Strengthening the case that elevated levels of programmed death ligand 1 predict poor prognosis in hepatocellular carcinoma patients

Immunotherapy for hepatocellular carcinoma: Recent advances and future targets

Immunotherapy is a promising approach to treating various types of cancers, including hepatocellular carcinoma (HCC). While single immunotherapy drugs show limited effectiveness on a small subset of patients, the combination of the anti PD-L1 atezolizumab and anti-vascular endothelial growth factor bevacizumab has shown significant improvement in survival compared to sorafenib as a first-line treatment. However, the current treatment options still have a low success rate of about 30%. Thus, more effective treatments for HCC are urgently required. Several novel immunotherapeutic methods, including the use of novel immune checkpoint inhibitors, innovative immune cell therapies like chimeric antigen receptor T cells (CAR-T), TCR gene-modified T cells and stem cells, as well as combination strategies are being tested in clinical trials for the treatment of HCC. However, some crucial issues still exist such as the presence of heterogeneous antigens in solid tumors, the immune-suppressive environment within tumors, the risk of on-target/off-tumor, infiltrating CAR-T cells, immunosuppressive checkpoint molecules, and cytokines. Overall, immunotherapy is on the brink of major advancements in the fight against HCC.

Immune checkpoint inhibitors in HCC: Cellular, molecular and systemic data

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer related deaths in the world, and for patients with advanced disease there are few therapeutic options available. The complex immunological microenvironment of HCC and the success of immunotherapy in several types of tumours, has raised the prospect of potential benefit for immune based therapies, such as immune checkpoint inhibitors (ICIs), in HCC. This has led to significant breakthrough research, numerous clinical trials and the rapid approval of multiple systemic drugs for HCC by regulatory bodies worldwide. Although some patients responded well to ICIs, many have failed to achieve significant benefit, while others showed unexpected and paradoxical deterioration. The aim of this review is to discuss the pathophysiology of HCC, the tumour microenvironment, key clinical trials evaluating ICIs in HCC, various resistance mechanisms to ICIs, and possible ways to overcome these impediments to improve patient outcomes.

Current Treatment Options for HCC: From Pharmacokinetics to Efficacy and Adverse Events in Liver Cirrhosis

BACKGROUND

Hepatocellular carcinoma (HCC) is among the world's most common cancers. For over ten years, the only medical treatment for it has been the multikinase inhibitor Sorafenib. Currently, however, other first or second-line therapeutic options have also shown efficacy against HCC, such as multikinase inhibitors (Regorafenib, Lenvatinib, and Cabozantinib), a monoclonal antibody against the vascular endothelial growth factor receptor 2 (Ramucirumab), and immune-checkpoint inhibitors (Nivolumab, Pembrolizumab, Ipilimumab).

AIM

The aim of this paper is to review the metabolic pathways of drugs that have been tested for the treatment of HCC and the potential influence of liver failure over those pathways.

METHODS

The Food and Drug Administration (FDA)'s and European Medicines Agency (EMA)'s datasheets, results from clinical trials and observational studies have been reviewed.

RESULTS

This review summarizes the current knowledge regarding targets, metabolic pathways, drug interactions, and adverse events of medical treatments for HCC in cirrhotic patients.

CONCLUSION

The new scenario of systemic HCC therapy includes more active drugs with different metabolic pathways and different liver adverse events. Clinical and pharmacological studies providing more data on the safety of these molecules are urgently needed.

Immune Checkpoint Inhibitors in Hepatocellular Cancer: Current Understanding on Mechanisms of Resistance and Biomarkers of Response to Treatment

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy worldwide and a leading cause of death worldwide. Its incidence continues to increase in the US due to hepatitis C infection and nonalcoholic steatohepatitis. Liver transplantation and resection remain the best therapeutic options for cure, but these are limited by the shortage of available organs for transplantation, diagnosis at advanced stage, and underlying chronic liver disease found in most patients with HCC. Immune checkpoint inhibitors (ICIs) have been shown to be an evolving novel treatment option in certain advanced solid tumors and have been recently approved for inoperable, advanced, and metastatic HCC. Unfortunately, a large cohort of patients with HCC fail to respond to immunotherapy. In this review, we discuss the ICIs currently approved for HCC treatment and their various mechanisms of action. We will highlight current understanding of mechanism of resistance and limitations to ICIs. Finally, we will describe emerging biomarkers of response to ICIs and address future direction on overcoming resistance to immune checkpoint therapy.

