A Study of SCTB35 in Patients with Systemic Lupus Erythematosus

Inclusion Criteria: 1. Age 18-75 years； 2. Diagnosed with SLE for ≥12 weeks prior to screening (2019-ACR/EULAR criteria); 3. SLEDAI-2K ≥ 8 at screening, or ≥6 if there is hypocomplementemia or elevated anti-dsDNA antibody levels; 4. Positive for ANA (1:80) or positive for anti-dsDNA and/or anti-Sm antibodies within the last 12 months or at screening; 5. Currently receiving ≥1 stable dose of standard treatment: oral corticosteroids, antimalarials, or conventional immunosuppressive drugs 1. Stable corticosteroid dose for ≥4 weeks prior to baseline; 2. Stable dose of antimalarial drugs for ≥4 weeks prior to baseline; 3. Stable dose of immunosuppressive agents for ≥4 weeks prior to baseline; 6. All male participants or females of reproductive potential must agree to use reliable contraception with their partner from signing the ICF through 6 months after the last dose of the study drug; 7. Understanding of the study procedures and voluntary signing of the informed consent form. Exclusion Criteria: 1. Severe active or unstable lupus-related neuropsychiatric disorders; 2. Other autoimmune diseases that may interfere with efficacy evaluation; 3. Catastrophic antiphospholipid syndrome; 4. Received treatments that may affect the drug's effect: 5. Received live vaccines or attenuated vaccines within 28 days prior to baseline or screening; 6. Clinically significant bleeding risk; 7. Abnormal laboratory results: 1. AST or ALT \>2.5 x ULN; 2. Total bilirubin \>1.5 x ULN; 3. ANC \<1.5x10⁹/L; 4. Platelets \<75x10⁹/L; 5. Hemoglobin \<100g/L; 8. eGFR \<30 mL/min/1.73 m²; 9. Positive serum HCG; 10. Received any investigational treatment within 30 days prior to baseline or within 5 half-lives of the investigational drug (whichever is longer); 11. Participants with recurrent, chronic, or other active infections as assessed by the investigator; 12. Severe or uncontrolled disease, which would prevent participation in the study; 13. Positive viral serology tests, including HIV, HCV, and HBV; 14. Tuberculosis screening: Known active tuberculosis or latent tuberculosis infection (LTBI); 15. Any type of active infection except nail bed fungal infections; 16. Severe infections; 17. History of progressive multifocal leukoencephalopathy (PML); 18. Diagnosed with type 1 or type 2 diabetes with poor control; 19. Uncontrolled hypertension (systolic \>140 mmHg or diastolic \>90 mmHg); 20. History of malignancy within 5 years prior to baseline; 21. Alcohol abuse or drug misuse within 12 months prior to screening; 22. Intolerance to the study drug or contraindications, including a history of severe allergic reactions to monoclonal antibodies or any component of SCTB35 injection; 23. Required hospitalization for major surgery within 4 weeks prior to screening or within 12 weeks post-study drug administration; 24. Participants with mental disorders or poor compliance; 25. Severe lupus nephritis; 26. History of solid organ or hematopoietic stem cell/bone marrow transplant, or expected to undergo transplant surgery during the study; 27. Pregnant or breastfeeding; 28. Any other condition that the investigator deems unsuitable for participation in the study.