Tolerance in liver transplantation: Biomarkers and clinical relevance

Transplantation is the optimal treatment for end-stage organ failure,and modern immunosuppression has allowed important progress in short-term outcomes. However,immunosuppression poorly influences chronic rejection and elicits chronic toxicity in current clinical practice. Thus,a major goal in transplantation is to understand and induce tolerance. It is well established that human regulatory T cells expressing the transcription factor Fox P3 play important roles in the maintenance of immunological self-tolerance and immune homeostasis. The major regulatory T cell subsets and mechanisms of expansion that are critical for induction and long-term maintenance of graft tolerance and survival are being actively investigated. Likewise,other immune cells,such as dendritic cells,monocyte/macrophages or natural killer cells,have been described as part of the process known as "operational tolerance". However,translation of these results towards clinical practice needs solid tools to identify accurately and reliably patients who are going to be tolerant. In this way,a plethora of genetic and cellular biomarkers is raising and being validated worldwide in large multicenter clinical trials. Few of the studies performed so far have provided a detailed analysis of the impact of immunosuppression withdrawal on pre-existing complications derived from the long-term administration of immunosuppressive drugs and the side effects associated with them. The future of liver transplantation is aimed to develop new therapies which increase the actual low tolerant vs non-tolerant recipients ratio.

De novo malignancies after liver transplantation: The effect of immunosuppression-personal data and review of literature

BACKGROUND Immunosuppression has undoubtedly raised the overall positive outcomes in the post-operative management of solid organ transplantation. However, long-term exposure to immunosuppression is associated with critical systemic morbidities. De novo malignancies following orthotopic liver transplants (OLTs) are a serious threat in pediatric and adult transplant individuals. Data from different experiences were reported and compared to assess the connection between immunosuppression and de novo malignancies in liver transplant patients. AIM To study the role of immunosuppression on the incidence of de novo malignancies in liver transplant recipients. METHODS A systematic literature examination about de novo malignancies and immunosuppression weaning in adult and pediatric OLT recipients was described in the present review. Worldwide data were collected from highly qualified institutions performing OLTs. Patient follow-up, immunosuppression discontinuation and incidence of de novo malignancies were reported. Likewise, the review assesses the differences in adult and pediatric recipients by describing the adopted immunosuppression regimens and the different type of diagnosed solid and blood malignancy.RESULTS Emerging evidence suggests that the liver is an immunologically privileged organ able to support immunosuppression discontinuation in carefully selected recipients. Malignancies are often detected in liver transplant patients undergoing daily immunosuppression regimens. Post-transplant lymphoproliferative diseases and skin tumors are the most detected de novo malignancies in the pediatric and adult OLT population, respectively. To date, immunosuppression withdrawal has been achieved in up to 40% and 60% of well-selected adult and pediatric recipients, respectively. In both populations, a clear benefit of immunosuppression weaning protocols on de novo malignancies is difficult to ascertain because data have not been specified in most of the clinical experiences. CONCLUSION The selected populations of tolerant pediatric and adult liver transplant recipients greatly benefit from immunosuppression weaning. There is still no strong clinical evidence on the usefulness of immunosuppression withdrawal in OLT recipients on malignancies. An interesting focus is represented by the complete reconstitution of the immunological pathways that could help in decreasing the incidence of de novo malignancies and may also help in treating liver transplant patients suffering from cancer.

Hepatitis B virus recurrence after liver transplantation: An old tale or a clear and present danger?

Hepatitis B virus(HBV) recurrence after liver transplantation(LT) has been described more than 50 years ago. Similarly, to other clinical conditions, in which impairment of host immune defense favors viral replication, early reports described in details recurrence and reactivation of HBV in liver transplant recipients. The evidence of a possible, severe, clinical evolution of HBV reappearance in a significant percentage of these patients, allowed to consider,for some years, HBV positivity a contraindication for LT. Moving from the old to the new millennium this picture has changed dramatically. Several studies contributed to establish efficient prophylactic protocols for HBV recurrence and with the advent of more potent anti-viral drugs an increased control of infection was achieved in transplanted patients as well as in the general immunecompetent HBV population. Success obtained in the last decade led some authors to the conclusion that HBV is now to consider just as a "mere nuisance".However, with regard to HBV and LT, outstanding issues are still on the table:(1)A standard HBV prophylaxis protocol after transplant has not yet been clearly defined;(2) The evidence of HBV resistant strains to the most potent antiviral agents is claiming for a new generation of drugs;and(3) The possibility of prophylaxis withdrawal in some patients has been demonstrated, but reliable methods for their selection are still lacking. The evolution of LT for HBV is examined in detail in this review together with the description of the strategies adopted to prevent HBV recurrence and their pros and cons.

