After an initial screening phase during which a first kidney biopsy is performed, all patients that meet the inclusion criteria will be randomized to one of the treatment arms:~EUROLUPUS regimen: 3 daily pulses of 750 mg of intravenous Methylprednisolone, followed by oral corticosteroid therapy starting with a dose of 0.5 mg / kg / day for 4 weeks, then decreased by 2.5 mg of Prednisolone / day each 2 weeks. A low dose of glucocorticoid (5-7.5 mg / day) is maintained until 24 months after enrollment. All patients will receive Cyclophosphamide intravenously starting day 1, 6 pulses at a fixed dose of 500 mg given at 2 weeks. After 3 months, Azathioprine (2 mg / kg / day) is initiated 2 weeks after the last administration of Cyclophosphamide and maintained for the next 21 months.~RITUXILUP regimen: 2 doses of Rituximab 1 g and Methylprednisolone 500 mg on days 1 and 15. Patients will receive Mycophenolate Mofetil, initially 500 mg twice daily, titrated to a maximum of 1.5 g twice daily, depending on leukocyte count and digestive tolerance, which will be maintained 24 months.~Second kidney biopsy will be performed 6 months after the start of the treatment phase.
The aim of the study is to evaluate the efficacy of a therapeutic regimen which decreases glucocorticoid exposure compared with standard therapy in patients with proliferative lupus nephritis during remission induction by evaluating the histological and clinical remission.