Protocol liver biopsies in stable long-term pediatric liver transplant recipients: risk or benefit?

Elastography-The New Standard in the Assessment of Fibrosis After Pediatric Liver Transplantation?

BACKGROUND

The development of graft fibrosis after pediatric liver transplantation (PLT) remains a major concern as it can lead to graft failure and ultimately graft loss. Elastography is a non-invasive method to assess liver fibrosis, but its role in the posttransplant setting is unclear. The aim of our study was to evaluate shear wave elastography (SWE) in the assessment of liver fibrosis after PLT, including split-liver recipients.

METHODS

We retrospectively analyzed data from PLT recipients who underwent surveillance liver biopsy and concurrent 2D-SWE during the study period from April 2018 to July 2021. Spearman's correlation was used to compare histologic fibrosis stages with liver stiffness measurements (LSM) by 2D-SWE. AUROC analysis was performed to evaluate the performance. One sample t-test was used to compare results with reference values of healthy children.

RESULTS

62 cases were included. 29% showed histologic fibrosis. LSM by 2D-SWE were feasible in all children regardless of age or graft type. There was a significant correlation between LSM and fibrosis stage for all three scoring systems used (Ishak, p = 0.003; METAVIR, p = 0.005; LAF Score, p = 0.003). Patients with a history of biliary complications had increased liver stiffness (p = 0.015). The AUROC of 2D-SWE for predicting significant liver graft fibrosis was 0.81. Liver stiffness after PLT without graft fibrosis was higher than in healthy subjects, but comparable to that in children with chronic liver disease without fibrosis.

CONCLUSION

2D-SWE can reliably detect children with significant liver graft fibrosis, even in split-liver recipients. This study demonstrates the value of a non-invasive tool for fibrosis staging after PLT. 2D-SWE has the potential to improve long-term outcomes after PLT and to reduce the number of surveillance liver biopsies. But elastography is not a substitute for liver biopsy.

Are protocol graft biopsies after pediatric liver transplantation useful? Experience in a single center over 20 years

BACKGROUND

The role of protocol liver biopsies (PLB) in the follow-up of pediatric liver transplant recipients remains questionable. This single-center retrospective study aimed to evaluate their clinical impact on the long-term management of pediatric liver transplant recipients.

METHODS

We described histopathological lesions and clinical consequences for patient management of PLB performed 1, 5, 10, 15, 20, and 25 years after pediatric liver transplantation (LT).

RESULTS

A total of 351 PLB performed on 133 patients between 1992 and 2021 were reviewed. PLB found signs of rejection in 21.7% of cases (76/351), and moderate to severe fibrosis in 26.5% of cases (93/351). Overall, 264 PLB (75.2%) did not cause any changes to patient care. Immunosuppression was enhanced after 63 PLB, including 23 cases of occult rejection. The 1-year PLB triggered significantly more changes, while biopsies at 15, 20, and 25 years produced the lowest rates of subsequent modifications. PLB had a significantly higher probability of inducing therapeutic changes if the patient had abnormal biological or imaging results (odds ratio [OR] 2.82 and 2.06), or a recent history of rejection or bacterial infection (OR 2.22 and 2.03).

CONCLUSION

Our results suggest that, although it often does not prompt any treatment changes, PLB could be performed because of its ability to detect silent rejection requiring an increase in immunosuppression. PLB could be carried out 1, 5, and 10 years after LT and then every 10 years in patients with normal biological and imaging results and no recent complications, while other patients could be kept on a 5-year protocol.

Clinical Value of Surveillance Biopsies in Pediatric Liver Transplantation

Although pediatric liver transplantation (LT) results in excellent long-term outcomes, a high incidence of early acute cellular rejection and late graft fibrosis persists. Routine measurement of allograft enzymes may not reliably detect rejection episodes, identify candidates for immunosuppression minimization, or indicate allograft fibrosis. Surveillance biopsies (SBs) can provide valuable information in this regard, but their role in pediatric LT is not fully established. A retrospective cohort of 236 pediatric LT recipients from a high-volume center was studied to characterize the risks and benefits of SB versus for-cause biopsies (FCBs). The study population was 47.1% male and 54.7% Hispanic, and 31% received living donor grafts. Our data suggest that patients in the SB group had better transplant outcomes (rejection-free, graft, and patient survival) compared with patients who had FCBs or who never underwent biopsy. Among 817 biopsies obtained from 236 patients, 150 (18.4%) were SBs. Only 6 patients had a biopsy-related complication, and none were observed in the SB subset. Graft biochemical blood tests did not accurately predict rejection severity on biopsy, with aspartate aminotransferase area under the receiver operating characteristic curve (AUROC) 0.66, alanine aminotransferase AUROC 0.65 (very poor predictions), and gamma-glutamyltransferase AUROC 0.58 (no prediction). SBs identified subclinical rejection in 18.6% of biopsies, whereas 63.3% of SBs had evidence of fibrosis. SBs prompted changes in immunosuppression including dose reduction. Our experience suggests that SB in pediatric LT is safe, offers valuable information about subclinical rejection episodes, and can guide management of immunosuppression, including minimization. Improved outcomes with SB were likely multifactorial, potentially relating to a more favorable early posttransplant course and possible effect of management optimization through SB. Further multicenter studies are needed to examine the role of SBs on long-term outcomes in pediatric LT.

Impact of donor-specific antibodies on long-term graft survival with pediatric liver transplantation

BACKGROUND

In a previous paper, we reported a high prevalence of donor-specific antibody (DSA) in pediatric patients with chronic rejection and expressed the need for confirmation of these findings in a larger cohort.

AIM

To clarify the importance of DSAs on long-term graft survival in a larger cohort of pediatric patients.

METHODS

We performed a retrospective analysis of 123 pediatric liver transplantation (LT) recipients who participated in yearly follow-ups including Luminex testing for DSA at our center. The cohort was split into two groups according to the DSA status (DSA-positive n = 54, DSA-negative n = 69). Groups were compared with regard to liver function, biopsy findings, graft survival, need for re-LT and immunosuppressive medication.

RESULTS

DSA-positive pediatric patients showed a higher prevalence of chronic rejection (P = 0.01), fibrosis (P < 0.001) and re-transplantation (P = 0.018) than DSA-negative patients. Class II DSAs particularly influenced graft survival. Alleles DQ2, DQ7, DQ8 and DQ9 might serve as indicators for the risk of chronic rejection and/or allograft fibrosis. Mean fluorescence intensity levels and DSA number did not impact graft survival. Previous episodes of chronic rejection might lead to DSA development.

CONCLUSION

DSA prevalence significantly affected long-term liver allograft performance and liver allograft survival in our cohort of pediatric LT. Screening for class II DSAs in combination with assessment of protocol liver biopsies for chronic antibody-mediated rejection improved early identification of patients at risk of graft loss.