Feasibility of steroid-free tacrolimus-basiliximab immunosuppression in pediatric liver transplantation and predictors for steroid requirement

Avoidance of steroids in pediatric liver transplantation may reduce toxicity and morbidity. The aim of this study was to analyze the feasibility of a steroid-free tacrolimus-basiliximab immunosuppression scheme, the risk factors associated with steroid requirement, and safety parameters. Patients who underwent liver transplantation for biliary atresia between 2011 and 2019 were included and followed for 6 months after transplantation. Immunosuppression consisted of tacrolimus-based treatment with basiliximab induction. Steroid-free survival was estimated, and risk factors for steroid requirement were evaluated using multivariate Cox regression analysis. A total of 76 patients were included, of whom 42 (55.3%) required steroids (>14 d) due to biopsy-proven acute rejection (47.6%, n = 20), instability in liver function tests (35.7%, n = 15), tacrolimus-related adverse drug reactions (14.3%, n = 6), or other reasons (bronchospasm episode, n = 1). Steroid-free survival was 45.9% (95% CI, 35.9-58.8). Independent factors associated with steroid requirement included tortuosity in tacrolimus trough levels (≥1.76 vs. <1.76: HR 5.8, 95% CI, 2.6-12.7; p < 0.001) and mean tacrolimus trough levels (≥ 6.4 ng/mL vs. < 6.4 ng/mL: HR 0.4, 95% CI, 0.2-0.7; p = 0.002). The rate of bacterial and viral infections was comparable between patients with and without steroids, although in the former group, cytomegalovirus infection developed earlier ( p = 0.03). Patients receiving steroids had higher total cholesterol, LDL, and HDL levels ( p < 0.05) during follow-up, but no changes in the height Z-score were observed 1 year after transplantation. Basiliximab induction in combination with tacrolimus-based treatment avoided steroid requirements in 45% of the patients. Tacrolimus variability and trough levels below 6.4 ng/mL independently increased the risk of steroid requirement. Further efforts should be focused on personalizing immunosuppressive treatment.

Population pharmacokinetics of sublingually administered tacrolimus in infants and young children with liver transplantation

AIMS

Pharmacokinetics of tacrolimus after sublingual administration is not characterized in paediatric liver transplant patients. Therefore, we aimed to develop a population pharmacokinetic model of sublingually administered tacrolimus in patients who cannot swallow the capsules due to their age, sedation status and/or mechanical ventilation during the first weeks post-transplantation.

METHODS

Demographic, clinical and pharmacological variables, including tacrolimus whole blood concentrations obtained from therapeutic drug monitoring and data from dense-sampling pharmacokinetic profiles, were recorded in 26 paediatric patients with biliary atresia who underwent liver transplantation between 2016 and 2021. Population pharmacokinetic analysis was performed with NONMEM v7.4.

RESULTS

Disposition of tacrolimus was best characterized by a 2-compartment model with clearance achieving half of the maximum elimination capacity (CL_MAX  = 4.1 L/h) at 4.6 days post-transplantation (T₅₀ ). Compared to sedated patients, nonsedated status showed an increased first-order absorption rate constant (1.1 vs. 0.1 h^-1 ) and a 24% reduction in bioavailability (F_NS ) at 14 days post-transplant. The model was able to explain the oral absorption pattern in nonsedated patients as the result of gut bioavailability (0.9) and hepatic extraction ratio, with the latter being responsible for first-pass effects. Estimates of interindividual variability remained moderate (25.9% for the gut bioavailability) to high (79.8% for the apparent volume of distribution of the central compartment, and 101% for T₅₀ ).

CONCLUSION

A population pharmacokinetic model of sublingually administered tacrolimus in paediatric patients was developed to characterize different absorption mechanisms. Once the model is externally validated, the effect of post-transplant time on clearance and the sedation status may be considered in routine dosing management.

Childhood liver tumors in Argentina: Incidence trend and survival by treatment center. A report from the national pediatric cancer registry, ROHA network 2000-2015

BACKGROUND

Information on the epidemiology of pediatric liver tumors in Latin America is limited.

