Expression of programmed death ligand-1 and programmed death 1 in hepatocellular carcinoma and its clinical significance

Immunohistochemical expression of immune check point protein PDL-1 in hepatocellular carcinoma denotes its prognostic significance and association with survival

This study was designed to evaluate the immunohistochemical expression of programmed death ligand-1 (PD-L1) in tumor cells (TCs) and tumor-infiltrating immune cells (TICs) in hepatocellular carcinoma (HCC) and to correlate its expression with clinicopathological parameters. Seventy-two formalin-fixed paraffin-embedded blocks of HCC were collected. The data were collected from the patients' records. The blocks were stained with hematoxylin and eosin. Additionally, they were immunostained with PD-L1. Membranous staining was considered positive expression including the entire membrane or part of it ± cytoplasmic staining, and the percentage of total cancer cells ≥ 5% was evaluated as positive staining for TCs. The TICs were considered positive if they expressed membranous ± cytoplasmic staining of PD-L1 ≥ 1%. Of the total cases, 34.7% expressed PD-L1 positively in TCs and 15.3% expressed PD-L1 positively in TICs. Significant associations were observed between PD-L1 expression in TCs and tumor grade, capsular and/or vascular invasion, tumor stage, nodal metastasis, and the expression of PD-L1 in paracancerous tissue. The cases that positively expressed PD-L1 exhibited reduced overall survival (OS). PD-L1 was expressed in HCC TCs and TICs. Its expression in TCs was associated with higher HCC grades, advanced stages, capsular and/or vascular invasion, and nodal metastasis, and cases that expressed PD-L1 displayed reduced OS. Therefore, PD-L1 might serve as a poor prognostic indicator and a tumor immunotherapy target.

Immunotherapy against programmed death-1/programmed death ligand 1 in hepatocellular carcinoma: Importance of molecular variations, cellular heterogeneity, and cancer stem cells

Hepatocellular carcinoma (HCC) is a heterogeneous malignancy related to diverse etiological factors. Different oncogenic mechanisms and genetic variations lead to multiple HCC molecular classifications. Recently, an immune-based strategy using immune checkpoint inhibitors (ICIs) was presented in HCC therapy, especially with ICIs against the programmed death-1 (PD-1) and its ligand PD-L1. However, despite the success of anti-PD-1/PD-L1 in other cancers, a substantial proportion of HCC patients fail to respond. In this review, we gather current information on biomarkers of anti-PD-1/PD-L1 treatment and the contribution of HCC heterogeneity and hepatic cancer stem cells (CSCs). Genetic variations of PD-1 and PD-L1 are associated with chronic liver disease and progression to cancer. PD-L1 expression in tumoral tissues is differentially expressed in CSCs, particularly in those with a close association with the tumor microenvironment. This information will be beneficial for the selection of patients and the management of the ICIs against PD-1/PD-L1.

The Role of Immunotherapy in Hepatocellular Carcinoma: A Systematic Review and Pooled Analysis of 2,402 Patients

BACKGROUND

Immune checkpoints inhibitors (ICIs) have emerged as a treatment option for several malignancies. Nivolumab, pembrolizumab, nivolumab plus ipilimumab, and atezolizumab plus bevacizumab have been approved for the management of advanced-stage hepatocellular carcinoma (HCC). We aimed to systematically review the literature and summarize the characteristics and outcomes of patients with HCC treated with ICIs.

METHODS

A systematic literature search of PubMed, the Cochrane Library, and ClinicalTrials.gov was performed according to the PRISMA statement (end of search date: November 7, 2020). Quality of evidence assessment was also performed.

RESULTS

Sixty-three articles including 2,402 patients were analyzed, 2,376 of whom received ICIs for unresectable HCC. Response to ICIs could be evaluated in 2,116 patients; the overall objective response rate (ORR) and disease control rate (DCR) were 22.7% and 60.7%, respectively, and the mean overall survival (OS) was 15.8 months. The ORR, DCR, and OS for nivolumab (n = 846) were 19.7%, 51.1%, and 18.7 months, respectively; for pembrolizumab (n = 435) they were 20.7%, 64.6% and 13.3 months, respectively. The combination of atezolizumab/bevacizumab (n = 460) demonstrated an ORR and DCR of 30% and 77%, respectively. The overall rate of treatment discontinuation because of adverse events was 14.9%. Fifteen patients received ICIs in the liver transplant (LT) setting (one pre-LT for bridging, 14 for post-LT recurrence); fatal graft rejection was reported in 40.0% (n = 6/15) and mortality in 80.0% (n = 12/15).

