• Age ≥18 and ≤70

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

• For participants taking chronic corticosteroids for management of the disease under study, the prednisone (or equivalent) dose must be ≤40 mg/day at 6 weeks prior to Screening and stable for ≥ 14 days before start of Screening

• Negative SARS-CoV-2 test

• For subjects on immunosuppressives or immunomodulators (other than corticosteroids), all doses must be stable for ≥ 4 weeks prior to Screening

⁃ LN-specific Inclusion Criteria:

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

• Active biopsy proven lupus nephritis Class III or Class IV with or without Class 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. For subjects with primarily Class III or Class IV LN, the biopsy must have at least mild to moderate activity score (≥4/24) and no more than moderate chronicity index (≤ 6/12) per NIH indices

• Active renal disease as defined by urinary protein:creatinine ratio (UPCR) ≥ 1.5 g/g or proteinuria ≥1.5 g/day on a 24-hour collection and ≤ 7 g/day by either measure

• 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 (immunosuppressant and corticosteroid/or immunomodulatory agent, and corticosteroid at therapeutic range for at least 90 days), and had an inadequate response to therapy despite being on a therapeutic dose for ≥ 90 days

⁃ 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 spot UPCR ≥ 3.5 g/g or proteinuria ≥ 3.5 g/day on a 24-hour collection

• Positive anti-PLA2R antibodies

• Refractory or intolerant to at least one induction therapy for pMN (immunosuppressant and corticosteroid or immunomodulatory agent and/corticosteroid) and defined as not achieving a complete remission after 180 days, or partial remission after 90 days