• Age ≥18 and ≤65

• Progression despite maximal tolerated doses of renin-angiotensin system (RAS) blockade agents

• For participants taking chronic corticosteroids for management of the disease under study, stable dose for ≥ 14 days before the screening visit with planned reduction to ≤ 5 mg prednisone by the time of LD start

• Negative SARS-CoV-2 test

⁃ LN-specific Inclusion Criteria:

• Score of 10 or more points on the American College of Rheumatology (ACR) 2019 classification criteria for SLE

• Active nephritis Class III, IV, and/or V using the 2018 International Society of Nephrology and Renal Pathology Society (ISN/RPS) criteria (Bajema 2018) as evidenced on kidney biopsy during screening or within 6 months before screening. Per NIH indices, subjects must have at least moderate activity score and no more than moderate chronicity index

• Active renal disease as defined by urinary protein:creatinine ratio (UPCR) ≥ 1.5 g/g or proteinuria ≥1.5 g/day and ≤ 7 g/day

• Positive antinuclear antibodies (ANA) ≥ 1:80 OR anti-dsDNA OR anti-Smith (anti-Sm)

• Refractory LN defined as having received ≥ 2 prior therapies for LN

⁃ pMN-specific Inclusion Criteria:

• Evidence of pMN by renal biopsy during screening or within 6 months before screening

• Active renal disease at screening defined by UPCR ≥ 3.5 g/g or proteinuria ≥ 3.5 g/day

• Positive anti-PLA2R antibodies

• Refractory or intolerant to either B cell-depleting agents and/or cyclophosphamide and/or calcineurin inhibitors defined as not achieving a complete remission after 180 days, or partial remission after 90 days