A Decade of Experience Using mTor Inhibitors in Liver Transplantation. J Transplant. 2011;2011:913094. [PMID: 21461386 PMCID: PMC3064995 DOI: 10.1155/2011/913094]

Prädiktoren für erfolgreiche Lebertransplantationen und Risikofaktoren

Die Lebertransplantation ist die einzige kurative Therapieoption einer chronischen Leberinsuffizienz im Endstadium. Daneben stellen onkologische Lebererkrankungen wie das HCC eine weitere Indikation für die Lebertransplantation dar, ebenso wie das akute Leberversagen.

Seit der ersten erfolgreichen Lebertransplantation durch Professor Thomas E. Starzl im Jahr 1967 haben sich nicht nur die chirurgischen, immunologischen und anästhesiologischen Techniken und Möglichkeiten geändert, sondern auch die Indikationen und das Patientengut. Hinzu kommt, dass die Empfänger ein zunehmendes Lebensalter und damit einhergehend mehr Begleiterkrankungen aufweisen.

Die Zahl an Lebertransplantationen ist weltweit weiter ansteigend. Es benötigen aber mehr Menschen eine Lebertransplantation, als Organe zur Verfügung stehen. Dies liegt am zunehmenden Bedarf an Spenderorganen bei gleichzeitig weiter rückläufiger Zahl postmortaler Organspenden.

Diese Diskrepanz zwischen Spenderorganen und Empfängern kann nur zu einem kleinen Teil durch Split-Lebertransplantationen oder die Leberlebendspende kompensiert werden.

Um den Spenderpool zu erweitern, werden zunehmend auch marginale Organe, die nur die erweiterten Spenderkriterien („extended donor criteria [EDC]“) erfüllen, allokiert. In manchen Ländern zählen hierzu auch die sogenannten DCD-Organe (DCD: „donation after cardiac death“), d. h. Organe, die erst nach dem kardiozirkulatorischen Tod des Spenders entnommen werden.

Es ist bekannt, dass marginale Spenderorgane mit einem erhöhten Risiko für ein schlechteres Transplantat- und Patientenüberleben nach Lebertransplantation einhergehen.

Um die Qualität marginaler Spenderorgane zu verbessern, hat sich eine rasante Entwicklung der Techniken der Organkonservierung über die letzten Jahre gezeigt. Mit der maschinellen Organperfusion besteht beispielsweise die Möglichkeit, die Organqualität deutlich zu verbessern. Insgesamt haben sich die Risikokonstellationen von Spenderorgan und Transplantatempfänger deutlich geändert.

Aus diesem Grunde ist es von großer Bedeutung, spezifische Prädiktoren für eine erfolgreiche Lebertransplantation sowie die entsprechenden Risikofaktoren für einen schlechten postoperativen Verlauf zu kennen, um das bestmögliche Transplantat- und Patientenüberleben nach Lebertransplantation zu ermöglichen.

Diese Einflussfaktoren, inklusive möglicher Risiko-Scores, sollen hier ebenso wie die neuen technischen Möglichkeiten in der Lebertransplantation beleuchtet werden.

Endoscopic retrograde cholangiopancreatography and liver biopsy in the evaluation of elevated liver function tests after liver transplantation

BACKGROUND

Abnormal liver function tests (LFTs) in post-liver transplant (LT) patients pose a challenge in the timing and selection of diagnostic modalities. There are little data regarding the accuracy of endoscopic retrograde cholangiopancreatography (ERCP) and liver biopsy (LB) in diagnosing post-transplant complications.

AIM

To evaluate the diagnostic performance of ERCP and LB in patients with non-vascular post-LT complications.

METHODS

This single-center retrospective study evaluated patients undergoing both ERCP and LB for evaluation of elevated LFTs within 6 mo of LT from 2000 to 2017. Diagnostic operating characteristics including accuracy, sensitivity and specificity for various diagnoses were calculated for ERCP and LB. The R factor (ratio of alkaline phosphatase to alanine aminotransferase) was also calculated for each patient.

RESULTS

Of the 1284 patients who underwent LT, 91 patients (74.7% males, mean age of 51) were analyzed. Anastomotic strictures (AS, 24.2%), acute cellular rejection (ACR, 11%) and concurrent AS/ACR (14.3%) were the most common diagnoses. ERCP carried an accuracy of 79.1% (95%CI: 69.3-86.9), LB had an accuracy of 93.4% (95%CI: 86.2-97.5), and the combination of the two had an accuracy of 100% (95%CI: 96-100). There was no difference between patients with AS and ACR in mean R factor (AS: 1.9 vs ACR: 1.1, P = 0.24). Adverse events did not differ between the two tests (ERCP: 3.1% vs LB: 1.1%, P = 0.31).

