Tacrolimus and steroids versus ciclosporin microemulsion, steroids, and azathioprine in children undergoing liver transplantation: randomised European multicentre trial

Patients Who Have Prior Solid Organ Transplants Have Increased Risk of 10-Year Periprosthetic Joint Infection Revision Following Primary Total Knee Arthroplasty: A Propensity-Matched Analysis

BACKGROUND

Total knee arthroplasty (TKA) for solid organ transplant (SOT) patients is becoming more prominent as life expectancy in this population increases. However, data on long-term (10 year) implant survivorship in this cohort are sparse. The purpose of this study was to compare 90-day, 2-year, 5-year, and 10-year implant survivability following primary TKA in patients who did and did not have prior SOT.

METHODS

The PearlDiver database was utilized to query patients who underwent unilateral elective TKA with at least 2 years of active follow-up. These patients were stratified into those who had a SOT before TKA and those who did not. The SOT cohort was propensity-matched to control patients based on age, sex, Charlson Comorbidity Index, and obesity in a 1:2 ratio. Cumulative incidence rates and hazard ratios (HRs) were compared between the SOT, matched, and unmatched cohorts.

RESULTS

No difference was observed in 10-year cumulative incidence and risk of all-cause revision surgery in TKA patients with prior SOT when compared to matched and unmatched controls. Compared to the matched control, the SOT cohort had no difference in the risk of revision when stratified by indication and timing. However, when compared to the unmatched control, patients who had prior SOT had a higher risk for revision due to periprosthetic joint infection at 10 years (HR: 1.80; 95% confidence interval: 1.17 to 2.76) as well as all-cause revision within 90 days after TKA (HR: 1.93; 95% confidence interval: 1.10 to 3.36).

CONCLUSIONS

Prior SOT patients have higher rates of all-cause revision within 90 days and periprosthetic joint infection within 10 years when compared to the general population, likely associated with the elevated number of comorbidities in SOT patients and not the transplant itself. Therefore, these patients should be monitored in the preoperative and early postoperative settings to optimize their known comorbidities.

Asian Pacific Association for the Study of the Liver clinical practice guidelines on liver transplantation

Liver transplantation is a highly complex and challenging field of clinical practice. Although it was originally developed in western countries, it has been further advanced in Asian countries through the use of living donor liver transplantation. This method of transplantation is the only available option in many countries in the Asia-Pacific region due to the lack of deceased organ donation. As a result of this clinical situation, there is a growing need for guidelines that are specific to the Asia-Pacific region. These guidelines provide comprehensive recommendations for evidence-based management throughout the entire process of liver transplantation, covering both deceased and living donor liver transplantation. In addition, the development of these guidelines has been a collaborative effort between medical professionals from various countries in the region. This has allowed for the inclusion of diverse perspectives and experiences, leading to a more comprehensive and effective set of guidelines.

Population pharmacokinetics of tacrolimus in Chinese adult liver transplant patients

Tacrolimus is widely used in organ transplantation to prevent rejection. However, the narrow therapeutic window and the large inter-and intra-individual variability in the pharmacokinetics (PK) of tacrolimus make it difficult for individualization of dosing. This study aimed at developing a population pharmacokinetic model for estimating the oral clearance of tacrolimus in Chinese liver transplant patients, and identifying factors that contribute to the PK variability of tacrolimus. Data of 151 liver transplant patients who received tacrolimus were analyzed in this study. The population PK model was analyzed and the covariates including population demographic and biochemical characteristics, drug combination, and genetic polymorphism were explored using non-linear mixed-effects modeling approach. A single-compartment population PK model was developed, and the final model was CL/F = (14.6-2.38 × cytochrome P450 (CYP) 3A5-3.72 × WZC+1.04 × (POD/9)+2.48 × COR) × Exp(η_i ), where CYP3A5 was 1 for CYP3A5*3/*3, Wuzhi Capsule (WZC) was 1 when patients took tacrolimus combined with WZC, otherwise it was 0, corticosteroids (COR) was 1 when patients take tacrolimus combined with COR, otherwise, it was 0, POD was the post-operative day. Visual inspection and bootstrap indicated that the final model was stable and robust. In this study, we developed the first tacrolimus population PK model in Chinese adult liver transplant patients. We first determined the influence of WZC on tacrolimus in these people, which could provide useful PK information for the drug combination of tacrolimus and WZC. We also revealed the influence of genetic polymorphism of CYP3A5, POD, and a combination of COR on tacrolimus PK. Therefore, these significant factors should be taken into consideration in optimizing dosage regimens.

Long-term Follow-up of a Randomized Trial of Tacrolimus or Cyclosporine A Microemulsion in Children Post Liver Transplantation

The aim of this study was to determine the long-term efficacy and safety of tacrolimus (Tac) and cyclosporine immunosuppression in pediatric liver transplantation (LTx).

Management and outcome of hepatic artery thrombosis after pediatric liver transplantation

BACKGROUND

Pediatric LT are at particular risk of HAT, and its management still constitutes a matter of debate. Our purpose was to study predisposing factors and outcome of HAT post-LT, including the impact of surgical revisions on survival and biliary complications.

METHODS

Among 882 primary pediatric LT performed between 1993 and 2015, 36 HAT were encountered (4.1%, 35 fully documented). Each HAT case was retrospectively paired with a LT recipient without HAT, according to diagnosis, age at LT, type of graft, and era.

RESULTS

Five-year patient survivals were 77.0% versus 83.9% in HAT and non-HAT paired groups, respectively (P = .321). Corresponding graft survivals were 20.0% versus 80.5% (P < .001), and retransplantation rates 77.7% versus 10.7%, respectively (P < .001). One-year biliary complication-free survivals were 16.6% versus 83.8% in the HAT and non-HAT groups, respectively (P < .001). Regarding chronology of surgical re-exploration, only HAT cases that occurred within 14 days post-LT were re-operated, fourteen of them being explored within 7 days post-LT (revascularization rate: 6/14), versus two beyond 7 days (no revascularization). When revascularization was achieved, graft and biliary complication-free survival rates at 1 year were 33.3% and 22.2%, respectively, both rates being 0.0% in case of failure.

CONCLUSIONS

The pejorative prognosis associated with HAT in terms of graft survival is confirmed, whereas patient survival could be preserved through retransplantation. Results suggest that HAT should be re-operated if occurring within 7 days post-LT, but not beyond.

