Early rituximab for children with nephrotic syndrome, compared with placebo

Who can take part

• Expresses the willingness to participate in the study and after obtaining information about the study, the patient / legal guardians will sign an informed consent form for participation in the study 2. Age at study entry> 2 years (> 24 months of age) and under 16 years of age 3. Meet the criteria for diagnosis of idiopathic steroid-dependent nephrotic syndrome (two relapses during steroid dose reduction or within two weeks of stopping steroid therapy) or nephrotic syndrome with frequent relapses (two or more relapses in 6 months on steroid therapy or four or more relapses in a period of 12 months) 4. Remission of NS immediately prior to study entry, defined as the absence or trace of protein in the urinalysis [uPCR <0.2 mg protein / mg creatinine (<20 mg protein / mmol creatinine) or <1+ in the test strip] for 3 consecutive days 5. Patients of childbearing age (conception) will commit to abstinence or to use effective contraception during the study period and up to 12 months after stopping RTX treatment; girls of childbearing potential will have a negative pregnancy test on qualifying for treatment initiation

Who cannot take part

• Previous use of immunosuppressants such as cyclophosphamide, cyclosporin A, tacrolimus, mycophenolate mofetil, levamisole 2. Diagnosis of steroid-resistant NS, nephritic syndrome or secondary NS 3. Previous severe infection (tuberculosis, systemic mycosis), HIV, HCV, HBV infection 4. Active infection 5. Severe heart diseases (heart failure, myocardial infarction, severe heart rhythm disturbances) 6. Vaccinations with live vaccines within 4 weeks prior to study inclusion 7. Poorly controlled hypertension 8. Abnormal kidney function (eGFR <90 ml / min) 9. Autoimmune disease (IgA vasculitis, systemic lupus) 10. Current or history of cancer 11. Status after organ transplantation 12. Allergy to methylprednisolone, paracetamol, cetirizine, co-trimoxazole 13. Laboratory abnormalities: leukocyte count <3000 / µl, neutrocyte count <1500 / µl, platelet count <75,000 / µl, severe liver dysfunction: ALT or AST 2.5 times upper limit of normal 14. Prior treatment with monoclonal antibodies 15. Use of another study drug within the 6 months prior to study entry, or participation in other studies at screening 16. Severe immunodeficiency 17. Pregnancy, breastfeeding or refusal to use methods of contraception in case of the ability to become pregnant (pregnancy test required - beta hCG in the blood serum at enrollment in the study) 18. Hypersensitivity to the active substance, mouse proteins, or any of the excipients of the study drug (i.e. sodium citrate, polysorbate 80, sodium chloride, sodium hydroxide, hydrochloric acid, water for injections)