- Steroid-dependent or multirelapsing NS (defined on the basis of the occurrence of more than 2 relapses in the previous year in spite of steroid and/or other immunosuppressive therapy). Only patients reported to invariably relapse upon treatment tapering or withdrawal who are on stable (from at least 1 month) complete (<0.3 g/24h for adults or <4 mg/h/m2 for children) or partial (<3.5 g/24h for adults or <40 mg/h/m2 for children) remission of the NS will be included;