Sequential Treatment of Biliary Atresia With Kasai Hepatoportoenterostomy and Liver Transplantation: Benefits, Risks, and Outcome in 393 Children

Introduction: Surgical treatment of biliary atresia (BA) is still based on sequential strategy with Kasai hepatoportoenterostomy (KP) followed by liver transplantation (LT), in case of complicated secondary biliary cirrhosis. Concerns have been expressed regarding the risks of LT related to previous KP, suggesting primary LT as an exclusive treatment of BA. Methods: Single-center retrospective analysis including 393 pediatric patients who underwent LT for BA from 1993 to 2018, categorized into two groups: with (KP) or without (NoKP) previous KP. Pre-LT clinical condition was estimated considering age at LT, time on waiting list, pediatric end-stage liver disease score (PELD), and presence of portal vein hypoplasia. Post-LT outcome was evaluated considering patient and graft survival rates, and need for early reoperation due to abdominal or graft-related complications (<45 days after LT). Results: Two-hundred ninety-six patients (75.3%) were categorized in the KP group, and 97 (24.7%) in the NoKP group. Median age at LT was 1.14 years in the KP group and 0.85 years in the NoKP group (p < 0.0001). PELD score was significantly less severe in KP patients (p < 0.05). One-year patient survival rates were 96.9 and 96.8% in the KP and NoKP groups, respectively (p = 0.43), and the corresponding graft survival was 92.5 and 94.8% (p = 0.97). The need for early reoperation was more frequent in the KP group (29.8%) vs. NoKP group (12.4%, p = 0.01). The rate of bowel perforation was non-significantly higher in the KP group (8.1%) vs. NoKP group (3.1%, p = 0.11). Conclusions: The sequential strategy including KP and LT allowed performing LT in patients with significant older age and better clinical conditions, when compared to those transplanted without previous KP. Patient and graft survivals were not impacted by previous KP. Although previous KP was associated with an increased rate of post-LT surgical complications, bowel perforation and bleeding did not occur significantly more frequently. Such results support the current strategy based on sequential treatment.

Projected 20- and 30-Year Outcomes for Pediatric Liver Transplant Recipients in the United States

BACKGROUND

Observed long-term outcomes no longer reflect the survival trajectory facing pediatric liver transplant (LT) recipients today. We aimed to use national registry data and parametric models to project 20- and 30-year post-transplant outcomes for recently transplanted pediatric LT recipients.

METHODS

We conducted a retrospective cohort study of 13,442 first-time pediatric (age <18) LT recipients using 1987 to 2018 Scientific Registry of Transplant Recipients data. We validated the proposed method (ie, to project long-term patient and graft survival using parametric survival models and short-term data) in 2 historic cohorts (1987-1996 and 1997-2006) and estimated long-term projections among patients transplanted between 2007 and 2018. Projections were stratified by raft type, recipient age, and indication for transplant.

RESULTS

Parsimonious parametric models with Weibull distribution can be applied to post-transplant data and used to project long-term outcomes for pediatric LT recipients beyond observed data. Projected 20-year patient survival for pediatric LT recipients transplanted in 2007 to 2018 was 84.0% (95% confidence interval 81.5-85.8), compared to observed 20-year survival of 72.8% and 63.6% among those transplanted in 1997 to 2006 and 1987 to 1996, respectively. Projected 30-year survival for pediatric LT recipients in 2007 to 2018 was 80.1% (75.2-82.7), compared to projected 30-year survival of 68.6% (66.1-70.9) in the 1997 to 2006 cohort and observed 30-year survival of 57.5% in the 1987 to 1996 cohort. Twenty- and 30-year patient and graft survival varied slightly by recipient age, graft type, and indication for transplant.

CONCLUSIONS

Projected long-term outcomes for recently transplanted pediatric LT recipients are excellent, reflective of substantial improvements in medical care, and informative for physician-patient education and decision making in the current era.

Pediatric Liver Transplantation: Then and Now

This paper reviews the past 50 years of liver transplantation in children from the perspective of patient demographics, perioperative patient management, surgical techniques, immunosuppression and patient outcomes.

Efficacy and safety of tacrolimus in de novo pediatric transplant recipients randomized to receive immediate- or prolonged-release tacrolimus

BACKGROUND AND AIMS

This multicenter trial compared immediate-release tacrolimus (IR-T) vs prolonged-release tacrolimus (PR-T) in de novo kidney, liver, and heart transplant recipients aged <16 years. Each formulation had similar pharmacokinetic (PK) profiles. Follow-up efficacy and safety results are reported herein.

MATERIALS AND METHODS

Patients, randomized 1:1, received once-daily, PR-T or twice-daily, IR-T within 4 days of surgery. After a 4-week PK assessment, patients continued randomized treatment for 48 additional weeks. At Year 1, efficacy assessments included the number of clinical acute rejections, biopsy-confirmed acute rejection (BCAR) episodes (including severity), patient and graft survival, and efficacy failure (composite of death, graft loss, BCAR, or unknown outcome). Adverse events were assessed throughout.

RESULTS

The study included 44 children. At Year 1, mean ± standard deviation tacrolimus trough levels were 6.6 ± 2.2 and 5.4 ± 1.6 ng/mL, and there were 2 and 7 acute rejection episodes in the PR-T and IR-T groups, respectively. No cases of graft loss or death were reported during the study. The overall efficacy failure rate was 18.2% (PR-T n = 1; IR-T n = 7).

CONCLUSIONS

In pediatric de novo solid organ recipients, the low incidence of BCAR and low efficacy failure rate suggest that PR-T-based immunosuppression is effective and well tolerated to 1-year post-transplantation.

