Pharmacokinetic-pharmacodynamic assessment of tacrolimus in liver-transplant recipients during the early post-transplantation period

External validation of population pharmacokinetic models of tacrolimus in Thai adult liver transplant recipients

OBJECTIVE

Several population pharmacokinetic models of tacrolimus in liver transplant patients were built, and their predictability was evaluated in their settings. However, the extrapolation in the prediction was unclear. This study aimed to evaluate the predictive performance of published tacrolimus models in adult liver transplant recipients using data from the Thai population as an external dataset.

METHODS

The selected published models were systematically searched and evaluated for their quality. The external dataset of patients who underwent the first liver transplant and received immediate-release tacrolimus was used to assess the predictive performance of each selected model. Trough concentrations between 3 and 6 months were retrospectively collected to evaluate the predictability of each model using prediction-based diagnostics, simulation-based diagnostics, and Bayesian forecasting.

RESULTS

Sixty-seven patients with 360 trough concentrations and eight selected published models were included in this study. None of the models met the predictive precision criteria in prediction-based diagnostics. Meanwhile, four published population pharmacokinetic models showed a normal distribution in NPDE testing. Regarding Bayesian forecasting, all models improved their forecasts with at least one prior information data point.

CONCLUSION

Bayesian forecasting is more accurate and precise than other testing methods for predicting drug concentrations. However, none of the evaluated models provides satisfactory predictive performance for generalization to Thai liver transplant patients. This underscores the need for future research to develop population PK models tailored to the Thai population. Such efforts should consider the inclusion of nonlinear pharmacokinetics and region-specific factors, including genetic variability, to improve model accuracy and applicability.

Immunosuppression Monitoring-What Clinician Needs to Know?

The liver is well known for its immunotolerance, but rejection without immunosuppression is frequently encountered post liver transplantation, especially in humans.1 Indeed, the amount of immunosuppression required post liver transplant is less compared to other organ transplants like kidney, heart, and intestine.2 Reports of successful weaning of immunosuppression have been reported but are not practiced for fear of unwanted alloimmune response leading to rejection. Life-long immunosuppression is needed in most patients for graft survival but is associated with side effects like renal dysfunction, metabolic abnormalities, or risk of de novo malignancies. Also, the appropriate dose of immunosuppression to achieve adequate graft function and prevention of toxicities is very important. One shoe does not fit all. There are significant individual variations in response and side effect profile. Also, the level of immunosuppression varies with the underlying liver disease like autoimmune disease requires higher immunosuppression. Thus, monitoring the adequate immunosuppression with the minimization of drug toxicity is imperative post-transplant. Unfortunately, the current methods for immunosuppression monitoring rely on testing the immunosuppressive drug levels rather than the immune system activity. We have discussed the concept of alloreactivity, available methods of immunosuppression and drug monitoring and investigational methods in this review.

Monitoring of Ex Vivo Cyclosporin a Activity in Healthy Volunteers Using T Cell Function Assays in Relation to Whole Blood and Cellular Pharmacokinetics

Therapeutic drug monitoring (TDM) of calcineurin inhibitors (i.e., tacrolimus and cyclosporin A) is standard of care after solid organ transplantation. Although the incidence of acute rejection has strongly decreased, there are still many patients who experience severe side effects or rejection after long-term treatment. In this healthy volunteer study we therefore aimed to identify biomarkers to move from a pharmacokinetic-based towards a pharmacodynamic-based monitoring approach for calcineurin inhibitor treatment. Healthy volunteers received a single dose of cyclosporine A (CsA) or placebo, after which whole blood samples were stimulated to measure ex vivo T cell functionality, including proliferation, cytokine production, and activation marker expression. The highest whole blood concentration of CsA was found at 2 h post-dose, which resulted in a strong inhibition of interferon gamma (IFNy) and interleukin-2 (IL-2) production and expression of CD154 and CD71 on T cells. Moreover, the in vitro effect of CsA was studied by incubation of pre-dose whole blood samples with a concentration range of CsA. The average in vitro and ex vivo CsA activity overlapped, making the in vitro dose–effect relationship an interesting method for prediction of post-dose drug effect. The clinical relevance of the results is to be explored in transplantation patients on calcineurin inhibitor treatment.

