Liquid biopsy in hepatocellular carcinoma: Challenges, advances, and clinical implications

Abstract

Hepatocellular carcinoma (HCC) is an aggressive primary liver malignancy often diagnosed at an advanced stage, resulting in a poor prognosis. Accurate risk stratification and early detection of HCC are critical unmet needs for improving outcomes. Several blood-based biomarkers and imaging tests are available for early detection, prediction, and monitoring of HCC. However, serum protein biomarkers such as alpha-fetoprotein have shown relatively low sensitivity, leading to inaccurate performance. Imaging studies also face limitations related to suboptimal accuracy, high cost, and limited implementation. Recently, liquid biopsy techniques have gained attention for addressing these unmet needs. Liquid biopsy is non-invasive and provides more objective readouts, requiring less reliance on healthcare professional's skills compared to imaging. Circulating tumor cells, cell-free DNA, and extracellular vesicles are targeted in liquid biopsies as novel biomarkers for HCC. Despite their potential, there are debates regarding the role of these novel biomarkers in the HCC care continuum. This review article aims to discuss the technical challenges, recent technical advancements, advantages and disadvantages of these liquid biopsies, as well as their current clinical application and future directions of liquid biopsy in HCC.

Keywords: Biomarker; Hepatocellular carcinoma; Liver cancer.

Figure 1.

Concept and workflow of liquid biopsy in HCC, including CTCs, EVs, and cfDNA. This schematic figure highlights the key components of the concept and workflow of liquid biopsy in HCC: the pre-analytical process, technical challenges associated with each type of liquid biopsy, technology development to address these challenges and clinical validation of liquid biopsy assays. CfDNA, cellfree DNA; CTC, circulating tumor cell; ctDNA, circulating tumor DNA; EV, extracellular vesicle; HCC, hepatocellular carcinoma; NGS, next-generation sequencing; PCR, polymerase chain reaction; WBC, white blood cell.

Figure 2.

Future application of liquid biopsy for early detection, prognostication, and detection of minimal residual disease in HCC. (A) Early detection of HCC. Signals from CTCs, cfDNA, and EVs are measured every 6 months in patients with cirrhosis or chronic hepatitis B who require HCC surveillance. Once these signals exceed predefined cut-off values, diagnostic methods such as CT or MRI are used to confirm an HCC diagnosis. (B) Prognostication of HCC. Blood samples are collected from HCC patients before surgery or locoregional therapies. Based on signals from CTCs, cfDNA, and EVs, HCC patients are classified into high-risk and low-risk groups for recurrence or progression. For high-risk patients, adjuvant therapy and close monitoring of early recurrence or progression may be warranted. (C) Detection of MRD in HCC. After curative surgery or locoregional therapies, blood samples are collected from HCC patients. High signals from CTCs, cfDNA, and EVs indicate an increased likelihood of MRD, warranting adjuvant therapy and close monitoring for early recurrence. CfDNA, cell-free DNA; CTC, circulating tumor cell; EV, extracellular vesicle; HCC, hepatocellular carcinoma; MRD, minimal residual disease.