Inclusion Criteria:  Age ≥18 years. Biopsy-proven membranous nephropathy with or without detectable circulating anti-PLA2R or anti-THSD7A antibodies. Background treatment with RAS blocking agents (ACE inhibitor and/or ARBs), at maximum tolerated doses and adequately controlled blood pressure (BP <140/90 mmHg in at least three consecutive readings at screening). One condition between: Anti-CD20 Resistance: residual proteinuria ≥3.5 g/day (mean of three consecutive 24-hour urine collections), with less than 50% reduction compared to pre-treatment values at least 12 months after anti-CD20 antibody therapy. Anti-CD20 Dependence: frequently relapsing NS (nephrotic-range proteinuria for >50% of time in the last five years or since disease onset, whichever is shorter) despite repeated treatments with anti-CD20 antibodies. Estimated GFR >30 ml/min/1.73m2 (CKD-EPI equation) and less than 50% of sclerotic glomeruli in patients receiving renal biopsy. A minimum 12-month wash-out from last anti-CD20 therapy with rituximab and/or other monoclonal antibodies. No significant (i.e. more than 2 weeks) immunosuppressive therapy over the last 6 months. Written informed consent.  Exclusion Criteria:  Intolerance to rituximab without rescue therapy with other humanized anti-CD20 antibodies. Clinically relevant neutropenia (neutrophils < 1.5 x 109/L), anemia (Hb levels <9.0 g/dL), thrombocytopenia (platelet count < 150.000/mm3), hypogammaglobulinemia (serum immunoglobulin ≤5.0 g/L), increased liver transaminase or bilirubin levels (total bilirubin, aspartate aminotransferase or alanine aminotransferase >1.5 x ULN, alkaline phosphatase >3.0 x ULN). Significant uncontrolled cardiovascular disease (including arterial or venous thrombotic or embolic events over the last three months) or cardiac insufficiency (New York Heart Association [NYHA] class IV) as judged by the investigator. Clinically relevant findings on a 12-lead electrocardiogram (ECG) as determined by the investigator at screening. History of significant cerebrovascular disease (stroke or transitory ischemic attack over the last three months) or sensory or motor neuropathy of toxicity ≥ grade 3. Any clinical condition that in the investigator judgment could affect the possibility to complete the study or could have a major confounding effect on study findings and data interpretation. Any active viral, bacterial or fungal infection. Serologic or virologic markers positive for HIV, hepatitis C (patients with positive antihepatitis C virus [anti-HCV] antibody but negative HCV RNA polymerase chain reaction [PCR] can enroll) or active or latent hepatitis B (patients with positive hepatitis B surface antigen [HBsAg] are excluded). For patients with isolated positive hepatitis B core antibody [anti-HBc], hepatitis B virus (HBV) DNA test by PCR must be non-detectable to enroll). History of malignancy within the prior 5 years. Participation in other clinical trials within 4 weeks of signing the consent form. Pregnancy or breast-feeding. Childbearing potential in males and females non using an effective method of contraception according to 2014 CTFG Recommendations related to contraception and pregnancy testing in clinical trials (accessedat:"https://www.hma.eu/fileadmin/dateien/Human_Medicines/01About_HMA/Working_Groups/C FG/2014_09_HMA_CTFG_Contraception.pdf"). Legal incapacity or limited legal capacity.