Genome-Wide Association Study of Tacrolimus Pharmacokinetics Identifies Novel Single Nucleotide Polymorphisms in the Convalescence and Stabilization Periods of Post-transplant Liver Function

After liver transplantation, the liver function of a patient is gradually restored over a period of time that can be divided into a convalescence period (CP) and a stabilizing period (SP). The plasma concentration of tacrolimus, an immunosuppressant commonly used to prevent organ rejection, varies as a result of variations in its metabolism. The effects of genetic and clinical factors on the plasma concentration of tacrolimus appear to differ in the CP and SP. To establish a model explaining the variation in tacrolimus trough concentration between individuals in the CP and SP, we conducted a retrospective, single-center, discovery study of 115 pairs of patients (115 donors and 115 matched recipients) who had undergone liver transplantation. Donors and recipients were genotyped by a genome-wide association study (GWAS) using an exome chip. Novel exons were identified that influenced tacrolimus trough concentrations and were verified with bootstrap analysis. In donors, two single-nucleotide polymorphisms showed an effect on the CP (rs1927321, rs1057192) and four showed an effect on the SP (rs776746, rs2667662, rs7980521, rs4903096); in recipients, two single-nucleotide polymorphisms showed an effect in the SP (rs7828796, rs776746). Genetic factors played a crucial role in tacrolimus metabolism, accounting for 44.8% in the SP, which was higher than previously reported. In addition, we found that CYP3A5, which is known to affect the metabolism of tacrolimus, only influenced tacrolimus pharmacokinetics in the SP.

Pharmacokinetics of tacrolimus granules in pediatric de novo liver, kidney, and heart transplantation: The OPTION study

Tacrolimus granules were developed for patients who are unable to swallow capsules. Therapeutic drug monitoring (TDM) is required to optimize efficacy and safety, which is based on C_trough for tacrolimus capsules. Pharmacokinetic (PK) data for tacrolimus granules are required to establish the basis for TDM in those who are unable to swallow capsules. In this phase IV study (NCT01371331) of children undergoing liver, kidney, or heart transplantation, patients received tacrolimus granules 0.15 mg/kg twice daily; first dose was administered within 24 hours of reperfusion. PK analysis samples were collected after reperfusion, after first dose of tacrolimus (Day 1), and at steady state (Day 7; >4 days stable dose). Of the 52 transplant recipients enrolled, 38 had two evaluable PK profiles. Mean AUC_tau after first dose of tacrolimus was 211, 97, and 224 hour*ng/mL in liver, kidney, and heart transplant recipients, respectively; corresponding mean AUC_tau at steady state was 195, 208, and 165 hour*ng/mL. C_trough and AUC_tau were positively correlated after first dose of tacrolimus and at steady state (Pearson's coefficients: r = 0.81 and r = 0.87, respectively). This study demonstrated that C_trough is a reliable marker for TDM in pediatric transplant recipients treated with tacrolimus granules, consistent with TDM for other tacrolimus formulations.

Tacrolimus Granules for Oral Suspension as Post-Transplant Immunosuppression in Routine Medical Practice in France: The OPTIMOD Study

Background

Different pharmaceutical forms of oral tacrolimus allow tailored administration. The granular formulation facilitates accurate dose adjustment of tacrolimus according to patient characteristics, such as weight, or potential concomitant drug interactions. Currently, there are no data describing the use of tacrolimus granules in transplant recipients in France.

Material/Methods

OPTIMOD was a 6-month prospective, observational multicenter study that aimed to describe patient characteristics and conditions of use of tacrolimus granules. The 25 participating centers enrolled patients at time of tacrolimus granules initiation and were to collect patient and treatment data at initiation and after 6 months of follow-up. All analyses were descriptive.

Results

Of 61 patients included, 55.7% were children (mainly kidney graft recipients) and 44.3% were adults (mostly lung graft recipients). Overall, 24.6% of patients (all children) initiated tacrolimus granules immediately post-transplant; the remaining 75.4% converted to tacrolimus granules from ciclosporin or immediate-release tacrolimus hard capsules. The main reasons for initiating tacrolimus granules, irrespective of whether first- or second-line therapy, were to offset potential drug–drug interactions in adults by adjusting dose, and to adapt to the particular needs of children as patients. Most patients (78.7%) underwent ≥1 dose modification during follow-up. Eleven rejection episodes occurred during follow-up, of which none led to graft loss. The adverse-event profile of the tacrolimus granules was similar to that of other tacrolimus formulations and 7 treatment-related adverse events were recorded.

Conclusions

Results suggest that tacrolimus granules are well tolerated and effective in preventing transplant rejection when administered in routine practice in France.

A Mechanism Study Underlying the Protective Effects of Cyclosporine-A on Lung Ischemia-Reperfusion Injury

AIM

This study is aimed at validating the hypothesis that administration of cyclosporine-A (CsA) would be protective in lung ischemia-reperfusion (I/R) injury and in exploring the underlying mechanism.

METHODS

Rabbits were divided into 4 groups: the control, sham operation, I/R, and I/R with CsA treatment. Flow cytometry was used to measure the mitochondrial membrane potential. Laser scanning confocal microscope was used to analyze mitochondrion permeability transition pore (MPTP). The apoptotic cell was detected by the TUNEL staining. Western blot was performed to analyze the protein expression levels.

RESULTS

CsA not only attenuated the histopathologic alterations in lung and mitochondria after I/R injury, but also attenuated I/R injury through increasing MPP and inhibiting MPTP opening. Besides, CsA attenuated I/R injury through suppressing the release of cytochrome-c (CytC), inhibiting cell apoptosis and decreasing the expression levels of cyclophilin-D (Cyp-D), adenine nucleotide translocase 1 (ANT1) and voltage-dependent anion channel 1 (VDAC1). Finally, we found that Cyp-D knockdown inhibits I/R injury-induced MPTP opening and cell apoptosis.

CONCLUSION

Our study found that the protective role of CsA on lung I/R injury depends on the inhibition of MPTP and CytC release, suppression of the activation of mitochondrial apoptosis pathway and the expressions of apoptotic-related proteins, as well as the decreased expression levels of ANT1 and VDAC1.

Management of Immunosuppression in Liver Transplantation

Liver transplantation outcomes have significantly improved over the past few decades owing largely to the introduction of effective immunosuppression medications. Further comprehension of the unique immune microenvironment of the liver has led to the development of newer molecular targeted therapeutics. Understanding the mechanism of action and adverse effect profiles of these medications is crucial for appropriate management of posttransplant patients. In this review, the author describes the immunologic response elicited by liver transplantation, chronicles the various immunosuppressant drug classes, discusses the evidence behind their use, and evaluates the management of special subpopulations of posttransplantation patients.

Living Donor Liver Transplantation in Children: Surgical and Immunological Results in 250 Recipients at Université Catholique de Louvain

OBJECTIVES

To evaluate the outcome of pediatric living donor liver transplantation (LDLT) regarding portal vein (PV) reconstruction, ABO compatibility, and impact of maternal donation on graft acceptance.