CONCLUSION

ICIs are safe and effective against unresectable HCC, but caution is warranted regarding their use in the LT setting because of the high graft rejection rate.

IMPLICATIONS FOR PRACTICE

This systematic review pooled the outcomes from studies reporting on the use of immune checkpoint inhibitors (ICIs) for the management of 2,402 patients with advanced-stage hepatocellular carcinoma (HCC), 2,376 of whom had unresectable HCC. The objective response rate and disease control rate were 22.7% and 60.7%, respectively, and the mean overall survival was 15.8 months. The overall rate of treatment discontinuation because of adverse events was 14.9%. Fifteen patients received ICIs in the liver transplant (LT) setting (one pre-LT for bridging, 14 for post-LT recurrence). Six of these patients experienced graft rejection (40.0%).

Programmed death 1, ligand 1 and 2 correlated genes and their association with mutation, immune infiltration and clinical outcomes of hepatocellular carcinoma

BACKGROUND

The exact regulation network of programmed death 1 (PD-1), programmed death ligand 1 (PD-L1), and programmed death ligand 2 (PD-L2) signaling in immune escape is largely unknown. We aimed to describe the gene expression profiles related to PD-1 as well as its ligands PD-L1 and PD-L2, thus deciphering their possible biological processes in hepatocellular carcinoma (HCC).

AIM

To find the possible mechanism of function of PD-1, PD-L1, and PD-L2 in HCC.

METHODS

Based on the expression data of HCC from The Cancer Genome Atlas, the PD-1/PD-L1/PD-L2 related genes were screened by weighted correlation network analysis method and the biological processes of certain genes were enriched. Relation of PD1/PD-L1/PD-L2 with immune infiltration and checkpoints was investigated by co-expression analysis. The roles of PD-1/PD-L1/PD-L2 in determination of clinical outcome were also analyzed.

RESULTS

Mutations of calcium voltage-gated channel subunit alpha1 E, catenin beta 1, ryanodine receptor 2, tumor suppressor protein p53, and Titin altered PD-1/PD-L1/PD-L2 expression profiles in HCC. PD-1, PD-L1, and PD-L2 related genes were mainly enriched in biological procedures of T cell activation, cell adhesion, and other important lymphocyte effects. In addition, PD-1/PD-L1/PD-L2 was related with immune infiltration of CD8 T cells, cytotoxic lymphocytes, fibroblasts, and myeloid dendritic cells. Immune checkpoints of CTLA4, CD27, CD80, CD86, and CD28 were significantly related to the PD-1/PD-L1/PD-L2 axis. Clinically, PD-1 and PD-L2 expression was correlated with recurrence (P = 0.005 for both), but there was no significant correlation between their expression and HCC patient survival.

CONCLUSION

Mutations of key genes influence PD-1, PD-L1, and PD-L2 expression. PD-1, PD-L1, and PD-L2 related genes participate in T cell activation, cell adhesion, and other important lymphocyte effects. The finding that PD-1/PD-L1/PD-L2 is related to immune infiltration and other immune checkpoints would expand our understanding of promising anti-PD-1 immunotherapy.

Prognostic and clinicopathological significance of PD-1 expression in hepatocellular carcinoma: a meta-analysis

Objective

We performed a meta-analysis to evaluate the prognostic and clinicopathological significance of programmed cell death-1 (PD-1) expression in patients with hepatocellular carcinoma (HCC).

Methods

We searched the Wanfang, Chinese Biomedical Literature, CNKI, PubMed, Embase, and Web of Science databases for relevant articles from inception to 1 July 2020. Statistical analysis was performed using RevMan 5.3 (Cochrane, London, UK) and Stata 14.0 software (StataCorp LP, College Station, TX, USA).

Results

Eight studies involving 732 patients with HCC were included. Higher expression of PD-1 predicted longer disease-free survival [hazard ratio (HR) 0.53, 95% confidence interval (CI): 0.38–0.72]. No significant correlation was observed between PD-1 expression and overall survival (HR 0.89, 95% CI: 0.58–1.35). PD-1 expression was correlated with age [odds ratio (OR) 0.66, 95% CI: 0.46–0.94] and alpha-fetoprotein level (OR 2.27, 95% CI: 1.45–3.55); no correlation was observed with sex, tumor size, tumor metastasis, hepatitis B virus history, tumor stage, or tumor multiplicity. Sensitivity analysis demonstrated no excessive effect on stability of the pooled results. No significant publication bias was found among the identified studies.

