MOR202 for Refractory MN

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: * Clinically relevant neutropenia (neutrophils \< 1.5 x 109/L), anemia (Hb levels \<9.0 g/dL), thrombocytopenia (platelet count \< 150.000/mm3), 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. * Known intolerance to the study drug or its excipients * Any viral, bacterial or fungal infection without complete symptoms resolution from at least two weeks. * 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). 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. * Expected need of anti SARS Cov 2 vaccination during the study period * Pregnancy or breast-feeding. * Childbearing potential in males and females non using an highly effective method of contraception according to 2020 CTFG Recommendations related to contraception and pregnancy testing in clinical trials (https://www.hma.eu/fileadmin/dateien/Human\_Medicines/01-About\_HMA/Working\_Groups/CTFG/2020\_09\_HMA\_CTFG\_Contraception\_guidance\_Version\_1.1\_updated.pdf). * Legal incapacity or limited legal capacity.