Comparison of extracorporeal cellular therapy (ELAD®) vs standard of care in a randomized controlled clinical trial in treating Chinese subjects with acute-on-chronic liver failure

Extracorporeal liver support and liver transplantation for acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is defined by acute decompensation, organ failure and a high risk of short-term mortality. This condition is characterized by an overwhelming systemic inflammatory response. Despite treating the precipitating event, intensive monitoring and organ support, clinical deterioration can occur with very poor outcomes. During the last decades, several extracorporeal liver support systems have been developed to try to reduce ongoing liver injury and provide an improved environment for the liver to regenerate or as a bridging therapy until liver transplantation. Several clinical trials have been performed to evaluate the clinical efficacy of extracorporeal liver support systems, but no clear impact on survival has been proven. DIALIVE is a novel extracorporeal liver support device that has been built to specifically address the pathophysiological derangements responsible for the development of ACLF by replacing dysfunctional albumin and removing pathogen and damage-associated molecular patterns (PAMPs and DAMPs). In phase II clinical trial, DIALIVE appears to be safe, and it seems to be associated with a faster time to the resolution of ACLF compared with standard medical treatment. Even in patients with severe ACLF, liver transplantation saves lives and there is clear evidence of transplant benefit. Careful selection of patients is required to attain good results from liver transplantation, but many questions remain unanswered. In this review, we describe the current perspectives on the use of extracorporeal liver support and liver transplantation for ACLF patients.

Artificial Liver Support Systems in Acute Liver Failure and Acute-on-Chronic Liver Failure: Systematic Review and Meta-Analysis

OBJECTIVES

To systematically review the safety and efficacy of nonbiological (NBAL) or biological artificial liver support systems (BAL) and whole-organ extracorporeal liver perfusion (W-ECLP) systems, in adults with acute liver failure (ALF) and acute-on-chronic liver failure (ACLF).

DATA SOURCES

Eligible NBAL/BAL studies from PubMed/Embase searches were randomized controlled trials (RCTs) in adult patients with ALF/ACLF, greater than or equal to ten patients per group, reporting outcomes related to survival, adverse events, transplantation rate, and hepatic encephalopathy, and published in English from January 2000 to July 2023. Separately, we searched for studies evaluating W-ECLP in adult patients with ALF or ACLF published between January1990 and July 2023.

STUDY SELECTION AND DATA EXTRACTION

Two researchers independently screened citations for eligibility and, of eligible studies, retrieved data related to study characteristics, patients and interventions, outcomes definition, and intervention effects. The Cochrane Risk of Bias 2 tool and Joanna Briggs Institute checklists were used to assess individual study risk of bias. Meta-analysis of mortality at 28-30 days post-support system initiation and frequency of at least one serious adverse event (SAE) generated pooled risk ratios (RRs), based on random (mortality) or fixed (SAE) effects models.

DATA SYNTHESIS

Of 17 trials evaluating NBAL/BAL systems, 11 reported 28-30 days mortality and five reported frequency of at least one SAE. Overall, NBAL/BAL was not statistically associated with mortality at 28-30 days (RR, 0.85; 95% CI, 0.67-1.07; p = 0.169) or frequency of at least one SAE (RR, 1.15; 95% CI, 0.99-1.33; p = 0.059), compared with standard medical treatment. Subgroup results on ALF patients suggest possible benefit for mortality (RR, 0.67; 95% CI, 0.44-1.03; p = 0.069). From six reports of W-ECLP (12 patients), more than half (58%) of severe patients were bridged to transplantation and survived without transmission of porcine retroviruses.

CONCLUSIONS

Despite no significant pooled effects of NBAL/BAL devices, the available evidence calls for further research and development of extracorporeal liver support systems, with larger RCTs and optimization of patient selection, perfusion durability, and treatment protocols.

Non-Cell-Based Extracorporeal Artificial Liver Systems: Historic Perspectives, Approaches and Mechanisms, Current Applications, and Challenges

BACKGROUND

Liver disease is a growing burden. Transplant organs are scarce. Extracorporeal liver support systems (ELSS) are a bridge to transplantation for eligible patients. For transplant-ineligible patients the objective becomes liver recovery.

