The purpose of the study is to evaluate the efficacy and safety of efgartigimod IV in Chinese patients with active lupus nephritis (LN). The study comprises an approximate 4-week screening period, a 24-week treatment period, and an 8-week follow- up period.

Inclusion Criteria:

• Aged ≥18 years when signing the informed consent form (ICF)
• Capable of providing signed informed consent, and complying with protocol requirements
• Diagnosis of SLE according to the Systemic Lupus Erythematosus International Collaborating Clinic (SLICC) 2012 classification criteria
• Active, proliferative LN Class III or IV [excluding Class III (C), IV-S (C), and IV-G (C)], either with or without the presence of Class V using the 2003 International Society of Nephrology (ISN)/Renal Pathology Society (RPS) criteria, proven by kidney biopsy within 6 months before randomization and confirmed by the central biopsy reading group
• Require LN induction therapy (glucocorticoids and MMF/MPA) based on investigator's clinical judgment. Induction therapy may begin before screening but should be initiated within 60 days before randomization
• Agree to use contraceptives consistent with local regulations. Full inclusion criteria can be found in the protocol

Exclusion Criteria:

• Active or chronic infection requiring treatment
• Any evidence of central nervous system lupus (including but not limited to seizures, psychosis, organic brain syndrome, cerebrovascular accident, cerebritis, or CNS vasculitis)
• Currently on renal dialysis or expected to require dialysis during study period
• Previous kidney transplantation or planned transplantation during study period
• History of malignancy unless deemed cured by adequate treatment with no evidence of recurrence for ≥3 years before randomization. The following cancers are not exclusionary: basal cell or squamous cell skin cancer; carcinoma in situ of the cervix; carcinoma in situ of the breast; incidental histological finding of prostate cancer
• Heart failure due to Systemic Lupus Erythematodes, or any other severe cardiovascular involvement with safety concerns according to investigator's judgment
• Any other known autoimmune disease that would interfere with an accurate assessment of clinical symptoms of SLE/LN or put the participant at undue risk
• Previously failed treatment with MMF or any form of mycophenolate-based induction therapy, based on the investigator's opinion
• Use of complementary therapies, including Traditional Chinese Medicine, herbs, or procedure (eg, acupuncture) that can potentially interfere with the efficacy and safety of participants as assessed by the investigator
• SARS-CoV-2 antigen-based positive test at screening. The test is required regardless of whether the participant has been vaccinated
• Known hypersensitivity or contraindication to efgartigimod, any excipient of the IMP, or SoC medication used in the study
• In the opinion of the investigator, current or history of (ie, within 12 months of randomization) alcohol, drug, or medication abuse
• Pregnant or lactating females and those who intend to become pregnant during study participation
• Any conditions or circumstances that in the opinion of the investigator may make the participant unsuitable for the study

The full list of criteria can be found in the protocol.