BACKGROUND

LDLT and ABO-mismatched transplantation constitute feasible options to alleviate organ shortage in children. Vascular complications of portal hypoplasia in biliary atresia (BA) and acute rejection (AR) are still major concerns in this field.

METHODS

Data from 250 pediatric LDLT recipients, performed at Cliniques Universitaires Saint-Luc between July 1993 and June 2012, were collected retrospectively. Results were analyzed according to ABO matching and PV complications. Uni- and multivariate analyses were performed to study the impact of immunosuppression, sex matching, and maternal donation on AR rate.

RESULTS

Overall, the 10-year patient survival rate was 93.2%. Neither patient or graft loss nor vascular rejection, nor hemolysis, was encountered in the ABO nonidentical patients (n = 58), provided pretransplant levels of relevant isoagglutinins were below 1/16. In BA recipients, the rate of PV complications was lower after portoplasty (4.6%) than after truncal PV anastomosis (9.8%) and to jump graft interposition (26.9%; P = 0.027). In parental donation, maternal grafts were associated with higher 1-year AR-free survival (55.2%) than paternal grafts (39.8%; P = 0.041), but only in BA patients.

CONCLUSIONS

LDLT, including ABO-mismatched transplantation, constitutes a safe and efficient therapy for liver failure in children. In BA patients with PV hypoplasia, portoplasty seems to constitute the best technique for PV reconstruction. Maternal donation might be a protective factor for AR.

The adolescent liver transplant patient

The rapid development of new diagnostic tests and improved therapy, especially the success of liver transplantation, has changed the outcome for children with liver disease, many of whom survive into adolescence without liver transplantation. The indications for transplantation in adolescence are similar to pediatric indications and reflect the medical advances made in this specialty that allow later transplantation. These young people need a different approach to management that involves consideration of their physical and psychological stage of development. A focused approach to their eventual transition to adult care is essential for long-term survival and quality of life.

Tacrolimus dose requirement in pediatric liver transplantation: influence of CYP3A5 gene polymorphism

AIM

Little information is available regarding the influence of CYP3A5 genetic polymorphisms on tacrolimus dose requirement in pediatric liver transplantation.

PATIENTS & METHODS

We performed a retrospective study among 179 pediatric liver recipients grafted between 2002 and 2009 in order to determine the influence of donor CYP3A5 genotype along with clinical variables on tacrolimus daily dose requirement during the first weeks following transplantation.

RESULTS

Mean stable tacrolimus daily dose requirement was higher among children who received a liver expressing CYP3A5 (carrying the CYPA3A5*1 allele) compared with those with a liver that did not express CYP3A5 (CYP3A5*3/*3 genotype): 0.29 ± 0.20 vs 0.18 ± 0.13 mg.kg(-1).d(-1), p = 0.005, respectively. A younger recipient age and fluconazole prescription were also significantly associated with tacrolimus daily dose requirement. Time to reach stable tacrolimus therapeutic trough concentrations was prolonged among patients with a CYP3A5-expressing graft (26 vs 21 days, p = 0.04).

CONCLUSION

Donor CYP3A5 genotype partially explains tacrolimus dose requirement. Original submitted 30 January 2013; Revision submitted 2 May 2013.

Clinical research in pediatric organ transplantation

Solid organ transplantation has greatly improved survival in children with end-stage disease, becoming one of the main treatment options in this population. Nonetheless, there are significant challenges associated with validating and optimizing the effects of these interventions in clinical trials. Therefore, we reviewed the main issues related to conducting clinical transplantation research in children. We divided these challenges into three different categories: (i) challenges related to surgical techniques and anesthetic procedures, (ii) challenges related to post-transplant care and (iii) challenges specific to a particular population group and disease type. Some of the observed burdens for clinical research in this field are related to the limitations of conducting studies with a placebo or sham procedure, determining the standard of care for a control group, low prevalence of cases, ethical concerns related to use of a placebo control group and lack of generalizability from animal studies and clinical trials conducted in adult populations. To overcome some of these barriers, it is necessary to utilize alternative clinical trial designs, such as observational studies or non-inferiority trials, and to develop multicenter collaborations to increase the recruitment rate. In conclusion, the lack of robust data related to pediatric transplantation remains problematic, and further clinical trials are needed to develop more efficacious and safer treatments.

Oral tacrolimus for pediatric steroid-resistant ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) occurring during childhood is generally extensive and is associated with severe flares that may require intravenous steroid treatment. In cases of corticosteroid resistance is necessary to introduce a second-line treatment to avoid or delay surgery.

AIMS

To describe the efficacy and safety of oral tacrolimus for the treatment of severe steroid-resistant UC.

METHODS

We performed a retrospective study that included all patients under age 18 suffering from severe steroid-resistant UC treated with oral tacrolimus during the period January 1998 to October 2012 and with a follow-up period after treatment of 24 months or more.

RESULTS

A total of ten patients were included. The age at baseline was 9.4±4.9 years, and the time from diagnosis was 1.3 months (IQR, 1-5.7). Seven of the patients were in their first flare of disease. All of them received an oral dose of 0.12 mg/kg/day of tacrolimus divided in two doses. Trough plasma levels of tacrolimus were maintained between 4 and 13 ng/ml. Response was seen in 5/10 patients at 12 months, colectomy was eventually performed in 60% of patients during the follow-up period.

CONCLUSIONS

Tacrolimus is useful in inducing remission in patients with severe steroid-resistant UC, preventing or delaying colectomy, and allowing the patient and family to prepare for a probable surgery. Tacrolimus may also be used as a treatment bridge for corticosteroid-dependent patients until the new maintenance therapy takes effect.

Population pharmacokinetic and pharmacogenetic analysis of tacrolimus in paediatric liver transplant patients

AIMS

To build a population pharmacokinetic model that describes the apparent clearance of tacrolimus and the potential demographic, clinical and genetically controlled factors that could lead to inter-patient pharmacokinetic variability within children following liver transplantation.

METHODS

The present study retrospectively examined tacrolimus whole blood pre-dose concentrations (n = 628) of 43 children during their first year post-liver transplantation. Population pharmacokinetic analysis was performed using the non-linear mixed effects modelling program (nonmem) to determine the population mean parameter estimate of clearance and influential covariates.

