Biogen's Litifilimab Receives FDA Breakthrough Designation, Phase 2 Data to be Presented at AAD
Biogen announced that litifilimab received FDA Breakthrough Therapy Designation for cutaneous lupus erythematosus and will present Phase 2 AMETHYST study results at the 2026 AAD Annual Meeting, with Phase 3 data expected in 2027.
Biogen Inc. (Nasdaq: BIIB) announced on January 28, 2026 that the U.S. Food and Drug Administration has granted Breakthrough Therapy Designation for litifilimab (BIIB059) for the treatment of cutaneous lupus erythematosus (CLE). The designation is based on the totality of litifilimab data, including results from the Phase 2 LILAC study, which were previously published in The New England Journal of Medicine and demonstrated that litifilimab reduced skin disease activity in people with CLE compared to placebo.
On March 19, 2026, Biogen announced upcoming scientific presentations at the 2026 American Academy of Dermatology (AAD) Annual Meeting, taking place March 27-31. Late-breaking data from Part A (Phase 2) of the AMETHYST Phase 2/3 study will be presented that highlight litifilimab's effect on cutaneous lupus erythematosus disease activity. The late-breaking oral presentation "Efficacy and Safety of Litifilimab in Cutaneous Lupus Erythematosus (CLE): 24-week results of the Phase 2 Study, AMETHYST Part A" is scheduled for Saturday, March 28 at 3:24 PM MT / 5:24 PM ET in Bellco Theatre 3. Results from the Phase 2 (Part A) part of the AMETHYST study supported the Breakthrough Therapy Designation, in addition to the previously presented Phase 2 LILAC study results.
Litifilimab is a potential first in-class, humanized IgG1 monoclonal antibody (mAb) targeting blood dendritic cell antigen 2 (BDCA2) and was the first investigational therapy to show positive results in CLE, as shown in the Phase 2 LILAC study. BDCA2 is a receptor that is predominantly expressed on a subset of human immune cells called Plasmacytoid Dendritic Cells (pDCs). Binding of litifilimab to BDCA2 has been shown to reduce production of pro-inflammatory molecules by pDCs, including type-I interferon (IFN-I) as well as other cytokines and chemokines. These pro-inflammatory mediators are thought to play a major role in the pathogenesis of systemic and cutaneous lupus.
The Phase 3 part of the AMETHYST study, which will further evaluate litifilimab in CLE, is on track and a data readout is expected in 2027. AMETHYST is a two-part, Phase 2/3 multicenter, double-blind, placebo controlled, randomized study to evaluate the efficacy and safety of litifilimab compared to placebo. The study aims to assess the efficacy of litifilimab in participants with active subacute cutaneous lupus erythematosus (SCLE) and/or chronic cutaneous lupus erythematosus (CCLE) who are refractory or intolerant to antimalarial therapy. The Phase 2 and Phase 3 parts of the study will each be 52 weeks in duration. Participants will be randomized to receive subcutaneous treatment with litifilimab or placebo every four weeks for 20 weeks with an additional dose at Week 2. All participants will receive litifilimab during the 28-week extended treatment period from Weeks 24 to 48.
CLE is a serious chronic autoimmune skin disease that can occur with or without systemic manifestations. The disease impacts the daily lives of patients and can lead to permanent scarring and disfigurement when left untreated, and has no targeted treatment option. The current standard of care for CLE includes topical steroids, antimalarials and immunosuppressants. While current treatments help manage symptoms, they do not alter the progression of the disease.
FDA Breakthrough Therapy Designation is granted to expedite the development and review of drugs for serious diseases. Litifilimab, discovered and developed in-house by Biogen scientists, is being investigated for the potential treatment of systemic lupus erythematosus (SLE) and cutaneous lupus erythematosus (CLE). Litifilimab is an investigational therapeutic candidate that has not yet been approved by any regulatory authority and its safety and effectiveness have not been established.