Biogen reports 52-week litifilimab lupus data

Biogen announced 52-week results on October 2, 2026, from Part A of its ongoing Phase 2/3 AMETHYST trial evaluating litifilimab in cutaneous lupus erythematosus. The findings, presented at the European Academy of Dermatology and Venereology Congress in Vienna, Austria, tracked 93 adults with active skin symptoms who were intolerant or refractory to antimalarial drugs.

By Week 52, 27.2% of participants who took litifilimab from baseline achieved clear or almost clear skin on the CLA-IGA-R erythema scale, up from 19.0% at Week 24. A 70% or greater improvement in disease activity on the CLASI-70 score was reached by 28.8% of these participants at Week 52, compared to 21.7% at Week 24. Participants who transitioned from placebo to litifilimab at Week 24 saw benefits begin within four weeks, with 33.7% reaching clear or almost clear skin by Week 52.

The drug was generally well tolerated, with nasopharyngitis, influenza, and arthralgia as the most common adverse events at rates of 5% or more during the extended period. Serious adverse events occurred in 3.4% of participants, or 3 out of 88 individuals, with no new safety signals detected.

The U.S. Food and Drug Administration granted litifilimab Breakthrough Therapy Designation for cutaneous lupus erythematosus in January 2026. Biogen stated that results from the blinded Phase 3 portion of the AMETHYST study are expected in the first half of 2027.