Liver transplantation in acute liver failure:A challengingscenario

Acute liver failure is a critical medical condition defined as rapid development of hepatic dysfunction associated with encephalopathy. The prognosis in these patients is highly variable and depends on the etiology, intervalbetween jaundice and encephalopathy, age, and the degree of coagulopathy. Determining the prognosis for this population is vital. Unfortunately, prognostic models with both high sensitivity and specificity for prediction of death have not been developed. Liver transplantation has dramatically improved survival in patients with acute liver failure. Still, 25% to 45% of patients will survive with medical treatment. The identification of patients who will eventually require liver transplantation should be carefully addressed through the combination of current prognostic models and continuous medical assessment. The concerns of inaccurate selection for transplantation are significant, exposing the recipient to a complex surgery and lifelong immunosuppression. In this challenging scenario, where organ shortage remains one of the main problems, alternatives to conventional orthotopic liver transplantation, such as living-donor liver transplantation, auxiliary liver transplant, and ABO-incompatible grafts, should be explored. Although overall outcomes after liver transplantation for acute liver failure are improving, they are not yet comparable to elective transplantation.

Lenvatinib as first-line therapy for recurrent hepatocellular carcinoma after liver transplantation:Is the current evidence applicable to these patients?

Liver transplantation(LT)is one of the leading curative therapies for hepatocellular carcinoma(HCC).Despite recent optimization of transplant selection criteria,including alpha-feto protein,HCC recurrence after LT is still the leading cause of death in these patients.During the last decades,effective systemic treatments for HCC,including tyrosine kinase inhibitors and immunotherapy,have been approved.We describe the clinical scenario of a patient with recurrence of HCC five years after LT,who received lenvatinib as first-line systemic therapy to introduce systemic treatment options in this clinical setting.In this opinion review,we detail first and second-line systemic treatment options,focusing on those feasible for patients with recurrent HCC after LT.Several trials have evaluated new drugs to treat HCC patients in first and secondline therapy,but patients with recurrent HCC after LT have been excluded from these trials.Consequently,most of the evidence comes from observational retrospective studies.Whether tyrosine kinase inhibitors will remain the primary therapeutic approach in these patients,due to a relative contraindication for immunotherapy,may be clarified in the near future.

Serious drug-induced liver disease secondary to ezetimibe

Ezetimibe is the f irst member of a new family of lipid- lowering drugs that inhibits uptake of dietary and bili- ary cholesterol. It was approved by the FDA in 2002 for hypercholesterolemia alone or in combination with statins. Its use has been spreading over the last years. Ezetimibe was considered a safe drug. We report a case of a woman who developed a serious hepatocellular drug-induced liver disease after 4 mo therapy with 10 mg daily of ezetimibe. After withdrawal of the drug, the patient recovered slowly. Ezetimibe may produce seri- ous toxic hepatitis and prompt withdrawal is mandatory in case of a signif icant abnormality in liver testing after beginning or during treatment with ezetimibe.

Immunosuppressive potency of mechanistic target of rapamycin inhibitors in solid-organ transplantation

Mammalian target of rapamycin, also known as me-chanistic target of rapamycin(m TOR) is a protein kinase that belongs to the PI3K/AKT/m TOR signaling pathway, which is involved in several fundamental cellular functions such as cell growth, proliferation, and survival. This protein and its associated pathway have been implicated in cancer development and the regulation of immune responses, including the rejection response generated following allograft transplantation. Inhibitors of m TOR(m TORi) such as rapamycin and its derivative everolimus are potent immunosuppressive drugs that both maintain similar rates of efficacy and could optimize the renal function and diminish the side effects compared with calcineurin inhibitors. These drugs are used in solid-organ transplantationtoinduceimmunosuppression while also promoting the expansion of CD4+CD25+FOXP3+ regulatory T-cells that could favor a scenery of immu-nological tolerance. In this review, we describe the mechanisms by which inhibitors of m TOR induce sup-pression by regulation of these pathways at different levels of the immune response. In addition, we par-ticularly emphasize about the main methods that are used to assess the potency of immunosuppressive drugs, highlighting the studies carried out about immunosuppressive potency of inhibitors of m TOR.

