Efficacy of Rituximab in Comparison to Continued Corticosteroid Treatment in Idiopathic Nephrotic Syndrome

Inclusion Criteria: * Age ≥ 18 years * Persistent proteinuria ≥ 2 g/ 24 hours or a protein-to-creatinine ratio ≥ 2 g/10mmol (2 g/g) after 8 weeks of treatment with high dose prednisone 1 mg/kg/day (max 80 mg/day) * Idiopathic nephrotic syndrome caused by biopsy proven minimal change disease or focal segmental glomerulosclerosis Exclusion Criteria: * Severe nephrotic syndrome with hypotension * Previous treatment with immunosuppressive medication other than prednisone * Treatment with prednisone \> 10 weeks in last six months * Secondary form of FSGS or minimal change disease * Patients who test positive for hepatitis B surface antigen (HBsAg) or hepatitis B core antibody (anti-HBc). * Patients infected with HIV or suffering from other active infections * Patients inoculated with a vaccine within 4 weeks prior to inclusion * Pregnancy, breast feeding, women with inadequate contraception * Malignancy * Kidney transplantation * Previous treatment with monoclonal antibodies within 2 years prior to inclusion * Neutrophils \< 1.5 x 109/L and/or platelet counts \< 75 x 109/L * Severe heart failure (New York Heart Association Class IV) or severe, uncontrolled cardiac disease * Active peptic ulcer * Known hypersensitivity to glucocorticoids * Insulin resistant diabetes mellitus * Treatment with carbamazepine, phenobarbital, phenytoin en rifampicin * Severe osteoporosis with vertebral fracture