Application of a novel liquid biopsy in patients with hepatocellular carcinoma undergoing liver transplantation

Applications of single-cell multi-omics in liver cancer

Primary liver cancer, more specifically hepatocellular carcinoma (HCC), remains a significant global health problem associated with increasing incidence and mortality. Clinical, biological, and molecular heterogeneity are well-known hallmarks of cancer and HCC is considered one of the most heterogeneous tumour types, displaying substantial inter-patient, intertumoural and intratumoural variability. This heterogeneity plays a pivotal role in hepatocarcinogenesis, metastasis, relapse and drug response or resistance. Unimodal single-cell sequencing techniques have already revolutionised our understanding of the different layers of molecular hierarchy in the tumour microenvironment of HCC. By highlighting the cellular heterogeneity and the intricate interactions among cancer, immune and stromal cells before and during treatment, these techniques have contributed to a deeper comprehension of tumour clonality, hematogenous spreading and the mechanisms of action of immune checkpoint inhibitors. However, major questions remain to be elucidated, with the identification of biomarkers predicting response or resistance to immunotherapy-based regimens representing an important unmet clinical need. Although the application of single-cell multi-omics in liver cancer research has been limited thus far, a revolution of individualised care for patients with HCC will only be possible by integrating various unimodal methods into multi-omics methodologies at the single-cell resolution. In this review, we will highlight the different established single-cell sequencing techniques and explore their biological and clinical impact on liver cancer research, while casting a glance at the future role of multi-omics in this dynamic and rapidly evolving field.

Microvascular Invasion in Hepatocellular Carcinoma: Some Puzzling Facets

BACKGROUND/AIMS

Hepatocellular carcinoma is the main type of primary liver cancer. Macroscopic vascular invasion is usually identified during imaging, whereas microvascular invasion is usually determined by histopathological evaluation. We aim to identify the association between microvascular invasion and other markers of tumor aggressiveness and to identify the role of microvascular invasion in the prognosis of patients who were treated by liver transplantation for hepatocellular carcinoma.

MATERIALS AND METHODS

This is a single-center retrospective analysis of prospectively collected data. Patients who received liver transplantation for hepatocellular carcinoma were included in the study. Data were collected regarding sociodemographic variables, criteria of selection for liver transplantation, pretransplant alpha-fetoprotein, presence or absence of microvascular invasion, presence or absence of recurrence, overall survival, and disease-free survival. Data were analyzed using Statistical Package for the Social Sciences.

RESULTS

Sociodemographic laboratory values and radiologic tumor characteristics were found to be similar in patients with or without microvascular invasion. Our study revealed that microvascular invasion is associated with increased recurrence, decreased diseasedfree survival, and decreased overall survival, only for patients with hepatocellular carcinoma beyond Milan criteria at the time of liver transplantation.

CONCLUSION

For patients beyond Milan criteria, but not within Milan criteria, microvascular invasion plays a significant role in predicting recurrence and shorter survival after liver transplantation.

EpCAM-positive circulating tumor cells and serum AFP levels predict outcome after curative resection of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has high recurrence rates exceeding 50% despite curative resection. The serum biomarker alpha-fetoprotein (AFP) is a well-known prognostic marker for HCC. EpCAM-positive circulating tumor cells (CTC) have a high predictive value for early HCC recurrence after curatively intended resection, most likely indicating micro-metastases at the time of resection. However, sensitivity remains low. The objective of this study was to evaluate a composite test comprising both CTC and AFP to identify patients at high risk for early HCC recurrence. We prospectively enrolled 58 patients undergoing curative intended resection for HCC at a tertiary referral center. Blood specimens were obtained prior to resection and analyzed for EpCAM-positive CTC and serum AFP levels. A positive result was defined as either detection of CTC or AFP levels ≥ 400 ng/ml. Eight patients tested positive for CTC, seven for AFP, and two for both markers. A positive composite test was significantly associated with shorter early recurrence-free survival (5 vs. 16 months, p = 0.005), time to recurrence (5 vs. 16 months, p = 0.011), and overall survival (37 vs. not reached, p = 0.034). Combining CTC and AFP identified patients with poor outcome after surgical resection, for whom adjuvant or neoadjuvant therapies may be particularly desirable.

