Low-dose rituximab is poorly effective in patients with primary membranous nephropathy

Background. The optimal dosing and the efficacy of rituximab for primary membranous nephropathy (PMN) has not been established. This multicentric prospective study evaluates the efficacy and safety of low-dose rituximab (RTX) therapy in patients with PMN in clinical practice. Methods. Thirty-four consecutive patients with PMN and nephrotic syndrome were included and received RTX (375 mg/m(2)) once (18 patients) or twice (16 patients). RTX was the first-line therapy for 19 (56%) and the second line for 15 (44%) patients. All patients were followed for 12 months after RTX and 24 for at least 18 months (mean 23.9 +/- 18.6 months). Results. At 12 months, 5 patients (14.7%) achieved complete response, 10 (29.4%) partial and 19 (55.8%) no response. Response occurred similar to 6 months after RTX. At 24 months, the clinical situation was unchanged: two non-responders achieved partial response and two responders relapsed. Responders had significantly higher baseline GFR and lower anti-PLA2R antibodies compared with non-responders. Outcome was similar between one or two doses of RTX (non-responders 55.5 versus 56%, respectively) and between patients who had received previous therapy versus those receiving RTX as first-line therapy (non-responders 40 versus 68%, respectively). In the 15 patients already treated, the response to RTX was comparable to that of previous therapies. Conclusion. Low-dose RTX obtains remission in < 50% of PMN patients. Probably, higher doses and longer treatments are needed to induce and maintain a response. The balance between the costs and benefits should guide the selection of the patient and the optimal dosage.