CD19 Repopulation and Anti-phospholipase A2 Receptor (PLA2R) following Rituximab in Membranous Nephropathy

Background: Rituximab is used for treatment in PMN. However, remission rates remain modest, and optimal dosing remains uncertain. Methods: 29 consecutive patients were followed prospectively after rituximab treatment. Clinical markers, Anti-PLA2R, CD19 count (cells/µL) were analysed at 1-week, 2-3-week, 4-6-week, 2-3-month, 4-6-month, 8-10-month, and 12-month. Results: Features and outcomes are in Table. Remission at 1-year was seen in 15 (52%) patients. All patients had CD19 depletion (<5) between 1-3 weeks. CD19 reconstitution was seen in 6% patients at 4-6 weeks, 25% at 2-3 months, and 60% at 4-6 months. Anti-PLA2R levels reduced at 3 months from baseline but remained at similar level until 12 months. There was significant correlation between CD19 and anti-PLA2R (R=0.89, p= 0.075). Notably, CD19 repopulation preceded rise in anti-PLA2R. Conclusion: Following rituximab treatment, CD19 levels correlate with anti-PLA2R, repopulation occurs in majority of patients by 4-6 months, and precedes emergence of antiPLA2R. This may explain the modest remission rates in PMN with rituximab and additional dosing at 4-6 months may improve remission. Baseline & Outcomes - N 29 2019-2023 Males 66% Age 56 Biopsy 29 (100%) Incident-14Relapse-15 PLA2R-ab +ve 90% Follow-up 13.5 mon Remission 15 (52%) Refractory 14 (48%) Time0 3 mon 6 mon 9 mon 12 mon Rescue Rx NA 0 0 6 0 eGFR 43 43 44 46 44 uPCR 893 582 485 407 177 Alb 23 26 27 30 31 CD19 155 2 13 22 69 Anti-PLA2R 88 22 27 18 27 Remission NA 14% 21% 33% 56% Values are median, median & %