CONCLUSION

In patients with abnormal LFTs after LT without vascular complications, the combination of LB and ERCP carries low risk and improves diagnostic accuracy over either test alone.

Acute allograft rejection in liver transplant recipients: Incidence, risk factors, treatment success, and impact on graft failure

Objective This study was performed to identify risk factors for acute cellular rejection after liver transplantation (LT). Methods Consecutive LT recipients who underwent surgery in our institution from 2002 to 2015 were retrospectively evaluated. Results In total, 176 patients were eligible for statistical analysis. During a mean observation period of 61.1 ± 36.3 months, 43 episodes of acute rejection were evident. Of these, 34 (79.0%) were responsive to methylprednisolone, 3 (7.0%) were treated by adjusting the dosage of immunosuppressive agents, and 6 (14.0%) were methylprednisolone-resistant and treated using anti-thymocyte globulin. Biliary complications (odds ratio [OR] = 4.89, 95% confidence interval [CI] = 2.00-11.98); donor-negative, recipient-positive CMV mismatch (OR = 9.88, 95% CI = 1.18-82.36); sex mismatch (OR = 3.16, 95% CI = 1.31-8.10); and sex mismatch with a female donor (OR = 3.00, 95% CI = 1.10-7.58) were identified as significant risk factors for acute graft rejection after LT. Conclusion In patients who develop acute cellular rejection after LT, biliary complications should be evaluated as a potential cause. Most acute rejections after LT respond to bolus corticosteroid therapy.

The impact of immunosuppressant therapy on the recurrence of hepatitis C post-liver transplantation

The use of immunosuppressants to reduce the likelihood of acute graft rejections is a cornerstone in the post-transplantation management of recipients. However, these agents were always associated with increased risk of deleterious effects such as infections vulnerability and comorbidities. The objective of this review is to discuss the impact of different immunosuppression strategies used in liver transplant recipients (LTRs) on the recurrence of hepatitis C virus (HCV) infections after transplantation. Traditionally, corticosteroids were a mainstay in immunosuppressive regimens in LTRs. Several trials have suggested early tapering of corticosteroids or steroid-free immunosuppression protocols to minimize metabolic complications and other accompanied adverse events. However, there is no consistent agreement on the apparent benefit of steroid-avoidance regimens on HCV recurrence. At present, calcineurin inhibitors alone or in combination with other immunosuppressants are the standard regimen for immunosuppression in LTRs. Although the use of mycophenolate mofetil and sirolimus were sometimes associated with a significantly lower risk of liver injury as a result of HCV recurrence, they were associated with an increased risk of acute graft rejection compared to calcineurin inhibitors. Consequently, reducing the incidence of HCV recurrence in LTRs could be at the expense of other potential complications. The appropriate selection of adequate immunosuppression could diminish the associated increased risk of HCV recurrence after liver transplantation. However, further clinical studies are still pivotal to establish the appropriate/optimal immunosuppressive therapies for HCV-positive LTRs.

Erzhi Pill® Repairs Experimental Liver Injury via TSC/mTOR Signaling Pathway Inhibiting Excessive Apoptosis

The present study aimed to investigate the mechanism of hepatoprotective effect of Erzhi Pill (EZP) on the liver injury via observing TSC/mTOR signaling pathway activation. The experimental liver injury was induced by 2-acetylaminofluorene (2-AAF) treatment combined with partial hepatectomy (PH). EZP treated 2-AAF/PH-induced liver injury by the therapeutic and prophylactic administration. After the administration of EZP, the activities of aspartic transaminase (AST), alanine aminotransferase (ALT), alkaline phosphatase (AKP), and gamma-glutamyl transpeptidase (γ-GT) were decreased, followed by the decreased levels of hepatocyte apoptosis and caspase-3 expression. However, the secretion of albumin, liver weight, and index of liver weight were elevated. Microscopic examination showed that EZP restored pathological liver injury. Meanwhile, Rheb and mammalian target of rapamycin (mTOR) activation were suppressed, and tuberous sclerosis complex (TSC) expression was elevated in liver tissues induced by 2-AAF/PHx and accompanied with lower-expression of Bax, Notch1, p70S6K, and 4E-EIF and upregulated levels of Bcl-2 and Cyclin D. Hepatoprotective effect of EZP was possibly realized via inhibiting TSC/mTOR signaling pathway to suppress excessive apoptosis of hepatocyte.