Immune Checkpoint Inhibitors in Hepatocellular Carcinoma: Opportunities and Challenges

Hepatocellular carcinoma (HCC) is the most common malignancy worldwide, and is especially common in China. A total of 70%-80% of patients are diagnosed at an advanced stage and can receive only palliative care. Sorafenib has been the standard of care for a decade, and promising results for regorafenib as a second-line and lenvatinib as a first-line treatment were reported only 1 or 2 years ago. FOLFOX4 was recently recommended as a clinical practice guideline by the China Food and Drug Administration. All approved systemic therapies remain unsatisfactory, with limited objective response rates and poor overall survival. Immune checkpoint inhibitors (CPIs) offer great promise in the treatment of a rapidly expanding spectrum of solid tumors. Immune checkpoint molecules are involved in almost the whole process of viral-related hepatitis with cirrhosis and HCC and in the most important resistance mechanism of sorafenib. The approval of nivolumab by the U.S. Food and Drug Administration on September 23, 2017, for the treatment of patients with HCC, based only on a phase I/II clinical trial, is a strong hint that immunotherapy will introduce a new era of HCC therapy. CPI-based strategies will soon be a main approach in anticancer treatment for HCC, and we will observe the rapid advances in the therapeutic use of CPIs, even in an adjuvant setting, with great interest. How shall we face the opportunities and challenges? Can we dramatically improve the prognosis of patients with HCC? This review may provide some informed guidance. IMPLICATIONS FOR PRACTICE: Immune checkpoint molecules are involved in almost the whole process of viral-related hepatitis with cirrhosis and hepatocellular carcinoma (HCC) and in the most important resistance mechanism of sorafenib. As all approved systemic therapies in HCC remain unsatisfactory, checkpoint inhibitor (CPI)-based strategies will soon be a main approach in anticancer treatment for advanced stage of HCC, even in an adjuvant setting. In virus-related HCC, especially hepatitis B virus-related HCC, whether CPIs can control virus relapse should be further investigated. Combination strategies involving conventional therapies and immunotherapies are needed to increase clinical benefit and minimize adverse toxicities with regard to the underlying liver disease.

Prognostic role of PD-L1 for HCC patients after potentially curative resection: a meta-analysis

Background

A series of studies has investigated the prognostic role and clinical significance of programmed death ligand 1 (PD-L1) in hepatocellular carcinoma (HCC). However, the results were inconsistent. We aimed to clarify the prognostic role of PD-L1 and relationship between PD-L1 expression and several important clinicopathological features.

Methods

PubMed, EMBASE and the Science Citation Index Expanded were systematically searched. All cohort or case–control studies comparing the prognosis and clinical features between the high PD-L1 and low PD-L1 groups were included. Publication bias was evaluated using funnel plots and Begg’s test. Subgroup analysis, sensitivity analysis and meta-regression analysis were performed.

Results

Seventeen studies including 2979 patients were eligible. The overall survival (OS) was not significantly different between the high and low PD-L1 groups (hazard ratio [HR]: 1.27; 95% confidence interval [CI] 0.98–1.65: P = 0.07) with significant heterogeneity (P < 0.001; I² = 81%). The recurrence-free survival (RFS) was not significantly different between the high and low PD-L1 groups (HR: 1.22; 95% CI 0.97–1.53; P = 0.09) with significant heterogeneity (P < 0.001; I² = 78%). The expression of PD-L1 was found to be significantly correlated with alpha-fetoprotein, hepatitis history, and tumour-infiltrating lymphocytes. Begg’s test found no significant publication bias for OS and RFS. Sensitivity analysis established the robustness of our results. Subgroup analysis and meta-regression analysis found the region of research as a significant contributor to inter-study heterogeneity in RFS, indicating some racial differences in the prognostic role of PD-L1.

Conclusions

Our study found no significant prognostic role of PD-L1 in HCC patients after potential curative hepatectomy based on our included studies. The expression of PD-L1 was significantly correlated with AFP, hepatitis history, and TILs. The prognostic role of PD-L1 in HCC warrants further investigation.

Electronic supplementary material

The online version of this article (10.1186/s12935-019-0738-9) contains supplementary material, which is available to authorized users.