RESULTS

The final model identified time post-transplantation and CYP3A5*1 allele as influential covariates on tacrolimus apparent clearance according to the following equation: TVCL = 12.9 x (Weight/13.2)(0.75) x EXP(-0.00158 x TPT) x EXP(0.428 x CYP3A5) where TVCL is the typical value for apparent clearance, TPT is time post-transplantation in days and the CYP3A5 is 1 where *1 allele is present and 0 otherwise. The population estimate and inter-individual variability (%CV) of tacrolimus apparent clearance were found to be 0.977 l  h(-1)  kg(-1) (95% CI 0.958, 0.996) and 40.0%, respectively, while the residual variability between the observed and predicted concentrations was 35.4%.

CONCLUSION

Tacrolimus apparent clearance was influenced by time post-transplantation and CYP3A5 genotypes. The results of this study, once confirmed by a large scale prospective study, can be used in conjunction with therapeutic drug monitoring to recommend tacrolimus dose adjustments that take into account not only body weight but also genetic and time-related changes in tacrolimus clearance.

Markers of operational immune tolerance after pediatric liver transplantation in patients under immunosuppression

A prospective identification of the estimated 20-50% of pediatric LTX recipients developing operational tolerance would be of great clinical advantage. So far markers of immune tolerance - T-cell subpopulations or gene expression profiles - have been investigated only retrospectively in successfully weaned patients. Fifty children aged 8-265 months (median 89) were investigated 1-180 months (median 44) after LTX under ongoing immunosuppression. T-cell subpopulations were measured during regular post-transplant visits using FACS (Vδ1- vs. Vδ2-γδ-T cells and Tregs). A Vδ1/Vδ2-γδ-T-cell ratio ≥1.42 previously reported in operational tolerance was found in 12 of 50 (24%) patients. In analogy, a Treg count ≥44 per μL was found in 35 of 50 (70%) patients and a Treg proportion ≥2.23% of CD3(+) -T cells in 39 of 50 (78%) patients. Only 9 of 50 patients (18%) fulfilled both criteria. The parameters Vδ1/Vδ2-γδ-T-cell ratio and Tregs were not significantly correlated to each other or with donor type or immunosuppression. Vδ1/Vδ2-γδ-T-cell ratio was more stable in serial examinations compared with Treg analyses. The observed proportion of 18% pediatric LTX patients with potential operational tolerance is in accordance with previous reports. However, clinical experience shows that rejections may happen even after long-time weaning of immunosuppression. This suggests that operational tolerance is a dynamic process, with uncertain prediction by Vδ1/Vδ2-γδ-T-cell ratio and/or Tregs under immunosuppression.

Intraoperative cryoprecipitate transfusion and its association with the incidence of biliary complications after liver transplantation--a retrospective cohort study

Background

Cryoprecipitate is largely used for acquired hypofibrinogenemia in the setting of massive hemorrhage in liver transplantation (LT). However, the influence of intraoperative cryoprecipitate transfusion on biliary complications (BC) after LT has not been studied in detail.

Study Design and Methods

In a series of 356 adult patients who received their first LT, the causes of BC were retrospectively studied by multivariate logistic regression analysis. The clinical relationship between intraoperative cryoprecipitate transfusion and BC occurrence was studied through a retrospective cohort study in patients. All patients received follow-ups for one year, and, during the follow-up period, the time of BC occurrence and liver biopsies were recorded.

Results

Intraoperative cryoprecipitate transfusion (RR = 3.46, 95% CI [1.72–6.97], P<0.001), cold ischemia time >8 h (RR = 4.24, 95% CI [2.28–7.92], P<0.01), and high-level Child-Pugh ( RR = 1.71, 95% CI [1.11–2.63], P = 0.014) are independent risk factors to predict BC after LT according to time-to-event analysis. One year BC-free survival probability of patients received intraoperative cryoprecipitate transfusions was significantly lower when compared to the group that received no cryoprecipitate(P<0.001). Moreover, BC patients in the cryoprecipitate transfusion group owned different liver pathological feature, pathological micro-thrombus formation and cholestasis were seen more often (41.4% vs 0%, 62.1% vs 12.5%, respectively) than no cryoprecipitate transfusion group.

Conclusion

These findings suggested that intraoperative cryoprecipitate transfusion was associated with BC after LT. The mechanism of BC occurrence might involve micro-thrombus formation and immune rejection.

Prope tolerance after pediatric liver transplantation

pT, under mono- and infratherapeutic calcineurin inhibition, may constitute an optimal condition combining graft acceptance with low IS load and minimal IS-related toxicity. We reviewed 171 pediatric (<15.0 yr) survivors beyond one yr after LT, transplanted between April 1999 and June 2007 under tacrolimus-based regimens (median follow-up post-LT: 6.0 yr, range: 0.8-9.5 yr). Their current status regarding IS therapy was analyzed and correlated with initial immunoprophylaxis. pT was defined as tacrolimus monotherapy, with mean trough blood levels <4 ng/mL during the preceding year of follow-up, combined with normal liver function tests. The 66 children transplanted before April 2001 received a standard tacrolimus-steroid regimen. Beyond April 2001, 105 patients received steroid-free tacrolimus-basiliximab or tacrolimus-daclizumab immunoprophylaxis. In the latter group, 43 (41%) never experienced any acute rejection episode and never received steroids. In the long term, a total of 79 recipients (47%) developed pT (n = 73) or IS-free operational tolerance (n = 6), 27 of them belonging to the 43 steroid-free patients (63%). In contrast, only 52/128 (41%) children treated with steroids subsequently developed prope/operational tolerance (p = 0.012). Steroid-free tacrolimus-based IS seems to promote long-term graft acceptance under minimal/no IS. These results constitute the first evidence that minimization of IS, including steroid avoidance, might be tolerogenic in the long term after pediatric LT.

