A Study of ANX009 in Adult Participants With Lupus Nephritis

All participants may continue to receive stable background standard of care therapy for LN and systemic lupus erythematosus (SLE) as permitted by the protocol (for example, mycophenolate mofetil [MMF], azathioprine, antimalarials, glucocorticoids, cyclosporin, voclosporin, tacrolimus, angiotensin converting enzyme [ACE] inhibitors, angiotensin receptor blockers [ARBs]).

Key Inclusion Criteria:

• Participants who have a diagnosis of SLE according to European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) 2019 Criteria
• Has a history of International Society of Nephrology/Renal Pathology Society (ISN/RPS) Class III or IV with or without Class V glomerulonephritis on renal biopsy within 24 months prior to screening or as performed during screening.
• Has proteinuria level between ≥0.5 to 3.0 grams (g)/g/day assessed via urine protein to creatine ratio (UPCR) during screening.
• Has evidence of classical complement activation at screening
• Has a history of receiving one or more standard therapies for LN

Key Exclusion Criteria:

• Has a history of ISN/RPS Class VI or isolated Class V (without co-existent/predominant Class III or IV glomerulonephritis) glomerulonephritis on renal biopsy.
• Has severe kidney disease defined as eGFR of <30 milliliters (mL)/minute/1.73 square meter (m^2) or end-stage renal disease (ESRD) requiring dialysis or kidney transplantation.
• Has a concurrent systemic autoimmune disease that may confound study assessments other than SLE, LN, or cutaneous lupus erythematosus.

NOTE: Other inclusion and/or exclusion criteria may apply.