[Long-term efficacy of low-dose rituximab treatment in patients with primary membranous nephropathy]

Objective: To explore the long-term efficacy of low-dose rituximab (RTX) treatment in patients with primary membranous nephropathy (PMN). Methods: Patients with biopsy-proven PMN who received low-dose RTX as initial or second-line regimen from August 2018 to May 2020 in the Department of Nephrology, Tianjin Medical University General Hospital were respectively enrolled. The clinical parameters of patients were urinary protein>3.5 g/24 h, serum albumin<30 g/L and estimated glomerular filtration rate (eGFR)>20 ml·min^-1·(1.73 m²)^-1. The treatment response of patients with PMN was observed during follow-up, and the remission rate of patients with urinary protein<8 g/24 h or ≥8 g/24 h, anti-PLA2R antibody<150 RU/ml or ≥150 RU/ml, eGFR≥ 60 ml·min^-1·(1.73 m²)^-1 or<60 ml·min^-1·(1.73 m²)^-1 were analyzed, respectively. Results: A total of 40 patients were enrolled, including 26 males and 14 females, aged (53±15) years. There were 14 patients received RTX as initial treatment and 26 patients as second-line therapy. The total median dose of RTX in the first course was 800 (425, 1 075) mg. The overall remission rate at the 1st, 3rd, 6th, 12th and 24th months were 12.5% (5/40), 17.5% (7/40), 47.5% (19/40), 57.5% (23/40), 60% (24/40), respectively. The median overall response time was 6.0 (3.0, 7.5) months. Two cases relapsed. Patients with remission (n=24) had a higher level of baseline eGFR [(93.9±28.0) vs (62.4±28.1) ml·min^-1·(1.73 m²)^-1, P=0.001), and a lower level of both urinary protein [5.9 (5.0, 6.5) vs 11.7 (8.6, 15.5) g/24 h, P<0.001] and anti-PLA2R antibody level [73 (29, 132) vs 453 (182, 950) RU/ml, P=0.004] than those without remission (n=16) 24 month after treatment. There was no statistically significant difference in the remission rate between initial and second-line treatment (P=0.101). Moreover, patients had a higher remission rate in urinary protein<8 g/24 h group (21/26 vs 3/14, P<0.001), anti-PLA2R antibody<150 RU/ml group (16/19 vs 5/16, P=0.002) and eGFR ≥ 60 ml·min^-1·(1.73 m²)^-1 group (22/29 vs 2/11, P=0.003). Conclusions: Low-dose RTX treatment in PMN is effective during long-term follow-up, and has a lower recurrence rate. The results also suggest that it is more suitable for patients with baseline urinary protein<8 g/24 h, anti-PLA2R antibody<150 RU/ml and eGFR≥ 60 ml·min^-1·(1.73 m²)^-1.