METHODS

We review seven decades of non-cell-based ELSS research in humans. Where possible, we emphasize randomized controlled trials (RCTs). When RCTs are not available, we describe the available human clinical data.

RESULTS

There are three broad cell-free approaches to remove protein-bound toxins (PBTs) and treat liver failure. The first is a dialysate binder suspension. A material that binds the PBT (the binder) is added to the dialysate. Binders include albumin, charcoal, and polystyrene sulfonate sodium. The unbound fraction of the PBT crosses the dialyzer membrane along a chemical gradient and binds to the binder. The second approach is using grains of sorbent fixed in a plastic housing to remove PBTs. Toxin-laden blood or plasma flows directly through the column. Toxins are removed by binding to the sorbent. The third approach is exchanging toxin-laden blood, or fractions of blood, for a healthy donor blood product. Most systems lack widespread acceptance, but plasma exchange (PE) is recommended in many guidelines. The large donor plasma requirement of PE creates demand for systems to complement or replace it.

CONCLUSIONS

Now that PE has become recommended in some, but not all, jurisdictions, we discuss the importance of reporting precise PE protocols and dose. Our work provides an overview of promising new systems and lessons from old technologies to enable ELSS improvement.

Genetically Modified Hepatocytes Targeting Bilirubin and Ammonia Metabolism for the Construction of Bioartificial Liver System

Acute liver failure (ALF) is a complex syndrome that impairs the liver's function to detoxify bilirubin, ammonia, and other toxic metabolites. Bioartificial liver (BAL) aims to help ALF patients to pass through the urgent period by temporarily undertaking the liver's detoxification functions and promoting the recovery of the injured liver. We genetically modified the hepatocellular cell line HepG2 by stably overexpressing genes encoding UGT1A1, OATP1B1, OTC, ARG1, and CPS1. The resulting SynHeps-II cell line, encapsulated by Cytopore microcarriers, dramatically reduced the serum levels of bilirubin and ammonia, as demonstrated both in vitro using patient plasma and in vivo using ALF animal models. More importantly, we have also completed the 3-dimensional (3D) culturing of cells to meet the demands for industrialized rapid and mass production, and subsequently assembled the plasma-cell contacting BAL (PCC-BAL) system to fulfill the requirements of preclinical experiments. Extracorporeal blood purification of ALF rabbits with SynHeps-II-embedded PCC-BAL saved more than 80% of the animals from rapid death. Mechanistically, SynHeps-II therapy ameliorated liver and brain inflammation caused by high levels of bilirubin and ammonia and promoted liver regeneration by modulating the nuclear factor κB (NF-κB) and signal transducer and activator of transcription 3 (STAT3) pathways. Also, SynHeps-II treatment reduced cerebral infiltration of neutrophils, reduced reactive oxygen species (ROS) levels, and mitigated hepatic encephalopathy. Taken together, SynHeps-II cell-based BAL was promising for the treatment of ALF patients and warrants clinical trials.

Liver transplantation for acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) occurs in the context of advanced liver disease and is associated with hepatic and extrahepatic organ failure, eventually leading to a major risk of short-term mortality. To date, there are very few effective therapeutic options for ACLF. In many cases, liver transplantation is the only life-saving treatment that has acceptable outcomes in carefully selected recipients. This Review addresses key aspects of the use of liver transplantation for patients with ACLF, providing an in-depth discussion of existing evidence regarding candidate selection, the optimal window for transplantation, potential prioritisation of liver grafts for this indication, and the global management of ACLF to bridge patients to liver transplantation.

Review article: Emerging and current management of acute-on-chronic liver failure

BACKGROUND

Acute-on-chronic liver failure (ACLF) is a clinically and pathophysiologically distinct condition from acutely decompensated cirrhosis and is characterised by systemic inflammation, extrahepatic organ failure, and high short-term mortality.

