A Study of Felzartamab in Participants With Lupus Nephritis

Inclusion Criteria:

* Diagnosis of Systemic Lupus Erythematosus (SLE) according to the 2019 European League Against Rheumatism (EULAR)/ American College of Rheumatology (ACR) criteria
* Diagnosis of International Society of Nephrology/ Renal Pathology Society (ISN/RPS) 2003 Class III or IV LN as evidenced by renal biopsy performed within 1 year prior to or during screening, either with or without the presence of Class V LN
* Proteinuria (urine protein to creatinine ratio) \> 1.0 gram per gram (g/g), based on 24-hour urine collection during screening
* eGFR ≥ 45 milliliter/minute/1.73 square meters (mL/min/1.73 m\^2) (as calculated by the Chronic Kidney Disease Epidemiology Collaboration formula)
* History of inadequate response, for lack of efficacy or intolerance, to at least a three-month course of one standard of care treatment for lupus nephritis, as determined by the treating physician

Exclusion Criteria:

* Presence of rapidly progressive glomerulonephritis, as defined by at least one of the following: crescent formation in \> 50% of glomeruli on renal biopsy, sustained doubling of serum creatinine within 12 weeks of screening, or the investigator's opinion that the participant has rapidly progressive glomerulonephritis
* Greater than 50% of glomeruli with sclerosis on renal biopsy
* Currently requiring hemodialysis or peritoneal dialysis or expected to require dialysis during the study treatment period
* A previous kidney transplant or other organ transplant, or planned transplant within study treatment period

Other protocol-defined inclusion/exclusion criteria may apply