Study recruitment is paused due to business reasons, but not due to regulatory or safety concerns.

The objective of the study is to evaluate the effect of atacicept compared to placebo on changes to renal response in adult subjects with LN.

The study will assess atacicept vs. placebo on the impact of renal function. Safety and patient reported outcomes will be clinically assessed. The clinical study is comprised of a 104 week double-blind treatment period, followed by a 52 week open-label treatment period and a 26 week safety follow-up period.

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