Can We Predict Individual Concentrations of Tacrolimus After Liver Transplantation? Application and Tweaking of a Published Population Pharmacokinetic Model in Clinical Practice

BACKGROUND

Various population pharmacokinetic models have been developed to describe the pharmacokinetics of tacrolimus in adult liver transplantation. However, their extrapolated predictive performance remains unclear in clinical practice. The purpose of this study was to predict concentrations using a selected literature model and to improve these predictions by tweaking the model with a subset of the target population.

METHODS

A literature review was conducted to select an adequate population pharmacokinetic model (L). Pharmacokinetic data from therapeutic drug monitoring of tacrolimus in liver-transplanted adults were retrospectively collected. A subset of these data (70%) was exploited to tweak the L-model using the $PRIOR subroutine of the NONMEM software, with 2 strategies to weight the prior information: full informative (F) and optimized (O). An external evaluation was performed on the remaining data; bias and imprecision were evaluated for predictions a priori and Bayesian forecasting.

RESULTS

Seventy-nine patients (851 concentrations) were enrolled in the study. The predictive performance of L-model was insufficient for a priori predictions, whereas it was acceptable with Bayesian forecasting, from the third prediction (ie, with ≥2 previously observed concentrations), corresponding to 1 week after transplantation. Overall, the tweaked models showed a better predictive ability than the L-model. The bias of a priori predictions was -41% with the literature model versus -28.5% and -8.73% with tweaked F and O models, respectively. The imprecision was 45.4% with the literature model versus 38.0% and 39.2% with tweaked F and O models, respectively. For Bayesian predictions, whatever the forecasting state, the tweaked models tend to obtain better results.

CONCLUSIONS

A pharmacokinetic model can be used, and to improve the predictive performance, tweaking the literature model with the $PRIOR approach allows to obtain better predictions.

Population Pharmacokinetic Models of Tacrolimus in Adult Transplant Recipients: A Systematic Review

BACKGROUND AND OBJECTIVES

Numerous population pharmacokinetic (PK) models of tacrolimus in adult transplant recipients have been published to characterize tacrolimus PK and facilitate dose individualization. This study aimed to (1) investigate clinical determinants influencing tacrolimus PK, and (2) identify areas requiring additional research to facilitate the use of population PK models to guide tacrolimus dosing decisions.

METHODS

The MEDLINE and EMBASE databases, as well as the reference lists of all articles, were searched to identify population PK models of tacrolimus developed from adult transplant recipients published from the inception of the databases to 29 February 2020.

RESULTS

Of the 69 studies identified, 55% were developed from kidney transplant recipients and 30% from liver transplant recipients. Most studies (91%) investigated the oral immediate-release formulation of tacrolimus. Few studies (17%) explained the effect of drug-drug interactions on tacrolimus PK. Only 35% of the studies performed an external evaluation to assess the generalizability of the models. Studies related variability in tacrolimus whole blood clearance among transplant recipients to either cytochrome P450 (CYP) 3A5 genotype (41%), days post-transplant (30%), or hematocrit (29%). Variability in the central volume of distribution was mainly explained by body weight (20% of studies).

CONCLUSION

The effect of clinically significant drug-drug interactions and different formulations and brands of tacrolimus should be considered for any future tacrolimus population PK model development. Further work is required to assess the generalizability of existing models and identify key factors that influence both initial and maintenance doses of tacrolimus, particularly in heart and lung transplant recipients.

Maintenance Immunosuppression in Solid Organ Transplantation: Integrating Novel Pharmacodynamic Biomarkers to Inform Calcineurin Inhibitor Dose Selection

Calcineurin inhibitors, the primary immunosuppressive therapy used to prevent alloreactivity of transplanted organs, have a narrow therapeutic index. Currently, treatment is individualized based on clinical assessment of the risk of rejection or toxicity guided by trough concentration monitoring. Advances in immune monitoring have identified potential markers that may have value in understanding calcineurin inhibitor pharmacodynamics. Integration of these markers has the potential to complement therapeutic drug monitoring. Existing pharmacokinetic-pharmacodynamic (PK-PD) data is largely limited to correlation between the biomarker and trough concentrations at single time points. Immune related gene expression currently has the most evidence supporting PK-PD integration. Novel biomarker-based approaches to pharmacodynamic monitoring including development of enhanced PK-PD models are proposed to realize the full clinical benefit.