The PD-L1- and IL6-mediated dampening of the IL27/STAT1 anticancer responses are prevented by α-PD-L1 or α-IL6 antibodies

Interleukin-27 (IL27) is a type-I cytokine of the IL6/IL12 family and is predominantly secreted by activated macrophages and dendritic cells. We show that IL27 induces STAT factor phosphorylation in cancerous cell lines of different tissue origin. IL27 leads to STAT1 phosphorylation and recapitulates an IFN-γ-like response in the microarray analyses, with up-regulation of genes involved in antiviral defense, antigen presentation, and immune suppression. Like IFN-γ, IL27 leads to an up-regulation of TAP2 and MHC-I proteins, which mediate increased tumor immune clearance. However, both cytokines also upregulate proteins such as PD-L1 (CD274) and IDO-1, which are associated with immune escape of cancer. Interestingly, differential expression of these genes was observed within the different cell lines and when comparing IL27 to IFN-γ. In coculture experiments of hepatocellular carcinoma (HCC) cells with peripheral blood mononuclear cells, pre-treatment of the HCC cells with IL27 resulted in lowered IL2 production by anti-CD3/-CD28 activated T-lymphocytes. Addition of anti-PD-L1 antibody, however, restored IL2 secretion. The levels of other T_H 1 cytokines were also enhanced or restored upon administration of anti-PD-L1. In addition, we show that the suppression of IL27 signaling by IL6-type cytokine pre-stimulation-mimicking a situation occurring, for example, in IL6-secreting tumors or in tumor inflammation-induced cachexia-can be antagonized by antibodies against IL6-type cytokines or their receptors. Therapeutically, the antitumor effects of IL27 (mediated, e.g., by increased antigen presentation) might thus be increased by combining IL27 with blocking antibodies against PD-L1 or/and IL6-type cytokines.

IL-6/STAT3 pathway intermediates M1/M2 macrophage polarization during the development of hepatocellular carcinoma

Human cancers, including hepatocellular carcinoma (HCC), are characterized by a high degree of drug resistance in chemotherapy. However, the underlying molecular mechanism remains unknown. To the role of interleukin-6 (IL-6)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in the regulation of macrophage polarization, M1-type and M2-type macrophages were separately induced using lipopolysaccharide and interleukin-4 (IL-4), and we found that the IL-6/STAT3 signaling pathway was inhibited in M1-type macrophages but activated in M2-type macrophages. After anti-IL-6-treated macrophages were separately induced by lipopolysaccharide and IL-4, we found that the inhibition of IL-6/STAT3 signaling pathway turned macrophages into M1-type. Co-culture with M1-type macrophages reduced HCC cell viability, proliferation, invasion, migration, drug resistance, but increased apoptosis. Co-culture with M2-type macrophages yielded reciprocal results. The inhibition of IL-6/STAT3 signaling pathway mediated by anti-IL6 was shown to significantly enhance the effects of M1-type macrophages on HCC cells and rescue HCC cells from co-culture with M2-type macrophages. Tumor xenografts of co-cultured HCC cells were established in nude mice and the results showed that the inhibition of IL-6/STAT3 signaling pathway mediated by anti-IL6 was found to reduce tumor formation of HCC cells co-cultured with M1- or M2-type macrophages and lung metastases. The current study reveals a novel mechanism of IL-6/STAT3 signaling pathway in the regulation of macrophage polarization, thus contributing to HCC metastasis and drug resistance in chemotherapy.

Prognostic value of PD -L1 expression in patients with primary solid tumors

Programmed death-ligand 1 (PD-L1) is thought to play a critical role in immune escape by cancer, but whether PD-L1 expression can influence prognosis of patients with solid tumors is controversial. Therefore, we meta-analyzed available data on whether PD-L1 expression correlates with overall survival (OS) in such patients. PubMed, EMBASE and other databases were systematically searched for cohort or case-control studies examining the possible correlation between PD-L1 expression and OS of patients with solid tumors. OS was compared between patients positive or negative for PD-L1 expression using scatter plots, and subgroup analyses were performed based on tumor type and patient characteristics. Data from 59 studies involving 20,004 patients with solid tumors were meta-analyzed. The median percentage of tumors positive for PD-L1 was 30.1%. OS was significantly lower in PD-L1-positive patients than in PD-L1-negative patients at 1 year (P = 0.039), 3 years (P < 0.001) and 5 years (P < 0.001). The risk ratios of OS (and associated 95% confidence intervals) were 2.02 (1.56-2.60) at 1 year, 1.57 (1.34-1.83) at 3 years and 1.43 (1.24-1.64) at 5 years. Similar results were obtained in subgroup analyses based on patient ethnicity or tumor type. The available evidence suggests that PD-L1 expression negatively affects the prognosis of patients with solid tumors. PD-L1 might serve as an efficient prognostic indicator in solid tumor and may represent the important new therapeutic target.