Post-transplant recurrence of focal segmental glomerular sclerosis: consensus statements

Acute kidney injury in paediatric kidney transplant recipients

Acute kidney injury (AKI) in paediatric kidney transplant recipients is common. Infection including urinary tract infection (UTI) and rejection are the most common causes in children. Surgical complications often cause AKI early post-transplant, whereas BK polyomavirus nephropathy rarely occurs in the first month post-transplant. Understanding kidney physiology helps to appreciate the sensitivity of the allograft to AKI, more so than native kidneys. Although the cause of AKI is often multi-factorial, there may be an underlying process that is treatable. Eliciting the aetiology, in this regard, is of paramount importance. Pre-renal and post-renal causes of allograft dysfunction are important to distinguish from intrinsic kidney disease. Clinical information and examination of fluid balance, urine dipstick testing, blood tests, bladder and kidney transplant ultrasound, and kidney transplant biopsy remain vital assessment tools in narrowing the differential diagnosis. A careful prescribed and recreational drug history is always warranted as many drugs including supplements are nephrotoxic. Additional causes such as allograft rejection, recurrent disease, and calcineurin inhibitor toxicity need to be considered in cases of allograft dysfunction, which would not affect the native kidneys. Early detection and assessment of AKI is crucial in promoting recovery. Significant progress has been made in specific pathologies over the last 20 years, which has improved kidney allograft survival rates considerably. Research into identifying AKI biomarkers to assist early diagnosis, before the serum creatinine rises, is ongoing.

Kidney organoids: a 3-dimensional tool to unmask permeability factors in primary and recurrent FSGS

Primary focal segmental glomerulosclerosis is a glomerular disorder associated with a high risk of recurrence after transplantation. Compelling evidence supports the existence of circulating permeability factors whose identity remains elusive. In the current issue of Kidney International, Gupta et al. propose that kidney organoid can respond to these factors in patients with focal segmental glomerulosclerosis and may serve as a potential platform for predicting disease recurrence. Future studies are required to identify the critical factors driving focal segmental glomerulosclerosis recurrence and to develop a standardized organoid platform for predicting clinical outcome.

Review of plasma exchange and rituximab for prevention of recurrent focal segmental glomerulosclerosis after a prior graft loss

BACKGROUND

Focal segmental glomerulosclerosis (FSGS) often recurs after transplantation, leading to graft dysfunction and graft loss. Patients who have lost prior grafts due to recurrence are at particularly high risk of re-recurrence in subsequent grafts. Rituximab and plasma exchange have been used pre-emptively to prevent post-transplant recurrence. However, the efficacy of such preventative measures remains unclear.

AIM

To investigate the outcomes of preventative rituximab and plasma exchange for recurrent FSGS in transplant recipients after prior graft loss.

METHODS

We conducted a systematic review of 11 studies with 32 patients who had experienced prior graft loss due to post-transplant FSGS recurrence and were treated with either pre-emptive plasma exchange alone, rituximab alone, or a combination of both.

RESULTS

Overall, 47% of the 32 patients experienced recurrence despite prophylactic treatment. Re-recurrence was seen in 25% (1/4) with pre-emptive rituximab alone, and 45% recurrence (9/20) with plasma exchange alone. Re-recurrence was noted in 63% with the use of combined plasma exchange and rituximab.

CONCLUSION

There is a paucity of available evidence in the literature to draw clear conclusions on the benefits of pre-emptive measures to prevent FSGS re-recurrence. The small sample sizes and variations in protocols call for larger and controlled studies to serve this patient population at high risk of recurrence and graft loss.

Management and long-term outcome of recurrent idiopathic FSGS in pediatric kidney transplant recipients

Focal segmental glomerulosclerosis (FSGS) is a major cause of pediatric kidney failure. Most cases of FSGS in children are idiopathic and have a high risk of post-transplantation recurrence and graft loss. Common treatments for recurrent FSGS (rFSGS) post-transplantation include plasmapheresis, immunoadsorption, and/or immunomodulatory therapy. This study retrospectively evaluated the efficacy and safety of early plasmapheresis followed by rituximab for inducing and maintaining remission in rFSGS. Between 2014 and 2023, 8 of 65 pediatric kidney transplant recipients at our center were diagnosed with idiopathic FSGS. rFSGS was diagnosed based on nephrotic range proteinuria with no other cause and managed with plasmapheresis. Rituximab therapy was used for those who did not achieve complete remission with prolonged plasmapheresis or remained plasmapheresis dependent. 6 of 8 (75%) transplant recipients with idiopathic FSGS experienced rFSGS. All patients achieved partial or complete remission with plasmapheresis, with response times ranging from 8 to 379 days (median 13 days). Rituximab therapy was introduced for 5 plasmapheresis-dependent patients, leading to sustained remission and cessation of plasmapheresis in 3 patients, while 2 showed improved proteinuria and reduced plasmapheresis frequency. Adverse effects included rituximab-induced serum sickness in one patient and one mild allergic reaction. One patient experienced graft loss due to humoral rejection, but no grafts were lost to rFSGS, and all other grafts remained functional over an average follow-up of 50 months. Early plasmapheresis followed by rituximab therapy effectively induces remission in most post-transplantation rFSGS cases, is well tolerated, and prevents graft loss. Larger studies are needed to confirm these findings.

Anti-nephrin autoantibodies: novel predictors of post-transplant recurrence of focal segmental glomerular sclerosis

Post-transplant recurrence of focal segmental glomerular sclerosis (FSGS) is a major challenge in the field of kidney transplantation. Currently, the most reliable predictor of FSGS recurrence is disease recurrence in a previous allograft. Recent studies suggest a possible causal role of anti-nephrin autoantibodies in the primary disease (primary FSGS and minimal change disease), as well as post-transplant recurrence of FSGS. In this issue of Kidney International, Batal et al. evaluate pretransplant anti-nephrin autoantibodies as a specific predictor of FSGS recurrence and demonstrate colocalization of nephrin and punctate IgG in anti-nephrin-positive patients with disease recurrence.

Clinical Course of Nonresponders With Recurrent Focal Segmental Glomerulosclerosis After Pediatric Kidney Transplantation: A Retrospective Multicenter Study

BACKGROUND

Primary focal segmental glomerulosclerosis (FSGS) frequently recurs after kidney transplantation and is associated with poor graft survival. Patients who do not achieve remission (nonresponders) have an especially poor graft survival. However, the characteristics that may affect graft survival in nonresponders are unknown. This study aimed to determine the clinical characteristics associated with graft survival in nonresponders.

METHODS

We retrospectively collected the clinical records of patients with FSGS and an age at onset <16 years who experienced posttransplant recurrence of FSGS at six hospitals in Japan from 1993 to 2018.

RESULTS

Eight nonresponders with recurrent FSGS were enrolled in this study. The median time to recurrence after kidney transplantation was 1 day (interquartile range, 1-2 days). All patients received therapeutic plasma exchange and methylprednisolone pulse therapy. Rituximab was used as an add-on therapy in three patients. Five patients lost their graft within 2 years after kidney transplantation (rapid group). In contrast, three patients had much longer graft survival (nonrapid group). We compared the clinical characteristics of the rapid and nonrapid groups. Proteinuria tended to be lower in the nonrapid group at the third and subsequent months of therapy. The rapid group had persistent nephrotic syndrome. The rate of reduction in proteinuria was lower in the rapid group than in the nonrapid group.

CONCLUSIONS

Our study suggests that persistent nephrotic syndrome and a low rate of reduction in proteinuria may predict rapid progression to graft failure in nonresponders.