Victoria P. Werth, MD, discusses how litifilimab’s 52-week AMETHYST findings inform treatment expectations and timely reassessment of persistent cutaneous lupus symptoms.
Litifilimab’s 52-week AMETHYST findings point to continued improvement in difficult-to-treat cutaneous lupus erythematosus (CLE), bringing renewed attention to how quickly clinicians should reassess persistent skin inflammation. The investigational antibody offers a targeted approach for patients whose disease remains active despite antimalarial therapy, although phase 3 results are needed to establish its clinical role.1
For these patients, treatment delays carry consequences beyond discomfort. In an interview with Pharmacy Times, Victoria P. Werth, MD, professor of dermatology at the University of Pennsylvania and chief of dermatology at the Philadelphia VA Medical Center, emphasized the risk of lasting damage when inflammation remains uncontrolled.
Antimalarials are a mainstay of CLE treatment, but patients who do not respond often require immunosuppressants. Werth described methotrexate and mycophenolate mofetil as options that introduce additional treatment challenges without reliably controlling disease.
“They work in about half of patients, so we have a group of patients who are refractory to almost all therapies,” she said.
Litifilimab targets blood dendritic cell antigen 2 (BDCA2) on plasmacytoid dendritic cells, which contribute to lupus-associated inflammation. In the earlier phase 2 LILAC trial, treatment improved a measure of skin disease activity compared with placebo over 16 weeks, supporting further investigation.2
AMETHYST’s phase 2 portion enrolled 93 adults with active CLE who were refractory or intolerant to antimalarial treatment. At week 16, 14.7% of litifilimab recipients achieved clear or almost clear skin on the Cutaneous Lupus Activity Investigators’ Global Assessment Revised (CLA-IGA-R) erythema assessment, compared with 2.9% receiving placebo. The primary endpoint was met.3
Among participants who received litifilimab from the study’s start, 27.2% achieved a CLA-IGA-R erythema score of 0 or 1 at week 52, compared with 19.0% at week 24. These sponsor-reported findings were presented at the 2026 European Academy of Dermatology and Venereology Congress.1
“Complete clearance is probably more than what most patients need to feel much better,” Werth said.
She explained that an approximately 50% improvement in the Cutaneous Lupus Erythematosus Disease Area and Severity Index activity score (CLASI-A) can represent meaningful benefit. Patients can experience less redness and scaling even when they do not reach clear or almost clear skin. Research has linked reductions in CLASI-A with meaningful improvements in patient-reported quality of life.4
“Quality of life can improve dramatically, even if you do not achieve clear or almost clear skin,” she said.
This distinction matters when discussing treatment expectations. A clearance endpoint captures one aspect of response; residual lesions do not necessarily mean a patient has experienced little benefit.
Participants who switched from placebo to litifilimab at week 24 showed improvement as early as 4 weeks after starting treatment. Werth contrasted that timing with hydroxychloroquine, which she said takes approximately 2 months to begin working.1
During that interval, active discoid lupus can continue causing scarring, including permanent hair loss. Werth also noted that uncontrolled disease can produce pigmentary changes.
“An early response is very important to improve outcomes over time for these patients,” she said.
The AMETHYST findings do not establish that litifilimab prevents scarring or permanent hair loss. They describe changes in disease activity, leaving prevention of irreversible damage as an important question for future evaluation.
For pharmacists hearing that hydroxychloroquine is not working, Werth emphasized whether skin inflammation has begun improving.
“If somebody is not responding to hydroxychloroquine—if they are not starting to improve with less erythema and less scale within 2 months—it is really important to make sure the diagnosis is correct,” she said.
Her recommendation supports timely communication with the treating clinician, rather than prolonged acceptance of uncontrolled symptoms. She encouraged specialist referral when the clinician managing the patient is uncomfortable escalating treatment.
Safety also requires continued evaluation. During AMETHYST’s initial 24 weeks, adverse events occurred in 74.6% of litifilimab recipients and 64.7% of placebo recipients; serious adverse events occurred in 6.8% and 2.9%, respectively. The extended period identified no new safety signals, with serious adverse events reported in 3.4% of participants.1,3
Because all participants received active treatment after week 24, later findings offer information about sustained response but lack a concurrent placebo comparison. Phase 3 results are expected in the first half of 2027.1,3
If those findings support approval, Werth envisions an early role for patients with severe disease at risk of permanent disfigurement. For pharmacists, the immediate opportunity is recognizing persistent inflammation and helping patients obtain reassessment before further damage accumulates.
