Sustained Renal Response to Rituximab Induction and Maintenance Therapy in a Severe Form of MPO ANCA Positive-Associated Vasculitis

Background: Kidney involvement is frequent in antineutrophil cytoplasmic antibody-associated vasculitis (AAV), with a proportion of 70% in granulomatosis with polyangiitis (GPA) and almost 100% in microscopic polyangiitis (MPA). Renal prognosis is still unfavorable, even with newer induction and maintenance regimens. Indeed, up to 25% of affected individuals will experience end-stage kidney disease within a few years of diagnosis. It remains cumbersome to adequately predict renal outcome in those patients. Because of limited data supporting rituximab and glucocorticoids in patients presenting with reduced glomerular filtration rate (GFR < 30 mL/min,), a cyclophosphamide-based regimen (either alone or combined with rituximab) is considered preferable as induction therapy. Case report: Here we describe the case of a 62-year-old Caucasian male with a prior history of gout who presented with severe acute kidney injury. One month before diagnosis, he developed severe asthenia, weight loss (15 kg in one year), and severe acute kidney injury. Laboratory tests showed high anti- myeloperoxidase (MPO) titers. Renal biopsy revealed pauci-immune necrotizing glomerulonephritis, focal class, with severe chronic lesions suggesting poor renal prognosis. The 3-year renal survival was estimated to be 54%, according to the improved Antineutrophil cytoplasmic antibody (ANCA) Kidney Risk Score. Induction therapy consisted of intravenous corticosteroids followed by rituximab, and was associated with a mild renal response at six months (serum creatinine 5.29 mg/dL to 2.38 mg/dL). The patient did not need dialysis. The maintenance therapy included prolonged rituximab infusions and low-dose oral corticosteroids for 54 months. The patient experienced slow and sustained improvement of proteinuria and renal function (serum creatinine 1.5 mg/dL at 24 months; 1.6 mg/dL at 54 months). Conclusions: This case demonstrates the possibility of sustained renal recovery, despite unfavorable initial prognostic features, and the use of Rituximab in a patient with severely reduced estimated GFR (i.e., serum creatinine > 4 mg/dL).