Tacrolimus trough levels, rejection and renal impairment in liver transplantation: a systematic review and meta-analysis

Review on immunosuppression in liver transplantation

The optimal level of immunosuppression in solid organ transplantation, in particular for the liver, is a delicate balance between the benefit of preventing rejection and the adverse side effects of immunosuppression. There is uncertainty about when this level is achieved in any individual recipient. Immunosuppression regimens vary between individual centers and changes with time as new agents and data are available. Presently concerns about the adverse side effects of calcineurin inhibitor, the main class of immunosuppressive agents used in liver transplantation (LT), has led to consideration of the use of antibody induction therapies for patients at higher risk of developing adverse side effects. The longevity of the transplanted organ is potentially improved by better management of rejection episodes and special consideration for tailoring of immunosuppression to the individual with viral hepatitis C, hepatocellular carcinoma or pregnancy. This review provides an overview of the current strategies for post LT immunosuppression and discusses modifications to consider for special patient populations.

Is minimal, [almost] steroid-free immunosuppression a safe approach in adult liver transplantation? Long-term outcome of a prospective, double blind, placebo-controlled, randomized, investigator-driven study

OBJECTIVE

To investigate the safety of minimal immunosuppression (IS) in liver transplantation (LT).

BACKGROUND

The lack of long-term follow-up studies, including pathologic data, has led to a protean handling of IS in LT.

METHODS

Between February 2000 and September 2004, 156 adults were enrolled in a prospective, randomized, double-blind, placebo-controlled minimization trial comparing tacrolimus placebo (TAC-PLAC) and TAC short-term steroid (TAC-STER) IS. All patients had a minimum clinical, biochemical, and histological follow-up of 5 years.

RESULTS

Five-year actual patient and graft survival rates in TAC-PLAC and TAC-STER groups were 78.1% and 82.1% (P=0.89) and 74.2% and 76.9% (P=0.90), respectively. Five-year biopsies were available in 112 (89.6%) of 125 survivors. Twelve patients refused a biopsy because of their excellent evolution; tissue material was insufficient in 1 patient; 11 had normal liver tests; and 2 patients had developed alcoholic and secondary biliary cirrhosis. Histology was normal in 44 (39.3%) patients; 35 (31.3%) had disease recurrence. The remaining biopsies showed nonspecific chronic hepatitis (14.3%), mild inflammatory infiltrates (10.7%), and steatosis (3.5%). All findings were equally distributed between both groups. In each group, 3 patients (4.8%) presented with acute cellular rejection after the first year and only 1 (0.9%) TAC-PLAC patient developed chronic rejection after IS withdrawal because of pneumonitis. Arterial hypertension, diabetes mellitus, renal insufficiency, hypercholesterolemia, gout, and obesity were equally low in both groups.

CONCLUSIONS

Excellent long-term results can be obtained under minimal IS and absence of steroids. TAC-based monotherapy is feasible in most adult liver recipients until 5 years of follow-up.

Lack of agreement for defining 'clinical suspicion of rejection' in liver transplantation: a model to select candidates for liver biopsy

The gold standard to diagnose acute cellular rejection (ACR) after liver transplantation (LT) is histological evaluation, but there is no consensus to select patients for liver biopsy. We aimed to evaluate the agreement among clinicians to select candidates for liver biopsy early after LT. From a protocol biopsy population (n = 690), we randomly selected 100 LT patients in whom the biopsy was taken 7-10 days after LT. The clinical information between LT and protocol biopsy was given to nine clinicians from three transplant centres who decided whether a liver biopsy was needed. The agreement among clinicians to select candidates for liver biopsy was poor: κ = 0.06-0.62, being κ < 0.40 in 76% of comparisons. The concordance between indication for liver biopsy and moderate-severe ACR in the protocol biopsy was κ < 0.30 in all cases. A multivariate model based on the product age-by-MELD (OR = 0.81; P = 0.013), delta eosinophils (OR = 1.5; P = 0.002) and mean tacrolimus trough concentrations <6 ng/ml within the prior 4 days (OR = 11.4; P = 0.047) had an AUROC = 0.84 to diagnose moderate-severe histological ACR. In conclusion, the agreement among clinicians to select patients for liver biopsy is very poor. If further validated the proposed model would provide an objective method to select candidates for liver biopsy after LT.

