High-Dose Rituximab and Early Remission in PLA2R1-Related Membranous Nephropathy.

Background And Objectives: Different rituximab protocols are used to treat membranous nephropathy. We compared two rituximab protocols in patients with membranous nephropathy.

Design, Setting, Participants, & Measurements: Twenty-eight participants from the NICE cohort received two infusions of 1-g rituximab at 2-week intervals, whereas 27 participants from the Prospective Randomized Multicentric Open Label Study to Evaluate Rituximab Treatment for Membranous Nephropathy (GEMRITUX) cohort received two infusions of 375 mg/m at 1-week interval. We measured serum rituximab levels and compared remission at month 6 and before any treatment modification and analyzed factors associated with remission and relapses.

Results: Remissions occurred in 18 (64%) versus eight (30%) from the NICE and GEMRITUX cohort (=0.02) at month 6, respectively, and in 24 (86%) versus 18 (67%) participants (=0.12) before treatment modification, respectively. Median time to remission was 3 [interquartile range (IQR), 3-9] and 9 [IQR, 6-12] months for NICE and GEMRITUX cohorts respectively (=0.01). Participants from the NICE cohort had higher circulating level of rituximab and lower CD19 counts (3.3 µg/L [IQR, 0.0-10.8] versus 0.0 [IQR, 0.0-0.0] <0.001 and 0.0 [IQR, 0.0-2.0] versus 16.5 [IQR, 2.5-31.0] <0.001) at month 3, lower level of anti-PLA2R1 antibodies at month 6 (0.0 [IQR, 0.0-8.0] versus 8.3 [IQR, 0.0-73.5] =0.03). In the combined study population, lower epitope spreading at diagnosis and higher rituximab levels at month 3 were associated with remissions at month 6 (13/26 (50%) versus 22/29 (76%) =0.05 and 2.2 µg/ml [IQR, 0.0-10.9] versus 0.0 µg/ml [IQR, 0.0-0.0] <0.001 respectively). All non-spreaders entered into remission whatever the protocol. Eight of the 41 participants who reached remission had relapses. Epitope spreading at diagnosis (8/8 (100%) versus 16/33 (48%) =0.01) and incomplete depletion of anti-PLA2R1 antibodies at month 6 (4/8 (50%) versus 5/33 (9%) =0.05) were associated with relapses.

Conclusions: Our work suggests that higher dose rituximab protocol is more effective on depletion of B-cells and lack of epitope spreading is associated with remission of membranous nephropathy.