European Society for Organ Transplantation Consensus Statement on Biomarkers in Liver Transplantation

Currently, one-year survival following liver transplantation (LT) exceeds 90% in large international registries, and LT is considered definitive treatment for patients with end-stage liver disease and liver cancer. Recurrence of disease, including hepatocellular carcinoma (HCC), significantly hampers post-LT outcomes. An optimal approach to immunosuppression (IS), including safe weaning, may benefit patients by mitigating the effect on recurrent diseases, as well as reducing adverse events associated with over-/under-IS, including chronic kidney disease (CKD). Prediction of these outcome measures-disease recurrence, CKD, and immune status-has long been based on relatively inaccurate clinical models. To address the utility of new biomarkers in predicting these outcomes in the post-LT setting, the European Society of Organ Transplantation (ESOT) and International Liver Transplant Society (ILTS) convened a working group of experts to review literature pertaining to primary disease recurrence, development of CKD, and safe weaning of IS. Summaries of evidence were presented to the group of panelists and juries to develop guidelines, which were discussed and voted in-person at the Consensus Conference in Prague November 2022. The consensus findings and recommendations of the Liver Working Group on new biomarkers in LT, clinical applicability, and future needs are presented in this article.

Is liquid biopsy the future commutator of decision-making in liver transplantation for hepatocellular carcinoma?

Liver transplant (LT) is the most favorable treatment option for patients with early stage hepatocellular carcinoma (HCC). Numerous attempts have been pursued to establish eligibility criteria and select HCC patients for LT, leading to various systems that essentially integrate clinico-morphological variables. Lacking of sufficient granularity to recapitulate the biological complexity of the disease, all these alternatives display substantial limitations and are thus undeniably imperfect. Liquid biopsy, defined as the molecular analysis of circulating analytes released by a cancer into the bloodstream, was revealed as an incomparable tool in the management of cancers, including HCC. It appears as an ideal candidate to refine selection criteria of LT in HCC. The present comprehensive review analyzed the available literature on this topic. Data in the field, however, remain scarce with only 17 studies. Although rare, these studies provided important and encouraging findings highlighting notable prognostic values and supporting the contribution of liquid biopsy in this specific clinical scenario. These results underpinned the critical and urgent need to intensify and accelerate research on liquid biopsy, in order to determine whether and how liquid biopsy may be integrated in the decision-making of LT in HCC.

Neoadjuvant Therapy for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is characterized by low resection and high postoperative recurrence rates, and conventional treatment strategies have failed to meet clinical needs. Neoadjuvant therapy (NAT) is widely employed in the routine management of several solid tumors because it increases resectability and reduces the rate of postoperative recurrence. However, a consensus has not been reached regarding the effects of NAT on HCC. As systemic therapy, particularly targeted therapy and immunotherapy, is given for HCC treatment, accumulating evidence shows that the “spring” of NAT for HCC is imminent. In the future, HCC researchers should focus on identifying biomarkers for treatment response, explore the mechanisms of resistance, and standardize the endpoints of NAT.

Liver Transplantation for Hepatocellular Carcinoma: How Should We Improve the Thresholds?

Simple Summary

The ideal treatment for hepatocellular carcinoma (HCC) is liver transplantation (LT), which both eliminates the HCC and cures the diseased liver. Once considered an experimental treatment with dismal survival rates, LT for HCC entered a new era with the establishment of the Milan criteria over 20 years ago. However, over the last two decades, the Milan criteria, which are based on tumor morphology, have come under intense scrutiny and are now largely regarded as too restrictive, and limit the access of transplantation for many patients who would otherwise achieve good clinical outcomes. The liver transplant community has been making every effort to reach a goal of establishing more reliable selection criteria. This article addresses how the criteria have been extended, as well as the concept of pre-transplant down-staging to maximize the eligibility.

Abstract

Hepatocellular carcinoma (HCC) is the third highest cause of cancer-related mortality, and liver transplantation is the ideal treatment for this disease. The Milan criteria provided the opportunity for HCC patients to undergo LT with favorable outcomes and have been the international gold standard and benchmark. With the accumulation of data, however, the Milan criteria are not regarded as too restrictive. After the implementation of the Milan criteria, many extended criteria have been proposed, which increases the limitations regarding the morphological tumor burden, and incorporates the tumor’s biological behavior using surrogate markers. The paradigm for the patient selection for LT appears to be shifting from morphologic criteria to a combination of biologic, histologic, and morphologic criteria, and to the establishment of a model for predicting post-transplant recurrence and outcomes. This review article aims to characterize the various patient selection criteria for LT, with reference to several surrogate markers for the biological behavior of HCC (e.g., AFP, PIVKA-II, NLR, 18F-FDG PET/CT, liquid biopsy), and the response to locoregional therapy. Furthermore, the allocation rules in each country and the present evidence on the role of down-staging large tumors are addressed.