AIMS

To provide a narrative review of the diagnostic criteria, prognosis, epidemiology, and general management principles of ACLF. Four specific interventions that are explored in detail are intravenous albumin, extracorporeal liver assist devices, granulocyte-colony stimulating factor, and liver transplantation.

METHODS

We searched PubMed and Cochrane databases for articles published up to July 2023.

RESULTS

Approximately 35% of hospital inpatients with decompensated cirrhosis have ACLF. There is significant heterogeneity in the criteria used to diagnose ACLF; different definitions identify different phenotypes with varying mortality. Criteria established by the European Association for the Study of the Liver were developed in prospective patient cohorts and are, to-date, the most well validated internationally. Systemic haemodynamic instability, renal dysfunction, coagulopathy, neurological dysfunction, and respiratory failure are key considerations when managing ACLF in the intensive care unit. Apart from liver transplantation, there are no accepted evidence-based treatments for ACLF, but several different approaches are under investigation.

CONCLUSION

The recognition of ACLF as a distinct entity from acutely decompensated cirrhosis has allowed for better patient stratification in clinical settings, facilitating earlier engagement with the intensive care unit and liver transplantation teams. Research priorities over the next decade should focus on exploring novel treatment strategies with a particular focus on which, when, and how patients with ACLF should be treated.

EASL Clinical Practice Guidelines on acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF), which was described relatively recently (2013), is a severe form of acutely decompensated cirrhosis characterised by the existence of organ system failure(s) and a high risk of short-term mortality. ACLF is caused by an excessive systemic inflammatory response triggered by precipitants that are clinically apparent (e.g., proven microbial infection with sepsis, severe alcohol-related hepatitis) or not. Since the description of ACLF, some important studies have suggested that patients with ACLF may benefit from liver transplantation and because of this, should be urgently stabilised for transplantation by receiving appropriate treatment of identified precipitants, and full general management, including support of organ systems in the intensive care unit (ICU). The objective of the present Clinical Practice Guidelines is to provide recommendations to help clinicians recognise ACLF, make triage decisions (ICU vs. no ICU), identify and manage acute precipitants, identify organ systems that require support or replacement, define potential criteria for futility of intensive care, and identify potential indications for liver transplantation. Based on an in-depth review of the relevant literature, we provide recommendations to navigate clinical dilemmas followed by supporting text. The recommendations are graded according to the Oxford Centre for Evidence-Based Medicine system and categorised as 'weak' or 'strong'. We aim to provide the best available evidence to aid the clinical decision-making process in the management of patients with ACLF.

Extracorporeal Liver Support: An Updated Review of Mechanisms and Current Literature

INTRODUCTION

Acute liver failure is a cause of major mortality in the United States. Although the liver possesses regenerative capabilities, liver transplantation is the mainstay of treating acute liver failure. This modality is associated with many financial and logistic challenges. In this regard, Extracorporeal Liver Support (ECLS) might help in reducing mortality as well as bridge a patient to liver transplant. In some cases, the sequelae of liver failure such as hepatic encephalopathy and multi-organ failure can be postponed long enough for the native liver to self-recover function. With this rationale, we sought to describe the mechanism of various ECLS modalities, provide an overview of the current evidence regarding its use and to highlight future advancements that could overcome hindrances in its use.

METHODS

A scoping review was performed using PubMed and other databases from 1990 to 2020 with the keywords: 'extracorporeal liver support', 'acute liver failure', 'acute on chronic liver failure', 'albumin dialysis', 'artificial' and 'bioartificial'.

RESULTS AND CONCLUSIONS

ECLS has shown significant improvements in bilirubin and urea levels. Various forms of ECLS might also reduce mortality due to liver failure. However, many complications, such as hypotension, anemia, bleeding issues, sepsis, can be anticipated. There are a few barriers to mainstream use of ECLS, such as specific design requirements and high cost that reduce the overall utility of this modality in a small group of liver transplant candidates. Furthermore, a multidisciplinary team approach is required to supervise ECLS, a luxury only available at major academic hospitals. Some advancements for overcoming these barriers include investigation of new scaffolding systems. In order to expand the usage of ECLS, clinical trials focusing on a comparison of different modalities of ECLS with renal replacement therapy in patients with liver failure should be promoted.

