This clinical trial is focused on studying the long-term safety and effectiveness of a treatment called litifilimab, also known by its code name BIIB059. The study is specifically for adults with a condition called Systemic Lupus Erythematosus (SLE), which is an autoimmune disease where the immune system mistakenly attacks healthy tissues in the body. The treatment is administered as an injection under the skin.

The purpose of the study is to evaluate how safe and tolerable litifilimab is over an extended period. Participants in the study will receive either the active treatment or a placebo, which looks like the treatment but does not contain the active ingredient. The study will monitor participants for any side effects and assess the treatment’s impact on their condition over time.

Participants will be involved in the study for a long-term period, during which they will have regular visits to the study center. These visits will include health assessments and monitoring to ensure the safety and effectiveness of the treatment. The study aims to provide valuable information on how well litifilimab works in managing symptoms of Systemic Lupus Erythematosus and its long-term safety profile.