PURPOSE

To describe the incidence of liver tumors in a pediatric registry in Argentina according to geographic region, national trends over 16 years, and survival related to stage, age, sex, and care center.

METHODS

Newly diagnosed liver tumors cases are registered in the Argentine Pediatric Oncology Hospital Registry (ROHA) with an estimated coverage of 91% of national cases. Age-standardized incidence rate per millon (ASR) was calculated based on the National Vital Statistics Reports. Five-year overall survival (OS) was estimated using the Kaplan-Meier method. The log-rank test was used to compare subgroup survival.

RESULTS

Two hundred seven cases of hepatoblastoma (HB) and 73 of hepatocellular carcinoma (HCC) were identified. ASR of liver tumors was 1.8/million (95% confidence Interval [CI], 1.6-2.0) per year. ASR was 1.4 (1.2-1.6) for HB and 0.4 (0.3-0.5) for HCC. For HB, the highest incidence was found in the northwest region including the Altiplano. OS was 60.4% (53.4-66.8) for HB and 36.1% (25.2-47.2) for HCC. Five-year survival rate of children with metastatic HB treated at liver transplant hospitals (LTH) was 54.2% (30.3-73.0) compared to 13.3% (2.2-34.6) for those seen at other hospitals (OH) (P = .02), while for HCC this rate was 46.3% (30.7-60.6) at LTH compared to 17.5% (3.1-41.9) at OH (P = .01).

CONCLUSIONS

The incidence rate of pediatric liver tumors was stable over the 16-year study period. Patients may benefit if at treatment initiation they are evaluated jointly with LTH specialists to define treatment strategies.

Prognostic Factors in Pediatric Early Liver Retransplantation

The most common indications for early liver retransplantation (eRe-LT) are vascular complications and primary nonfunction (PNF). These patients are usually in a critical clinical condition that can affect their chances of survival. In fact, the survival of these patients is usually lower compared with the patients undergoing a first transplant. To the best of our knowledge, no specific series of pediatric patients undergoing eRe-LT has been published to date. Therefore, the aim of this study is to report the results of eRe-LT and to analyze factors potentially related to success or failure. Our work is of a retrospective cohort study of patients who underwent eRe-LT at the Juan P. Garrahan Pediatric Hospital of Buenos Aires, Argentina, between May 1995 and December 2018 (n = 60). Re-LT was considered early when performed ≤30 days after the previous LT. A total of 40 (66.7%) patients were enrolled due to vascular causes and 20 (33.3%) were enrolled because of PNF. Of all the relisted patients, 36 underwent eRe-LT, 14 died on the waiting list, and 10 recovered without eRe-LT. A total of 23 (63.9%) patients died after eRe-LT, most of them due to infection-related complications. Survival rates at 1 and 5 years were 42.4% and 33.9%, respectively. On univariate logistic regression analysis, Pediatric End-Stage Liver Disease (PELD)/Model for End-Stage Liver Disease (MELD) scores, transplant era, and advanced life support at eRe-LT were found to be related to 60-day mortality. However, on multivariate analysis, era (odds ratio [OR], 9.3; 95% confidence interval [CI], 1.19-72.35; P = 0.033) and PELD/MELD scores (OR, 1.07; 95% CI, 1-1.14; P = 0.036) were significantly associated with 60-day patient mortality. This study found that the level of acuity before retransplant, measured by the requirement of advanced life support and the PELD/MELD score at eRe-LT, was significantly associated with the chances of post-eRe-LT patient survival.