Circulating Tumor Cells in Hepatocellular Carcinoma: A Comprehensive Review and Critical Appraisal

Hepatocellular carcinoma (HCC) is the fifth most common neoplasm and a major cause of cancer-related death worldwide. There is no ideal biomarker allowing early diagnosis of HCC and tumor surveillance in patients receiving therapy. Liquid biopsy, and particularly circulating tumor cells (CTCs), have emerged as a useful tool for diagnosis and monitoring therapeutic responses in different tumors. In the present manuscript, we evaluate the current evidence supporting the quantitative and qualitative assessment of CTCs as potential biomarkers of HCC, as well as technical aspects related to isolation, identification, and classification of CTCs. Although the dynamic assessment of CTCs in patients with HCC may aid the decision-making process, there are still many uncertainties and technical caveats to be solved before this methodology has a true impact on clinical practice guidelines. More studies are needed to identify the optimal combination of surface markers, to increase the efficiency of ex-vivo expansion of CTCs, or even to target CTCs as a potential therapeutic strategy to prevent HCC recurrence after surgery or to hamper tumor progression and extrahepatic spreading.

Circulating Cancer Stem Cells Expressing EpCAM/CD90 in Hepatocellular Carcinoma: A Pilot Study for Predicting Tumor Recurrence after Living Donor Liver Transplantation

Background/Aims

Circulating tumor cells (CTCs) with cancer stemness have been demonstrated to be a direct cause of tumor recurrence, and only few studies have reported the role of CTCs in liver transplantation (LT) for hepatocellular carcinoma (HCC).

Methods

Epithelial cell adhesion molecule+ (EpCAM+), cluster of differentiation 90+ (CD90+) and EpCAM+/CD90+ CTCs were sorted via fluorescence-activated cell sorting, and transcripts level of EpCAM, K19 and CD90 in the peripheral blood were analyzed via real-time polymerase chain reaction preoperatively and on postoperative days 1 and 7 in 25 patients who underwent living donor liver transplantation (LDLT) for HCC. EpCAM protein was assessed in HCC tissue using immunohistochemical staining. The median follow-up duration was 40 months.

Results

HCC after LDLT recurred in four out of 25 patients. Detection of EpCAM+ or CD90+ CTCs correlated well with their messenger RNA levels (p<0.05). EpCAM+ CTCs were readily detected in HCC tissue expressing EpCAM protein. The detection of EpCAM+ CTCs or EpCAM+/CD90+ CTCs before surgery and on postoperative day 1 was significantly associated with HCC recurrence after LT (all p<0.05). Pretransplant serum PIVKA-II >100 mAU/mL and postoperative day 1 EpCAM+/CD90+ CTCs were independent risk factors for HCC recurrence (hazard ratio, 14.64; 95% confidence interval, 1.08 to 198.20; p=0.043 and hazard ratio, 26.88; 95% confidence interval, 1.86 to 387.51; p=0.016, respectively).

Conclusions

EpCAM+/CD90+ CTCs can be used preoperatively and 1 day after LDLT as key biological markers in LT candidate selection and post-LDLT management.

Clearance of Circulating Tumor Cells in Patients with Hepatocellular Carcinoma Undergoing Surgical Resection or Liver Transplantation

BACKGROUND

In patients with hepatocellular carcinoma (HCC), a complete clearance of circulating tumor cells (CTCs) early after liver transplantation (LT) or surgical resection (LR) could prevent tumor recurrence.

METHODS

prospective pilot study including patients with HCC who underwent LR or LT from September 2017 to May 2020. Enumeration of CTCs was performed in peripheral blood samples (7 mL) using the Isoflux^® system (Fluxion Biosciences) immediately before surgery, at post-operative day 5 and at day 30. A clinically relevant number of CTCs was defined as >30 CTCs/sample.

RESULTS

41 HCC patients were included (mean age 58.7 ± 6.3; 82.9% male). LR was performed in 10 patients (24.4%) and 31 patients (75.6%) underwent LT. The main etiology of liver disease was chronic hepatitis C (31.7%). Patients undergoing LR and LT were similar in terms of preoperative CTC count (p = 0.99), but clearance of CTCs within the first month was more pronounced in the LT group. Clusters of CTCs at baseline were associated with incomplete clearance of CTCs at day 30 (54.2% vs. 11.8%, p = 0.005), which in turn impacted negatively on survival (p = 0.038).

CONCLUSION

Incomplete clearance of CTCs after surgery could be a surrogate marker of HCC aggressiveness.

Liquid Biopsy in Hepatocellular Carcinoma: Where Are We Now?

