The objective of this observational study is to compare the efficacy and safety of telitacicept versus belimumab in systemic lupus erythematosus (SLE) patients aged 18-65 years. The primary questions it aims to answer are:

• In the overall SLE population: What are the SRI-4 response rates for both drugs?
• In the lupus nephritis subgroup: What are the major renal response rates for both drugs?

Participants will autonomously select their treatment regimen (add-on telitacicept or belimumab) based on:

• The patient's objective clinical condition at enrollment
• Physician's assessment
• Joint decision-making between physicians and patients/family members As an observational study, no active intervention will be implemented.

Inclusion Criteria:

• Age range: 18 - 65 years old;
• Meets the revised SLE classification criteria of the American College of Rheumatology in 1997 or the SLE diagnostic classification criteria issued by EULAR/ACR in 2019;
• The SELENA-SLEDAI score is at least 8 points (clinical symptoms are no less than 6 points, excluding positive anti-double-stranded DNA (anti-dsDNA) and low complement);
• Has not responded well to hormone and/or immunosuppressant treatment, is intolerant or has recurrence, and is willing to accept tixocortinib/belimumab as a therapeutic drug.

Exclusion Criteria:

• Any of the following conditions exists: active central nervous system disease, severe active lupus nephritis, HIV infection, hepatitis B or C virus infection, low gamma globulinemia, liver dysfunction;
• eGFR < 30 mL/min/1.73m², or undergoing hemodialysis or kidney transplantation;
• Pregnant women, or women who are about to become pregnant in the near future, or lactating women;
• Participants who are simultaneously participating in other clinical studies;
• Within 1 year before randomization, received B-cell targeted therapy (including belimumab);
• During treatment, used traditional Chinese medicine with immunosuppressive effects (such as Tripterygium wilfordii, White Peony Root, etc.) in combination.

Patients who were diagnosed with systemic lupus erythematosus through clinical examination at the First Affiliated Hospital of Shandong First Medical University, the Affiliated Hospital of Shandong University of Traditional Chinese Medicine, and the People's Hospital of Wuhan University