1. Study Design This is a single-center, prospective, randomized, controlled, exploratory clinical trial. The study is designed to evaluate and compare the efficacy and safety of two biologic-based induction regimens against standard of care (SOC) and a triple-combination regimen in patients with active proliferative lupus nephritis (LN).

2. Study Objectives Primary Objective: To compare the 6-month complete renal response (CRR) rate among patients receiving biologic-based induction therapy, SOC induction therapy, and triple-combination induction therapy.

   Secondary Objectives: To compare the rates of partial renal response (PRR) and overall renal response (ORR) at monthly intervals up to Month 6; to assess the time to achieve CRR/PRR; to evaluate changes in clinical and immunological parameters from baseline; and to compare the safety profiles of the three treatment regimens.

3. Key Eligibility Criteria Patients aged 14-65 years with biopsy-proven active Class III or IV (±V) LN according to ISN/RPS 2018 classification, an SLE-DAI score >6, and 24-hour urine protein >1.0 g/d will be eligible. Key exclusion criteria include an eGFR ≥45 ml/min/1.73m², recent use of renal replacement therapy or potent immunosuppressive procedures, significant concurrent infections, severe hematological/ hepatic abnormalities, and known hypersensitivity to the study biologics.

4. Treatment Groups and Intervention

   Eligible patients will be randomized in a 2:2:1 ratio to one of three treatment arms for a 6-month induction period:

   Biologics Group (n≈20): Glucocorticoids + either Belimumab or Telitacicept. SOC Group (n≈20): Glucocorticoids + Mycophenolate Mofetil (MMF). Triple Therapy Group (n≈10): Glucocorticoids + MMF + either Belimumab or Telitacicept.

   The choice between Belimumab and Telitacicept within the Biologics and Triple Therapy groups will be determined jointly by the investigator and the patient.

5. Study Medications & Administration Glucocorticoids: All patients will receive oral prednisone (or equivalent) starting at 0.5 mg/kg/day (max 40 mg/day), with a mandatory taper to ≤5 mg/day by Month 4 and stable dosing from Months 5-6. Intravenous methylprednisolone pulses are permitted per investigator discretion.

   Mycophenolate Mofetil (MMF): Administered only in the SOC and Triple Therapy groups. The target dose is 1.5-2.0 g/day, maintained until the end of the treatment period.

   Belimumab: Administered via intravenous infusion at 10 mg/kg (600 mg/dose) every 2 weeks.

   Telitacicept: Administered via subcutaneous injection at 160 mg once weekly. Patients in the Biologics or SOC groups showing no response by Month 3 may directly switch to the Triple Therapy regimen.

6. Primary Efficacy Endpoint

The primary endpoint is the proportion of patients achieving Complete Renal Response (CRR) at Month 6. CRR is strictly defined as:

24-hour urine protein <0.5 g/d, AND Estimated Glomerular Filtration Rate (eGFR) ≥85% of the baseline value, AND No requirement for rescue therapy or premature treatment withdrawal. 7. Secondary Efficacy & Safety Assessments Key secondary efficacy assessments include monthly CRR, PRR, and ORR rates; time to response; incidence of renal-related events; and changes in proteinuria, eGFR, serum creatinine, and disease activity scores (SELENA-SLEDAI, BILAG-2004, PGA). Safety will be evaluated through the incidence and severity of adverse events, with special attention to infections, infusion/injection reactions, and metabolic parameters.

8. Statistical Considerations This is an exploratory study with a planned enrollment of 40-50 patients. The primary analysis will use the Full Analysis Set (FAS) under the intention-to-treat principle. The difference in the Month 6 CRR rate among the three groups will be analyzed using the Chi-square test. Time-to-event data will be analyzed using the Kaplan-Meier method with Log-rank test for comparisons.

9. Hypothesis: This study protocol outlines a head-to-head comparison of novel biologic-based induction strategies against current SOC for active LN. It aims to generate critical preliminary data on whether glucocorticoids combined with a biologic (Belimumab or Telitacicept) alone can induce effective renal remission, potentially offering a targeted treatment option with a different safety profile compared to conventional immunosuppressive therapy. The results may inform the design of larger, confirmatory trials in LN management.

