Treatment of rituximab in patients with idiopathic membranous nephropathy: a case series and literature review

Background/Aims: Membranous nephropathy (MN) is a major cause of nephrotic syndrome in adults. This study aimed to evaluate the effect of rituximab (RTX) in patients with idiopathic MN (iMN) who have a high risk of progression. Methods: We retrospectively analyzed data of 13 patients with iMN, who received RTX treatments from January 2014 to July 2020. RTX was indicated in patients with iMN with severe proteinuria and decreasing estimated glomerular filtration rate (eGFR) in the previous 6 months despite other immunosuppressive therapies. Results: The patients were predominantly males (n = 11) and with a mean age of 55.3 years; median eGFR, 37.0 mL/ min/1.73 m² (interquartile range [IQR], 26.3 to 66.5); serum albumin level, 2.6 g/dL (IQR, 1.9 to 3.1); and spot urine pro-tein-to-creatinine ratio at baseline, 6.6 g/g (IQR, 5.7 to 12.9). In a median follow-up of 22 months, eight patients (61.5%) achieved complete or partial remission. In responder group (n = 8), median eGFR increased from 31.5 to 61.5 mL/min/1.73 m² (p = 0.049) and serum albumin level increased from 2.3 to 4.2 g/dL (p = 0.017) from RTX initiation to last follow-up. Antiphospholipase A2 receptor antibody (anti-PLA2R-Ab) was positive in six among seven tested patients, which markedly decreased in the responder group. There were no adverse events after RTX. Conclusions: This study suggests that RTX is a safe and effective treatment option for patients with iMN who have a high risk of progression. Individualized therapy based on anti-PLA2R-Ab titer would be needed for better outcomes.