Atacicept in Subjects With Active Lupus Nephritis (COMPASS)

Key Inclusion Criteria: 1. Male or Female at least 18 years of age at time of signing consent 2. Must have the ability to understand and sign and date a written informed consent form 3. Diagnosis of SLE 4. Biopsy- Proven Active LN 5. Requires high-dose corticosteroids and immunosuppressive therapy for the treatment of active LN 6. Subject is willing to take oral MMF for the duration of the study Key Exclusion Criteria: 1. eGFR of ≤30 mL/min/1.73 m2. 2. Sclerosis in 50% of glomeruli on renal biopsy. 3. Evidence of rapidly progressive glomerulonephritis. 4. Currently requiring renal dialysis or expected to require dialysis during the study. 5. Serum igG \<7 g/L 6. Active infection or high infectious risk