Pharmakologische Aspekte

Kortikosteroide waren die ersten Therapeutika zur Kontrolle von Abstoßungsreaktionen nach Transplantation. Sie sind seit Langem und immer noch wichtiger Bestandteil vieler immunsuppressiver Therapiekonzepte. Kortikosteroide besitzen zahlreiche antiinflammatorische und immunsuppressive Effekte. Sie beeinflussen über die Bindung spezifischer zytoplasmatischer Rezeptoren die Gentranskriptionsrate für zentrale, immunregulatorische Proteine wie Interleukin 1β (IL-1β), IL-6, Tumor-Nekrose-Faktor α (TNF-α) mit resultierender Suppression der Makrophagenfunktion und konsekutiver T-Zell-Aktivierung. Sie inhibieren auch die IL-2-Synthese, hemmen damit die T-Zell-Proliferation und reduzieren die IL- 2-Rezeptorbindungsfähigkeit. Andererseits stimulieren sie die Synthese des inhibierenden Zytokins „transforming growth factor β“ (TGF-β), was in einem „antiinflammatorisch“ geprägten T-Helfer-Zell-2-artigen Zytokinprofil resultiert. Über die Inhibition der Expression von interferonabhängigen Adhäsionsmolekülen (einschließlich MHC-Klasse-II-Moleküle) bewirken Kortikosteroide darüber hinaus die Alteration von Leukozytenverkehr und -transmigration sowie eine Induktion der Lymphozytenapoptose.

Intracellular ATP production in CD4+ T cells as a predictor for infection and allograft rejection in trough-level guided pediatric liver transplant recipients under calcineurin-inhibitor therapy

BACKGROUND

The assessment of cell-mediated immune responses through the measurement of intracellular adenosine-tri-phosphate (iATP) production (Cylex ImmuKnow) as a pharmacodynamic biomarker of immune function represents a potential tool to optimize individual immunosuppressive therapy independent of drug dosage or trough levels. This study aims to investigate the correlations between iATP and adverse events, immunosuppression, calcineurin-inhibitor-trough levels, and age.

METHODS

In this prospective trial, 31 nontransplant pediatric subjects and 50 consecutive children were included after they underwent liver transplantation (LTX). During the study period, 4 allograft rejections and 3 acute infections occurred. The patients were treated with cyclosporine, tacrolimus, mycophenolate mofetil, and everolimus either as monotherapy or in combinations. The reactivity of the immune system was measured as iATP concentration in CD4+ T-cells after in vitro stimulation by phytohemagglutinin.

RESULTS

The iATP concentrations in patients with intercurrent, clinically significant infections were in the low immune response range (median iATP 181 versus 251 ng/mL, P = 0.308), whereas the patients with incidental allograft rejection had significantly higher iATP concentrations as compared with the event-free group (median iATP 444 versus 251 ng/mL, P = 0.017). However, there was a wide range of iATP concentrations in both nontransplant and LTX patient groups, and no clear iATP cut-off values for an increased risk of infection or rejection could be defined. Post LTX, stable-phase patients showed a significantly lower iATP compared with respective controls (median iATP 297 versus 384 ng/mL, P = 0.013). No significant correlation between calcineurin-inhibitor-trough concentrations and iATP was found. iATP was not correlated with age, but was inversely correlated with time after transplantation.

CONCLUSIONS

The observed correlation between clinical events and iATP concentrations is similar to the findings previously reported in adult patients who underwent transplantation. The lack of correlation of iATP with trough drug concentrations suggests that the ImmuKnow assay provides independent information that may be useful to guide immunosuppressive therapy in pediatric (liver) transplant patients. However, the wide range of iATP levels in event-free patients suggests that serial iATP measurements will be necessary to assess and guide the individual immunosuppressive therapy. Further investigations are needed to evaluate and extend these findings.

Liver transplantation in an African setting

Liver disease in children in the developing world is a frequent occurrence, which is generally inadequately managed because of lack of resources. However, increasingly, there has been a demand for liver transplantation, where primary medical or surgical therapies have failed. The expertise and infrastructure required for a successful outcome are no different from those in more developed countries; if anything, the challenges are greater. Lack of deceased donors because of cultural and religious factors has driven the use of living donors. Short-term survival has generally been good, but long-term outcomes have rarely been reported. In this article, we review the experience of 2 centers at opposite ends of the continent and share our experience of slightly different settings and show that success can be achieved even in resource-reduced environments.

Current status of immunosuppressive agents for solid organ transplantation in children

Immunosuppression after organ transplantation is complex and ever evolving. Over the past two decades, newer immunosuppressive agents have been introduced with an aim to provide better patient and graft survival. Improved therapeutic strategies have been developed offering the option to use combinations of drugs with non-overlapping toxicities. There are, however, only a few clinical studies with robust data to rationalize the use of these agents in children. This review will discuss the newer immunosuppressive agents used for solid organ transplant, their current status in post-transplant management and prevention of allograft rejection.

Radiofrequency ablation in the treatment of liver tumors in children

Hepatoblastoma and liver metastasis of Wilms' tumors are rare hepatic tumors in children. Treatment of both tumors consists of a combination of chemotherapy and liver surgery. Radiofrequency ablation (RFA) is frequently used for the treatment of adult liver tumors but is rarely mentioned as a treatment option in pediatric liver tumors. We present a patient with hepatoblastoma and 1 with liver metastasis from a Wilms' tumor. Both patients were treated according to the latest protocols except that surgery included use of RFA. Both are well and recurrence free 8 and 3 years after surgery. Radiofrequency ablation may be a good addition to the existing arsenal of treatment modalities for pediatric liver tumors.

Sirolimus as renal and immunological rescue agent in pediatric liver transplant recipients

CNI have improved the outcome of LT. However, their inherent potential to nephrotoxic and sometimes-inadequate immunosuppressive effect has lead to the usage of newer drugs like SRL. Aim of this study was to review children who received SRL. Thirty-seven (20 women) children post-LT, median age 10.4 yr (0.8-17.4) with a minimum follow-up of six months comprised the study group. Indications for SRL were biopsy-proven resistant acute allograft rejection (n = 12), early CR (n = 12), and CNI-induced nephropathy with MMF intolerance (n = 11). In two patients, the indication was the recurrence of BSEP disease in the allograft. In patients with acute rejection, AST normalized in 10/12 patients. In patients with CR, AST normalized in 6/12 patients. Those with renal impairment showed improvement in their creatinine levels from a mean baseline of 99-56.7 μm (p = 0.03) and their mean cystatin C was 1.02 after SRL. Side effects leading to discontinuation of SRL were seen in three patients. SRL was effective in rescuing patients with acute and chronic allograft rejection and improving renal function in CNI-induced nephropathy group.