Changing Etiologies and Prognostic Factors in Pediatric Acute Liver Failure

After the implementation of universal hepatitis A virus vaccination in Argentina, the outcome of pediatric acute liver failure (PALF) remains unknown. We aimed to identify variables associated with the risk of liver transplantation (LT) or death and to determine the causes and short-term outcomes of PALF in Argentina. We retrospectively included 135 patients with PALF listed for LT between 2007 and 2016. Patients with autoimmune hepatitis (AIH), Wilson's disease (WD), or inborn errors of metabolism (IEM) were classified as PALF-chronic liver disease (CLD), and others were classified as "pure" PALF. A logistic regression model was developed to identify factors independently associated with death or need of LT and risk stratification. The most common etiologies were indeterminate (52%), AIH (23%), WD (6%), and IEM (6%). Overall, transplant-free survival was 35%, whereas 50% of the patients underwent LT and 15% died on the waiting list. The 3-month risk of LT or death was significantly higher among patients with pure PALF compared with PALF-CLD (76.5% versus 42.5%; relative risk, 1.8 [1.3-2.5]; P < 0.001), and 3 risk factors were independently associated with worse outcome: international normalized ratio (INR) ≥3.5 (odds ratio [OR], 3.1; 95% confidence interval [CI], 1.3-7.2]), bilirubin ≥17 mg/dL (OR, 4.4; 95% CI, 1.9-10.3]), and pure PALF (OR, 3.8; 95% CI, 1.6-8.9). Patients were identified by the number of risk factors: Patients with 0, 1, or ≥2 risk factors presented a 3-month risk of worse outcome of 17.6%, 36.6%, and 82%, respectively. In conclusion, although lacking external validation, this simple risk-staging model might help stratify patients with different transplant-free survival rates and may contribute to establishing the optimal timing for LT.

Prognostic factors for event-free survival in liver transplantation for hepatoblastoma: A single-center experience

Hepatoblastoma (HB) is the most common malignant liver tumor in children. Twenty percent of the cases may remain unresectable after neoadjuvant chemotherapy and, for these patients, liver transplant (LT) is an accepted therapeutic option. To analyze the risk factors to event-free survival (EFS) that influence the clinical outcome of patients with HB receiving LT, we retrospectively analyzed 21 patients with HB who underwent LT between January 1, 2005, and May 1, 2018. Overall survival (OS) was 90%. The univariate analysis shows that the AFP level at the time of LT was associated with a higher risk of EFS. With a ROC curve analysis, we established a cutoff point value of AFP levels at 16 000 ng/dL, with a sensitivity of 71.43% and a specificity of 85.71%. Multivariate analysis showed that patients with higher values of pretransplant AFP (>16 000 ng/dL) had a significantly higher risk of EFS than those transplanted with lower levels (HR: 10.180; 95% CI: 1.54-66.97; P = .02). Efforts should be made to improve the selection of candidates for LT for unresectable HB, aiming at a better definition of chemoresistance as a risk factor of poor outcomes.

Identification of Factors Affecting Tacrolimus Trough Levels in Latin American Pediatric Liver Transplant Patients

Tacrolimus is the cornerstone in pediatric liver transplant immunosuppression. Despite close monitoring, fluctuations in tacrolimus blood levels affect safety and efficacy of immunosuppressive treatments. Identifying the factors related to the variability in tacrolimus exposure may be helpful in tailoring the dose. The aim of the present study was to characterize the clinical, pharmacological, and genetic variables associated with systemic tacrolimus exposure in pediatric liver transplant patients. De novo transplant patients with a survival of more than 1 month were considered for inclusion and were genotyped for cytochrome P450 3A5 (CYP3A5). Peritransplant clinical factors and laboratory covariates were recorded retrospectively between 1 month and 2 years after transplant, including alanine aminotransferase (ALT), aspartate aminotransferase, hematocrit, and tacrolimus predose steady-state blood concentrations collected 12 hours after tacrolimus dosing. A linear mixed effect (LME) model was used to assess the association of these factors and the log-transformed tacrolimus dose-normalized trough concentration (logC0/D) levels. Bootstrapping was used to internally validate the final model. External validation was performed in an independent group of patients who matched the original population. The developed LME model described that logC0/D increases with increases in time after transplant (β = 0.019, 95% confidence interval [CI], 0.010-0.028) and ALT values (β = 0.00030, 95% CI, 0.00002-0.00056), whereas logC0/D is significantly lower in graft CYP3A5 expressers compared with nonexpressers (β = -0.349, 95% CI, -0.631 to -0.062). In conclusion, donor CYP3A5 genotype, time after transplant, and ALT values are associated with tacrolimus disposition between 1 month and 2 years after transplant. A better understanding of tacrolimus exposure is essential to minimize the occurrence of an out-of-range therapeutic window that may lead to adverse drug reactions or acute rejection.

