently experience flares, transient worsening of disease activity that can lead to permanent organ damage, increased morbidity, and even early mortality. 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.

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. 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. 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).

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). 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). 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.

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. In the Phase 3 PHOENYCS GO study, DZP demonstrated a generally favorable safety profile, with safety findings consistent with previous DZP studies. 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.

Dapirolizumab pegol is a novel investigational humanized Fc-free polyethylene glycol (PEG)-conjugated antigen-binding (Fab?) fragment. 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. Dapirolizumab pegol is presently in Phase 3 clinical development for the treatment of systemic lupus erythematosus (SLE) under a collaboration between UCB and Biogen.

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.