Inclusion Criteria:  Active proliferative LN Class III or IV either with or without the presence of Class V according to the 2003 ISN/RPS classification Renal biopsy obtained within 6 months prior to signing the ICF or during Screening Period. Urine protein to creatinine ratio > 1 mg/mg (113.17 mg/mmol) eGFR ≥ 35 mL/min/1.73 m2 (as calculated by the Chronic Kidney Disease Epidemiology Collaboration formula). Fulfills updated 2019 EULAR/ACR SLE classification criteria. No signs of symptoms of active TB prior to or during screening or no treatment for latent TB  Exclusion Criteria:  A diagnosis of pure Class V LN based on the renal biopsy obtained within 6 months prior to signing the ICF or during Screening. Known history of a primary immunodeficiency, splenectomy, or any underlying condition that predisposes the participant to infection, or a positive result for HIV confirmed by the central lab at Screening - an HIV test must be performed during Screening, and the result should be available prior to Week 0 (Day 1). Evidence of hepatitis C or active hepatitis B. Any history of cancer except sucessfully cured skin squamos or basal skin carcinoma and cervical cancer in situ. Receipt of the following for the current LN flare (ie, since the qualifying renal biopsy): IV cyclophosphamide > 2 pulses of high-dose (≥ 0.5 g/m2) or > 4 doses of low dose (500 mg every 2 weeks) or Average MMF > 2.5 g/day (or > 1800 mg/day of enteric coated mycophenolate sodium) for more than 8 weeks or Tacrolimus > 4 mg/day for more than 8 weeks; Cyclosporine for more than 8 weeks or during last 8 weeks prior to signing the ICF; Voclosporin for more than 8 weeks or during last 8 weeks prior to signing the ICF; Belimumab for more than 12 weeks or during last 12 weeks prior the ICF. Previous receipt of >◦2 investigation treatments (other than anifrolumab) for LN or SLE since time of diagnosis and through the ICF. Known intolerance to ≤ 1.0 g/day of MMF. Any history of severe COVID-19 infection.