Pharmacogenetic-Whole blood and intracellular pharmacokinetic-Pharmacodynamic (PG-PK2-PD) relationship of tacrolimus in liver transplant recipients

Tacrolimus (TAC) is the cornerstone of immunosuppressive therapy in liver transplantation. This study aimed at elucidating the interplay between pharmacogenetic determinants of TAC whole blood and intracellular exposures as well as the pharmacokinetic-pharmacodynamic relationship of TAC in both compartments. Complete pharmacokinetic profiles (Predose, and 20 min, 40 min, 1h, 2h, 3h, 4h, 6h, 8h, 12h post drug intake) of twice daily TAC in whole blood and peripheral blood mononuclear cells (PBMC) were collected in 32 liver transplanted patients in the first ten days post transplantation. A non-parametric population pharmacokinetic model was applied to explore TAC pharmacokinetics in blood and PBMC. Concurrently, calcineurin activity was measured in PBMC. Influence of donor and recipient genetic polymorphisms of ABCB1, CYP3A4 and CYP3A5 on TAC exposure was assessed. Recipient ABCB1 polymorphisms 1199G>A could influence TAC whole blood and intracellular exposure (p<0.05). No association was found between CYP3A4 or CYP3A5 genotypes and TAC whole blood or intracellular concentrations. Finally, intra-PBMC calcineurin activity appeared incompletely inhibited by TAC and less than 50% of patients were expected to achieve intracellular IC₅₀ concentration (100 pg/millions of cells) at therapeutic whole blood concentration (i.e.: 4–10 ng/mL). Together, these data suggest that personalized medicine regarding TAC therapy might be optimized by ABCB1 pharmacogenetic biomarkers and by monitoring intracellular concentration whereas the relationship between intracellular TAC exposure and pharmacodynamics biomarkers more specific than calcineurin activity should be further investigated.

Toward a robust tool for pharmacokinetic-based personalization of treatment with tacrolimus in solid organ transplantation: A model-based meta-analysis approach

AIMS

The objective of this study is to develop a generic model for tacrolimus pharmacokinetics modelling using a meta-analysis approach, that could serve as a first step towards a prediction tool to inform pharmacokinetics-based optimal dosing of tacrolimus in different populations and indications.

METHODS

A systematic literature review was performed and a meta-model developed with NONMEM software using a top-down approach. Historical (previously published) data were used for model development and qualification. In-house individual rich and sparse tacrolimus blood concentration profiles from adult and paediatric kidney, liver, lung and heart transplant patients were used for model validation. Model validation was based on successful numerical convergence, adequate precision in parameter estimation, acceptable goodness of fit with respect to measured blood concentrations with no indication of bias, and acceptable performance of visual predictive checks. External validation was performed by fitting the model to independent data from 3 external cohorts and remaining previously published studies.

RESULTS

A total of 76 models were found relevant for meta-model building from the literature and the related parameters recorded. The meta-model developed using patient level data was structurally a 2-compartment model with first-order absorption, absorption lag time and first-time varying elimination. Population values for clearance, intercompartmental clearance, central and peripheral volume were 22.5 L/h, 24.2 L/h, 246.2 L and 109.9 L, respectively. The absorption first-order rate and the lag time were fixed to 3.37/h and 0.33 hours, respectively. Transplanted organ and time after transplantation were found to influence drug apparent clearance whereas body weight influenced both the apparent volume of distribution and the apparent clearance. The model displayed good results as regards the internal and external validation.

CONCLUSION

A meta-model was successfully developed for tacrolimus in solid organ transplantation that can be used as a basis for the prediction of concentrations in different groups of patients, and eventually for effective dose individualization in different subgroups of the population.

Tacrolimus diffusion across the peripheral mononuclear blood cell membrane: impact of drug transporters

