Open-label, two-parallel-arm, controlled randomized clinical trial testing the superiority of Ofatumumab over Rituximab in maintaining steroid- and calcineurin-inhibitor-free disease remission in SD-INS.

Eligible participants will enter a 1-month run-in period, during which instruction on urine collection and dipstick readings will be carefully reviewed, compliance assessed, and therapy with RAS inhibitors withdrawn and, in hypertensive children replaced by other anti-hypertensive drug.

After run-in period, children will be randomized to either the intervention arm (Ofatumumab) or the comparator arm (Rituximab).

After infusion of intervention or comparator, steroids will be maintained at initial dose for 30 days and then tapered off by 0.3 mg/kg per week until complete withdrawal.

One week after the steroid withdrawal calcineurin inhibitors will be decreased by 50% and withdrawn within 2 additional weeks.

All patients will be followed for up to 24 months. In case of relapses during the study (see outcome section for definition) patients will be treated with 60 mg/m2of prednisone p.o. in order to achieve remission. At remission, patients will be treated with another infusion of either Oftumumab or Rituximab, according to the initial randomization.

After infusion of intervention or comparator, steroids will be maintained at initial dose for 30 days and then tapered off by 0.3 mg/kg per week until complete withdrawal.

One week after the steroid withdrawal calcineurin-inhibitors will be decreased by 50% and withdrawn within 2 additional weeks. This strategy will be repeated to treat full relapses during the study.

Inclusion Criteria:

To be eligible for inclusion into this study, participants will have to fulfill the following criteria:

• To be in complete disease remission
• Drug dependence: remission has to be maintained with both steroids and CNI steroid dependence is defined by two consecutive relapses during corticosteroid therapy or within 14 days of ceasing therapy. CNI (cyclosporine/tacrolimus) dependence is defined by presence of relapse at discontinuation.
• Ability to provide consent and assent: parents'/guardian's written informed consent, and child's assent given before any study-related procedure not part of the subject's normal medical care, with the understanding that consent may be withdrawn by the subject at any time without prejudice to his or her future medical care.
• Age between 2 and 24 years

Exclusion Criteria:

Children will be excluded if any of the following criteria apply:

• Positivity to autoimmunity tests (ANA, nDNA, ANCA)
• Reduction of C3 levels.
• eGFR<90/ml/min/1,73 m2 valuated according to revised Bedside Schwartz Formula for patients between 2 and 17 years and with CKD-EPI Creatinine 2009 Equation for 18 years old patients.
• Pregnancy
• Neoplasm
• Infections: previous or actual HBV (with HBeAb positivity) or HCV infection
• CD20 B lymphocytes count <2,5%
• Treatment with Rituximab or cyclophosphamide in the last 6 months