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 used within 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 C virus-positive or patients with abnormal liver function (2 or more times of alamine aminotransferase or total bilirubin was exceeded the normal value, and continued to rise for 2 weeks) * There are chronic active infections such as Epstein-Barrvirus, cytomegalovirus or Mycobacterium tuberculosis, and the usage of steroids and immunosuppressive agents may 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 organs illness 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 to the enrollment * Those who was not suitable for participating this study judged by investigator