Is there such a thing as protocol immunosuppression in liver transplantation?

Protocol immunosuppression in liver transplantation is largely an outdated concept. Immunosuppression is now personalized to the individual patient on the basis of several factors including underlying etiology of original liver disease (e.g., HCV, hepatocellular carcinoma), renal function, metabolic co-morbidities and the patient's immunological state. These include omission of corticosteroids in HCV infection and those with major metabolic risk factors, the minimization of calcineurin inhibitors in the presence of renal dysfunction and the use of mTOR inhibitors in patients with malignancy. The basis for such decision-making is discussed in this editorial.

An analysis of tacrolimus-related complications in the first 30 days after liver transplantation

OBJECTIVES

Orthotopic liver transplantation has improved survival in patients with end-stage liver disease; however, therapeutic strategies that achieve ideal immunosuppression and avoid early complications are lacking. To correlate the dose and level of Tacrolimus with early complications, e.g., rejection, infection and renal impairment, after liver transplantation. From November 2011 to May 2013, 44 adult liver transplant recipients were studied in this retrospective comparative study.

RESULTS

The most frequent indication for liver transplantation was hepatitis C cirrhosis (47.7%), with a higher prevalence observed in male patients (68.18%). The ages of the subjects ranged from 19-71 and the median age was 55.5 years. The mean length of the hospital stay was 16.1±9.32 days and the mean Model for End-stage Liver Disease score was 26.18±4.28. There were five cases of acute cellular rejection (11.37%) and 16 cases of infection (36.37%). The blood samples that were collected and analyzed over time showed a significant correlation between the Tacrolimus blood level and the deterioration of glomerular filtration rate and serum creatinine (p<0.05). Patients with infections had a higher serum level of Tacrolimus (p = 0.012). The dose and presence of rejection were significantly different (p = 0.048) and the mean glomerular filtration rate was impaired in patients who underwent rejection compared with patients who did not undergo rejection (p = 0.0084).

CONCLUSION

Blood Tacrolimus levels greater than 10 ng/ml were correlated with impaired renal function. Doses greater than 0.15 mg/kg/day were associated with the prevention of acute cellular rejection but predisposed patients to infectious disease.

''Minimizing tacrolimus'' strategy and long-term survival after liver transplantation

AIM: To investigate the effect of the ‘‘minimizing tacrolimus’’ strategy on long-term survival of patients after liver transplantation (LT).

METHODS: We conducted a retrospective study of 319 patients who received LT between January 2009 and December 2011 at the First Affiliated Hospital of Zhejiang University School of Medicine. Following elimination of ineligible patients, 235 patients were included in the study. The relationship between early tacrolimus (TAC) exposure and survival period was analyzed by Kaplan Meier curves. Adverse effects related to TAC were evaluated by the χ² test. Routine monitoring of blood TAC concentration (TC) was performed using the PRO-Trac^TM II Tacrolimus Elisa Kit (Diasorin, United States).

RESULTS: Of 235 subjects enrolled in the study, 124 (52.8%) experienced adverse effects due to TAC. When evaluating mean TC, the survival time of patients with a mean TC < 5 ng/mL was significantly shorter than that in the other groups (911.3 ± 131.6 d vs 1381.1 ± 66.1 d, 911.3 ± 131.6 d vs 1327.3 ± 47.8 d, 911.3 ± 131.6 d vs 1343.2 ± 83.1 d, P < 0.05), while the survival times of patients with a mean TC of 5-7, 7-10 and 10-15 ng/mL were comparable. Adverse effects due to TAC in all four groups were not significantly different. When comparing the standard deviation (SD) of TC among the groups, the survival time of patients with a SD of 2-4 was significantly longer than that in the other groups (1388.8 ± 45.4 d vs 1029.6 ± 131.3 d, 1388.8 ± 45.4 d vs 1274.9 ± 57.0 d, P < 0.05), while in patients with a SD < 2 and SD > 4, the survival time was not statistically different. Adverse effects experienced in all three groups were not statistically different. In Cox regression analysis, male patients and those with a primary diagnosis of benign disease, mean TC > 5 ng/mL and TC SD 2-4 had better outcomes.