Activation of Autophagy by Everolimus Confers Hepatoprotection Against Ischemia-Reperfusion Injury

As the criteria for liver donation have been extended to include marginal donors, liver grafts are becoming particularly vulnerable to hepatic ischemia-reperfusion injury (IRI). However, no specific measures have been validated to ameliorate hepatic IRI. In this article, we explored whether everolimus has protective effects against hepatic IRI in relation with autophagy. The effects of everolimus were investigated in both in vitro and in vivo hepatic IRI models. Mouse hepatocyte AML12 cells and BALB/c mice were utilized for the establishment of each model. In the IRI-induced AML12 cells, everolimus treatment increased the expressions of autophagic markers (microtubule-associated protein 1 light chain 3 and p62) and decreased pro-apoptotic proteins (cleaved caspase 3 and cleaved poly-ADP ribose polymerase). The blockage of autophagy, using either bafilomycin A1 or si-autophagy-related protein 5, abrogated these anti-apoptosis effects of everolimus. Subsequently, everolimus administration to the hepatic IRI-induced mice provided hepatoprotective effects in terms of (1) decreasing the expressions of pro-apoptotic proteins, (2) inhibiting the release of pro-inflammatory cytokines (IL-6 and tumor necrosis factor-α), (3) reducing elevated liver enzymes (aspartate transaminase, alanine transaminase, and ammonia), and (4) restoring liver histopathology. These findings suggest that everolimus protects the liver against hepatic IRI by way of activating autophagy, and thus could be a potential therapeutic agent for hepatic IRI.

The role of mammalian target of rapamycin inhibitors in the management of post-transplant malignancy

Post-transplant malignancies, which occur either de novo or as cancer recurrences, are due to chronic exposure to immunosuppressive agents and are often more aggressive than those that develop in the non-transplant setting. Mammalian target of rapamycin (mTOR) inhibitors have antitumor and immunosuppressive effects. The dual effects of this class of agents may provide adequate immunosuppression to prevent organ rejection while simultaneously reducing the risk of post-transplant malignancy. mTOR inhibitors have become established approved agents for treating renal cell carcinoma and other cancers and, as reviewed herein, accumulating experience among organ transplant recipients collectively points toward a potential to prevent the development of de novo malignancies of various types in the post-transplant period. To date, most research efforts surrounding mTOR inhibitors and cancer control in the transplant population have been in the area of skin cancer prevention, but there have also been interesting observations regarding regression of post-transplant Kaposi's sarcoma and post-transplantation lymphoproliferative disorder that warrant further study.

The Role of mTOR Inhibitors in Liver Transplantation: Reviewing the Evidence

Despite the success of liver transplantation, long-term complications remain, including de novo malignancies, metabolic syndrome, and the recurrence of hepatitis C virus (HCV) and hepatocellular carcinoma (HCC). The current mainstay of treatment, calcineurin inhibitors (CNIs), can also worsen posttransplant renal dysfunction, neurotoxicity, and diabetes. Clearly there is a need for better immunosuppressive agents that maintain similar rates of efficacy and renal function whilst minimizing adverse effects. The mammalian target of rapamycin (mTOR) inhibitors with a mechanism of action that is different from other immunosuppressive agents has the potential to address some of these issues. In this review we surveyed the literature for reports of the use of mTOR inhibitors in adult liver transplantation with respect to renal function, efficacy, safety, neurological symptoms, de novo tumors, and the recurrence of HCC and HCV. The results of our review indicate that mTOR inhibitors are associated with efficacy comparable to CNIs while having benefits on renal function in liver transplantation. We also consider newer dosing schedules that may limit side effects. Finally, we discuss evidence that mTOR inhibitors may have benefits in the oncology setting and in relation to HCV-related allograft fibrosis, metabolic syndrome, and neurotoxicity.