Fatty liver disease,an emerging etiology of hepatocellular carcinoma in Argentina

AIM To investigate any changing trends in the etiologies of hepatocellular carcinoma(HCC) in Argentina during the last years. METHODS A longitudinal cohort study was conducted by 14 regional hospitals starting in 2009 through 2016. All adult patients with newly diagnosed HCC either with pathology or imaging criteria were included. Patients were classified as presenting non-alcoholic fatty liver disease(NAFLD) either by histology or clinically, provided that all other etiologies of liver disease were ruled out, fatty liver was present on abdominal ultrasound and alcohol consumption was excluded. Complete follow-up was assessed in all included subjects since the date of HCC diagnosis until death or last medical visit.RESULTS A total of 708 consecutive adults with HCC were included. Six out of 14 hospitals were liver transplant centers(n = 484). The prevalence of diabetes mellitus was 27.7%. Overall, HCV was the main cause of liver disease related with HCC(37%) including cirrhotic and non-cirrhotic patients, followed by alcoholic liver disease 20.8%, NAFLD 11.4%, cryptogenic 9.6%, HBV 5.4% infection, cholestatic disease and autoimmune hepatitis 2.2%, and other causes 9.9%. A 6-fold increase in the percentage corresponding to NAFLDHCC was detected when the starting year, i.e., 2009 was compared to the last one, i.e., 2015(4.3% vs 25.6%; P < 0.0001). Accordingly, a higher prevalence of diabetes mellitus was present in NAFLD-HCC group 61.7% when compared to other than NAFLD-HCC 23.3%(P < 0.0001). Lower median AFP values at HCC diagnosis were observed between NAFLD-HCC and non-NAFLD groups(6.6 ng/m L vs 26 ng/m L; P = 0.02). Neither NAFLD nor other HCC etiologies were associated with higher mortality.CONCLUSION The growing incidence of NAFLD-HCC documented in the United States and Europe is also observed in Argentina, a confirmation with important Public Health implications.

Pre-treatment prediction of response to peginterferon plus ribavirin in chronic hepatitis C genotype 3

AIM: To evaluate pre-treatment factors associated with sustained virological response(SVR) in patients with hepatitis C virus(HCV) genotype 3 treated with peginterferon and ribavirin(RBV). METHODS: We retrospectively analyzed treatment naive, mono-infected HCV genotype 3 patients treated with peginterferon and RBV. Exclusion criteria included presence of other liver disease, alcohol consumption and African American or Asian ethnicity. The variables collected and compared between patients who achieved an SVR and patients who did not were as follows: gender, age, fibrosis stage, diabetes, body mass index,steatosis, INFL3 polymorphism, pre-treatment HCVRNA, type of peginterferon, RBV dose and adherence. RESULTS: A total of 107 patients treated between June, 2004 and March, 2013 were included. Mean treatment duration was 25.1(± 1.8) wk. Overall, 58%(62/107) of the patients achieved an SVR and 42%(45/107) did not. In the multivariate logistic regression analysis, pre-treatment HCV-RNA ≥ 600000 UI/m L(OR = 0.375, 95%CI: 0.153-0.919, P = 0.032) and advanced fibrosis(OR = 0.278, 95%CI: 0.113-0.684,P = 0.005) were significantly associated with low SVR rates. In patients with pre-treatment HCV-RNA ≥600000 UI/m L and advanced fibrosis, the probability of achieving an SVR was 29%(95%CI: 13.1-45.2).In patients with pre-treatment HCV-RNA < 600000UI/m L and mild to moderate fibrosis, the probability of achieving an SVR was 81%(95%CI: 68.8-93.4).CONCLUSION: In patients with HCV genotype 3infections the presence of advance fibrosis and high pre-treatment viral load might be associated with poor response to peginterferon plus RBV. These patients could benefit the most from new direct antiviral agentsbased regimes.

Establishing a blueprint for successful liver transplantation for alcohol-related cirrhosis:the importance of a multidisciplinary team

Liver transplantation(LT)for alcohol-related liver disease(ALD)has come a long way since the implementation of LT as a standard procedure.Initially considered a contra-indication due to poor outcomes and moral issues(1,2),it is nowadays the most common indication for LT in Western countries(3,4).Patient and graft survival in this setting are excellent(5).However,relapse rates remain high(6),which jeopardizes long-term survival and the acceptance of the transplant team for these procedures.The evaluation of the suitability to a LT for a potential candidate is therefore essential.The length of sobriety,namely over six months,has longtime been considered as the condition sine qua non.The“6-month rule”is insufficient to predict the risk of relapse and is progressively being abandoned by learned societies recommendations(7,8).Moreover,situations in which a recent alcohol consumption is obvious,such as alcoholic hepatitis or positive blood and/or urine test before the procedure,are associated with good outcomes(9-11).