CONCLUSION: The early ‘‘minimizing tacrolimus’’ strategy with a mean TC of 5-10 ng/mL and SD of 2-4 was beneficial in terms of long-term survival after LT.

Effect of low-dose tacrolimus with mycophenolate mofetil on renal function following liver transplantation

AIM: To determine whether low-dose tacrolimus (TAC) combined with mycophenolate mofetil (MMF) is a safe approach to decrease the incidence of chronic kidney disease (CKD) in liver transplantation (LT) recipients.

METHODS: We analyzed the medical records of 689 patients who underwent LT between March 1999 and December 2012 in a single Chinese center. Immunosuppression was initiated with a calcineurin inhibitor (TAC or CSA) and prednisone with or without MMF. CKD is defined by the glomerular filtration rate (GFR), estimated by an abbreviated Modification of Diet in Renal Disease formula, < 60 mL/min per 1.73 m² for at least 3 consecutive months after LT. Individuals with TAC trough concentrations ≤ 8 ng/mL at 3 mo after LT were defined as the low-dose group. The incidence of CKD within 5 years was compared between the TAC group and the CSA group, as well as between four subgroups (low-dose and high-dose TAC groups with or without MMF).

RESULTS: No difference regarding the occurrence of pre-LT renal dysfunction or that of post-LT rejection was found between the TAC and CSA groups or between the four subgroups. With a definition of GFR < 60 mL/min per 1.73 m², the overall incidence of CKD was significantly higher in the CSA group than in the TAC group. The incidence of CKD in the low-dose TAC + MMF group (7.7%) was significantly lower than that observed in the low-dose TAC group (15.9%), high-dose TAC group (24.6%) and high-dose TAC + MMF group (18.5%). The cumulative 1-, 3- and 5-year incidence rates of CKD were 12.7%, 14.5% and 16.7%, respectively. The cumulative 5-year survival rates were 61.7% and 82.2% in patients with or without CKD, respectively.

CONCLUSION: In LT patients, the choice of immunosuppressive therapy appears to affect renal function and patient survival.

Liver transplantation: immunosuppression and oncology

PURPOSE OF REVIEW

Long-term survival of liver transplant recipients is threatened by increased rates of de-novo malignancy and recurrence of hepatocellular carcinoma (HCC), both events tightly related to immunosuppression.

RECENT FINDINGS

There is accumulating evidence linking increased exposure to immunosuppressants and carcinogenesis, particularly concerning calcineurin inhibitors (CNIs), azathioprine and antilymphocyte agents. A recent study including 219 HCC transplanted patients showed that HCC recurrence rates were halved if a minimization of CNIs was applied within the first month after liver transplant. With mammalian target of rapamycin (mTOR) inhibitors as approved immunosuppressants for liver transplant patients, pooled data from several retrospective studies have suggested their possible benefit for reducing HCC recurrence.

SUMMARY

Randomized controlled trials with sufficiently long follow-up are needed to evaluate the influence of different immunosuppression protocols in preventing malignancy after LT. Currently, early minimization of CNIs with or without mTOR inhibitors or mycophenolate seems a rational strategy for patients with risk factors for de-novo malignancy or recurrence of HCC after liver transplant. A deeper understanding of the immunological pathways of rejection and cancer would allow for designing more specific and safer drugs, and thus to prevent cancer after liver transplant.

Current strategies for immunosuppression following liver transplantation

BACKGROUND

New strategies for immunosuppression (IS) after liver transplantation (LTx) are in part responsible for the increased patient and graft survival seen over time. With a few basic exceptions-notably the continued use of steroids and calcineurin inhibitors (CNIs)-IS drugs and regimens being used today are different from those used 30 years ago. While graft loss due to acute or chronic rejection has become rare, the side effect burden of IS drugs exerts a significant toll on patients.

CONCEPTS/TRENDS

CNIs continue to form the backbone of IS regimens, although their use is hampered by nephrotoxicity and other adverse effects. Consequently, a variety of CNI reduction or withdrawal strategies have formed the basis of clinical trials or entered into clinical practice. These trials have included the use of everolimus, an mTOR inhibitor, and anti-interleukin-2 receptor antibodies. Basiliximab, as well as other lymphocyte nondepleting and depleting agents, have shown benefit in induction regimens.