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer related death worldwide. Diagnostic, prognostic, and predictive biomarkers are urgently needed in order to improve patient survival. Indeed, the most widely used biomarkers, such as alpha-fetoprotein (AFP), have limited accuracy as both diagnostic and prognostic tests. Liver biopsy provides an insight on the biology of the tumor, but it is an invasive procedure, not routinely used, and not representative of the whole neoplasia due to the demonstrated intra-tumoral heterogeneity. In recent years, liquid biopsy, defined as the molecular analysis of cancer by-products, released by the tumor in the bloodstream, emerged as an appealing source of new biomarkers. Several studies focused on evaluating extracellular vesicles, circulating tumor cells, cell-free DNA and non-coding RNA as novel reliable biomarkers. In this review, we aimed to provide a comprehensive overview on the most relevant available evidence on novel circulating biomarkers for early diagnosis, prognostic stratification, and therapeutic monitoring. Liquid biopsy seems to be a very promising instrument and, in the near future, some of these new non-invasive tools will probably change the clinical management of HCC patients.

Utility of Liquid Biopsy Analysis in Detection of Hepatocellular Carcinoma, Determination of Prognosis, and Disease Monitoring: A Systematic Review

BACKGROUND & AIMS

Liquid biopsies, or blood samples, can be analyzed to detect circulating tumor cells (CTCs), cell-free DNA (cfDNA), and extracellular vesicles, which might identify patients with hepatocellular carcinoma (HCC) or help determine their prognoses. We performed a systematic review of studies of analyses of liquid biopsies from patients with HCC and their comparisons with other biomarkers.

METHODS

We performed a systematic review of original studies published before December 1, 2019. We included studies that compared liquid biopsies alone and in combination with other biomarkers for the detection of HCC, performed multivariate analyses of the accuracy of liquid biopsy analysis in determining patient prognoses, or evaluated the utility of liquid biopsy analysis in monitoring treatment response.

RESULTS

Our final analysis included 112 studies: 67 on detection, 46 on determining prognosis, and 25 on treatment monitoring or selection. Ten studies evaluated assays that characterized cfDNA for detection of HCC in combination with measurement of α-fetoprotein (AFP)-these studies found that the combined measurement of cfDNA and AFP more accurately identified patients with HCC than measurement of AFP alone. Six studies evaluated assays for extracellular vesicles and 2 studies evaluated assays for CTC in detection of HCC, with and without other biomarkers-most of these studies found that detection of CTCs or extracellular vesicles with AFP more accurately identified patients with HCC than measurement of AFP alone. Detection of CTCs before surgery was associated with HCC recurrence after resection in 13 of 14 studies; cfDNA and extracellular vesicles have been studied less frequently as prognostic factors. Changes in CTC numbers before vs after treatment more accurately identify patients with HCC recurrence than pretreatment counts alone, and measurements of cfDNA can identify patients with disease recurrence or progression before changes can be detected by imaging. We found little evidence that analyses of liquid biopsies can aid in the selection of treatment for HCC. Quality assessment showed risk of bias in studies of HCC detection and determination of prognosis.

CONCLUSIONS

In a systematic review of 112 studies of the accuracy of liquid biopsy analysis, we found that assays for CTCs and cfDNA might aid in determining patient prognoses and monitoring HCC, and assays for cfDNA might aid in HCC detection, but there is a risk of bias in these studies. Studies must be standardized before we can assess the clinical utility of liquid biopsy analysis in the detection and management of patients with HCC.

Relationship between circulating tumor cells undergoing EMT and short-term efficacy following interventional treatment in patients with hepatocellular carcinoma

Objective

A growing number of studies have indicated that epithelial-mesenchymal transition (EMT) phenotypes and the number of circulating tumor cells (CTCs) are significant indicators of tumor characteristics and treatment efficacy, and thus have a broad range of potential applications in the diagnosis and treatment of malignant tumors. The value of data on CTC phenotypes and CTC counts in the diagnosis of hepatocellular carcinoma (HCC) and assessment of efficacy after comprehensive interventional therapy remains unclear.

Methods

Data of 107 patients who exhibited space-occupying lesions in the liver on enhanced CT/MRI scans at the Guangdong Provincial People’s Hospital (a tertiary medical center) between August 2017 and October 2018, were retrospectively analyzed. All enrolled patients were treated with transcatheter arterial chemoembolization (TACE) combined with microwave ablation (MWA). An imFISH CTC assay was used to isolate and count CTCs with different EMT phenotypes in the patients’ peripheral blood, which facilitated an analysis of the value of CTC phenotype and CTC count data in the diagnosis or treatment of HCC.