Survival Time to Biopsy-Proven Acute Rejection and Tacrolimus Adverse Drug Reactions in Pediatric Liver Transplantation

BACKGROUND

Despite advances in surgical procedures and the optimization of immunosuppressive therapies in pediatric liver transplantation, acute rejection (AR) and serious adverse drug reaction (ADR) to tacrolimus still contribute to morbidity and mortality. Identifying risk factors of safety and efficacy parameters may help in optimizing individual immunosuppressive therapies. This study aimed to identify peritransplant predictors of AR and factors related to the risk of ADR to tacrolimus in a large Latin American cohort of pediatric liver transplant patients.

METHODS

We performed a retrospective cohort study in a pediatric liver transplant population (n = 72). Peritransplant variables were collected retrospectively including demographic, clinical, laboratory parameters, genomic (CYP3A5 donor and recipients polymorphism), and tacrolimus trough concentrations (C0) over a 2-year follow-up period. Variability in tacrolimus C0 was calculated using percent coefficient of variation and tortuosity. ADR- and AR-free survival rates were calculated using the Kaplan-Meier method, and risk factors were identified by multivariate Cox regression models.

RESULTS

Cox-proportional hazard models identified that high tortuosity in tacrolimus C0 was associated with an 80% increased risk of AR [hazard ratio (HR), 1.80; 95% confidence interval (CI), 1.01-3.22; P < 0.05], whereas steroid in maintenance doses decreased this risk (HR, 0.56; 95% CI, 0.31-0.99; P < 0.05). Forty-six patients experienced at least one ADR including hypomagnesemia, nephrotoxicity, hypertension, malignancies, and tremor as a first event. Multivariate analysis showed that C0 values 10 days before the event (HR, 1.25; 95% CI, 1.21-1.39; P < 0.0001) and CYP3A5 expresser recipients (HR, 2.05; 95% CI, 1.03-4.06; P < 0.05) were independent predictors of ADR.

CONCLUSIONS

Tacrolimus C0 values, its variability, and CYP3A5 polymorphisms were identified as risk factors of AR and tacrolimus ADR. This knowledge may help to control and reduce their incidence in pediatric liver transplant patients. Prospective studies are important to validate these results.

Waiting list outcome of Peld/Meld exceptions: A single-center experience in Argentina

As PELD/MELD-based allocation policy was adopted in Argentina in 2005, a system of exception points has been in place in order to award increased waitlist priority to those patients whose severity of illness is not captured by the PELD/MELD score. We aimed to investigate the WL outcome of patients with granted PELD/MELD exceptions. A retrospective cohort study was conducted in children under 18 years old. WL outcomes were evaluated using univariable analysis. From 07/2005 to 01/2014, 408 children were listed for LT. There were 304 classified by calculated PELD/MELD. During this time, 85 (30%) PELD/MELD exceptions were granted. In this cohort, 89.4% (76 of 85) were transplanted and 7.1% (6 of 85) died while on the WL. The remaining 3 pts (3.5%) were removed from the WL due to other causes. We compared the impact of PELD/MELD exceptions in those 85 patients to outcomes in 87 non-exception patients with PELD/MELD ≥19 points. Patients with the exception had significantly better access to WL and lower WL mortality. Our data suggest that children listed by PELD/MELD exceptions had an advantage compared to children with CLD with equivalent PELD/MELD listing priorities.