SUMMARY

Along with steroid reduction or elimination, current strategies for IS after LTx continue to explore novel combinations of agents, with an aim toward striking a balance between diminution of rejection and the need for avoiding adverse effects of the IS drugs. Long-term maintenance strategies are also discussed in this review, as is development of tolerance and antibody-mediated rejection.

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.

Risk factors for acute renal injury in living donor liver transplantation: evaluation of the RIFLE criteria

Acute renal injury (ARI) is a serious complication after liver transplantation. This study investigated the usefulness of the RIFLE criteria in living donor liver transplantation (LDLT) and the prognostic impact of ARI after LDLT. We analyzed 200 consecutive adult LDLT patients, categorized as risk (R), injury (I), or failure (F), according to the RIFLE criteria. ARI occurred in 60.5% of patients: R-class, 23.5%; I-class, 21%; and F-class, 16%. Four patients in Group-A (normal renal function and R-class) and 26 patients in Group-B (severe ARI: I- and F-class) required renal replacement therapy (P < 0.001). Mild ARI did not affect postoperative prognosis regarding hospital mortality rate in Group A (3.2%), which was superior to that in Group B (15.8%; P = 0.0015). Fourteen patients in Group B developed chronic kidney disease (KDIGO stage 3/4). The 1-, 5- and 10-year survival rates were 96.7%, 90.6%, and 88.1% for Group A and 71.1%, 65.9%, and 59.3% for Group B, respectively (P < 0.0001). Multivariate analysis revealed risk factors for severe ARI as MELD ≥ 20 [odds ratio (OR) 2.9], small-for-size graft (GW/RBW <0.7%; OR 3.1), blood loss/body weight >55 ml/kg (OR 3.7), overexposure to calcineurin inhibitor (OR 2.5), and preoperative diabetes mellitus (OR 3.2). The RIFLE criteria offer a useful predictive tool after LDLT. Severe ARI, defined beyond class-I, could have negative prognostic impact in the acute and late postoperative phases. Perioperative treatment strategies should be designed and balanced based on the risk factors for the further improvement of transplant prognosis.

Reduced exposure to calcineurin inhibitors early after liver transplantation prevents recurrence of hepatocellular carcinoma

BACKGROUND & AIMS

Recurrence of hepatocellular carcinoma (HCC) is a major complication after liver transplantation (LT). The initial immunosuppression protocol may influence HCC recurrence, but the optimal regimen is still unknown.

METHODS

219 HCC consecutive patients under Milan criteria, who received an LT at 2 European centres between 2000 and 2010, were included. Median follow-up was 51 months (IQR 26-93). Demographic characteristics, HCC features, and immunosuppression protocol within the first month after LT were evaluated against HCC recurrence by using Cox regression.

RESULTS

In the explanted liver, 110 patients (50%) had multinodular HCC, and largest nodule diameter was 3±2.1cm. Macrovascular invasion was incidentally detected in 11 patients (5%), and microvascular invasion was present in 41 patients (18.7%). HCC recurrence rates were 13.3% at 3 years and 17.6% at 5 years. HCC recurrence was not influenced by the use/non-use of steroids and antimetabolites (p=0.69 and p=0.70 respectively), and was similar with tacrolimus or cyclosporine (p=0.25). Higher exposure to calcineurin inhibitors within the first month after LT (mean tacrolimus trough concentrations >10ng/ml or cyclosporine trough concentrations >300ng/ml), but not thereafter, was associated with increased risk of HCC recurrence (27.7% vs. 14.7% at 5 years; p=0.007). The independent predictors of HCC recurrence by multivariate analysis were: high exposure to calcineurin inhibitors defined as above (RR=2.82; p=0.005), diameter of the largest nodule (RR=1.31; p<0.001), microvascular invasion (RR=2.98; p=0.003) and macrovascular invasion (RR=4.57; p=0.003).

CONCLUSIONS

Immunosuppression protocols with early CNI minimization should be preferred in LT patients with HCC in order to minimize tumour recurrence.

