Treatment with the humanized monoclonal antibody litifilimab for patients with systemic lupus erythematosus (SLE) led to greater improvements in joint manifestations than did placebo in an international phase 2 trial that reflects keen interest in targeting type 1 interferon and the innate immune system.
Litifilimab was associated with an approximately three-joint reduction in the number of swollen and tender joints, compared with placebo, over 24 weeks in the study, which was published in The New England Journal of Medicine.
The study was the first part of the LILAC trial, a two-part, phase 2 study. The second part involved cutaneous lupus erythematosus (CLE) with or without systemic manifestations. Treatment led to improvements in skin disease, as measured by Cutaneous Lupus Erythematosus Disease Area and Severity Index–Activity (CLASI-A) scores. It was published in the New England Journal of Medicine.
Dr. Richard A. Furie
The investigational drug targets blood dendritic cell antigen 2 (BDCA2). The antigen is expressed solely on plasmacytoid dendritic cells (pDCs), which accumulate in skin lesions and organs of patients with SLE. When the antibody binds to BDCA2, “the synthesis of a variety of cytokines is shut down – type 1 interferons, type 3 interferons, TNF [tumor necrosis factor], and [other cytokines and chemokines] made by the pDCs,” Richard A. Furie, MD, lead author of the article, said in an interview.
In a phase 1 trial involving patients with SLE and CLE, the drug’s biologic activity was shown by a dampened interferon signature in blood and modulated type 1 interferon-induced proteins in the skin, he and his coinvestigators noted.
Dr. Furie is chief of rheumatology at Northwell Health and professor of medicine at the Feinstein Institutes for Medical Research at Northwell and at the Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Uniondale, New York.
Impact on the joints
The primary analysis in the SLE trial involved 102 patients who had SLE, arthritis, and active skin disease. The patients received litifilimab 450 mg or placebo, administered subcutaneously, at weeks 0, 2, 4, 8, 12, 16, and 20. The patients were required to have at least four tender joints and at least four swollen joints, and these active joints had to be those classically involved in lupus arthritis.
The mean (± standard deviation) baseline number of active joints was 19 ± 8.4 in the litifilimab group and 21.6 ± 8.5 in placebo group. From baseline to week 24, the least-squares mean (± standard deviation) change in the total number of active joints was –15.0 ± 1.2 with litifilimab and –11.6 ± 1.3 with placebo (mean difference, –3.4; 95% confidence interval, –6.7 to -0.2; P = .04).
Most of the secondary endpoints did not support the results of the primary analysis. However, improvement was seen in the SLE Responder Index (SRI-4) – a three-component global index that Dr. Furie and others developed in 2009 using data from the phase 2 SLE trial of belimumab (Benlysta).
The composite index, used in the phase 3 trial of belimumab, captures improvement in disease activity without a worsening of the condition overall or new significant disease activity in other domains. “It’s a dichotomous measure – either you’re a responder or not,” Dr. Furie said in the interview.
Response on the SRI-4 was defined as a reduction of at least 4 points from baseline in the SLEDAI-2K score (the Systemic Lupus Erythematosus Disease Activity Index), no new disease activity as measured by one score of A (severe) or more than one score of B (moderate) on the BILAG (British Isles Lupus Assessment Group) index, and no increase of 0.3 points or more on the Physician’s Global Assessment.
A total of 56% of the patients in the litifilimab group showed responses on the SRI-4 at week 24, compared with 29% in the placebo group (least-squares mean difference, 26.4%; 95% confidence interval [CI], 9.5-43.2). This is “a robust response” that is much greater than the effect size seen in the phase 3 trial of belimumab or in research on anifrolumab (Saphnelo). Both of those drugs are approved for SLE, Dr. Furie said. “We’ll need to see if it’s reproduced in phase 3.”
There’s “little question that litifilimab works for the skin,” Dr. Furie noted. In the second part of the LILAC study, which focused on CLE, litifilimab demonstrated efficacy, and the SLE trial lends more support. Among several secondary endpoints evaluating skin-related disease activity, a reduction of at least 7 points from baseline in the CLASI-A score (a clinically relevant threshold) occurred in 56% of the litifilimab group and 34% of the placebo group.
The trial was conducted at 55 centers in Asia, Europe, Latin America, and the United States. The SLE part of the study began as a dose-ranging study aimed at evaluating cutaneous lupus activity, but owing to “slow enrollment and to allow an assessment of the effect of litifilimab on arthritis in SLE,” the protocol and primary endpoint were amended before the trial data were unblinded to evaluate only the 450-mg dose among participants with active arthritis and skin disease (at least one active skin lesion), the investigators explained.
Background therapy for SLE was allowed if the therapy was initiated at least 12 weeks before randomization and if dose levels were stable through the trial period. Glucocorticoids had to be tapered to ≤ 10 mg/day according to a specified regimen.