Evaluation of tumor mutational burden in small early hepatocellular carcinoma and progressed hepatocellular carcinoma

Overcoming Resistance to Immune Checkpoint Blockade in Liver Cancer with Combination Therapy: Stronger Together?

Primary liver cancer, represented mainly by hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (CCA), is one of the most common and deadliest tumors worldwide. While surgical resection or liver transplantation are the best option in early disease stages, these tumors often present in advanced stages and systemic treatment is required to improve survival time. The emergence of immune checkpoint inhibitor (ICI) therapy has had a positive impact especially on the treatment of advanced cancers, thereby establishing immunotherapy as part of first-line treatment in HCC and CCA. Nevertheless, low response rates reflect on the usually cold or immunosuppressed tumor microenvironment of primary liver cancer. In this review, we aim to summarize mechanisms of resistance leading to tumor immune escape with a special focus on the composition of tumor microenvironment in both HCC and CCA, also reflecting on recent important developments in ICI combination therapy. Furthermore, we discuss how combination of ICIs with established primary liver cancer treatments (e.g. multikinase inhibitors and chemotherapy) as well as more complex combinations with state-of-the-art therapeutic concepts may reshape the tumor microenvironment, leading to higher response rates and long-lasting antitumor immunity for primary liver cancer patients.

Histopathological Spectrum and Molecular Characterization of Liver Tumors in the Setting of Fontan-Associated Liver Disease

PURPOSE

Univentricular heart is corrected with the Fontan procedure (FP). In the long term, so-called Fontan-associated liver diseases (FALDs) can develop. The aim of this study is to analyze the molecular profile of FALDs.

METHODS

FALDs between January 1990 and December 2022 were reviewed for histology and immunohistochemistry, laboratory data, and images. Targeted next generation sequencing (NGS), performed on the DNA and RNA of both neoplastic and non-lesional liver tissue, was applied.

RESULTS

A total of 31/208 nodules > 1 cm in diameter were identified on imaging, but a liver biopsy was available for five patient demonstrating the following: one hepatocellular adenoma (HA), two hepatocellular carcinomas (HCCs), one fibrolamellar carcinoma (FLC), and one intrahepatic cholangiocarcinoma (ICC). Molecular analysis showed a copy number alteration involving FGFR3 in three cases (two HCCs and one ICC) as well as one HCC with a hotspot mutation on the CTNNB1 and NRAS genes. Tumor mutational burden ranged from low to intermediate. A variant of uncertain significance in GNAS was present in two HCCs and in one ICC. The same molecular profile was observed in a non-lesional liver. A DNAJB1-PRKACA fusion was detected only in one FLC.

CONCLUSIONS

Neoplastic FALDs show some unusual molecular profiles compared with non-Fontan ones. The presence of the same alterations in non-lesional cardiac cirrhosis could contribute to the development of FALD.

Mechanisms of Resistance to Immunotherapy in Hepatocellular Carcinoma

Systemic treatment for advanced hepatocellular carcinoma (HCC) has been revolutionized over the last few years following the approval of immune checkpoint inhibitors (ICI). Despite the promising survival extension seen with ICI combination regimens, responses are not universally seen and the optimal partner for programmed cell death 1 pathway inhibitors remains to be identified. Even fewer encouraging results have been demonstrated with ICI used for monotherapy. Several mechanisms of resistance have been described so far, involving characteristics of cancer cells (intrinsic mechanisms) and of the surrounding tumor microenvironment (extrinsic mechanisms). Factors related to therapy may also contribute to the development of resistance. Increasing research efforts are being dedicated to the discovery of novel approaches and targets to overcome resistance, some of which may be introduced into clinic in the future. Herein we describe a selection of resistance mechanisms that have been involved in impairing response to ICI and propose potential therapeutic approaches to overcome resistance.

Immunotherapy Plus Locoregional Therapy Leading to Curative-Intent Hepatectomy in HCC: Proof of Concept Producing Durable Survival Benefits Detectable with Liquid Biopsy

BACKGROUND

Immunotherapy has emerged as an improved systemic treatment for select patients with advanced unresectable HCC. Objective response is reported in 30% of patients, yet complete response (pCR) allowing for curative-intent resection is rare. Locoregional therapies (LRTs) seem to show synergistic effects with immunotherapy, though this effect has not been scientifically reported. We report a cohort of patients showing pCR to immunotherapy + LRT as a proof of concept for the proposed treatment approach for locally unresectable HCC.

METHODS

Patients with unresectable HCC treated with immunotherapy as an intended destination therapy from 2016 to 2023 were included. The electronic health record was queried for oncologic information, locoregional therapies, surgical interventions, and long-term outcomes. Circulating tumor DNA (ctDNA) testing was obtained using Guardant360, and tumor mutational burden (TMB) was defined as the number of somatic mutations per megabase.

RESULTS

Ninety-six patients with advanced HCC received immunotherapy + LRT as a destination therapy. In total, 11 of 96 patients showed a complete response according to mRECIST criteria. Four of these (36.4%) ultimately underwent curative-intent resection. The median follow-up was 24.9 (IQR 15.6-38.3) months. Overall survival rates in those with complete response at 1, 3, and 5 years were 100%, 91%, and 81.8%, respectively, which were significantly improved compared to those of the cohort not achieving pCR (p < 0.001). All four patients undergoing immunotherapy + LRT followed by curative-intent hepatectomy have no evidence of disease (NED). Of those undergoing surgery, ctDNA was cleared in 75% (n = 3), providing an additional objective measurement of complete response. All four patients were TMB+ before beginning this treatment course, with three being TMB-, indicating stable and complete disease response.

