BIIB•BIIB•Biogen and UCB published Phase 3 PHOENYCS GO results showing a 50% BICLA response rate at Week 48 with dapirolizumab pegol plus standard of care versus 35% on placebo (p=0.011). Endpoints including severe flares, FACIT-Fatigue and glucocorticoid tapering also favored active treatment, and the confirmatory Phase 3 PHOENYCS FLY trial is currently recruiting.
In the PHOENYCS GO trial, 50% (103/208) of patients receiving dapirolizumab pegol plus standard of care achieved a BICLA response at Week 48 compared with 35% (37/107) on placebo plus standard of care (p=0.011). This primary endpoint demonstrated a statistically significant improvement in overall disease activity for moderate-to-severe SLE patients.
Although the key secondary endpoint at Week 24 was not met, subsequent analyses showed consistent benefits across multiple measures, including reductions in severe BILAG flares, improvements in SRI-4 and SLEDAI-2K scores, decreases in anti-dsDNA antibodies and complement C3/C4 levels, and clinically meaningful gains in FACIT-Fatigue scores.
Dapirolizumab pegol exhibited a generally favorable safety profile: treatment-emergent adverse events occurred in 82.6% of the active arm versus 75.0% with placebo, while serious adverse events were lower at 10.0% versus 14.8%. Discontinuations due to adverse events were low in both groups (4.7% vs. 3.7%).
Based on these positive findings, Biogen and UCB are advancing the confirmatory Phase 3 PHOENYCS FLY trial, which is currently recruiting patients to support future regulatory submissions and potential approval for systemic lupus erythematosus.