De novo sirolimus and reduced-dose tacrolimus versus standard-dose tacrolimus after liver transplantation: the 2000-2003 phase II prospective randomized trial

We studied whether the use of sirolimus with reduced-dose tacrolimus, as compared to standard-dose tacrolimus, after liver transplantation is safe, tolerated and efficacious. In an international multicenter, open-label, active-controlled randomized trial (2000-2003), adult primary liver transplant recipients (n=222) were randomly assigned immediately after transplantation to conventional-dose tacrolimus (trough: 7-15 ng/mL) or sirolimus (loading dose: 15 mg, initial dose: 5 mg titrated to a trough of 4-11 ng/mL) and reduced-dose tacrolimus (trough: 3-7 ng/mL). The study was terminated after 21 months due to imbalance in adverse events. The 24-month cumulative incidence of graft loss (26.4% vs. 12.5%, p=0.009) and patient death (20% vs. 8%, p=0.010) was higher in subjects receiving sirolimus. A numerically higher rate of hepatic artery thrombosis/portal vein thrombosis was observed in the sirolimus arm (8% vs. 3%, p=0.065). The incidence of sepsis was higher in the sirolimus arm (20.4% vs. 7.2%, p=0.006). Rates of acute cellular rejection were similar between the two groups. Early use of sirolimus using a loading dose followed by maintenance doses and reduced-dose tacrolimus in de novo liver transplant recipients is associated with higher rates of graft loss, death and sepsis when compared to the use of conventional-dose tacrolimus alone.

Renal dysfunction in liver transplant recipients: evaluation of the critical issues

Major progress has been made in the field of liver transplantation since the first procedure was performed nearly 50 years ago. Despite these improvements, renal dysfunction before and after liver transplantation remains a major complicating factor associated with increased health care costs, morbidity, and mortality. Creatinine-based estimates of renal function are inaccurate in the setting of end-stage liver disease and often lead to underdiagnosis and late intervention. This issue is critical in that it is important to understand both the etiology and chronicity of renal dysfunction before liver transplantation because the treatment clearly varies, especially with respect to simultaneous liver-kidney (SLK) transplantation. Because of the scarcity of available grafts, identifying appropriate candidates for SLK transplantation is crucial. Hepatorenal syndrome is common in liver transplant candidates; however, other etiologies of renal dysfunction need to be considered. Renal dysfunction after liver transplantation is common and may have an acute or chronic presentation. Although calcineurin inhibitors (CNIs) have been associated with post-liver transplant nephrotoxicity, their role may be overestimated, and other contributing etiologies should remain in a clinician's differential diagnosis. Alternatives to CNIs have been evaluated; however, a safe immunosuppressive regimen that achieves the preservation of renal function in liver transplant recipients remains to be established. In this review of the literature, renal dysfunction in the setting of liver transplantation is evaluated, and the critical issues that are barriers to improved outcomes are highlighted.

A randomized, controlled study to assess the conversion from calcineurin-inhibitors to everolimus after liver transplantation--PROTECT

Posttransplant immunosuppression with calcineurin inhibitors (CNIs) is associated with impaired renal function, while mTor inhibitors such as everolimus may provide a renal-sparing alternative. In this randomized 1-year study in patients with liver transplantation (LTx), we sought to assess the effects of everolimus on glomerular filtration rate (GFR) after conversion from CNIs compared to continued CNI treatment. Eligible study patients received basiliximab induction, CNI with/without corticosteroids for 4 weeks post-LTx, and were then randomized (if GFR > 50 mL/min) to continued CNIs (N = 102) or subsequent conversion to EVR (N = 101). Mean calculated GFR 11 months postrandomization (ITT population) revealed no significant difference between treatments using the Cockcroft-Gault formula (-2.9 mL/min in favor of EVR, 95%-CI: [-10.659; 4.814], p = 0.46), whereas use of the MDRD formula showed superiority for EVR (-7.8 mL/min, 95%-CI: [-14.366; -1.191], p = 0.021). Rates of mortality (EVR: 4.2% vs. CNI: 4.1%), biopsy-proven acute rejection (17.7% vs. 15.3%), and efficacy failure (20.8% vs. 20.4%) were similar. Infections, leukocytopenia, hyperlipidemia and treatment discontinuations occurred more frequently in the EVR group. No hepatic artery thrombosis and no excess of wound healing impairment were noted. Conversion from CNI-based to EVR-based immunosuppression proved to be a safe alternative post-LTx that deserves further investigation in terms of nephroprotection.

Present state of immunosuppressive therapy in liver transplant recipients

1. Our increasing understanding of the signaling pathways and cellular interactions in transplant immunobiology has facilitated targeted strategies using novel immunosuppressive agents. 2. The pattern of immunosuppressive drug use in the United States continues to change, and the changes include the use of antibody induction therapy and the agents used in maintenance therapy. 3. The driving forces behind the development of new immunosuppressive regimens are the long-term complications of current immunosuppressive regimens (particularly renal dysfunction and metabolic disturbances).