#1315 Management and long-term outcome of recurrent idiopathic FSGS in pediatric renal transplant recipients

Abstract Background and Aims Focal segmental glomerulosclerosis (FSGS) is a leading cause of pediatric end-stage renal disease (ESRD). While approximately 30% of pediatric FSGS is attributed to monogenic disorders, most cases are idiopathic, carrying a high risk of post-transplantation recurrence and graft loss. Commonly used protocols for recurrent FSGS (rFSGS) include plasmapheresis or immunoadsorption, and/or immunomodulatory therapy. We retrospectively evaluated the efficacy and safety of early plasmapheresis followed by rituximab therapy for induction of remission in rFSGS. Method Between 2014-2023, 8/65 pediatric renal transplant recipients at our center were diagnosed with idiopathic FSGS. Five patients underwent preventive plasmapheresis initiated between day 7 pre-transplantation to day 1 post-transplantation, depending on donor source (living/deceased). rFSGS, was diagnosed based on nephrotic range proteinuria of no other cause, and managed with daily plasmapheresis, followed by frequency tapering. Failure to achieve complete remission while on prolonged plasmapheresis was managed with Rituximab therapy. Results 6/8 patients (75%) experienced rFSGS. All achieved partial or complete remission with plasmapheresis therapy. Nevertheless, 5/6 patients exhibited plasmapheresis-dependence, thereby necessitating rituximab therapy. Of these, 3/5 patients achieved sustained remission enabling plasmapheresis cessation, while in 2/5 showed markedly improved proteinuria, enabling reduction of plasmapheresis frequency to once weekly. Adverse effects included rituximab-induced serum sickness in one patient, requiring therapy discontinuation. While one patient suffered from graft loss due to humoral rejection, no graft was lost to rFSGS, and all other grafts remained functional over an average follow-up period of 50 months. Conclusion We suggest that early introduction of plasmapheresis and rituximab therapy effectively induces remission in most post-transplantation rFSGS, is well tolerated, and prevents graft loss. Additional, large scale studies are needed to establish our observation.