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Abstract: SA-PO959

Anti-PLA2R Antibody Levels and Treatment Response in Primary Membranous Nephropathy (MN)

Session Information

Category: Glomerular Diseases

  • 1402 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • van de Logt, Anne-Els, Radboudumc, Nijmegen, Gelderland, Netherlands
  • Vink-van Setten, Coralien, Radboudumc, Nijmegen, Gelderland, Netherlands
  • Wetzels, Jack F., Radboudumc, Nijmegen, Gelderland, Netherlands
Background

We introduced individualized therapy in patients with MN and positive anti-PLA2R antibodies (PLA2Rab) by IIFT test (Vink et al. Kidney International Reports 2023). Treatment (cyclophosphamide combined with steroids) was stopped when the IIFT test (measured at 8, 16, or 24 weeks) became negative. After 8 weeks, 71% of patients were in immunological remission. Unfortunately, 30% of these latter patients needed renewed therapy within 12 months because of immunological and/or clinical relapse. We questioned if quantitative PLA2Rab measurement would predict treatment response.

Methods

Available, stored serum samples were retrieved, and PLA2Rab levels were measured by ELISA in available samples collected at baseline, and 8, 16, and 24 weeks after start of therapy. (EUROIMMUN Lübeck, Germany).

Results

The analysis included 46 incident patients (M/F 35/11, age 59 ± 12 years, serum creatinine 127 µmol/l [98-164], serum albumin 20 g/l [16-25] and urine protein- creatinine ratio 8.2 gram/10 mmol [6.0-11.7]). Baseline PLA2Rab levels were 145 RU/ml [ IQR 97-381]. Thirty patients (65%) developed IIFT remission after 8 weeks, and of these 18 developed persistent clinical remission (group A1), while 12 patients received renewed therapy during follow-up (group A2; no clinical remission) . Sixteen patients received initial treatment ≥ 16 weeks (group B), with 7 patients needing continued therapy beyond 6 months. PLA2Rab titer was numerically lower in group A compared to Group B (median 120 RU/mL [IQR 91-261] vs 267 RU/mL [142-436], p = 0.059). Patients with baseline ELISA <80 RU/mL (n =7) developed persistent immunological and clinical remission after only 8 weeks of cyclophosphamide. In patients with baseline PLA2Rab > 80 RU/ml neither baseline PLA2Rab levels, nor absolute or percentage change of PLA2Rab levels from baseline to 8 weeks predicted response or duration of therapy. All patients with at 8 weeks PLA2Rab levels > 20 RU/ml required treatment beyond 6 months (n=4).

Conclusion

Changes in PLA2Rab levels after start of therapy are not helpful in guiding treatment decisions. Still, for a limited number of patients quantitative analysis of PLA2Rab levels at baseline and at 8 weeks after start of therapy provides information that can be used in counseling and treatment planning.