A 2-Part Study to Learn Whether Litifilimab (BIIB059) Injections Can Improve Symptoms of Adult Participants Who Have Active Cutaneous Lupus Erythematosus

Litifilimab is a humanized immunoglobulin G1 (IgG1) monoclonal antibody targeting blood dendritic cell antigen 2. It is an inhibitory receptor expressed on the surface of human plasmacytoid dendritic cell (pDCs) and is being investigated for the potential treatment of systemic lupus erythematosus and cutaneous lupus erythematosus. The primary objectives of the study are to evaluate the efficacy of litifilimab compared with placebo in reducing skin disease activity measured by the CLA-IGA-R score [Parts A] and the Cutaneous Lupus Erythematosus Disease Area and Severity Index Activity (CLASI-A) score [Part B] in participants with active SCLE and/or CCLE with or without systemic manifestations and refractory and/or intolerant to antimalarials. The secondary objectives of the study are to evaluate the efficacy of litifilimab in reducing SCLE and/or CCLE disease activity by CLA-IGA-R, CLASI-A; to evaluate additional efficacy parameters of litifilimab in reducing SCLE and/or CCLE disease activity; safety; tolerability; and immunogenicity of litifilimab [Parts A and B].

Key Inclusion Criteria:

• Histologically confirmed (in the past or during the Screening period) diagnosis of CLE with or without systemic manifestations.
• Must have active cutaneous manifestations that meet study criteria.
• Must have a CLASI-A score ≥10.
• Must have an active CLE lesion despite an adequate trial of antimalarial treatment.

Key Exclusion Criteria:

• Any active skin conditions other than CLE that may interfere with the study assessments of CLE.
• Diagnosis of mixed connective tissue disease [(within 1 year of signing the informed consent form (ICF)] or any history of overlap syndromes of SLE including concomitant presence with rheumatoid arthritis, dermatomyositis and/or polymyositis, systemic sclerosis, psoriatic arthritis, or any other autoimmune disease that may confound the evaluation of the disease activity or the effect of the investigational product. Exceptions for overlap syndrome of SLE include participants with overlap syndrome of SLE with myositis and secondary Sjögren's syndrome at screening is permitted provided the participant also meets the criteria for classification as SLE. A past history of mixed connective tissue disease that over time has developed into a diagnosis of SLE is permitted, provided diagnosis of SLE has been present for at least 1 year.
• Active severe lupus nephritis.
• Active neuropsychiatric SLE.
• Use of intralesional corticosteroids within 1 week prior to Screening and during the study.
• Use of immunosuppressive or disease-modifying treatments for SLE or CLE [via an oral, intravenous (IV), or SC route] that were initiated less than 12 weeks prior to screening, have not been at a stable and allowable dose.

NOTE: Other protocol-defined Inclusion/Exclusion criteria may apply