UCB and Biogen Announce Publication in The Lancet of Positive Dapirolizumab Pegol (DZP) Phase 3 Study Results in Systemic Lupus Erythematosus

• Publication adds to previously reported findings from Phase 3 PHOENYCS GO study, demonstrating statistically significant improvement in disease activity at Week 48 with dapirolizumab pegol plus standard of care versus placebo plus standard of care
• Findings showed results in favor of dapirolizumab pegol plus standard of care versus placebo plus standard of care across endpoints, including multiple disease activity measures, severe flares, patient-reported outcomes, including fatigue, and glucocorticoid tapering
• Results support the continued development of dapirolizumab pegol; the ongoing confirmatory Phase 3 PHOENYCS FLY clinical trial is currently recruiting
  
  

BRUSSELS, Belgium and CAMBRIDGE, Mass., June 01, 2026 (GLOBE NEWSWIRE) -- UCB (Euronext Brussels: UCB) and Biogen Inc. (Nasdaq: BIIB) today announced that The Lancet, a world-leading medical journal, has published the full results from the Phase 3 PHOENYCS GO clinical trial evaluating dapirolizumab pegol (DZP), an investigational, novel Fc-free CD40L inhibitor, in patients living with moderate-to-severe active systemic lupus erythematosus (SLE). The results showed statistically significant improvement in disease activity with DZP added to standard of care (SOC) versus placebo plus standard of care.¹

“The publication of the PHOENYCS GO results in The Lancet reflects the importance of these data to the rheumatology community, providing evidence of dapirolizumab pegol as a potential treatment option for people living with systemic lupus erythematosus,” said Megan E. B. Clowse, M.D., MPH, Chief of the Division of Rheumatology and Immunology, Duke University, and primary author of the publication. “Given the acute need for additional treatment options for SLE, these findings are encouraging for both clinicians and patients and clearly warrant further evaluation in the confirmatory Phase 3 PHOENYCS FLY study.”

In the Phase 3 study, DZP successfully met the primary endpoint: a significantly greater proportion of patients receiving DZP plus standard of care (SOC) achieved British Isles Lupus Assessment Group (BILAG)-based Composite Lupus Assessment (BICLA) response at Week 48 (50%; 103/208) compared to placebo plus SOC (35%; 37/107; p=0.011).¹ BICLA is a composite endpoint measuring clinically relevant improvement of disease activity across all affected organ systems with no worsening in other lupus domains; a higher BICLA response rate reflects a treatment response and is associated with clinical benefit.¹

Because the first key secondary endpoint was not met (BICLA response at week 24), subsequent outcomes were not controlled for multiplicity. Results in favor of DZP plus SOC were observed across multiple outcomes, including severe BILAG flares, SRI-4, SLEDAI-2K, skin- and joint-related outcomes, and the serological markers anti-dsDNA antibodies and complement C3 and C4.¹ Additionally, at week 48 the data showed clinically meaningful improvements in patient-reported FACIT-Fatigue, which is often cited by patients as one of the most debilitating symptoms of SLE.^1,2 Importantly, these results were achieved within the context of glucocorticoid tapering in line with treatment guidelines.^1,3 At week 48, a greater proportion of patients in the DZP plus SOC group versus PBO plus SOC were able to reduce their glucocorticoid dose from >7.5 mg/day to ≤7.5 mg/day, suggesting a glucocorticoid-sparing effect of DZP.¹

In the PHOENYCS GO study, DZP demonstrated a generally favorable safety profile, with safety findings consistent with previous DZP studies.^1,4 Treatment-emergent adverse events (TEAEs) were more common with DZP plus SOC versus PBO plus SOC (82.6% [176/213] vs. 75.0% [81/108], respectively), while serious TEAEs were less frequent in the DZP plus SOC arm (10.0% [21/213] vs. 14.8% [16/108]) respectively.¹ Discontinuations due to TEAEs were low in both groups (4.7% vs. 3.7%) respectively.¹

These positive Phase 3 results support the continued development of DZP. UCB and Biogen are actively progressing the confirmatory Phase 3 PHOENYCS FLY clinical trial (NCT06617325), which is currently recruiting patients and is intended to support future regulatory filings.⁵

Further data from the PHOENYCS GO study will be presented this week at the Annual European Congress of Rheumatology (EULAR).

About Dapirolizumab Pegol
Dapirolizumab pegol is a novel investigational humanized Fc-free polyethylene glycol (PEG)-conjugated antigen-binding (Fab’) fragment.⁴ 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.⁴ Dapirolizumab pegol is presently in Phase 3 clinical development for the treatment of systemic lupus erythematosus (SLE) under a collaboration between UCB and Biogen.^5,6

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, 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 11,000 people in approximately 40 countries, the company 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 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.

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This news release contains forward-looking statements, including, among others, relating to: the potential benefits, safety and efficacy of dapirolizumab pegol (DZP); the potential of dapirolizumab pegol to be an important option in addressing the effects of systemic lupus erythematosus; the anticipated benefits, risks and potential of Biogen's collaboration arrangements with UCB; the potential of Biogen's commercial business and pipeline programs, including dapirolizumab pegol; potential regulatory discussions, submissions and approvals and the timing thereof; and the risks and uncertainties associated with drug development and commercialization. These forward-looking statements may be accompanied by such words as “aim,” “anticipate,” “assume,” “believe,” “contemplate,” “continue,” “could,” “estimate,” “expect,” “forecast,” “goal,” “guidance,” “hope,” “intend,” “may,” “objective,” “outlook,” “plan,” “possible,” “potential,” “predict,” “project,” “prospect,” “should,” “target,” “will,” “would,” and other words and terms of similar meaning. Drug development and commercialization involve a high degree of risk, and only a small number of research and development programs result in commercialization of a product. Results in early-stage clinical trials may not be indicative of full results or results from later stage or larger scale clinical trials and do not ensure regulatory approval. You should not place undue reliance on these statements. Given their forward-looking nature, these statements involve substantial risks and uncertainties that may be based on inaccurate assumptions and could cause actual results to differ materially from those reflected in such statements.

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References:

1. 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.
2. Cornet A, Andersen J, Myllys K, et al. Living with systemic lupus erythematosus in 2020: a European patient survey. Lupus Sci Med. 2021;8:e000469.
3. Fanouriakis A, Kostopoulou M, Alunno A, et al. 2019 update of the EULAR recommendations for the management of systemic lupus erythematosus. Ann Rheum Dis 2019; 78(6): 736–45.
4. 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.
5. ClinicalTrials.gov (NCT06617325). A Study to Evaluate the Efficacy and Safety of Dapirolizumab Pegol in Study Participants With Moderately to Severely Active Systemic Lupus Erythematosus (PHOENYCS FLY) 2024. Available at: https://clinicaltrials.gov/study/NCT06617325. Retrieved May 18, 2026.
6. 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. Available at: https://clinicaltrials.gov/ct2/show/NCT04294667. Retrieved May 18, 2026.