Inclusion Criteria:  Adults (≥18 years old) on the day of signing informed consent. Primary membranous nephropathy. Availability of a recent (over the last month) diagnostic kidney biopsy to confirm the diagnosis of membranous nephropathy and quantify the severity of chronic changes and the number of glomerular podocytes. High-risk of progression to end-stage kidney disease due to persistent nephrotic-range proteinuria (urinary protein excretion > 3.5 g/24-hours as a median of three consecutive measurements) despite background treatment with RAS-inhibitors (ACEi and/or ARBs) at the maximum tolerated doses for at least six months before inclusion.  Failure to definitively and effectively respond to rituximab therapy because of the following:  RITUXIMAB-INTOLERANCE, i.e. any previous severe hypersensitivity reaction to rituximab (acute grade III or IV adverse reactions requiring advanced care, or late reactions including delayed serum sickness syndrome) that, independent of response to treatment, preclude further exposure to the drug; or RITUXIMAB-RESISTANCE: no evidence of nephrotic syndrome complete remission (24-hour proteinuria < 0.3 g/day, normal serum albumin and stable renal function) or partial remission (24-hour proteinuria < 3.5 g/day with > 50% decrease from baseline, normal serum albumin and stable renal function) for at least 12 months after rituximab administration; or RITUXIMAB-DEPENDENCE:frequently-relapsing nephrotic syndrome (≥ 2 relapses) with nephrotic-range proteinuria for ≥ 50% of time in the 24 months preceding enrolment Estimated GFR/eGFR) ≥40 mL/min/1.73m2 (calculated using the CKD-EPI equation) or qualified endogenous creatinine clearance ≥40 mL/min based on 24-hour urine collection during screening. Ability to understand and provide a valid written consent to the study according to the guidelines of the Declaration of Helsinki. Compliance with an effective contraception without interruption, from 28 days before treatment start up to 18 months after treatment discontinuation, agreeing not to donate semen during treatment and for 18 months after discontinuation (if the patient is male), or to undergo pregnancy test during the course of the study (if the patient is female).  Exclusion Criteria:  Secondary forms of membranous nephropathy (associated with systemic lupus erythematosus, active hepatitis B, malignancy, drugs such as gold salts and penicillamine, and others). Rituximab treatment or any other prolonged (i.e. for more than two weeks) immunosuppressive treatment in the 12 months preceding anti-CD20 infusion. Uncontrolled hypertension (systolic BP ≥160 and/or diastolic BP >90 mmHg despite therapy). Active bacterial, viral and/or fungal infections. Seropositivity for HIV, regardless of viral load. Active or recent (< 5 years before enrolment) history of malignancy. Known hypersensitivity or allergy to any of the medicaments under investigation. Any other serious medical condition, uncontrolled intercurrent illness or laboratory abnormality that, according to the investigator's judgement, would constitute an unacceptable risk of premature discontinuation from the study. Known history of drug induced liver injury, alcoholic liver disease, non-alcoholic steatohepatitis, primary biliary cirrhosis, ongoing extra-hepatic obstruction caused by cholelithiasis, cirrhosis of the liver or portal hypertension. Pregnancy or breast-feeding Childbearing potential and unwillingness or impossibility to comply with a scientifically acceptable birth-control method. Legal incapacity, limited legal capacity, intellectual disability, uncooperative attitude or any other evidence that the patient will not be able to understand the study aims and procedures.