Litifilimab in CLE: Part A of the phase II/III AMETHYST trial

Results from Week 24 of Part A of the phase II/III AMETHYST (NCT05531565) trial evaluating litifilimab (n = 59) vs placebo (n = 34) in patients with cutaneous lupus erythematosus (CLE) were presented by Joseph F. Merola at the European Alliance of Associations for Rheumatology (EULAR) 2026 Congress, June 3–6, 2026, London, UK. The primary endpoint was the proportion of patients who achieved Cutaneous Lupus Activity Investigator’s Global Assessment-Revised (CLA-IGA-R) erythema 0–1 at Week 16.

Key data: The primary endpoint was met, with a significantly greater proportion of patients receiving litifilimab vs placebo achieving CLA-IGA-R erythema 0–1 (14.7% vs 2.9%; p<0.05) at Week 16, with efficacy maintained at Week 24 (19.0% vs 4.2%; p<0.05). Change from baseline in Cutaneous Lupus Disease Area and Severity Index (CLASI)-activity (A) score was also significantly greater in patients receiving litifilimab vs placebo at both Week 16 (−43.4% vs −29.3%) and Week 24 (−45.1% vs −26.4%). Significantly more patients receiving litifilimab vs placebo achieved ≥50% reduction from baseline in CLASI (CLASI-50; 40.8% vs 21.0%) and ≥70% reduction from baseline in CLASI (CLASI-70; 21.7% vs 5.8%) at Week 24. Treatment-related adverse events (TRAEs) were reported in 20.3% vs 26.5% of patients and serious adverse events (SAEs) were reported in 6.8% vs 2.9% of patients.

Key learning: Litifilimab demonstrated greater levels of CLA-IGA-R erythema 0–1 attainment and greater improvements in CLASI responses at Week 24 vs placebo and was well tolerated in patients with CLE, with no new safety signals detected.