Results

The CTC count and EMT phenotypes in HCC patients were not associated with patient characteristics such as age, sex, Hepatitis B Virus (HBV)-DNA status, alcohol consumption history, Aspartate Transaminase (AST) to Platelet Ratio Index (APRI) score, Eastern Cooperative Oncology Group (ECOG) score, Child-Pugh score, alpha-fetoprotein (AFP), number and size of tumors, vascular invasion, or metastasis (P ​> ​0.05). The CTC count and EMT phenotypes in HCC patients before treatment were not predictive of short-term efficacy (P ​> ​0.05). Comprehensive interventional therapy reduced the total CTC count and mesenchymal CTC count (P ​= ​0.034 and 0.022, respectively).

Conclusion

TACE in combination with ablation reduced the total CTC count and mesenchymal CTC count. The CTC count and EMT phenotypes may be associated with long-term efficacy.

Tumour evolution in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the most common form of primary liver cancer, typically develops on the background of chronic liver disease and is an aggressive disease with dismal prognosis. Studies using next-generation sequencing of multiple regions of the same tumour nodule suggest different patterns of HCC evolution and confirm the high molecular heterogeneity in a subset of patients. Different hypotheses have been proposed to explain tumour evolution, including clonal selection or neutral and punctuated acquisition of genetic alterations. In parallel, data indicate a fundamental contribution of nonmalignant cells of the tumour microenvironment to cancer clonal evolution. Delineating these dynamics is crucial to improve the treatment of patients with HCC, and particularly to help understand how HCC evolution drives resistance to systemic therapies. A number of new minimally invasive techniques, such as liquid biopsies, could help track cancer evolution in HCC. These tools might improve our understanding of how systemic therapies affect tumour clonal composition and could facilitate implementation of real-time molecular monitoring of patients with HCC.

Clinical significance of detecting circulating tumor cells in patients with esophageal squamous cell carcinoma by EpCAM‑independent enrichment and immunostaining‑fluorescence in situ hybridization

Circulating tumor cells (CTCs) are tumor cells present in the bloodstream, which originate from tumor sites, and are ultimately responsible for metastasis or relapse in several types of cancer. However, to the best of our knowledge, only a few studies have investigated these extremely rare cells in esophageal squamous cell carcinoma (ESCC). In the present study, 63 patients with ESCC and 50 healthy donors were recruited, and the potential clinical significance of CTCs was assessed using subtraction enrichment and immunostaining‑fluorescence in situ hybridization. Blood samples were collected at the following times: At first diagnosis, following neoadjuvant chemoradiotherapy, 24 h and 13 days post‑surgery, and every 3 months during follow‑up. Cytokeratin (CK)‑positive and clustered CTCs only accounted for 1% of total CTCs detected, whereas most CTCs were CK‑negative aneuploid cells. Patients with ESCC (n=63) had higher CTC counts compared with healthy donors (control group; n=50) (area under curve=0.807, median CTC count, 2 vs. 0). However, there was no statistical association between CTC counts and sex, age, pathological stage, tumor location, tumor depth or lymph node involvement (P>0.05). The association of tumor development with CTC status and other circulating biomarkers was monitored in patients for a further 2 years. The results revealed that a change in CTC counts between first diagnosis and 13 days post‑surgery (ΔCTC) of ≥2/7.5 ml peripheral blood could be applied for predicting progression‑free survival (hazard ratio, 3.922; 95% confidence interval, 0.907‑16.951; P<0.05) in patients with ESCC. In conclusion, ΔCTC evaluation may be a promising indicator for predicting tumor prognosis and the clinical efficacy of treatment in patients with ESCC.

Selecting patients with hepatocellular carcinoma for liver transplantation: incorporating tumor biology criteria

Liver transplantation (LT) is the optimal therapeutic option for patients with liver cirrhosis and hepatocellular carcinoma (HCC). Due to universal donor shortage, only the patients with limited tumor burden (under the so-called Milan criteria) are considered as potential candidates for LT in most institutions. It is expected that in the near future, more liver grafts will be available for patients with HCC due to the implementation of new direct antivirals against hepatitis C, leaving a prone scenario to consider expanding Milan criteria. A moderate expansion of Milan criteria could be implemented without increasing the risk of tumor recurrence if patients with favorable biological behavior are carefully selected. Incorporating information regarding tumor biology in the decision-making algorithm would result in a more rational use of LT in patients with HCC. In the present review, surrogate markers of tumor biology are critically evaluated as potential tools to be combined with existing radiological criteria. In addition, the current state of liquid biopsy is discussed, as this cutting-edge technology may reshape the management of HCC in the upcoming years.