Risk factors for hepatocellular carcinoma recurrence after liver transplantation

Liver transplantation(LT)provides an excellent option for the long-term survival of patients with unresectable hepatocellular carcinoma(HCC)based on the Milan criteria.Despite careful selection of patients,HCC may still recur after LT,which represents the most important negative predictor of post-transplant survival.The growing demand for LT in HCC has led to the expansion of patient selection criteria,with a resultant increase in the risk of post-transplant HCC recurrence.Numerous tumor and host factors predict HCC recurrence.The morphological,histological,and serological characteristics of tumors in predicting HCC recurrence have been extensively studied.Furthermore,the type and duration of anticancer response before LT has also been considered a surrogate marker of tumor aggressiveness and is associated with the risk of recurrence.The demographic and clinical characteristics of recipients,as well as the type and duration of exposure to immunosuppressive therapy,represent the main host-related risk factors.Many studies have attempted to describe predictive models for the risk of HCC recurrence,considering evaluable parameters both before and after LT.Although many models have been proposed,relatively few have been externally validated on different patient populations.This paper aims to comprehensively summarize the available data on the predictive factors of HCC recurrence after LT,and to examine and discuss those that have been externally validated.

Hepatitis C virus infection in Argentina: Burden of chronic disease

AIM: To estimate the progression of the hepatitis C virus(HCV) epidemic and measure the burden of HCVrelated morbidity and mortality. METHODS: Age- and gender-defined cohorts were used to follow the viremic population in Argentina and estimate HCV incidence, prevalence, hepatic complications, and mortality. The relative impact of two scenarios on HCV-related outcomes was assessed:(1) increased sustained virologic response(SVR); and(2) increased SVR and treatment.RESULTS: Under scenario 1, SVR raised to 85%-95% in 2016. Compared to the base case scenario, there was a 0.3% reduction in prevalent cases and liverrelated deaths by 2030. Given low treatment rates, cases of hepatocellular carcinoma and decompensated cirrhosis decreased < 1%, in contrast to the base case in 2030. Under scenario 2, the same increases in SVR were modeled, with gradual increases in the annual diagnosed and treated populations. This scenario decreased prevalent infections 45%, liver-related deaths 55%, liver cancer cases 60%, and decompensated cirrhosis 55%, as compared to the base case by 2030. CONCLUSION: In Argentina, cases of end stage liver disease and liver-related deaths due to HCV are still growing, while its prevalence is decreasing. Increasing in SVR rates is not enough, and increasing in the number of patients diagnosed and candidates for treatment is needed to reduce the HCV disease burden. Based on this scenario, strategies to increase diagnosis and treatment uptake must be developed to reduce HCV burden in Argentina.

Antiviral treatment for chronic hepatitis B in renal transplant patients

Chronic hepatitis B infection is frequent in renal transplant patients. It negatively impacts long term outcomes reducing graft and patient survival. Current guidelines clearly define who needs treatment, when to start, what is the first line therapy, how to monitor treatment response, when to stop, and how patients must be controlled for its safety. There is some datashowing a favorable safety and efficacy profile of nucleos(t)ide analogue(NUC) treatment in the renal transplant setting. Entecavir, a drug without major signs of nephrotoxicity, appears to be the first option for NUC na?ve patients and tenofovir remains the preferred choice for patients with previous resistance to lamivudine or any other NUC. Renal transplant recipients under anti HBV therapy should be monitored for its efficacy against HBV but also for its safety with a close renal monitoring. Studies including a large number of patients with long term treatment and follow up are still needed to better demonstrate the safety and efficacy of newer NUCs in this population.

Breath Biopsy^(®) to Identify Exhaled Volatile Organic Compounds Biomarkers for Liver Cirrhosis Detection

Background and Aims:The prevalence of chronic liver dis-ease in adults exceeds 30%in some countries and there is significant interest in developing tests and treatments to help control disease progression and reduce healthcare burden.Breath is a rich sampling matrix that offers non-invasive so-lutions suitable for early-stage detection and disease moni-toring.Having previously investigated targeted analysis of a single biomarker,here we investigated a multiparametric approach to breath testing that would provide more robust and reliable results for clinical use.Methods:To identify can-didate biomarkers we compared 46 breath samples from cir-rhosis patients and 42 from controls.Collection and analysis used Breath Biopsy OMNI™,maximizing signal and contrast to background to provide high confidence biomarker detec-tion based upon gas chromatography mass spectrometry(GC-MS).Blank samples were also analyzed to provide de-tailed information on background volatile organic compounds(VOCs)levels.Results:A set of 29 breath VOCs differed significantly between cirrhosis and controls.A classification model based on these VOCs had an area under the curve(AUC)of 0.95±0.04 in cross-validated test sets.The seven best performing VOCs were sufficient to maximize classifica-tion performance.A subset of 11 VOCs was correlated with blood metrics of liver function(bilirubin,albumin,prothrom-bin time)and separated patients by cirrhosis severity using principal component analysis.Conclusions:A set of seven VOCs consisting of previously reported and novel candidates show promise as a panel for liver disease detection and mon-itoring,showing correlation to disease severity and serum biomarkers at late stage.