A Study to Learn About the Safety of Litifilimab (BIIB059) Injections and Whether They Can Improve Symptoms of Adult Participants Who Have Systemic Lupus Erythematosus

The primary objective of the study is to demonstrate the efficacy of litifilimab compared with placebo in participants with active SLE, who are receiving background lupus standard of care (SOC) therapy in reducing disease activity. The secondary objectives of this study are to demonstrate efficacy of litifilimab compared with placebo in participants with active SLE, who are receiving background lupus SOC therapy in reducing disease activity and occurrence of flare up to Week 52; to demonstrate organ-specific efficacy of litifilimab compared with placebo in participants with active SLE, who are receiving background lupus SOC therapy in reducing joint disease activity and skin disease activity; to demonstrate and evaluate effect of litifilimab compared with placebo in reducing oral corticosteroid(s) (OCS) use; to evaluate additional efficacy of litifilimab compared with placebo in reducing disease activity with additional disease activity measures; assess the difference between litifilimab and placebo on participant reported health-related quality of life (HRQoL), symptoms, and impacts of SLE; to evaluate the safety, tolerability and immunogeneicty of litifilimab in participants with active SLE.