LAUSR

Background Rituximab had been shown to be effective in inducing remission of nephrotic syndrome in patients with idiopathic membranous nephropathy (iMN). This study applied rituximab therapy for 36 non-responsive iMN patients to investigate its effects and safety. Methods Thirty-six iMN patients who were non-responsive to prior immunosuppression were enrolled. Rituximab was used for B-cell depletion in patients, with a goal of <5 B cells/mm3 in the circulation. After completing the study, patients were monitored for a median of 12.0 months [interquartile range (IQR) 9.0-19.3]. Results Fifteen of the 36 (41.7%) patients achieved partial (n = 13) or complete (n = 2) response to the rituximab treatment. The median time for achieving partial response was 4.0 months (IQR 3.0-6.0). The responders had relatively lower levels (118 ± 112 U/mL versus 345 ± 357 U/mL, P = 0.03) of anti-phospholipase 2 receptor (PLA2R) antibodies before the rituximab treatment, and all of them achieved antibody depletion or reduction. B-cell depletion was achieved in all patients. Renal function remained stable in the responders [estimated glomerular filtration rate (eGFR) 53.3 ± 40.5 versus 55.6 ± 33.2 mL/min/1.73 m2, P = 0.67] but deteriorated in the non-responders (eGFR 57.5 ± 29.3 versus 45.3 ± 32.8 mL/min/1.73 m2, P = 0.02) with two patients reaching end-stage kidney disease. Two of the 15 patients relapsed during the follow-up period with anti-PLA2R antibody reoccurrence and B-cell reconstitution. The second course of rituximab combined with tacrolimus induced a faster partial response again in one patient. Conclusion Rituximab therapy could induce remission of proteinuria and stabilization of renal function in non-responsive iMN patients, even those with damaged renal function. Anti-PLA2R antibodies may be used as a marker for individualized rituximab dosage and treatment monitoring.