UCB and Biogen Present Positive Phase 3 Results for Dapirolizumab Pegol in Treating Systemic Lupus Erythematosus at EULAR 2025

• Dapirolizumab pegol (DZP) showed efficacy across multiple clinical endpoints in the PHOENYCS GO study, including fatigue and measures of disease activity
• DZP showed consistent improvements in fatigue, a common and debilitating symptom of systemic lupus erythematosus (SLE)
• At Week 48, more individuals receiving DZP experienced no or low disease activity compared to standard of care with differences observed as early as Week 12

BRUSSELS, Belgium and CAMBRIDGE, Mass. — UCB (Euronext Brussels: UCB) and Biogen Inc. (NASDAQ: BIIB) today presented additional detailed results from the Phase 3 PHOENYCS GO study evaluating dapirolizumab pegol (DZP), a novel Fc-free anti-CD40L drug candidate. In the study, DZP demonstrated significant clinical improvements in disease activity in people living with moderate-to-severe systemic lupus erythematosus (SLE), as measured by the British Isles Lupus Assessment Group (BILAG)-based Composite Lupus Assessment (BICLA) at Week 48, the primary endpoint. Improvements were also seen across additional clinical measures, including fatigue and disease activity/remission. These results were presented at EULAR 2025, the European Alliance of Associations for Rheumatology’s annual meeting, in Barcelona, Spain. The safety and efficacy of DZP in SLE have not been established, and it is not approved for use in SLE by any regulatory authority worldwide. A second Phase 3 trial of dapirolizumab pegol is ongoing with the goal of confirming the results from PHOENYCS GO.

“Despite being a common manifestation of systemic lupus erythematosus, fatigue is a difficult-to-treat symptom that can severely impact a person’s quality of life, and remains a challenge to address,” said Ioannis Parodis, MD, PhD, Associate Professor of Rheumatology, Karolinska University Hospital, Sweden. “The results we observed in this Phase 3 study indicate that participants treated with dapirolizumab pegol have the potential to achieve consistent improvements in fatigue beyond the current standard of care.”

In an analysis of the impact of DZP on patient-reported fatigue in people with SLE participating in the PHOENYCS GO study, individuals receiving DZP in addition to standard of care (SOC) treatment demonstrated improvements across two fatigue measurements:

• Improvements in Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue scores were greater in the DZP group (change from baseline, 8.9), compared with SOC alone (5.2; nominal* p=0.0024) at Week 48.
• Using FATIGUE-PRO, a measure recently developed to capture the patient experience of fatigue in SLE, greater improvements from baseline (nominal* p<0.05) were observed in people receiving DZP compared with SOC alone in the Physical Fatigue (change from baseline difference between groups,7.6), Mental and Cognitive (5.6), and Susceptibility to Fatigue (7.8) scales at Week 48.

“Being able to address both fatigue and remission are areas of critical unmet need in lupus care, an important treatment goal is to improve the quality of life for patients as well as to reduce the long-term risk of organ damage through disease remission,” said Eric F. Morand, MBBS, Head of the Monash Health Rheumatology Unit, Monash University, Australia. “In the PHOENYCS GO study, dapirolizumab pegol has shown meaningful impact in helping patients achieve remission and low disease activity, offering the exciting possibility for improved disease control while reducing exposure to glucocorticoids. Dapirolizumab pegol has the potential to become a significant new medication for people living with SLE, as shown by the breadth of effect seen in the study and I look forward to seeing results from the second Phase 3 study.”

In an additional analysis, improvements were seen on measures of low disease activity, as measured by Low Lupus Disease Activity State (LLDAS) and disease remission, as measured by Definition of Remission in SLE (DORIS). Both measures include assessments of disease activity, in addition to a required low dose glucocorticoid intake (<7.5 mg prednisone / day in LLDAS; <5 mg prednisone / day in DORIS).

