More than a quarter achieve clear or almost clear skin at one year in litifilimab cutaneous lupus trial

For patients with cutaneous lupus erythematosus, the burden of skin rashes can extend to pigment changes, hair loss, and permanent scarring, making sustained suppression of inflammation more consequential than short-term improvement. Newly announced 52-week follow-up results for litifilimab, an antibody drug being developed by Biogen, show that the proportion of participants who received the drug from the start of the trial and met the assessment criterion for clear or almost clear skin lesions increased further from week 24.

These data were presented on October 2 at the European Academy of Dermatology and Venereology (EADV) annual meeting in Vienna and came from the Phase 2 portion of the Phase 2/3 AMETHYST study. The study enrolled 93 adults with ongoing active skin symptoms who had an inadequate response to or could not tolerate antimalarial treatment; 59 were randomly assigned to litifilimab and 34 to placebo. Treatment was administered by subcutaneous injection every four weeks, with an additional dose at week 2.

According to results released by Biogen, in the group that received litifilimab from the outset, the proportion achieving a physician-assessed CLA-IGA-R erythema score of 0 or 1, indicating clear or almost clear skin, increased from 19.0% at week 24 to 27.2% at week 52. CLASI, another measure of skin disease activity, also showed improvement: the proportion with an activity score reduction of at least 70% from baseline rose from 21.7% to 28.8%. These figures reflect reduced inflammatory activity and cannot be directly interpreted as showing that existing scars have disappeared.

A key limitation of the extended follow-up lies in the treatment switch midway through the trial. The original placebo group switched to litifilimab at week 24, after which all participants received the investigational drug. Dermatology Times reported that the group that switched showed improvement as early as four weeks after starting treatment, with 33.7% meeting the criterion for clear or almost clear skin at week 52. However, in an HCPLive interview, study abstract coauthor Victoria Werth cautioned that this stage primarily examined changes in each group over time, with no concurrent placebo group for comparison, and that the percentages in the two groups should not be used to conclude that starting treatment later is more effective.

Litifilimab targets BDCA2 on the surface of plasmacytoid dendritic cells. These immune cells are involved in the inflammatory response in lupus, and the drug is designed to reduce inflammatory signaling through this target. The Lupus Research Alliance noted that patients with cutaneous lupus have long relied on treatments that were not developed specifically for the disease; this one-year follow-up provides new data for assessing whether this targeted treatment can sustain disease control.

Regarding safety, Biogen said that 3 of the 88 participants in the extended treatment period experienced serious adverse events, representing 3.4%; more common adverse events included nasopharyngitis, influenza, and joint pain. The company said no new safety signals were identified, but the occurrence of adverse events does not mean they have been confirmed as caused by the drug, and a study of this size is also insufficient to rule out rare or longer-term risks.

The publicly available evidence currently comes mainly from conference presentations, company announcements, and related interviews. The increase in response rates over the follow-up period supports the possibility that continued treatment may bring further improvement, but it remains uncertain how long improvement lasts for each patient or whether it persists after treatment stops. The Phase 3 portion of AMETHYST remains blinded, and Biogen expects to announce results in the first half of 2027; litifilimab remains an investigational drug and has not yet received regulatory approval.