To Evaluate the Efficacy and Safety of SG301 SC Injection in Systemic Lupus Erythematosus

1. Voluntarily participate in the clinical study and sign a written informed consent form.

2. Participants must be diagnosed with SLE in accordance with the 2019 European League Against Rheumatism (EULAR)/American College of Rheumatism (ACR) SLE classification criteria and have inadequate response to standard treatment, intolerance to standard treatment, or recurrent disease.

3. SLEDAI-2K score ≥ 8 points, with clinical features corresponding to a SLEDAI-2K score ≥ 4 points.

4. Positive serological test results for autoantibodies, defined as antinuclear antibody (ANA) positivity and/or anti-double-stranded DNA (anti-dsDNA) antibody positivity.

5. Body weight ≥ 35 kg.

6. Must have received standard treatment for at least 8 weeks before the first dose and maintained a stable dose of the treatment unchanged for at least 4 weeks before the first dose.

7. Participants of childbearing potential or whose partners are of childbearing potential must agree to use effective contraceptive measures throughout the entire study period and within 6 months after the last dose.

1. Previous use of CD38 or monoclonal antibodies targeting CD38.

2. Active central nervous system (CNS) disease within 2 months before the first dose, or CNS disease that the investigator believes may require treatment with prohibited therapies specified in the protocol.

3. Diagnosis of mixed connective tissue disease or a history of any overlap syndrome between SLE and systemic sclerosis.

4. Laboratory abnormalities.

5. Current acute or chronic infection meeting any of the following criteria.

6. Participation in any other clinical trial within 4 weeks before the first dose (excluding participants who provided informed consent but did not receive trial treatment, or only received placebo).

7. Use of any targeted T or B lymphocyte drugs (e.g., rituximab) within 3 months before the first dose.

8. Receipt of any B cell-depleting drugs (such as belimumab, telitacicept) within 4 weeks or 5 half-lives (whichever is shorter) before the first dose.

9. Receipt of JAK inhibitor treatment within 2 weeks before the first dose.

10. Presence of severe cardiovascular and cerebrovascular diseases.

11. Mycobacterium tuberculosis infection.

12. Presence of HIV infection, active hepatitis B, or hepatitis C.

13. Known history of active syphilis.

14. History of major organ transplantation (e.g., heart, lung, kidney, liver) or hematopoietic stem cell/or bone marrow transplantation.

15. Other conditions that the investigator believes would prevent the participant from participating in the study.