Measuring tacrolimus (TAC) concentration in peripheral blood mononuclear cells (PBMCs) could better reflect the drug effect on its target (calcineurin (CaN) in lymphocytes) than whole blood concentrations. Mechanisms influencing TAC diffusion into PBMC are not well characterized. This work aimed at describing, ex vivo, TAC diffusion kinetics into PBMC and investigating the contribution of membrane transporters to regulate TAC intracellular concentration as well as the impact on CaN activity. PBMCs were incubated with TAC for 5 min to 4 h and under several experimental conditions: 37 °C (physiological conditions), 4 °C (inhibition of influx and efflux active transport), 37 °C + transporter inhibitors (verapamil, carvedilol, and probenecid and bromosulfophthalein, respectively, inhibitors of P-gp, OAT, and OATP). TAC concentration and CaN activity were measured in PBMC using liquid chromatography coupled with mass spectrometry. TAC intra-PBMC concentration was maximal after 1 h of incubation. Mean TAC PMBC concentrations were significantly lower in samples incubated at 4 °C compared to the 37 °C groups. Addition of verapamil slightly increased TAC accumulation in PBMC while other inhibitors had no effect. A significant correlation was found between TAC intra-PBMC concentration and the level of inhibition of CaN. Using an ex vivo cellular model, these results suggest that P-gp is involved in the drug efflux from PBMC while influx active transporters likely to regulate TAC intra-PBMC disposition remain to be identified. TAC concentration in PBMC is correlated with its pharmacodynamic effect. Then, TAC intra-PBMC concentration appears to be a promising biomarker to refine TAC therapeutic drug monitoring.

Pharmacodynamic Monitoring of Tacrolimus-Based Immunosuppression in CD14+ Monocytes After Kidney Transplantation

BACKGROUND

Monocytes significantly contribute to ischemia-reperfusion injury and allograft rejection after kidney transplantation. However, the knowledge about the effects of immunosuppressive drugs on monocyte activation is limited. Conventional pharmacokinetic methods for immunosuppressive drug monitoring are not cell type-specific. In this study, phosphorylation of 3 signaling proteins was measured to determine the pharmacodynamic effects of immunosuppression on monocyte activation in kidney transplant patients.

METHODS

Blood samples from 20 kidney transplant recipients were monitored before and during the first year after transplantation. All patients received induction therapy with basiliximab, followed by tacrolimus (TAC), mycophenolate mofetil, and prednisolone maintenance therapy. TAC whole-blood predose concentrations were determined using an antibody-conjugated magnetic immunoassay. Samples were stimulated with phorbol 12-myristate 13-acetate (PMA)/ionomycin, and phosphorylation of p38MAPK, ERK, and Akt in CD14 monocytes was quantified by phospho-specific flow cytometry.

RESULTS

Phosphorylation of p38MAPK and Akt in monocytes of immunosuppressed recipients was lower after 360 days compared with before transplantation in the unstimulated samples [mean reduction in median fluorescence intensity 36%; range -28% to 77% for p-p38MAPK and 20%; range -22% to 53% for p-Akt; P < 0.05]. P-ERK was only decreased at day 4 after transplantation (mean inhibition 23%; range -52% to 73%; P < 0.05). At day 4, when the highest whole-blood predose TAC concentrations were measured, p-p38MAPK and p-Akt, but not p-ERK, correlated inversely with TAC (rs = -0.65; P = 0.01 and rs = -0.58; P = 0.03, respectively).

CONCLUSIONS

Immunosuppressive drug combination therapy partially inhibits monocyte activation pathways after kidney transplantation. This inhibition can be determined by phospho-specific flow cytometry, which enables the assessment of the pharmacodynamic effects of immunosuppressive drugs in a cell type-specific manner.

In vitro immune cell monitoring as a guide for long-term immunosuppression in adult liver transplant recipients

Backgrounds/Aims

We evaluated the clinical usability of immune cell monitoring in adult liver transplantation (LT) recipients.

Methods

This study was composed of two parts as using calcineurin phosphatase (CNP) activity assay and ImmuKnow assay independently as in vitro monitoring tools of immune cell function in adult LT recipients.

Results

There was a rough correlation between CNP activity and tacrolimus concentration in 33 patients. This association was evident in patients who were only administered tacrolimus, but disappeared after the co-administration of mycophenolate. In 118 healthy individuals, the mean proportion of helper T-cells was 37.4±8.1%. According to ImmuKnow assay, their immune responses were strong in 12 patients (10.2%), moderate in 92 patients (78.0%), and low in 14 patients (11.9%). In 85 patients waiting for LT, there was a rough correlation between the ImmuKnow ATP level and age. Their immune responses were strong in 0 patients (0%), moderate in 8 patients (9.4%), and low in 77 patients (90.6%). There was a difference in the ImmuKnow ATP levels between healthy individuals and patients with liver disease. In 137 LT recipients, there was no correlation between the ImmuKnow ATP levels and tacrolimus concentration. This trend did not change after grouping the patients according to co-administration with mycophenolate. Eight recipients experienced acute rejection, but none showed strong immune response.