A multivariate analysis of pre-, peri-, and post-transplant factors affecting outcome after pediatric liver transplantation

OBJECTIVE

The purpose of this study was to identify significant, independent factors that predicted 6 month patient and graft survival after pediatric liver transplantation.

SUMMARY BACKGROUND DATA

The Studies of Pediatric Liver Transplantation (SPLIT) is a multicenter database established in 1995, of currently more than 4000 US and Canadian children undergoing liver transplantation. Previous published analyses from this data have examined specific factors influencing outcome. This study analyzes a comprehensive range of factors that may influence outcome from the time of listing through the peri- and postoperative period.

METHODS

A total of 42 pre-, peri- and posttransplant variables evaluated in 2982 pediatric recipients of a first liver transplant registered in SPLIT significant at the univariate level were included in multivariate models.

RESULTS

In the final model combining all baseline and posttransplant events, posttransplant complications had the highest relative risk of death or graft loss. Reoperation for any cause increased the risk for both patient and graft loss by 11 fold and reoperation exclusive of specific complications by 4 fold. Vascular thromboses, bowel perforation, septicemia, and retransplantation, each independently increased the risk of patient and graft loss by 3 to 4 fold. The only baseline factor with a similarly high relative risk for patient and graft loss was recipient in the intensive care unit (ICU) intubated at transplant. A significant center effect was also found but did not change the impact of the highly significant factors already identified.

CONCLUSIONS

We conclude that the most significant factors predicting patient and graft loss at 6 months in children listed for transplant are posttransplant surgical complications.

Intensive care management of liver transplanted patients

Advances in pre-transplant treatment of cirrhosis-related organ dysfunction, intraoperative patient management, and improvements in the treatment of rejection and infections have made human liver transplantation an effective and valuable option for patients with end stage liver disease. However, many important factors, related both to an increasing "marginality" of the implanted graft and unexpected perioperative complications still make immediate post-operative care challenging and the early outcome unpredictable. In recent years sicker patients with multiple comorbidities and organ dysfunction have been undergoing Liver transplantation; appropriate critical care management is required to support prompt graft recovery and prevent systemic complications. Early post-operative management is highly demanding as significant changes may occur in both the allograft and the "distant" organs. A functioning transplanted liver is almost always associated with organ system recovery, resulting in a new life for the patient. However, in the unfortunate event of graft dysfunction, the unavoidable development of multi-organ failure will require an enhanced level of critical care support and a prolonged ICU stay. Strict monitoring and sustainment of cardiorespiratory function, frequent assessment of graft performance, timely recognition of unexpected complications and the institution of prophylactic measures to prevent extrahepatic organ system dysfunction are mandatory in the immediate post-operative period. A reduced rate of complications and satisfactory outcomes have been obtained from multidisciplinary, collaborative efforts, skillful vigilance, and a thorough knowledge of pathophysiologic characteristics of the transplanted liver.

Safety and efficacy of tacrolimus in pediatric liver recipients

Pediatric liver transplantation is now so successful that we expect more than 80% of children to survive into adolescence and adulthood. As the focus of care shifts toward long-term patient management, immunosuppressive regimens should, in addition to preventing acute and chronic rejection, promote good quality of life and be free of significant long-term side effects. Historically, the most effective immunosuppressive regimens have been based on induction with a combination of calcineurin inhibitors (cyclosporin or tacrolimus) and steroids. Usually, maintenance is monotherapy with cyclosporin or tacrolimus or dual therapy with low-dose alternate-day steroids to encourage growth. A number of studies, including long-term follow-up, have shown significantly lower incidences of rejection, hypertension, hyperlipidemia and cosmetic side effects in patients treated initially with tacrolimus compared with cyclosporin. The use of anti-interleukin-2 inhibitors as induction therapy, with low-dose tacrolimus or in combination with mycophenolate mofetil, has a key role in preventing significant renal dysfunction and reducing infection and rejection. Steroid-free immunosuppression is also proving to be an effective option for the management of pediatric liver recipients. The main challenges now facing pediatricians include ensuring long-term quality of life, optimizing immunosuppression while preventing associated adverse events, and managing a smooth transition from childhood to adolescence and adulthood.

FK506 (tacrolimus) and endothelin combined treatment induces mobility of melanoblasts: new insights into follicular vitiligo repigmentation induced by topical tacrolimus on sun-exposed skin

BACKGROUND

Topical tacrolimus (FK506) has been considered as a treatment option for treating vitiligo, a dermatosis characterized by disappearance of melanocytes (MCs). Previous reports have shown that a significant portion of treated patients demonstrated follicular repigmentation, indicating that the activation of MC precursor cells residing in the outer root sheath of hair follicles played an important role during the tacrolimus-induced repigmentation process.

OBJECTIVES

To investigate the mechanisms involved in follicular pigmentation induced by topical tacrolimus.

METHODS

As stem cells of MC lineage are identified in the lower portion of mouse hair follicles throughout the hair cycle, immature mouse melanoblasts (MBs) derived from neural crest cells (NCCmelb4) were used for this study. Relevant maturation parameters were evaluated.

RESULTS

Our results revealed that FK506 stimulated the expressions of protein kinase A, protein kinase C and phosphorylated p38 mitogen-activated protein kinase. However, cell motility, a parameter associated with MB differentiation, was not enhanced by FK506 treatment. Endothelin (ET)-3, a prodifferentiation factor of MBs, also failed to promote NCCmelb4 cell locomotion. Combining ET-3 and FK506, however, stimulated cell mobility. ET B receptor, which was not present in NCCmelb4 cells, was induced after FK506 treatment.

CONCLUSIONS

In summary, we have shown that FK506 is an efficient differentiation-stimulating agent, especially for cells of neural origin. The clinical efficacy of topical tacrolimus on vitiligo may be enhanced by combination with ET-3.

Immunosuppressants: what's new?

PURPOSE OF REVIEW

Advances in surgical techniques and combinations of conventional immunosuppressants have made paediatric liver transplantation the success story it is today. However, the increasing numbers of survivors reaching adulthood highlight important issues of long-term quality of life and drug induced complications. The aim of this review is to describe the trends and advances in immunosuppression for paediatric liver transplantation over the last 12 months.

