Posttransplant biopsy risk for stable long-term pediatric liver transplant recipients: 451 percutaneous biopsies from two multicenter immunosuppression withdrawal trials

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.

Banff 2022 Liver Group Meeting report: Monitoring long-term allograft health

The Banff Working Group on Liver Allograft Pathology met in September 2022. Participants included hepatologists, surgeons, pathologists, immunologists, and histocompatibility specialists. Presentations and discussions focused on the evaluation of long-term allograft health, including noninvasive and tissue monitoring, immunosuppression optimization, and long-term structural changes. Potential revision of the rejection classification scheme to better accommodate and communicate late T cell-mediated rejection patterns and related structural changes, such as nodular regenerative hyperplasia, were discussed. Improved stratification of long-term maintenance immunosuppression to match the heterogeneity of patient settings will be central to improving long-term patient survival. Such personalized therapeutics are in turn contingent on a better understanding and monitoring of allograft status within a rational decision-making approach, likely to be facilitated in implementation with emerging decision-support tools. Proposed revisions to rejection classification emerging from the meeting include the incorporation of interface hepatitis and fibrosis staging. These will be opened to online testing, modified accordingly, and subject to consensus discussion leading up to the next Banff conference.

The role of 18F-FDG PET/CT metabolic parameters in the differential diagnosis of post-transplant lymphoproliferative disorder after pediatric liver transplantation

Background

Post-transplant lymphoproliferative disorder (PTLD) is a significant complication after liver transplantation. Research on the diagnostic value of the Fluorine-18 fluorodeoxyglucose positron emission tomography/computerized tomography (18F-FDG PET/CT) metabolic parameters of PTLD in pediatric liver transplantation (pLT) recipients is limited. This study sought to evaluate the diagnostic efficacy of 18F-FDG PET/CT in differentiating between PTLD and non-PTLD lymphadenopathy in pLT recipients.

Methods

This retrospective study collected the 18F-FDG PET/CT scans with clinical and pathological information of all consecutive children who were clinically suspected of PTLD from November 2016 to September 2022 at the Beijing Friendship Hospital. The 18F-FDG PET/CT metabolic parameters of the two groups were analyzed. We then established a diagnostic model composed of the clinical characteristics and metabolic parameters.

Results

In total, 57 eligible patients were enrolled in this study, of whom 40 had PTLD and 17 had non-PTLD lymphadenopathy. Of the metabolic parameters examined in this study, total lesion glycolysis (TLG) had the highest area under the curve (AUC) value [0.757, 95% confidence interval (CI): 0.632-0.883, P=0.002]. The AUCs of the other metabolic parameters were all less than the AUC of TLG, including the maximum standardized uptake value (SUVmax) (AUC: 0.725, 95% CI: 0.597-0.853, P=0.008), mean standardized uptake value (SUVmean) (AUC: 0.701, 95% CI: 0.568-0.834, P=0.017), metabolic tumor volume total (MTVtotal) (AUC: 0.688, 95% CI: 0.549-0.827, P=0.040), TLG total (AUC: 0.674, 95% CI: 0.536-0.812, P=0.026). The diagnostic model, which was composed of clinical characteristics (digestive symptoms), the SUVmax, TLG, and the MTVtotal, showed excellent performance in the differential diagnosis (sensitivity: 0.675, 95% CI: 0.508-0.809; specificity: 0.941, 95% CI: 0.692-0.997; positive predictive value: 0.964, 95% CI: 0.798-0.998; and negative predictive value: 0.552, 95% CI: 0.360-0.730).

Conclusions

The 18F-FDG PET/CT metabolic parameters can be used to distinguishing between PTLD and non-PTLD lymphadenopathy in pLT recipients.

