Monthly Mini-Dose Rituximab for Primary Membranous Nephropathy: A Different Approach

Abstract

Abstract Background The dose of rituximab for primary membranous nephropathy is as high as that for lymphoma. This study assessed the efficacy of monthly mini-dose rituximab monotherapy in patients with primary membranous nephropathy. Methods This retrospective study included 32 patients with primary membranous nephropathy treated at Peking University Third Hospital between March 2019 and July 2022. All patients were anti-phospholipase A2 receptor (PLA2R) antibody-positive and received rituximab 100 mg intravenously monthly for at least 3 months without other immunosuppressive therapy. Results The baseline parameters included: proteinuria, 8.5 ± 3.6 g/day; serum albumin, 24.8 ± 3.4 g/L; and anti-PLA2R antibody, 160 (20-2659) RU/mL. B-cell depletion was achieved in 87.5% patients after the first dose of rituximab 100 mg and in 100% after the second equivalent dose. Twenty-five (78%) patients achieved remission; 8 (25%) patients achieved complete remission at 12 months. Patients were stratified into the low-titer (< 150 RU/mL, n = 17) and high-titer groups (≥ 150 RU/mL, n = 15) based on the anti-PLA2R titer. Sex, age, urinary proteins, serum albumin, and estimated glomerular filtration rate at baseline did not differ significantly between the two groups. At 12 months, the rituximab dose (847 ± 217 vs 659 ± 255 mg, p = 0.033), and urinary proteins were higher (2.7 ± 2.5 vs 1.0 ± 1.2 g/day, p = 0.028), while serum albumin (33.4 ± 6.8 vs 39.6 ± 3.9 g/L, p = 0.007) and the clinical remission rate (60% vs 94%, p = 0.020) were lower in the high-titer group compared to the low-titer group. Conclusions Monthly rituximab 100 mg is effective for treating anti-PLA2R-associated primary membranous nephropathy. The lower the anti-PLA2R titer, the lower the rituximab dose required to achieve remission. Trial registration: A retrospective study, registered at ChiCTR (ChiCTR2200057381) on March 10, 2022.