RECENT DEVELOPMENTS

As our knowledge of the immune cell populations and intracellular mechanisms involved in alloreactivity improves, induction immunosuppression has emerged as a powerful therapeutic manoeuvre to counter the initial alloimmune response. Many centres have adopted a more focused use of biological agents at induction to improve immunosuppression in the critical peritransplant period and to reduce the level of subsequent maintenance requirements. Corticosteroid avoidance and calcineurin inhibitors minimization trials have obtained encouraging results. New immunosuppressive strategies have evolved towards the goal of inducing operational tolerance, and paediatric liver transplant recipients seem to be a particularly promising target. New strategies are being developed also to improve quality of life and reduce nonadherence in adolescents and young adults who underwent liver transplantation. New drugs target B-cell and complement driven rejection and new monoclonal antibodies and small molecules are under trial to inhibit specific signals in the immune response.

SUMMARY

We review current trends of immunosuppressive protocols in paediatric liver transplantation, focusing on induction agents, corticosteroid avoidance and calcineurin inhibitor sparing protocols, protocols for adult transition and new drugs currently under development.

School outcomes in children registered in the studies for pediatric liver transplant (SPLIT) consortium

School performance is an important aspect of functional outcomes for pediatric liver transplant (LT) recipients. This longitudinal analysis conducted through the Studies of Pediatric Liver Transplantation (SPLIT) research consortium examines several indicators of school function in these patients. A total of 39 centers participated in data collection using a semistructured questionnaire designed specifically for this study. The survey queried school attendance, performance and educational outcomes including the need for special educational services. Participants included 823 of 1133 (73%) eligible patients, mean age 11.34 +/- 3.84 years, 53% female, median age at LT 4.6 (range 0.05-17.8) years, and mean interval from transplant was 5.42 +/- 2.79. Overall, 34% of patients were receiving special educational services and 20% had repeated a grade, with older participants more likely to have been held back (P = 0.0007). Missing more than 10 days of school per year was reported by one-third of the group, with this level of absence being more common in older participants (P = 0.0024) and children with shorter intervals from LT (P < 0.0001). Multivariate analysis revealed the following factors were associated with the need for special educational services; type of immunosuppression at 6 months post-LT, cyclosporine A (odds ratio [OR] = 1.8, confidence interval [CI] = 1.1-3.1), or other (OR = 4.9, 95% CI = 1.4-17.6) versus tacrolimus, symptomatic cytomegalovirus infection within 6 months of liver transplantation (OR = 3.1, CI = 1.6-6.1), and pretransplant special educational services (OR = 22.5, CI = 8.6-58.4).

Risk factors for posttransplant lymphoproliferative disorder in pediatric liver transplant recipients with cytomegalovirus antigenemia

Epstein-Barr virus (EBV) infections, associated with posttransplant lymphoproliferative disorder (PTLD) are known to develop in cytomegalovirus (CMV)-infected transplant recipients due to the indirect effects of CMV. This study evaluated risk factors for PTLD among pediatric liver transplant recipients with CMV infections. We reviewed the medical records of 119 patients<or=18 years old who underwent liver transplantation between September 1996 and April 2009. Sixty-six subjects (55.5%) displayed CMV antigenemia during the study period; 15 (12.6%) developed PTLD. Of these, 10 developed PTLD after CMV antigenemia. The other patients (n=5) were excluded due to negative CMV antigenemia. The incidence of PTLD influenced by CMV infection was not significantly different from the incidence of PTLD without underlying CMV (P=.258). There were no differences in age, gender, antiviral prophylaxis, type of liver transplantation, or acute rejection episodes in the incidence of between patients with versus without PTLD. EBV but not CMV high-risk groups were a predictor for the development of PTLD (P=.035). CMV syndrome, tissue-invasive CMV disease, and CMV peak titer were not associated with an increased risk of PTLD. The primary risk factor for PTLD was EBV high-risk patients (donor positive/recipient negative). CMV disease was not associated with PTLD in pediatric liver transplant recipients with CMV infections.

CD25 appears non essential for human peripheral T(reg) maintenance in vivo

Background

IL-2 has been reported to be critical for peripheral T_reg survival in mouse models. Here, we examined T_reg maintenance in a series of paediatric liver transplant recipients who received basiliximab, a therapeutic anti-CD25 monoclonal antibody.

Methodology/Principal Findings

FoxP3⁺ CD4 T cells were analyzed by flow cytometry before liver grafting and more than 9 months later. We found that in vivo CD25 blockade did not lead to T_reg depletion: the proportion of FoxP3⁺ cells among CD4 T cells and the level of FoxP3 expression were both unchanged. IL-2Rβ expression was enhanced in FoxP3⁺ cells both before and after basiliximab treatment, while the level of IL-2Rγ expression was similar in T_regs and non-T_regs. No significant change in the weak or absent expression of IL-7Rα and IL-15Rα expression on FoxP3⁺ cells was observed. Although the proportion of FoxP3⁺ cells among CD4 T cells did not vary, food allergies occurred more rapidly after liver grafting in patients who received basiliximab, raising questions as to T_reg functionality in vivo in the absence of functional CD25.

Conclusions

CD25 appears non essential for human T_reg peripheral maintenance in vivo. However, our results raise questions as to T_reg functionality after therapeutic CD25 targeting.

A new pediatric liver transplantation program in Southern Germany. The Heidelberg experience

pLTx is a highly complex procedure. It can only be performed safely by experienced teams. Starting a new pLTx program in a country with established centers must therefore avoid a learning curve. We have initiated a liver transplantation program for children in 2003. Medical standards were defined by a team of surgeons, pediatricians, radiologists, anesthesiologists, and pathologists before the first transplantation. An external expert in the field of pLTx supervised the whole process. In a pilot phase, six children weighing more than 20 kg were successfully transplanted. Following this series, the clinical pathways were re-evaluated, and the program was opened for children of all age groups. Between 2003 and 2008, 32 children received 34 organs. Sixty-eight percent of patients received a split-liver, 26% a full size organ, and 6% a reduced size graft. Four LRLTx were performed. Patient survival rate was 91%. We conclude that a new pLTx program can be established without a significant learning curve regarding mortality if a strict strategy of team-building is followed. In the pilot phase, small children and infants have to be referred and transplanted in an established center. An interdisciplinary team of specialists closely working together is the key for sustained success.