CONCLUSIONS

Immunotherapy + locoregional therapy can help downstage a significant proportion of patients with initially unresectable HCC, allowing for curative-intent surgery. The survival benefit associated with complete response seems durable up to 3 years after achieving this response. ctDNA measurement was converted from positive to negative in this cohort, providing additional indication of response.

Current Evidence for Immune Checkpoint Inhibition in Advanced Hepatocellular Carcinoma

The treatment of advanced unresectable HCC (aHCC) remains a clinical challenge, with limited therapeutic options and poor prognosis. The results of IMbrave150 and HIMALAYA have changed the treatment paradigm for HCC and established immune checkpoint inhibition (ICI), either combined with anti-angiogenic therapy or dual ICI, as preferred first-line therapy for eligible patients with aHCC. Numerous other combination regimens involving ICI are under investigation with the aim of improving the tumour response and survival of patients with all stages of HCC. This review will explore the current evidence for ICI in patients with advanced HCC and discuss future directions, including the unmet clinical need for predictive biomarkers to facilitate patient selection, the effects of cirrhosis aetiology on response to ICI, and the safety of its use in patients with impaired liver function.

Tumor Mutational Burden for Predicting Prognosis and Therapy Outcome of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC), the primary hepatic malignancy, represents the second-highest cause of cancer-related death worldwide. Many efforts have been devoted to finding novel biomarkers for predicting both patients' survival and the outcome of pharmacological treatments, with a particular focus on immunotherapy. In this regard, recent studies have focused on unravelling the role of tumor mutational burden (TMB), i.e., the total number of mutations per coding area of a tumor genome, to ascertain whether it can be considered a reliable biomarker to be used either for the stratification of HCC patients in subgroups with different responsiveness to immunotherapy, or for the prediction of disease progression, particularly in relation to the different HCC etiologies. In this review, we summarize the recent advances on the study of TMB and TMB-related biomarkers in the HCC landscape, focusing on their feasibility as guides for therapy decisions and/or predictors of clinical outcome.

The benefit of immunotherapy in patients with hepatocellular carcinoma: a systematic review and meta-analysis

Background: A systemic review of the survival benefit of immune checkpoint inhibitors (ICIs) in phase III hepatocellular carcinoma (HCC) trials was conducted. Methods: Meta-analyses were performed with the generic inverse-variance method with a fixed-effects model. Results: In 10 trials encompassing 6123 patients, ICI-based therapy (monotherapy/combination) improved overall survival (OS) compared with the control arm (hazard ratio [HR]: 0.77; 95% CI: 0.70-0.84; p < 0.001). The survival benefit was consistent across variable treatment lines, Eastern Cooperative Oncology Group performance status and AFP levels. While the OS benefit was more pronounced in hepatitis B-related HCC (HR: 0.70; 95% CI: 0.63-0.77; p < 0.001), OS was improved in hepatitis C-related (HR: 0.83; 95% CI: 0.71-0.98) and nonviral HCC (HR: 0.86; 95% CI: 0.77-0.97). Conclusion: ICI-based therapies should be the standard for all patients with advanced HCC.

Expert Insights on Current Treatments for Hepatocellular Carcinoma: Clinical and Molecular Approaches and Bottlenecks to Progress

Hepatocellular carcinoma (HCC) is a primary liver tumor that typically occurs in the setting of chronic liver disease/cirrhosis. Treatment modalities for HCC have evolved and given the variety of treatment options, a multi-disciplinary approach requiring input from surgical, medical, and radiation oncology, hepatology, and interventional radiology is necessary. Multiple advances have been made over the last decade regarding treatment of HCC, especially advanced disease. Resection and transplantation remain as cornerstone curative-intent treatment options. For patients who are not candidates for curative-intent therapy, exciting progress has been made in molecular and cellular approaches to systemic therapy for HCC including immunotherapies and tyrosine kinase inhibitors. Although the prognosis for advanced HCC remains poor, the armamentarium of therapies has increased, and valuable years of life can be gained with these therapies. While the main therapeutic modality for early-stage disease remains resection, multimodal immunotherapy has emerged as first-line treatment for advanced disease. We herein review different clinical and molecular treatment modalities related to the treatment of HCC, as well as provide insights into future directions for HCC treatment. We highlight how research and progress are needed to move into a new era of molecular and cellular treatments.

Highlighting novel targets in immunotherapy for liver cancer

INTRODUCTION

Alterations to the hepatic immune microenvironment can play a key role in the development and progression of cancer. This is especially true in the liver due to its evolutionarily conserved immunotolerant state. The presence of chronic inflammation can facilitate the development and progression of hepatocellular carcinoma (HCC) by disrupting the hepatic immune microenvironment. Recently, the addition of the immunotherapy atezolizumab (PD-L1 inhibitor) with bevacizumab (VEGF inhibitor) became the recommended first-line systemic treatment for advanced HCC.

AREAS COVERED

Given recent updates to the guidelines and emerging data on immunotherapy, we herein provide an overview of currently available and novel immunotherapy approaches for the treatment of HCC, including immune checkpoint inhibitors, adoptive cell therapy, and vaccine development. This review performed an extensive literature search to investigate benchwork, clinical research, and clinical trials that evaluate current immunotherapy and establish new targets. Literature was focused on the most up-to-date research and included ongoing clinical trials to better evaluate the obstacles and future direction of the field.

EXPERT OPINION

Given the heterogeneity of HCC tumors, improvement in outcomes will likely come from targeting multiple immune mechanisms. Continued research and clinical trials of combination immunotherapies are necessary to move the field forward.