The development of artificial livers

PURPOSE OF REVIEW

While liver transplantation is an established treatment for liver failure, the number of patients with liver failure amenable to such intervention far outnumbers the donor supply of livers. Technologies serving to bridge this gap are required. Artificial livers may serve as an alternative. In this review, we discuss the development of artificial liver technologies.

RECENT FINDINGS

The accrued clinical data suggest that current liver assist devices may serve a role in specific liver diseases, but for the most part no survival benefit has been demonstrated. More clinical trials are expected to elucidate their utilization. Simultaneously, recent advances in materials and tissue engineering are allowing for exciting developments for novel artificial livers.

SUMMARY

As there continues to be more clinical data regarding the use of current liver devices, new intricate artificial liver technologies, with the use of sophisticated three-dimensional materials, are being developed that may help improve outcomes of liver failure patients.

Uncertainty in the impact of liver support systems in acute-on-chronic liver failure: a systematic review and network meta-analysis

BACKGROUND

The role of artificial and bioartificial liver support systems in acute-on-chronic liver failure (ACLF) is still controversial. We aimed to perform the first network meta-analysis comparing and ranking different liver support systems and standard medical therapy (SMT) in patients with ACLF.

METHODS

The study protocol was registered with PROSPERO (CRD42020155850). A systematic search was conducted in five databases. We conducted a Bayesian network meta-analysis of randomized controlled trials assessing the effect of artificial or bioartificial liver support systems on survival in patients with ACLF. Ranking was performed by calculating the surface under cumulative ranking (SUCRA) curve values. The RoB2 tool and a modified GRADE approach were used for the assessment of the risk of bias and quality of evidence (QE).

RESULTS

In the quantitative synthesis 16 trials were included, using MARS®, Prometheus®, ELAD®, plasma exchange (PE) and BioLogic-DT®. Overall (OS) and transplant-free (TFS) survival were assessed at 1 and 3 months. PE significantly improved 3-month OS compared to SMT (RR 0.74, CrI: 0.6-0.94) and ranked first on the cumulative ranking curves for both OS outcomes (SUCRA: 86% at 3 months; 77% at 1 month) and 3-month TFS (SUCRA: 87%) and second after ELAD for 1-month TFS (SUCRA: 76%). Other comparisons did not reach statistical significance. QE was moderate for PE concerning 1-month OS and both TFS outcomes. Other results were of very low certainty.

CONCLUSION

PE seems to be the best currently available liver support therapy in ACLF regarding 3-month OS. Based on the low QE, randomized trials are needed to confirm our findings for already existing options and to introduce new devices.

Sequential versus mono double plasma molecular adsorption system in acute-on-chronic liver failures: A propensity-score matched study

AIMS

Efficacy of sequential double plasma molecular adsorb system (DPMAS) and plasma exchange (PE) on patients with acute on chronic liver failure (ACLF) has been rarely reported. We hereby reported the outcomes of a consecutive cohort of ACLF patients treated with sequential and mono DPMAS.

METHOD

Patients treated with artificial liver support system between January 2011 and December 2016 in XiJing hospital were retrospectively reviewed. A toal of 125 ACLF patients either received mono (DPMAS only) or sequential DPMAS (PE followed by DPMAS) therapy. One to one propensity-score matching (PSM) was used to compare the effects of sequential and mono DPMAS on survival and liver function.

RESULTS

After PSM, 80 patients were included with 40 patients in each group. Sequential therapy achieved significantly higher removal of total bilirubin, alanine aminotransferase, glutamic oxaloacetic transaminase, and alkaline phosphatase than mono DPMAS, but stabilized international normalized ratio. The effects of both regimens on white blood cell, platelet, creatinine, and liver function scores were similar. Survival rate on 90-day was 50% in the sequential group and 47.5% in the mono group.

CONCLUSION

For ACLF patients, sequential DPMAS and PE seemed to have a better effect on liver function improvement but provided no survival benefit compared with mono DPMAS.