UCB and Biogen: new post-hoc phase 3 analyses in lupus for dapirolizumab
Presented at the American College of Rheumatology's annual meeting (ACR Convergence 2026) in Orlando, in the form of five posters, these data were announced on November 9, 2026 by UCB and its partner Biogen. They are based on post-hoc analyses of the phase 3 PHOENYCS GO trial of dapirolizumab pegol, not on a new trial.
TRM-SLE: response rates higher than placebo, in post-hoc analysis
Applied for the first time to phase 3 data, the TRM-SLE (a tool for assessing treatment response in systemic lupus erythematosus) was developed by an international working group led by Monash University. This group brings together clinicians, patient representatives, industry representatives and regulatory experts.
Up to week 48, 61.2% of patients treated with dapirolizumab pegol in addition to standard of care achieved a clinically meaningful response in at least half of their active organ domains, compared with 43.2% in the placebo arm. For all active domains, the rates reached 52.5% versus 36.8%.
For Professor Eric F. Morand (Monash University), co-author of the analysis, this first application to phase 3 data is “an important step towards a possible future primary endpoint measure for clinical studies.”
At baseline, patients were mainly in the joint and skin domains. The authors stress that further validation of the tool is needed. The TRM-SLE was applied post hoc: it was neither a predefined endpoint of the trial nor an element of any regulatory submission.
More frequent sustained remission, more adverse events
A second set of post-hoc analyses focused on the maintenance of low disease activity and remission over the last three visits (weeks 40, 44 and 48). Sustained lupus low disease activity state (LLDAS) was achieved by 24.0% of patients on dapirolizumab pegol, compared with 10.3% on placebo (nominal p-value of 0.0012).
With a corticosteroid dose of no more than 5 mg per day in prednisone equivalent (LLDAS-5), the rates were 19.2% versus 5.6% (nominal p-value of 0.0002). Sustained remission according to the DORIS criteria concerned 11.5% of patients, compared with 4.7% (nominal p-value of 0.0253).
These analyses build on the PHOENYCS GO trial, published in The Lancet in May 2026, which met its primary endpoint: a 50% BICLA response at week 48, compared with 35% on placebo (p = 0.011). The secondary endpoint SRI-4 (60% versus 41%) was not controlled for multiplicity of testing.
The companies describe an overall favorable safety profile. Adverse events occurring on treatment were, however, more frequent in the dapirolizumab pegol arm, while serious adverse events were less frequent there. Discontinuations due to these events remained low in both groups.
Developed in collaboration by UCB and Biogen, the candidate remains in phase 3 and is not approved by any health authority. Donatello Crocetta, Chief Medical Officer of UCB, stated that both partners hope that, by refining the assessment of response, they will “contribute to the evolution of standards for lupus trials.”