Conclusions

We think that both CNP activity assay and ImmuKnow assay are too limited to objectively determine the level of immunosuppression. Further studies should be performed to identify other methods for immune function monitoring.

Determination of the most influential sources of variability in tacrolimus trough blood concentrations in adult liver transplant recipients: a bottom-up approach

Tacrolimus, an immunosuppressant drug, presents a narrow therapeutic window and a large pharmacokinetic variability with poor correlation between drug dosing regimen and blood concentration. The objective was to identify predictive factors influencing tacrolimus trough concentrations (C0) using a bottom-up approach. A physiologically based pharmacokinetic (PBPK) model of tacrolimus was proposed, taking into account the body weight, the proportion of fat (P(fat)), hematocrit, lipid fraction of organs, typical intrinsic clearance (CLi(typ)), CYP3A5 genotype of liver donor, plasma unbound fraction of tacrolimus (fu(p)), and concomitant drugs (CYP3A4 inhibitors). For the evaluation of the PBPK model, mean C0 and concentrations 2 h after oral dose of tacrolimus were compared with those from 66 liver transplant recipients included in a multicentric pharmacokinetic study and were found very close. Tacrolimus concentration profiles were simulated in a virtual population defined by a set of covariate values similar to those from the real population. The sensitivity of tacrolimus C0 with respect to each covariate has been tested to identify the most influential ones. With the range of covariate values tested, the impact of each covariate on tacrolimus C0 may be ranked as follows: fu(p), CLi(typ), bioavailability, body weight, hematocrit, CYP3A5 polymorphism, P(fat), and CYP3A4 inhibitory drug-drug interactions. Values for initial dosing regimen of tacrolimus in order to reach a C0 of 10 ng/ml at day 5 (assuming a constant dosing schedule) as a function of CYP3A5 donor genotype and patient's hematocrit and body weight are proposed.

Calcineurin Activity Assay Measurement by Liquid Chromatography–Tandem Mass Spectrometry in the Multiple Reaction Monitoring Mode

BACKGROUND

Blood concentrations of the calcineurin inhibitors (CNIs) cyclosporine and tacrolimus are currently measured to monitor immunosuppression in transplant patients. The measurement of calcineurin (CN) phosphatase activity has been proposed as a complementary pharmacodynamic approach. However, determining CN activity with current methods is not practical. We developed a new method amenable to routine use.

METHODS

Using liquid chromatography–multiple reaction monitoring mass spectrometry (LC-MRM-MS), we quantified CN activity by measuring the dephosphorylation of a synthetic phosphopeptide substrate. A stable isotope analog of the product peptide served as internal standard, and a novel inhibitor cocktail minimized dephosphorylation by other major serine/threonine phosphatases. The assay was used to determine CN activity in peripheral blood mononuclear cells (PBMCs) isolated from 20 CNI-treated kidney transplant patients and 9 healthy volunteers.

RESULTS

Linearity was observed from 0.16 to 2.5 μmol/L of product peptide, with accuracy in the 15% tolerance range. Intraassay and interassay recoveries were 100.6 (9.6) and 100 (7.5), respectively. Michaelis–Menten kinetics for purified CN were Km = 10.7 (1.6) μmol/L, Vmax = 2.8 (0.3) μmol/min · mg, and for Jurkat lysate, Km = 182.2 (118.0) μmol/L, Vmax = 0.013 (0.006) μmol/min · mg. PBMC CN activity was successfully measured in a single tube with an inhibitor cocktail.

CONCLUSIONS

Because LC-MRM-MS is commonly used in routine clinical dosage of drugs, this CN activity assay could be applied, with parallel blood drug concentration monitoring, to a large panel of patients to reevaluate the validity of PBMC CN activity monitoring.

Application of low dose of FK506 in pancreas transplantation model in Wistar-SD rats

OBJECTIVE

To probe into application of low dose of FK506(Tacrolimus) in pancreas transplantation.

METHODS

Effects of low-dose FK506 (Tacrolimus) in pancreas transplantation with examination of ELISA Electron microscopy and TUNEL by method of random control were studied.

