A Phase 3 Study of Inebilizumab in Participants With Primary Membranous Nephropathy

Inclusion Criteria:

* Adults aged ≥18 years and \<80 years.
* Able and willing to provide written informed consent.
* Primary membranous nephropathy (PMN) confirmed by renal biopsy (performed during screening or within 5 years before screening), or biopsy exemption for participants with anti-PLA2R antibody ≥20 RU/mL at screening.
* Participants with diabetes Hemoglobin A1c (HbA1c) \<7.5% require a renal biopsy report within 2 years before screening (or biopsy during screening) demonstrating PMN without diabetic nephropathy.
* Urine protein-to-creatinine ratio (UPCR) ≥3.5 from a 24-hour urine collection at screening.
* Receiving a maximally tolerated Angiotensin-Converting Enzyme (ACE) inhibitor or (Angiotensin II receptor blocker) ARB for ≥3 months before randomization with adequately controlled blood pressure (\<140/90 mmHg).

Exclusion Criteria:

* Secondary membranous nephropathy (e.g., due to autoimmune disease, infection, malignancy, or medications).
* Estimated glomerular filtration rate (eGFR) \<40 mL/min/1.73 m\^2 , ≥30% decline in eGFR during the previous 24 weeks, need for dialysis, kidney replacement therapy, kidney transplant, or planned transplant during the study.
* Recent thromboembolic event (within 3 months).
* Active HIV, hepatitis B infection, Hepatitis B surface antigen (HBsAg) positive, active hepatitis C infection, uncontrolled diabetes (HbA1c ≥7.5%), active or inadequately treated tuberculosis, recurrent herpes zoster or opportunistic infections, clinically significant active infection, recurrent serious infections, or immunodeficiency disorders.
* Clinically significant laboratory abnormalities, including severe anemia, neutropenia, thrombocytopenia, low Cluster of Differentiation (CD19+) B-cell count, hepatic dysfunction, or immunoglobulin G (IgG) \<400 mg/dL.
* History of solid organ or cell transplantation or progressive multifocal leukoencephalopathy.
* Recent treatment with prohibited therapies, including: B-cell-depleting biologics or other biologic immunomodulators, calcineurin inhibitors, alkylating agents within 3 months;( except history of resistance to calcineurin inhibitors); other immunosuppressive agents within 4 weeks; glucocorticoids within 1 month, or live or live-attenuated vaccines (within 4 weeks before randomization).

Note: Other protocol-defined Inclusion/Exclusion criteria may apply.