• At Week 48, the percentage of participants achieving low disease activity in the DZP group was twice that of the SOC only group (40.9% and 19.6%, respectively; nominal* p<0.0001). As early as Week 12, greater proportions of participants receiving DZP plus SOC achieved LLDAS versus SOC alone (nominal* p<0.05).
• 23.6% of participants receiving DZP plus SOC achieved low disease activity in ≥50% of visits through 48 weeks compared with 15.9% receiving SOC alone (nominal* p=0.1042).
• A higher proportion of those receiving DZP (19.2%) versus SOC alone (8.4%) also achieved DORIS at Week 48 (nominal* p=0.0056).

* Having met the primary endpoint, improvement of moderate-to-severe disease activity as assessed by achievement of BICLA after 48 weeks and the key secondary endpoint having a p-value = 0.1776, all subsequent secondary and tertiary endpoints are descriptive and nominal p-values are included.

The safety profile of DZP was generally favorable. The safety results were consistent with previous DZP studies and with that in study participants with SLE receiving an immunomodulator. A higher proportion of individuals receiving DZP plus SOC had treatment-emergent adverse events (TEAEs) compared to SOC alone (82.6% vs. 75.0%). The proportion of participants with serious TEAEs was 9.9% in participants receiving DZP plus SOC was lower as compared to 14.8% in those receiving SOC alone. Discontinuation of treatment or study participation due to TEAEs occurred in 4.7% (10) of participants receiving DZP plus SOC and 3.7% (4) of participants receiving SOC alone.

Participants from the PHOENYCS GO study (NCT04294667) will continue to be followed in a long-term open-label study. A second Phase 3 trial of dapirolizumab pegol, PHOENYCS FLY (NCT06617325) is ongoing.

 

About Systemic Lupus Erythematosus (SLE)
SLE is a chronic, multifactorial autoimmune disease that is caused by the activation of autoreactive T, B and antigen-presenting cells, resulting in manifestations across multiple organ systems with periods of illness or flares alternating with periods of inactivity.¹ SLE can present itself in several ways including rash, arthritis, anemia, thrombocytopenia, serositis, nephritis, seizures or psychosis.² SLE is associated with a greater risk of death from causes such as infection and cardiovascular disease.

An estimated 90% of people living with lupus are women; most begin to see symptoms between the ages of 15-55.^3,4,5 Individuals from populations of African, Hispanic, Asian and Native American descent are at a greater risk of earlier onset and more aggressive disease.^6,7 Pregnancy in women with SLE is high risk, with higher maternal and fetal mortality and morbidity than the general population.^8,9

 

About Dapirolizumab Pegol
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.¹⁰ Dapirolizumab pegol is presently in Phase 3 clinical development for the treatment of systemic lupus erythematosus (SLE) under a collaboration between UCB and Biogen.¹¹

 

About UCB
UCB, Brussels, Belgium (www.ucb.com) is a global biopharmaceutical company focused on the discovery and development of innovative medicines and solutions to transform the lives of people living with severe diseases of the immune system or of the central nervous system. With approximately 9,000 people in approximately 40 countries, the company generated revenue of €6.1 billion in 2024. 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 patient’s 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.

The company routinely posts information that may be important to investors on its website at www.biogen.com. Follow us on social media – Facebook, LinkedIn, X, YouTube.

 

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8. Mehta B, Luo Y, Xu J, Sammaritano L, Salmon J, Lockshin M, et al. Trends in Maternal and Fetal Outcomes Among Pregnant Women With Systemic Lupus Erythematosus in the United States: A Cross-sectional Analysis. Ann Intern Med. 2019;171(3):164-71. Epub 2019/07/10. doi: 10.7326/M19-0120. PubMed PMID: 31284305.
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11. Clinicaltrials.gov (NCT04294667). A Study to Evaluate the Efficacy and Safety of Dapirolizumab Pegol in Study Participants With Moderately to Severely Active Systemic Lupus Erythematosus (PHOENYCS GO) 2023 [cited August 2024] Available at: https://clinicaltrials.gov/ct2/show/NCT04294667. Retrieved July 25, 2024.