Rituximab for Patients with Proliferative Glomerulonephritis with Monoclonal Immunoglobulin Deposits (PGNMID): A Case Series

Introduction: Monoclonal gammopathy of renal significance (MGRS) is defined is a clonal disorder characterized by renal monoclonal immune deposition without adequate criteria for a specific malignancy. PGNMID, a subtype of MGRS, is further defined by granular deposits without organization that are predominantly located in the mesangium and / or subendothelium on electron microscopy. Here we present a case series of 5 patients treated with regimens including rituximab. Case Description: Patients were aged between 17 and 72. Creatinine on presentation ranged from 0.66 to 3.22 mg/dL. All patients had proteinuria with 4 patients with nephrotic range proteinuria. Three patients had monoclonal IgG3 with kappa predominant deposits. One patient had both kappa and lambda deposits. One patient had lambda restricted deposits. All patients received rituximab and steroids. One patient received cyclophosphamide. Of the 5 patients, three patients responded (> 30% reduction in proteinuria without decrease in GFR >25%) to therapy. These three patients have maintained response to date with progression free survival of 42, 70 and 91 months respectively. None of these patients have required dialysis to date. Two patients did not respond to therapy. One patient later responded to velcade, dexamethasone, and daratumumab. The other patient required dialysis prior to treatment and eventually passed away with a survival of 3.2 months. Discussion: Here we present a case series of 5 patients that received rituximab-based regimens. Three patients had durable renal remissions with rituximab-based regimens. Two patients did not respond. One of these patients did eventually respond to a plasma cell directed therapy. This case series suggests that for some patients a rituximab-based regimen is adequate to induce and maintain a renal remission; however, there is a subset of patients that may benefit from plasma cell directed treatment.