Regular protocol liver biopsy is useful to adjust immunosuppressant dose after adult liver transplantation

INTRODUCTION

Adjusting immunosuppression to minimal levels post-adult liver transplantation (LT) is critical; however, graft rejection has been reported in LT recipients with normal liver function evaluated by liver biopsy (LBx). Continual protocol liver biopsy (PLB) is performed regularly in LT recipients with normal liver function in some centers; however, its usefulness remains inadequately evaluated. This study aimed to assess retrospectively the usefulness of late PLB after adult LT.

METHODS

LBx evaluations of LT recipients with normal liver function and hepatitis B and C virus seronegativity were defined as PLB. The cases requiring immunosuppressive therapy for rejection findings based on Banff criteria were extracted from the PLBs, and pathological data collected before and after immunosuppressive dosage adjustment (based on modified histological activity index [HAI] score) were compared.

RESULTS

Among 548 LBx cases, 213 LBx in 110 recipients fulfilled the inclusion criteria for PLB. Immunosuppressive therapy after PLB was intensified in 14 LBx (6.6%) recipients (12.7%); of these, nine had late-onset acute rejection, three had isolated perivenular inflammation, one had plasma cell-rich rejection, and one had early chronic rejection. Follow-up LBx after immunosuppressive dose adjustment showed improvement in the modified HAI score grading in 10 of 14 cases (71.4%). No clinical background and blood examination data, including those from the post-LT period, immunosuppressant trough level, or examination for de novo DSA, predicted rejection in PLB. Complications of PLB were found in only three cases.

CONCLUSION

PLB is useful in the management of seemingly stable LT recipients, to discover subclinical rejection and allow for appropriate immunosuppressant dose adjustment.

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.

Population pharmacokinetics of mycophenolate mofetil in pediatric patients early after liver transplantation

Objective: To investigate the factors influencing the pharmacokinetics of mycophenolate mofetil (MMF) in pediatric patients after liver transplantation, and to establish a population pharmacokinetics model, which can provide a reference for clinical dosage adjustment.

Methods: A prospective study in a single center was performed on pediatric patients who were administrated with mycophenolate mofetil dispersible tablets (MMFdt) for at least 4 days after liver transplantation continuously. Blood samples were collected in ethylene diamine tetraacetic acid anticoagulant tubes before dosing and 0.5, 1, 2, 4, 8, and 12 h after the morning intake of MMFdt. The concentrations of mycophenolic acid (MPA) in plasma were assayed with a validated reverse-phase high-performance liquid chromatography method. UGT1A8 518C > G, UGT1A9 -275T > A, UGT1A9 -2152C > T, UGT2B7 211G > T, SLC O 1B1 521T > C polymorphism were determined by Sanger sequencing. Nonlinear mixed effects modeling was used to establish the population pharmacokinetics (PPK) model. The predictability and stability of the model were internally evaluated by the goodness of fit plots, visual prediction check, normalized prediction errors, and bootstraps.

Results: A two-compartment model with first-order absorption and first-order elimination was established with 115 MPA concentrations from 20 pediatric patients. The final model were: CL/F (L/h) = 14.8×(WT/7.5)^0.75×(DOSE/11.16)^0.452×е^0.06, Ka (h⁻¹) = 2.02×(WT/7.5)^−0.25, Vc/F (L) = 6.01×(WT/7.5), Vp/F (L) = 269 (fixed), Q/F (L/h) = 15.4×(WT/7.5)^0.75×е^1.39. Where CL/F was the apparent clearance rate, Ka was the absorption rate constant, Vc/F was the apparent distribution volume of the central compartment, Vp/F was the apparent distribution volume of the peripheral compartment, Q/F was the atrioventricular clearance rate, WT was the body weight of the subject, and DOSE was the MMFdt administered dose. The model indicated there was large inter-individual variability in CL/F and Q/F after multiple dosing of MMFdt. Internal evaluation results showed that the final model had good stability and prediction performance.

Conclusion: A stable and predictive population pharmacokinetic model of MMFdt in pediatric patients after the early stage of liver transplantation was established. The pediatric patient’s weight and the dose of MMFdt can be a reference to adjust the MMFdt dose.

