Authorship note: GH and JML are co-first authors. Conflict of interest: LB, GL, and DJS are coinventors on the patent Diagnostics for Membranous Nephropathy (US 8,507,215 B2) with royalty income through Boston University (LB and DJS) and CNRS (GL). LB reports a grant from Sanofi Genzyme and advisory board fees from Visterra and receives author royalty and peer review payments from UpToDate, Inc. relating to topic cards on the subject of membranous nephropathy. DJS reports a grant from Sanofi Genzyme; consulting and advisory board fees from Advance Medical, Pfizer, and Visterra; and royalty payments from UpToDate, Inc. relating to topic cards on the subject of membranous nephropathy.

Background and objectivesDifferent rituximab protocols are used to treat membranous nephropathy. We compared two rituximab protocols in patients with membranous nephropathy.Design, setting, participants, & measurementsTwenty-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/m2 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.ResultsRemissions occurred in 18 (64%) versus eight (30%) from the NICE and GEMRITUX cohort (P=0.02) at month 6, respectively, and in 24 (86%) versus 18 (67%) participants (P=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 (P=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] P<0.001 and 0.0 [IQR, 0.0–2.0] versus 16.5 [IQR, 2.5–31.0] P<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] P=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%) P=0.05 and 2.2 µg/ml [IQR, 0.0–10.9] versus 0.0 µg/ml [IQR, 0.0–0.0] P<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%) P=0.01) and incomplete depletion of anti-PLA2R1 antibodies at month 6 (4/8 (50%) versus 5/33 (9%) P=0.05) were associated with relapses.ConclusionsOur 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.

The phospholipase A2 receptor (PLA2R1) is the major autoantigen in primary membranous nephropathy. Several PLA2R1 epitopes have been characterized, and a retrospective study identified PLA2R1 epitope spreading as a potential indicator of poor prognosis. Here, we analyzed the predictive value of anti-PLA2R1 antibody (PLA2R1-Ab) titers and epitope spreading in a prospective cohort of 58 patients positive for PLA2R1-Ab randomly allocated to rituximab (=29) or antiproteinuric therapy alone (=29). At baseline, the epitope profile (CysR, CysRC1, CysRC7, or CysRC1C7) did not correlate with age, sex, time from diagnosis, proteinuria, or serum albumin, but epitope spreading strongly correlated with PLA2R1-Ab titer (<0.001). Ten (58.8%) of the 17 patients who had epitope spreading at baseline and were treated with rituximab showed reversal of epitope spreading at month 6. In adjusted analysis, epitope spreading at baseline was associated with a decreased remission rate at month 6 (odds ratio, 0.16; 95% confidence interval, 0.04 to 0.72; =0.02) and last follow-up (median, 23 months; odds ratio, 0.14; 95% confidence interval, 0.03 to 0.64;=0.01), independently from age, sex, baseline PLA2R1-Ab level, and treatment group. We propose that epitope spreading at baseline be considered in the decision for early therapeutic intervention in patients with primary membranous nephropathy.