Effect of B-cell Depleting Therapies on PLA2R-specific B Cells in Patients With Membranous Nephropathy

This is a non-pharmacological interventional monocentric study to primarily assess the levels of circulating phospholipase A2 receptor (PLA2R)-specific B cells in patients with PLA2R-mediated MN enrolled in the ORION and MONET studies, before and at the different time points after therapy. It will also compare the phenotype of circulating PLA2R-specific B cell subsets over time in patients who achieved long-term remission, who experience MN relapses or did not respond to Obinutuzumab or Felzartamab therapies, and evaluate changes in lymphocyte subpopulations, including T cells and NK cells, possibly involved in the autoimmune process and in the response to B-cell depleting therapy.