• 18 to 65 years old, male or female.

• A diagnosis of SLE according to the 2019 EULAR (European League Against Rheumatism)/ACR (American College of Rheumatology).

• Inclusion criteria applicable to the LN subgroup: active type III or IV lupus nephritis (with or without type V) confirmed by renal biopsy according to the 2018 International Society of Nephrology/Renal Pathology Society (ISN/RPS) criteria. An activity index ≥2 and a chronicity index no more than moderate according to the 2018 RPS Task Force for LN pathologic types and the National Institutes of Health (NIH) Lupus Nephritis Activity and Chronicity Index Score criteria. Urine protein/creatinine ratio (UPCR) ≥ 1.0 g/g or 24-hour urine protein quantification ≥ 1.0 g/day.

• One of the following at screening: positive antinuclear antibody (ANA) OR positive anti-dsDNA OR positive anti-Smith antibody.

• SLEDAI-2000 score ≥ 8.

• Prior to screening, having received glucocorticoids combined with immunosuppressants and/or biologics for at least 3 months with stable doses for \>2 weeks, but disease still active (i.e., received glucocorticoids + immunosuppressants or glucocorticoids + immunosuppressants + biologics; monotherapy with any of the above drugs is not eligible).

• Hematologic, hepatic, renal, pulmonary, and cardiac function criteria at screening were as follows: ① leukocytes ≥ 2 ×109/L and lymphocyte count ≥ 0.5 ×109 /L; ② serum ALT and AST ≤ 3 times the upper limit of normal; ③ total bilirubin ≤ 1.5 times the upper limit of normal, with the exception of patients with Gilbert's syndrome, for whom total bilirubin was ≤ 3.0 times the upper limit of normal; ④ eGFR (based on the creatinine based on the CKD-EPI formula) ≥ 30 ml/min/1.73m2; ⑤ oxygen saturation ≥ 92% in non-oxygenated state under indoor ventilation; no clinically significant pleural effusion; ⑥ left ventricular ejection fraction ≥ 45%, and no clinically significant abnormal findings on ECG.

• For participants not receiving therapeutic anticoagulation: International standardized ratio (INR) ≤ 1.5 times the upper limit of normal, or prothrombin time (PT) ≤ 1.5 times the upper limit of normal.

• Participants receiving hematopoietic growth factor support therapy, including erythropoietin (EPO), granulocyte colony-stimulating factor (G-CSF), granulocyte macrophage-colony-stimulating factor (GM-CSF), and platelet agonists (TPO), must have a 2-week interval between the last growth factor support therapy and the screening period assessment; those receiving blood product transfusion that require at least 1 week between the screening period platelet assessment and the last platelet transfusion, and at least 2 weeks between the screening period hemoglobin assessment and the last red blood cell transfusion.

• Female participants of childbearing potential must have a negative serum pregnancy test at screening (women who are surgically sterilized or have been menopausal for at least 2 years are not considered to be of childbearing potential). Female subjects of childbearing potential and male subjects must use highly effective methods of contraception throughout the clinical study and for 1 year after the last study treatment; they should also commit not to donate eggs (oocytes, oocytes)/sperm for assisted reproduction for 1 year after the last study treatment.

• Participants are willing to participate in this study and sign a paper version of the informed consent form.