Inclusion Criteria:

• 1.Signed written informed consent form. 2.Age 14-65 years (inclusive), any gender. 3.Meets the American College of Rheumatology (ACR) SLE diagnostic criteria (1997).

  4.All patients have biopsy-confirmed class III/IV ± V LN within the past six months.

  5.SLE-DAI score > 6. 6.Urine protein quantification > 1.0 g/d.

Exclusion Criteria:

• 1.Estimated glomerular filtration rate (eGFR) ≥45 ml/min/1.73 m². 2.Patients who have received renal replacement therapy, plasma exchange, immunoadsorption, or high-dose intravenous immunoglobulin (100g) within the past 2 months.

  3.Patients with concomitant critical organ damage or lupus crisis (e.g., pulmonary hemorrhage, encephalopathy, heart failure) deemed unsuitable for clinical trial participation by the investigator.

  4.Hematological abnormalities: White blood cells <3000/μL, absolute neutrophil count <1500/μL, or lymphocytes <800/μL, platelet count <50,000/μL (unless due to SLE activity).

  5.Liver function abnormalities: ALT, AST, or bilirubin levels exceeding 2 times the upper limit of normal.

  6.Known allergy or contraindication to any component of belimumab and/or telitacicept.

  7.Active infection or intravenous antibiotic use within 1 month prior to enrollment.

  8.Pregnant or breastfeeding women. 9.Current or within the past 3 months: Active hepatitis B, hepatitis C, tuberculosis, cytomegalovirus pneumonia, active fungal infection, syphilis infection, or HIV infection; active peptic ulcer; history of drug abuse or alcoholism; severe malnutrition (BMI <16 kg/m²).

  10.Other conditions: Severe cardiovascular disease potentially life-threatening; chronic obstructive pulmonary disease, or asthma/allergic diseases requiring long-term oral steroid treatment; malignant hypertension; history of malignancy within the past 5 years (except for completely treated basal cell or squamous cell skin cancer or cervical intraepithelial neoplasia).

  11.Other situations deemed unsuitable for enrollment by the investigator.

This study will share de-identified Individual Participant Data (IPD) to support further research. Shared datasets include: 1. Demographics & Baseline: Age, sex, SLE/LN duration, renal biopsy type (Ⅲ/Ⅳ±Ⅴ), baseline medication, SELENA-SLEDAI score. 2. Efficacy: 24h-proteinuria, eGFR, serum creatinine at baseline and months 1-6. 3. Safety & Immunology: ds-DNA, C3, C4; blood counts; liver/kidney function; all AEs/SAEs. 4. Treatment & Outcomes: Randomization, drug exposure (dose/duration), time to CRR/PRR, treatment failure or withdrawal. All data will be de-identified per HIPAA/GDPR, removing direct (name, ID) and indirect identifiers to prevent re-identification.

IPD and supporting information will become available for sharing after the primary results of this study are officially published (expected no later than June 2028). The data will be accessible for at least 5 years thereafter (i.e., until June 2033) to provide the research community with sufficient time for secondary analyses and validation. The access period may be extended according to the policies of the data hosting platform or the terms of the Data Use Agreement. The specific start date will be updated in this plan and on the clinical trial registration platform concurrently with the publication of the primary paper.

Access is open to researchers from academic or non-profit institutions for legitimate academic purposes. For-profit entities may apply for non-commercial use, subject to data protection regulations.

Approved researchers will access the de-identified IPD dataset (see Plan Description) and supporting documents (Study Protocol, SAP, ICF). Access is read-only; downloading or redistributing raw data is prohibited.

Access is controlled via formal application, including: a detailed research proposal (scientific value, objectives, methods), ethical approval or waiver, and a signed Data Use Agreement (DUA). The DUA prohibits re-identification, restricts use to approved analyses, and requires proper citation of the original study. Applications are reviewed by the Principal Investigator or institutional Data Access Committee. Approved users will access data through a secure, encrypted platform.