Personalized Medicine for Membranous Nephropathy

Randomized, open label, multicentre (20 sites), prospective trial comparing the efficacy of two therapeutic strategies to obtain clinical remission 1 year after diagnosis of Idiopathic Membranous Nephropathy with nephrotic syndrome and anti-PLA2R1 (phospholipase A2 receptor 1) antibodies: * GEMRITUX protocol: 6 months of symptomatic antihypertensive and antiproteinuric therapy, and if the nephrotic syndrome persists at month-6 (urinary protein/creatinine ratio (UPCR) remains \> 3.5 g/g and albuminemia \< 30 g/l), two 375 mg/m2 rituximab infusions at 1-week interval. * Personalized treatment: * restricted anti-CysR activity at inclusion : 6-month symptomatic antihypertensive and antiproteinuric treatment (KDIGO) * restricted anti-CysR activity after 6 months of symptomatic treatment with persisting nephrotic syndrome (UPCR remains \> 3.5 g/g and albuminemia \< 30 g/l): two 375 mg/m2 rituximab infusions at 1-week interval; * Anti-CTLD (C-type lectin domains ) 1/7 activity at inclusion or after 6 months with persisting nephrotic syndrome (UPCR remains \> 3.5 g/g and albuminemia \< 30 g/l): two 1g rituximab infusions at 2-week interval at month 0 and/or month 6.