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 elevatedanti-dsDNA antibody levels;

4. Positive for ANA (1:80) or positive for anti-dsDNA and/or anti-Sm antibodies withinthe last 12 months or at screening;

5. Currently receiving ≥1 stable dose of standard treatment: oral corticosteroids,antimalarials, or conventional immunosuppressive drugs

6. Stable corticosteroid dose for ≥4 weeks prior to baseline;

7. Stable dose of antimalarial drugs for ≥4 weeks prior to baseline;

8. Stable dose of immunosuppressive agents for ≥4 weeks prior to baseline;

9. All male participants or females of reproductive potential must agree to usereliable contraception with their partner from signing the ICF through 6 monthsafter the last dose of the study drug;

10. Understanding of the study procedures and voluntary signing of the informed consentform.

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 orscreening;

6. Clinically significant bleeding risk;

7. Abnormal laboratory results:

8. AST or ALT >2.5 x ULN;

9. Total bilirubin >1.5 x ULN;

10. ANC <1.5x10⁹/L;

11. Platelets <75x10⁹/L;

12. Hemoglobin <100g/L;

13. eGFR <30 mL/min/1.73 m²;

14. Positive serum HCG;

15. Received any investigational treatment within 30 days prior to baseline or within 5half-lives of the investigational drug (whichever is longer);

16. Participants with recurrent, chronic, or other active infections as assessed by theinvestigator;

17. Severe or uncontrolled disease, which would prevent participation in the study;

18. Positive viral serology tests, including HIV, HCV, and HBV;

19. Tuberculosis screening: Known active tuberculosis or latent tuberculosis infection (LTBI);

20. Any type of active infection except nail bed fungal infections;

21. Severe infections;

22. History of progressive multifocal leukoencephalopathy (PML);

23. Diagnosed with type 1 or type 2 diabetes with poor control;

24. Uncontrolled hypertension (systolic >140 mmHg or diastolic >90 mmHg);

25. History of malignancy within 5 years prior to baseline;

26. Alcohol abuse or drug misuse within 12 months prior to screening;

27. Intolerance to the study drug or contraindications, including a history of severeallergic reactions to monoclonal antibodies or any component of SCTB35 injection;

28. Required hospitalization for major surgery within 4 weeks prior to screening orwithin 12 weeks post-study drug administration;

29. Participants with mental disorders or poor compliance;

30. Severe lupus nephritis;

31. History of solid organ or hematopoietic stem cell/bone marrow transplant, orexpected to undergo transplant surgery during the study;

32. Pregnant or breastfeeding;

33. Any other condition that the investigator deems unsuitable for participation in thestudy.