Abstract: SA-PO0697
First Documented Use of Pegcetacoplan for Fibrillary Glomerulonephritis: A Case Report
Session Information
- Glomerular Diseases: Complement-Mediated Glomerulopathies and Infection-Related GN
October 24, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Alhaddad, Juliano, Cleveland Clinic, Cleveland, Ohio, United States
- Huang, Yuan, Cleveland Clinic, Cleveland, Ohio, United States
- Ferreira Provenzano, Laura, Cleveland Clinic, Cleveland, Ohio, United States
- Cavanaugh, Corey J., Cleveland Clinic, Cleveland, Ohio, United States
Introduction
Guidelines for the management of idiopathic Fibrillary Glomerulonephritis (FGN) with reduced eGFR or nephrotic-range proteinuria are lacking, but B-cell-depleting therapy with Rituximab is currently the preferred therapy. We describe here a patient with FGN and nephrotic-range proteinuria who was approved for first-time compassionate-use treatment with Pegcetacoplan, a complement C3 inhibitor.
Case Description
Our patient is a 69-year-old female with MGUS and chronic spontaneous urticaria. In 2019, a kidney biopsy to evaluate subnephrotic-range proteinuria revealed FGN. She was started on losartan and spironolactone. The progression of her kidney function and proteinuria is shown in Figure 1. In 2025, losartan and spironolactone were held due to hyponatremia. A repeat renal biopsy for persistent proteinuria and AKI revealed mesangial proliferative and sclerosing glomerulonephritis with focal endocapillary proliferation, and positive staining for IgG, C3 (2+), κ, λ , and DNAJB9, consistent with FGN. She tolerated reintroduction of low-dose losartan. Due to persistent proteinuria (4.2g/g) and progressive kidney dysfunction, a decision was made to treat her FGN. Rituximab was denied by her insurance, and the patient opted against it due to her urticaria. We therefore submitted an investigational new drug application and were granted compassionate use authorization for Pegcetacoplan by the FDA, which she started in April 2026.
Discussion
The codominance of C3 with polyclonal IgG suggests that complement pathway is often recruited and could contribute to the glomerular damage in FGN. Complement inhibition with pegcetacoplan may offer a therapeutic strategy to slow disease progression and reduce proteinuria, as seen in C3 glomerulopathy and immune complex–mediated membranoproliferative glomerulonephritis. If treatment results in sustained proteinuria reduction and decreased or resolved C3 deposition on repeat biopsy, this case may provide proof-of-concept support for future studies evaluating C3 blockade in FGN. Updated clinical and histologic outcomes are anticipated by October 2026 for ASN 2026.