Immunosuppression minimization vs. complete drug withdrawal in liver transplantation

Despite the increase in long-term survival, liver transplant recipients still exhibit higher morbidity and mortality than the general population. This is in part attributed to the lifelong administration of immunosuppression and its associated side effects. Several studies reported in the last decades have evaluated the impact of immunosuppression minimization in liver transplant recipients, but results have been inconsistent due to the heterogeneity of study designs and insufficient sample sizes. On the other hand, complete immunosuppression withdrawal has proven to be feasible in approximately 20% of carefully selected liver transplant recipients, especially in older patients and those with longer duration after transplantation. The long-term risks and clinical benefits of this strategy, however, also need to be clarified. As a consequence, and despite the general perception that a large proportion of liver recipients are over-immunosuppressed, it is currently not possible to derive evidence-based guidelines on how to manage long-term immunosuppression to improve clinical outcomes. Large clinical trials of drug minimization and/or withdrawal focused on clinically-relevant long-term outcomes are required. Development of personalized medicine tools and a deeper understanding of the pathogenesis of idiopathic inflammatory graft lesions will be pre-requisites to achieve these goals.

Tacrolimus predose concentrations do not predict the risk of acute rejection after renal transplantation: a pooled analysis from three randomized-controlled clinical trials(†)

Therapeutic drug monitoring (TDM) for tacrolimus (Tac) is universally applied. However, the concentration-effect relationship for Tac is poorly defined. This study investigated whether Tac concentrations are associated with acute rejection in kidney transplant recipients. Data from three large trials were pooled. We used univariate and multivariate analysis to investigate the relationship between biopsy-proven acute rejection (BPAR) and Tac predose concentration at five time points (day 3, 10 and 14, and month 1 and 6 after transplantation). A total of 136/1304 patients experienced BPAR, giving an overall incidence of 10.4%. We did not find any significant correlations between Tac predose concentrations and the incidence of BPAR at the different time points. In the multivariate analysis, only delayed graft function (DGF) and the use of induction therapy were independently correlated with BPAR, with an odds ratio of 2.7 [95% CI: 1.8-4.0; p < 0.001] for DGF and 0.66 [95% CI: 0.44-0.99; p = 0.049] for induction therapy. The other variables, including the Tac predose concentrations, were not statistically significantly associated with BPAR. We did not find an association between the Tac predose concentrations measured at five time points after kidney transplantation and the incidence of acute rejection occurring thereafter. Based on this study it is not possible to define the optimal target concentrations for Tac.

Early tacrolimus exposure after liver transplantation: relationship with moderate/severe acute rejection and long-term outcome

BACKGROUND & AIMS

Liver transplant (LT) patients might be overimmunosuppressed as recommendations for tacrolimus trough concentrations (TC) within 4-6 weeks after liver transplantation are set too high (10-15 ng/ml). Early tacrolimus exposure was evaluated in relation to acute rejection and long-term outcomes.

METHODS

Four hundred and ninety-three consecutive LT patients receiving tacrolimus as primary immunosuppression (1995-2008) were analyzed. Acute rejection was diagnosed using protocol biopsies at day 6.1 ± 2.5. Median follow-up was 7.3 years (IQR 3.9-10.5). Early tacrolimus exposure (<15 days) was evaluated against moderate/severe acute rejection, chronic rejection, graft loss, chronic renal impairment and mortality using multiple logistic and Cox regression.

RESULTS

Maintenance immunosuppression was tacrolimus monotherapy (48.1%), double therapy combination with antimetabolites or steroids (18%), or triple therapy combination with antimetabolites and steroids (33.9%). Histological grade of acute rejection was moderate in 157 cases (31.8%) and severe in 19 cases (3.9%). Tacrolimus TC>7 ng/ml on the day of protocol biopsy was associated with less moderate/severe rejection (23.8%) compared with<7 ng/ml (41.2%) (p = 0.004). Mean tacrolimus TC 7-10 ng/ml within 15 days after LT were associated with reduced risk of graft loss (RR = 0.46; p = 0.014) compared to TC 10-15 ng/ml. A peak TC>20 ng/ml within this period was independently related to higher mortality (RR = 1.67; p = 0.005), particularly due to cardiovascular events, infections and malignancy (RR = 2.15; p = 0.001). Early tacrolimus exposure did not influence chronic rejection (p = 0.58), or chronic renal impairment (p = 0.25).

CONCLUSIONS

During the first 2 weeks after LT, tacrolimus TC between 7 and 10 ng/ml are safe in terms of acute rejection and are associated with longer graft survival.