#2154 Rituximab in the treatment of PLA2R-associated membranous nephropathy: insights from a hospital centre experience

Background and Aims Rituximab (RTX) is recommended as the first-line therapy for PLA2R-associated Membranous Nephropathy in patients with a moderate to high risk of progressive loss of kidney function, according to the KDIGO 2021 guidelines. This recommendation is based on the superior long-term efficacy and improved safety profile of RTX. This study aims to assess the use of RTX for the treatment of for PLA2R-associated Membranous Nephropathy at a hospital centre. Method A retrospective study was conducted on patients diagnosed with PLA2R-associated Membranous Nephropathy who underwent their first RTX administration between 2017 and 2022 at a tertiary hospital centre. Exclusion criteria involved patients with less than 6 months of follow-up post-RTX. The study evaluated the occurrence of immune remission, clinical remission, as well as instances of immune and proteinuria relapse, and recorded any adverse events. Results A total of 11 patients were included, with 54.5% being male. The mean age was 60.4 ± 14.7 years, and the median disease duration 69.0 [8.0-87.0] months. The mean follow-up time post-RTX was 36.7 ± 23.3 months. Regarding the risk of progressive loss of kidney function, 8 patients were classified as high risk, 1 as moderate risk, and 2 as low risk. RTX served as the initial immunosuppressive therapy for only 3 patients. Additional immunosuppressive therapies post-RTX, including further RTX doses, were administrated in 63.6% (n = 7) of patients. No response was observed in 18.2% (n = 2). Immune remission was achieved in 81.8% (n = 9), mean time of 3.8 ± 1.4 months. Within this group 55.5% (n = 5) patients achieved complete remission, 22.2% (n = 2) experienced partial remission, and 22.2% (n = 2) maintained nephrotic proteinuria, with immune remission consistently preceding clinical remission. Relapses occurred in 45.5% (n = 5), at a mean time of 20.8 ± 13.5 months. Patients with lower serum albumin at time of RTX administration were more likely to experience non-response or relapse (T (9) = 2.51, p = 0.03), with a Youden Index cut-off of 3.2 g/dL, demonstrating a sensitivity of 100% and a specificity of 85.7%. Patients with anti-PLA2R exceeding 150 RU/mL exhibited no response or relapsed. Four patients (36.4%) remained free of relapses throughout the entire follow-up period, mean time of 22.8 ± 10.0 months, with 1 keeping RTX maintenance therapy. During the 6 months post-RTX, 36.4% (n = 4) of patients experienced adverse events. Conclusion Rituximab demonstrated both efficacy and safety in treating PLA2R-associated Membranous Nephropathy. However, lower serum albumin levels and anti-PLA2R > 150 RU/mL at time of RTX administration were associated with worse response. Given the substantial need for additional immunosuppression, and considering lower albumin values and higher anti-PLA2R titres as risk markers, it is recommended to closely monitor these patients. Anti-PLA2R titres showed a meaningful association with disease activity, preceding changes in proteinuria levels. Therefore, tracking disease progression through the measurement of anti-PLA2R titres not only guides clinical decisions but also enables a judicious approach to subsequent RTX administrations.