Major complications after percutaneous biopsy of native or transplanted liver in pediatric patients: a nationwide inpatient database study in Japan

Aim

Although major complication rates following percutaneous liver biopsy (PLB) have been reported to be higher in children than in adults, scarce data are available regarding pediatric patients stratified by native and transplanted liver. We aimed to assess the factors associated with major complications after percutaneous biopsy of native or transplanted liver using a nationwide inpatient database.

Methods

Using the Japanese Diagnosis Procedure Combination database, we retrospectively identified pediatric patients who underwent PLB between 2010 and 2018. We described major complication rates and analyzed factors associated with major complications following PLB, stratified by native and transplanted liver.

Results

We identified 3584 pediatric PLBs among 1732 patients from 239 hospitals throughout Japan during the study period, including 1310 in the native liver and 2274 in the transplanted liver. Major complications following PLB were observed in 0.5% (n = 18) of the total cases; PLB in the transplanted liver had major complications less frequently than those in the native liver (0.2% vs. 1.0%, p = 0.002). The occurrence of major complications was associated with younger age, liver cancers, unscheduled admission, anemia or coagulation disorders in cases with native liver, while it was associated with younger age alone in cases with transplanted liver.

Conclusions

The present study, using a nationwide database, found that major complications occurred more frequently in pediatric cases with native liver and identified several factors associated with its major complications.

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

BACKGROUND

Follow-up after pediatric liver transplantation (LTX) is challenging and needs to be refined to extend graft survival as well as general functional health and patients´ quality of life. Strategies towards individual immunosuppressive therapy seem to play a key role. Our aim was to evaluate protocol liver biopsies (PLB) as a tool in personalized follow up after pediatric LTX.

PATIENTS AND METHODS

Our retrospective analysis evaluates 92 PLB in clinically asymptomatic pediatric patients after LTX between 2009 and 2019. Histological findings were characterized using the Desmet scoring system. In addition to PLB, other follow-up tools like laboratory parameters, ultrasound imaging and transient elastography were evaluated. Risk factors for development of fibrosis or inflammation were analyzed.

RESULTS

PLB revealed a high prevalence of graft fibrosis (67.4%) and graft inflammation (47.8%). Graft inflammation was significantly (P = 0.0353*) more frequent within the first 5 years after transplantation compared to later time points. Besides conventional ultrasound, the measurement of liver stiffness using transient elastography correlate with stage of fibrosis (r = 0.567, P = <0.0001***). Presence of donor-specific anti-human leukocyte antigen antibodies in blood correlates with grade of inflammation in PLB (r = 0.6040, P = 0.0018 **). None of the patients who underwent PLB suffered from intervention-related complications. Histopathological results had an impact on clinical decision making in one-third of all patients after PLB.

CONCLUSION

PLB are a safe and useful tool to detect silent immune-mediated allograft injuries in the context of normal liver parameters.

Prophylactic Strategy Against De Novo Hepatitis B Virus Infection for Pediatric Recipients Who Receive Hepatitis B Core Antibody-Positive Liver Grafts

