Biogen's Litifilimab Shows Continued Improvement in Cutaneous Lupus Erythematosus Patients

CAMBRIDGE, Mass., Oct. 02, 2026 /CourierPR/ -- Biogen's investigational monoclonal antibody, litifilimab, has demonstrated continued and rapid improvements in skin disease activity for patients with cutaneous lupus erythematosus (CLE) in new 52-week data from the ongoing Phase 2/3 AMETHYST study. The results, presented at the European Academy of Dermatology and Venereology (EADV) 2026 Congress in Vienna, Austria, show that participants on litifilimab from week 24 through week 52 experienced a higher rate of achieving clear or almost clear skin (27.2%; CLA IGA 0-1) and improvements in disease activity (28.8%; CLASI-70) compared to week 24 (19.0% and 21.7%, respectively).

The study, which evaluated 93 adults with active skin symptoms for whom standard antimalarial medications were not effective or not tolerable, further supports the potential of litifilimab as a first-in-class therapy for CLE. For participants who switched from placebo to litifilimab at week 24, the onset of benefit was rapid, with improvements in skin disease activity as early as four weeks. By week 52, approximately one in three (33.7%) of these crossover participants reported clear or almost clear skin.

The Phase 2 portion of the ongoing Phase 2/3 AMETHYST study, which is expected to read out in the first half of 2027, evaluated the efficacy and safety of litifilimab compared to placebo. Participants were randomized to receive subcutaneous treatment with litifilimab or placebo every four weeks for 20 weeks, with an additional dose at week 2. All participants received litifilimab during the 28-week extended treatment period from weeks 24 to 48. The Phase 3 part of the AMETHYST study remains blinded and is expected to provide additional data.

Over the course of the 52-week treatment period, litifilimab was generally well tolerated, with a safety profile consistent with previously reported Phase 2 studies. The majority of adverse events (AEs) reported were mild or moderate in severity, and serious AEs occurred in 3.4% (3/88) of participants during the extended treatment period. The most common AEs (≥5% during the extended treatment period) were nasopharyngitis, influenza, and arthralgia.

Litifilimab (BIIB059) is an investigational first-in-class monoclonal antibody that selectively targets BDCA2 receptors on plasmacytoid dendritic cells (pDCs) to reduce inflammation. The targeted mechanism of action acts early in the disease pathway to address the immune dysregulation that drives lupus. Biogen developed litifilimab over two decades as part of a dedicated lupus discovery and development program.

The AMETHYST (NCT05531565) Phase 3 trial of litifilimab in CLE is currently ongoing and will provide additional data on the efficacy and safety of the treatment. More information on the AMETHYST study is available at clinicaltrials.gov.

Founded in 1978, Biogen is a leading biotechnology company that pioneers innovative science to deliver new medicines to transform patients' lives and to create value for shareholders and our communities. The company applies deep understanding of human biology and leverages different modalities to advance first-in-class treatments or therapies that deliver superior outcomes.