Key Inclusion Criteria Summary

• SLE onset ≥ 6 months prior to Screening
• Positive ANA and/or elevated anti-dsDNA and/or elevated anti-Smith antibody test
• Active lupus at Screening and Baseline, as defined per-protocol and confirmed by the study's medical monitor, including a SLEDAI score at Screening of ≥ 6 and a clinical score at Baseline of ≥ 4
• Standard lupus medications must be stable prior to Screening

Key Exclusion Criteria Summary:

• Life-threatening or organ system-threatening lupus activity that is anticipated to require increased treatment during the study
• Proteinuria consistent with nephrotic syndrome
• Active lupus-related neuropsychiatric disease
• Drug-induced lupus
• Recent or serious ongoing infection; risk or history of serious infection
• Receipt of live vaccination within 8 weeks of Day 1, or expected to require live vaccination during the study
• Prior diagnosis of, or fulfills diagnostic criteria for, another rheumatic disease that overlaps with lupus or another autoimmune or inflammatory disease that may confound clinical assessments or increase subject risk in the study
• Diagnosis of, or fulfills diagnostic criteria for fibromyalgia
• Functional class IV
• Serious lupus disease activity, which warrants immediate immunosuppressive therapy not appropriate for the study or which makes the possibility of receiving placebo or investigational agent an inappropriate risk