A 2-Part Phase 2 Randomized, Double-Blind, Placebo-Controlled Study Evaluating the Efficacy and Safety of BIIB059 in Subjects With Systemic Lupus Erythematosus and Active Skin Manifestations and in Subjects With Active Cutaneous Lupus Erythematosus With or Without Systemic Manifestations

The primary purpose of the study is to evaluate the efficacy of BIIB059 (litifilimab) in
reducing disease activity in participants with systemic lupus erythematosus (SLE) with active
cutaneous manifestations and joint involvement (Part A), and in participants with active
cutaneous lupus erythematosus (CLE) (Subacute cutaneous lupus erythematosus (SCLE) or chronic
CLE, including discoid lupus erythematosus (DLE)) with or without systemic manifestations
(Part B). The secondary objective is to evaluate additional efficacy parameters of BIIB059 in
reducing SLE/CLE disease activity, pharmacokinetic parameters, safety and tolerability of
BIIB059 (Parts A and B).