This is an extension study for all participants who completed study 230LE303 (NCT04895241) and 230LE304 (NCT04961567) (parent phase 3 studies) through Week 52 and did not discontinue BIIB059 or placebo. Eligible participants from parent phase 3 studies will be followed for up to 180 weeks.
The primary objective of this study is to evaluate the long-term safety and tolerability of BIIB059 (litifilimab) in participants with active systemic lupus erythematosus (SLE).~The secondary objectives of this study are to evaluate the long-term effect of BIIB059 on disease activity in participants with SLE, to evaluate the long-term effect of BIIB059 in participants with SLE in maintaining low disease activity, to evaluate the effect of BIIB059 in participants with active SLE in preventing irreversible organ damage, to assess long-term use of oral corticosteroid (OCS) with participants receiving BIIB059 treatment, to assess the impact of BIIB059 on participant-reported Health-Related Quality-of-Life Questionnaire (HRQoL), symptoms, and impacts of SLE, to evaluate long-term effect of BIIB059 on laboratory parameters, and to evaluate immunogenicity of BIIB059.