Systemic lupus erythematosus (SLE) is a chronic inflammatory systemic autoimmune disease. Recurrent relapses of disease and development of long-term organ damage are two key unsolved clinical problems. Belimumab is the only FDA-approved biological agent for SLE. Data showed that treatment with belimumab on the background of standard therapy was effective in active SLE patients. However, the efficacy of low-dose belimumab for prevention of disease flares in SLE patients with low disease activity is to be explored.

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease with the incidence of about 70/100,000 in China. Recurrent relapses of disease and development of long-term organ damage are two key unsolved clinical problems. Its pathogenesis is still unclear, but B cells have been confirmed to play a vital role in it. Belimumab, a B-lymphocyte stimulating factor (Blys) inhibitor, was the only FDA-approved biological agent for SLE. BLISS-52 showed that more active lupus patients had their SELENA-SLEDAI score reduced by at least 4 points during 52 weeks with belimumab 10 mg/kg (58% vs 46%, p=0·0024) than with placebo. But there was limited data about belimumab in SLE patients with low disease activity. Our previous study indicated that even these patients still have an annual flare rate of 30-40%. Therefore, we try to explore whether low-dose of belimumab could prevent the disease flares in SLE patients with low disease activity.

Inclusion Criteria:

1. Age 18-70 years;
2. Patients with low disease activity (score≤ 6 at screening on SLEDAI); no British Isles Lupus Assessment Group (BILAG) A and no more than one B;
3. A stable treatment regimen with fixed doses of prednisone (≤ 20mg/day), antimalarial, or immunosuppressive drugs (azathioprine/mycophenolate mofetil/ methotrexate/ciclosporin/leflunomide/tacrolimus) for at least 30 days.
4. Sign the informed consent;

Exclusion Criteria:

1. Alanine aminotransferase (ALT)/ aspartate aminotransferase (AST) > 2 times upper normal limits;
2. Creatinine clearance rate < 60ml/min;
3. Exposure to cyclophosphamide within past 6 months before screening;
4. Exposure to any B cell targeted therapy (Rituximab/belimumab) within past 1 year before screening;
5. History of Malignancy;
6. History of herpes zoster with past 3 months before screening.
7. Chronic HBV/HCV hepatitis；
8. Current infections (HIV/tuberculosis)