Study of the Telitacicept in Pediatric Patients With Frequently Relapsing or Steroid Dependent Nephrotic Syndrome

Inclusion Criteria:

• Sensitive but frequent relapses or steroids dependence nephrotic syndrome

• Age: 2 to 18 years old

• Normal renal function: estimated glomerular filtration rate ≥90ml/ min/1.73m2

• Morning urine protein <1+ or urine protein-creatinine ratio <0.2g/g (<20 mg/ mmol)for 3 consecutive days and above when in enroll

• No rituximab was used within 6 months, no tacrolimus, mycophenolate mofetil,cyclosporine A, or cyclophosphamide was used within 3 months, no ACTH was usedwithin 3 months prior to the enrollment

Exclusion Criteria:

• Family history of nephrotic syndrome, chronic glomerulonephritis or uremia

• Leukopenia (White Blood Cells ≤ 3.0 * 10^9 / L)

• Moderate to severe anemia (hemoglobin <9.0 g/dL)

• Thrombocytopenia (platelet count <100*10^12/L)

• Positive Hepatitis B virus serological indicators (Hepatitis B surface antigen or /and Hepatitis B virus e antigen or / and Hepatitis B core antibody), Hepatitis Cvirus-positive or patients with abnormal liver function (2 or more times of alamineaminotransferase or total bilirubin was exceeded the normal value, and continued torise for 2 weeks)

• There are chronic active infections such as Epstein-Barrvirus, cytomegalovirus orMycobacterium tuberculosis, and the usage of steroids and immunosuppressive agentsmay aggravate the state of an illness

• Secondary nephrotic syndrome (such as purpuric nephritis, lupus nephritis, etc.)

• Those who with hematological or endocrine system diseases as well as serious organsillness such as heart, liver or kidney

• Those who with other autoimmune diseases or primary immunodeficiencies or tumors

• Those who have participated in other clinical trials within three months prior tothe enrollment

• Those who was not suitable for participating this study judged by investigator