Obinutuzumab Induced Decreases of PLA2R Antibodies in Membranous Nephropathy: a Pilot Study

Inclusion Criteria: * Age ≥ 18 years. * Diagnosis of PMN, confirmed by: 1. Kidney biopsy or 2. Positive serum PLA2Rab test either by IFT and/or ELISA) * Serum PLA2Rab titer \> 80 RU/ml * Proteinuria ≥ 3.5 g/24h despite supportive treatment for at least 6 months with a maximally tolerated and stable dose of ACE-i or ARB. * Serum albumin \< 30 g/l measured by BCP assay. * eGFR ≥ 30 ml/min/1.73m2. * Treatment with immunosuppression is warranted, as determined by the treating physician. Exclusion Criteria: * Secondary MN (e.g., hepatitis B or C infection, human immunodeficiency virus infection, active infection, systemic lupus erythematosus, sarcoidosis, IgG4-related, drug-induced, malignancy). * RTX within 12 months prior to inclusion. * CNI within 2 months prior to inclusion. * Treatment with other immunosuppressive drugs within 6 months prior to inclusion. * Proteinuria must not have decreased by \> 50% over 6 months whilst taking ACEi/ARB. * Life-threatening nephrotic syndrome resistant to treatment. * \> 20% increase in serum creatinine not otherwise explained during antiproteinuric supportive treatment. * Pregnancy or breastfeeding. Women of childbearing age and male patients with female partners of childbearing potential not willing to use contraception throughout the study and for at least 6 months after the last dose of obinutuzumab. * Suspected or known hypersensitivity, allergy, and/or immunogenic reaction history to monoclonal antibodies, corticosteroid, cyclophosphamide, any of their ingredients, and any other drugs from these same pharmacotherapeutic groups. * Known active infection of any kind or recent major episode of infection. * Any disorder or condition which might pose an unacceptable risk to patient's safety and well-being that might interfere with completion of the study. * Inability to understand or comply with the requirements of the study. * Incapable of recognizing the nature, significance, and scope of the clinical trial or giving consent even with a legal representative. * Use of an investigational agent.