Pharmacoepidemiology of tacrolimus in pediatric liver transplantation

AEs during immunosuppressive treatment with tacrolimus are very common. We retrospectively evaluated FK safety and efficacy in a large pediatric liver transplant cohort in Latin America. During 2-year follow-up, we analyzed data from patients who underwent liver transplantation over the period 2010-2012 and recorded FK exposure, AEs, and AR episodes. AEs were classified according causality and severity. Tacrolimus exposure before and during AE was compared using Wilcoxon matched-pairs test. Kaplan-Meier curves were used for survival analysis. In total, 46 patients (out of 72 patients) experienced 69 AEs, such as hypomagnesemia (49%), PTLD (6%), hypertension (6%), and/or nephrotoxicity (22%). 43% of AEs were classified as moderate or serious, and 89% were assigned as probable or definitive. Patients who had one or more AR episodes accounted for 65%. The 12-month acute rejection-free survival was 41% (95% CI, 30.1%-53.1%). A significant difference was observed in FK trough concentrations before and during hypomagnesemia and nephrotoxicity (P<.05). This study is the first report of FK safety in a large group of pediatric liver transplant patients in Latin America. Children experience AEs, even in protocols with low FK doses. Therapeutic monitoring is an important tool to manage immunosuppressive schemes containing tacrolimus in vulnerable populations.

Split liver transplantation: Report of right and left graft outcomes from a multicenter Argentinean group

Grafts from split livers (SLs) constitute an accepted approach to expand the donor pool. Over the last 5 years, most Argentinean centers have shown significant interest in increasing the use of this technique. The purpose of this article is to describe and analyze the outcomes of right-side grafts (RSGs) and left-side grafts (LSGs) from a multicenter study. The multicenter retrospective study included data from 111 recipients of SL grafts from between January 1, 2009 and December 31, 2013. Incidence of surgical complications, patient and graft survival, and factors that affected RSG and LSG survival were analyzed. Grafts types were 57 LSG and 54 RSG. Median follow-up times for LSG and RSG were 46 and 42 months, respectively. The 36-month patient and graft survivals for LSG were 83% and 79%, respectively, and for RSG were 78% and 69%, respectively. Retransplantation rates for LSG and RSG were 3.5% and 11%, respectively. Arterial complications were the most common cause of early retransplantation (less than 12 months). Cold ischemia time (CIT) longer than 10 hours and the use of high-risk donors (age ≥ 40 years or body mass index ≥ 30 kg/m2 or ≥ 5 days intensive care unit stay) were independent factors for diminished graft survival in RSG. None of the analyzed variables were associated with worse graft survival in LSG. Biliary complications were the most frequent complications in both groups (57% in LSG and 33% in RSG). Partial grafts obtained from liver splitting are an excellent option for patients in need of liver transplantation and have the potential to alleviate the organ shortage. Adequate donor selection and reducing CIT are crucial for optimizing results.

Ultrasonography, laboratory, and cholangiography correlation of biliary complications in pediatric liver transplantation

The aim of this study is to correlate the US, laboratory, and cholangiography findings in pediatric liver transplant patients with biliary complications, trying to identify reliable decision-making tools for the management of these complications. Retrospective review was carried out of US results in 39 consecutive patients, from 2011 to 2013, with biliary complications after LT, documented by PTC. According to US biliary dilation, patients were classified as: mild, moderate, and severe, and according to laboratory findings as: normal or abnormal serum bilirubin and level of serum GGT. Data were correlated with PTC findings, divided in three groups: mild, moderate, and severe/occlusive BDS. There was no statistically significant correlation between the US findings and the laboratory findings and between US findings with PTC. There was a statistically significant correlation between GGT and cholangiography. In our series, abnormal US could not predict the severity of BDS on PTC. Bilirubin results were not able to predict the US findings either. GGT results demonstrated a statistically significant correlation with the severity of BDS found on PTC. These findings emphasize the role of GGT in the evaluation and decision of biliary interventions in pediatric liver transplant recipients.

[Surgical risk scale in pediatric surgery]

INTRODUCTION

The need to measure the level of surgical risk arises from its direct relationship with the development of postoperative complications and the use of hospital resources. The construction of a surgical risk scale (ERQ) for pediatric surgery should be based on a common language, by using a small number of easy to collect and reproduce variables. The objectives of this study were to construct an ERQ for pediatric patients and to analyze the surgical performance.