The goal of this study was to evaluate the efficacy of a perioperative prophylactic strategy against de novo hepatitis B virus (HBV) infection in pediatric liver transplantation (LT) recipients with hepatitis B core antibody (HBcAb)-positive grafts. A total of 482 pediatric recipients transplanted between 2013 and 2017 were enrolled, and 170 recipients received HBcAb-positive liver grafts. The overall graft and recipient survival rates in HBcAb-positive and HBcAb-negative graft recipients were 91.8% versus 91.3% and 95.3% versus 94.2% at the end of follow-up. Preoperative hepatitis B surface antibody (HBsAb) titer ≥ 1000 IU/L and postoperative HBsAb titer ≥200 IU/L were our prophylactic targets for recipients receiving HBcAb-positive grafts. While 11 recipients developed de novo HBV infection, 10 received HBcAb-positive grafts. Both the preoperative and postoperative HBsAb targets were achieved in 78 recipients, the infection rate of de novo HBV was 1.3%; 24 recipients met the preoperative target, the infection rate was 4.2%; 52 recipients met the postoperative target, the infection rate was 1.9%; and 16 recipients met neither the preoperative nor postoperative HBsAb target, 43.8% of the recipients were infected with de novo HBV, which was significantly higher than the recipients who met both or either of the preoperative and postoperative targets. Split-liver grafts positive for HBcAb showed higher risk of de novo HBV infection. Postoperative application of lamivudine to recipients whose preoperative HBsAb titer < 1000 IU/L did not show preventive effect. Out of 11 infected recipients, 3 showed seroconversion under entecavir treatment. In conclusion, the graft and recipient survival rates were similar in pediatric LT recipients receiving HBcAb-positive or HBcAb-negative grafts. Our prophylactic strategy was effective for preventing de novo HBV infection in HBcAb-positive liver graft recipients.

Transjugular Versus Percutaneous Liver Biopsy in Children: Indication, Success, Yield, and Complications

BACKGROUND/OBJECTIVE

Percutaneous biopsy (PB) and transjugular liver biopsy (TJLB) are 2 main ways of obtaining liver tissue. We evaluated the indications, success rate, tissue yield, and complications of TJLB in comparison to PB in children.

METHODS

Electronic records of children undergoing liver biopsy (LB) were reviewed. Clinico laboratory data including indication, type of biopsy, complications, and tissue yield (length and number of complete portal tracts [CPT]) were noted.

RESULTS

Five hundred forty LB (indication: neonatal cholestasis [42.9%], chronic liver disease [43.7%], liver failure [3.7%], focal lesions [3.3%] and others [6.3%]) were done. Four hundred seventy-three were PB (317 boys, 14 [1--216] months) done by percussion (322 [68%]), real-time ultrasound guidance (125 [26.4%]), or plugged method [26 (5.5%)]. Sixty-seven (12.4%) were TJLB [38 boys, 140 (24--216) months], done in patients with contraindications for PB. Technical success (67/68 vs 473/473; P = 0.7) and complications (4 [6%]; vs 15 [3.3%]; P = 0.2) of TJLB and PB were similar. Major complications (0.5%) included supraventricular tachycardia (n = 1) in TJLB and hemoperitoneum (n = 2) in PB. Tissue yield of TJLB was poorer in terms of length (1.0 [0.2--2.0] vs 1.1 [0.4--2.1] cm; P < 0.001), CPT (4 [0--9] vs 5 [2--17]; P < 0.001) and adequacy for reporting (56/67 vs 459/473; P < 0.001). Biopsy yield of <6 CPT was predicted by cirrhosis at histology and TJLB. No factor identified risk of complications with LB.

CONCLUSIONS

LB is a safe procedure and only 12% children require TJLB because of contraindications of PB. Technical success and complications are similar but tissue yield is poorer in TJLB than PB. Presence of cirrhosis and TJLB adversely affected tissue yield.

Barriers to ideal outcomes after pediatric liver transplantation

Long-term survival for children who undergo LT is now the rule rather than the exception. However, a focus on the outcome of patient or graft survival rates alone provides an incomplete and limited view of life for patients who undergo LT as an infant, child, or teen. The paradigm has now appropriately shifted to opportunities focused on our overarching goals of "surviving and thriving" with long-term allograft health, freedom of complications from long-term immunosuppression, self-reported well-being, and global functional health. Experts within the liver transplant community highlight clinical gaps and potential barriers at each of the pretransplant, intra-operative, early-, medium-, and long-term post-transplant stages toward these broader mandates. Strategies including clinical research, innovation, and quality improvement targeting both traditional as well as PRO are outlined and, if successfully leveraged and conducted, would improve outcomes for recipients of pediatric LT.