A Study of Zetomipzomib (KZR-616) in Patients With Active Lupus Nephritis (PALIZADE)

Key Inclusion Criteria: * Body mass index of ≥18 kg/m\^2 * eGFR ≥30 mL/min/1.73 m\^2 * Unequivocally positive ANA test result and/or a positive anti-dsDNA serum antibody test * Diagnosis of LN according to 2003 or 2018 ISN/RPS criteria and confirmed by renal biopsy performed within 12 months prior to Screening. * UPCR ≥1.0 (Class III/IV +/-V) or UPCR ≥2.0 (Class V) * Adequate hematologic, hepatic, and renal function Key Exclusion Criteria: * Current or medical history of: * Central nervous system manifestations of SLE * Overlapping autoimmune condition that may affect study assessments/outcomes * Antiphospholipid syndrome with history of thromboembolic event of within the 52 weeks prior to Screening * Thrombocytopenia or at high risk for developing clinically significant bleeding or organ dysfunction requiring therapies (i.e., plasmapheresis or acute blood or platelet transfusions * Solid organ transplant or planned transplant during study * Malignancy of any type, with exceptions for non-melanoma skin cancers and certain cancers \>5 years ago * Has received dialysis within the 52 weeks prior to Screening * Positive test at Screening for HIV, hepatitis B/C * Known intolerance to MMF or equivalent and corticosteroids