MATERIALS AND METHODS

We retrospectively analyzed 105 primary surgical procedures under general anesthesia performed by liver transplantation service at Hospital Garrahan, between 29/6/08 and 25/3/10. Newborn patients were not considered. The ERQ was built by adding patient risk factors (PRL): weight (< o > 10 kg), co-morbidities (coagulopathy-obesity-diabetes) and life support; and the magnitude level of the surgical procedure (SPL): surgical time and requirement of blood transfusions. The surgical performance was considered as a relation between the level of surgical risk and the post-operative results, measured with the classification of surgical complications proposed by Clavien et al (STROC). The main end point of the study was the STROC > or = 3 (severe complications). The ERQ predictive power for serious complications was compared with the anaesthetic risk (ASA). Descriptive and analytical statistics took place. The predictive value for complications was calculated by means of a ROC curve. The estimation of the risk was calculated by relative risk.

RESULTS

The ERQ was constituted on a continuum of 6 risk levels (2 to 7). The ROC's curve predictive power to determine the development of severe post-operative complications (STROC > or = 3) was 0.87 (CI 0,80-0,94) for the ERQ and 0.81 (CI 0,73-0,89) for the ASA. Level of > or = 5 of ERQ was the cut-off point that better predicted the development of STROC > or = 3.

CONCLUSION

The ERQ is an easy tool, useful to quantify and compare surgical risks and results. It showed a high predictive power of postoperative complications.

New superhard phases for three-dimensional C60-based fullerites

We have explored new possible phases of 3D C60-based fullerites using semiempirical potentials and ab initio density functional methods. We have found three closely related structures-two body-centered orthorhombic and one body-centered cubic-having 52, 56, and 60 tetracoordinated atoms per molecule. These 3D polymers result in semiconductors with bulk moduli near 300 GPa, and shear moduli around 240 GPa, which make them good candidates for new low density superhard materials.

Prenatal and postnatal corticosteroid therapy to prevent neonatal necrotizing enterocolitis: a controlled trial

To determine whether prenatal corticosteroid therapy would reduce the incidence of neonatal necrotizing enterocolitis (NEC), we assigned a total of 466 women admitted in premature labor either to receive placebo (group A, n = 256), if delivery was expected to occur within 24 hours of admission, or to receive betamethasone (group B, n = 210) if delivery was expected to take place more than 24 hours after admission. All women were free of severe medical complications or drug therapy; cases of intrauterine growth retardation or premature rupture of the membranes were excluded. Their newborn infants, excluding malformed, congenitally infected, and growth-retarded infants, were enrolled in the study unless they had died before the age of 10 postnatal days. Babies born to group A mothers (n = 248) were further assigned to a treatment group (group A1, n = 130) receiving dexamethasone, 2 mg/kg/day by intravenous injection during the first 7 days of life, or to a control group (group A2, n = 118) receiving 10% dextrose solution placebo. Group B infants (prenatal betamethasone, n = 205) received neither treatment nor placebo. The incidence of NEC in group A1 was 6.9% (9/130), and in group A2 it was 14.4% (17/118) (p less than 0.05). In group B the incidence was 3.4% (7/205); this was much lower than in group A2 (p less than 0.01) and lower than in group A combined (10.4%) (p less than 0.01). There was no death from NEC and no surgical intervention among group B patients. The mortality rate for group A1 (11%) was lower than for group A2 (56%) (p less than 0.02). There were fewer indications for surgical intervention for NEC in group A1 than in group A2. Histologic studies confirmed bowel ischemia in all specimens analyzed. These data support the hypothesis that the incidence of NEC is significantly reduced after prenatal steroid treatment. Although postnatal therapy with steroids does not decrease the incidence as effectively as prenatal therapy, it improves clinical outcome of NEC.

Fetal growth rates in Argentina--a national collaborative study. Value of local intrauterine growth charts

A sample of 7,520 pregnancies, representative of the national population of Argentina was used to construct intrauterine Growth Charts. These are applicable nationwide and since 1974, when first designed, have proved efficient and more reliable in evaluating Argentine neonates than the Colorado Growth Charts. We have now evaluated the usefulness and have shown that despite certain changes, the Charts remain accurate and valuable as they were when first elaborated. Argentine infants do not grow at the same rate as those in other countries and, as expected, social and geographic variations can influence fetal growth. This effort should encourage the undertaking of similar ones in other Latin American countries, as they represent unique populations in need of knowledge of their own growth patterns.