RESULTS

Blood glucose concentration in control group is higher than that in treated group A (FK506) and treated group B (CsA) 7 days after transplantation (p < 0.05). Serum C-peptide and insulin concentrations in control group are less than that in treated group A (FK506) and treated group B (CsA) 7 days after transplantation (p < 0.05). Blood glucose, serum C-peptide and insulin concentrations are same as that in control group, group A (FK506) and group B (CsA) (p > 0.05).There are more apoptotic nuclei in control group than that in treated group A (FK506) and treated group B (CsA) (p < 0.05). There is no significant difference between group A (FK506) and treated group B (CsA) in sum of apoptotic nuclei (p > 0.05). There is no significant difference among treated group A (FK506) and treated group B (CsA) in electron microscopy fields.

CONCLUSION

Low-dose FK506 applied in pancreas transplantation could not only be effective for immunosuppressive, but also be safe for islet cells of pancreas.

Significance of trough monitoring for tacrolimus blood concentration and calcineurin activity in adult patients undergoing primary living-donor liver transplantation

PURPOSE

Tacrolimus pharmacokinetics and calcineurin activity in peripheral blood mononuclear cells (PBMCs) were investigated in adult patients undergoing primary living-donor liver transplantation (LDLT) in order to clarify the significance of monitoring the tacrolimus blood trough concentration during the early post-transplantation period.

METHODS

Fourteen patients were enrolled in this study, and time-course data following the oral administration of a conventional tacrolimus formulation twice daily were obtained at 1 and 3 weeks post-transplantation. The concentration of tacrolimus in whole blood and calcineurin activity in PBMCs were measured.

RESULTS

The apparent clearance of tacrolimus significantly increased at 3 weeks versus 1 week post-transplantation, although the trough concentration did not significantly differ at these time points. The concentration at each sampling time, except at 1 h post-dose, correlated well with the area under the concentration-time curve from 0 to 12 h (AUC(0-12)). Neither the concentration at the trough time point nor AUC(0-12) was correlated with the area under the calcineurin activity-time curve from 0 to 12 h; however, calcineurin activity at the trough time point was strongly correlated with the latter (r (2) > 0.92).

CONCLUSIONS

Based on these results, trough concentration monitoring can be considered an appropriate procedure for routine tacrolimus dosage adjustment in adult LDLT patients. Monitoring of calcineurin activity at the trough time point was also found to be potentially useful for predicting the immunological status of the patient during the tacrolimus dosing interval.

Deficiency in calcineurin activity in liver transplantation candidates with alcoholic cirrhosis or hepatocellular carcinoma

BACKGROUND

Tacrolimus and cyclosporin inhibits the activity of calcineurin, a serine/threonine phosphatase that is involved in many physiological and pathological pathways. However, the baseline calcineurin phosphatase activity (CPA) measured before the transplant is unknown. In this study, we determine baseline CPA in liver transplant (LT) candidates and explore some factors that might modify it.

PATIENTS AND METHODS

Thirty-two consecutive LT candidates (25 men, seven women, average age 53.4 years) were included. Seven millilitres of whole blood was collected from each patient. CPA was determined in lymphocytes quantifying a dephosphorylated peptide phosphorylated previously (D-L-D-V-P-I-P-G-R-F-D-R-R-V-S-V-A-A-E) by high-performance liquid chromatography. The relationship between CPA and the quantitative variables was tested according to Pearson's correlation. A two-way analysis of variance was performed to test the independent role of categorical parameters in CPA.

RESULTS

The median CPA was significantly lower in LT candidates than in healthy volunteers [179.2 (146.9-226.3) vs 247.8 (220.9-292.5) pmol/min/10(6) peripheral blood mononuclear cell (PBMC), respectively, P=0.0002]. CPA was also significantly lower in alcoholic cirrhosis (152.2 vs 211.1 pmol/min/10(6) PBMC, P=0.04) and in the presence of hepatocellular carcinoma (HCC) (152.0 vs 213.5 pmol/min/10(6) PBMC, P=0.0074) compared with other liver diseases. A two-way analysis of variance showed that these parameters were independently associated with lower CPA (P=0.05 for alcohol and P=0.0056 for HCC respectively).

CONCLUSION

This pilot study showed a lower CPA in patients with AC and HCC. This phenomenon may contribute towards lowering the risk of acute rejection in these patients after LT and, on the other hand, may increase the risk of de novo cancers.