This study is a 52-week, randomized, open, active-controlled trial of patients with active diffused lupus nephritis, to assess the efficacy and safety of a novel chemical synthetic agent iguratimod. The subjects will randomly receive iguratimod or cyclophosphamide followed with azathioprine, both combined with steroids.

Inclusion Criteria:

• Active lupus nephritis:

  • Fulfill ACR classification criteria (2009) for SLE
  • Proteinuria ≥1g/24h at screening
  • Nephritis of class III, IV, V, III+IV or IV+V, confirmed by renal pathology within 90 days prior to screening

• Body weight ≥40kg

• SLE-2K score ≥8

• Agreement of contraception

• Informed consent obtained

Exclusion Criteria:

• Active severe SLE-driven renal disease or unstable renal disease at screening
• Active severe or unstable neuropsychiatric SLE
• Clinically significant active infection including ongoing and chronic infections
• History of receiving cyclophosphamide, azathioprine, tacrolimus , mycophenolate moetil or rituximab treatment with 90 days prior to screening
• History of human immunodeficiency virus (HIV)
• Confirmed Positive tests for hepatitis B or positive test for hepatitis C
• Active tuberculosis
• Live or attenuated vaccine within 4 weeks prior to screening
• Subjects with significant hematologic abnormalities
• Abnormal liver function test at screening (ALT, AST or total bilirubin over 2 fold of upper normal level
• History of peptic ulcer or GI bleeding; treatment with warfarin or other anticoagulants within last 14 days