Conclusion

PD-1 overexpression predicted better disease-free survival in patients with HCC. Moreover, PD-1 expression was associated with age and alpha-fetoprotein level.

Killing efficiency affected by mutually modulated PD-1 and PD-L1 expression via NKT-hepatoma cell interactions

Aim: To explore the expression of programmed death-1 (PD-1) or programmed death ligand 1 (PD-L1), natural killer T (NKT) and hepatoma cells in coculture system, and the influence of abolishing PD-1 on antitumor efficiency. Materials & methods: CRISPR/Cas9 technology, flow cytometry, ELISA, CCK-8 assay and mouse models were performed to investigate the interactions between PD-1/PD-L1 expression on NKT and hepatoma cells, respectively. Results: The NKT and hepatoma cells mutually affected the expression of PD-1/PD-L1. The killing effect was positively correlated with NKT-mediated PD-L1 expression on hepatoma cells. Conclusion: Hepatoma cells in different genetic background responded differently to NKT-induced PD-L1 stimulation, and those cells with lower PD-L1 expression fail to PD-1 blocking intervention. Additionally, the killing effect was more time-efficient with PD-1 knockout than with monoclonal antibody blockade.

Clinicopathological and Prognostic Roles of the Expression Levels of the Programmed Cell Death-1 Gene in Patients with Hepatocellular Carcinoma: A Systematic Review and Meta-Analysis

Background: Multiple studies have explored the prognostic role and clinical significance of the expression of the programmed cell death-1 (PD-1) gene in hepatocellular carcinoma (HCC). However, the results have been inconsistent. This study evaluated PD-1 expression and its clinical significance in patients with HCC, as well as the correlation between HCC pathological features and prognoses. Methods: All related research in PubMed, Embase, and Web of Science prior to October 31, 2019, was retrieved. The Newcastle-Ottawa Scale was used to evaluate the quality of the literature. Stata 14.0 statistical software was used to analyze the data, and the correlations between PD-1 expression and the clinicopathological characteristics of patients were analyzed using the odds ratio (OR) and its 95% confidence interval (CI). The hazard ratio (HR) and its 95% CI were used to analyze the correlation between PD-1 high expression and patient prognosis. Begg's test was used to evaluate publication bias. Results: A total of 581 patients were analyzed in the six studies included in the meta-analysis. Pooled analysis revealed that high levels of PD-1 expression did not correlate with overall survival (HR = 0.79; 95% CI: [0.41-1.54]; p = 0.493). PD-1 positivity was associated with better disease-free survival (HR = 0.52; 95% CI: [0.38-0.72]; p < 0.0001). Furthermore, elevated PD-1 expression corrected for age (OR = 0.62, 95% CI: [0.41-0.96]; p = 0.030) and alpha-fetoprotein levels (OR = 2.27, 95% CI: [1.46-3.55]; p < 0.0001), were not correlated with patient sex, tumor size, tumor multiplicity, hepatitis B virus history, tumor node metastasis stage or Barcelona Clinic Liver Cancer stage. Conclusions: This meta-analysis revealed that PD-1 expression may be a useful prognostic marker in HCC patients. Prospective clinical studies are needed to support these findings.

Correlation Patterns Among B7 Family Ligands and Tryptophan Degrading Enzymes in Hepatocellular Carcinoma

Mechanisms of dysfunctional T cell immunity in Hepatocellular Carcinoma (HCC) need to be well defined. B7 family molecules provide both co-stimulatory and co-inhibitory signals to T cells while tryptophan degrading enzymes like Indoleamine 2,3 dioxygenase (IDO) and Tryptophan 2,3 Dioxygenase (TDO) mediate tumor immune tolerance. It is necessary to identify their in situ correlative expression, which informs targets for combined immunotherapy approaches. We investigated B7 family molecules, IDO, TDO and immune responsive effectors in the tumor tissues of patients with HCC (n = 28) using a pathway-focused quantitative nanoscale chip real-time PCR. Four best correlative expressions, namely (1) B7-1 & PD-L2, (2) B7-H2 & B7-H3, (3) B7-2 & PD-L1, (4) PD-L1 & PD-L2, were identified among B7 family ligands, albeit they express at different levels. Although TDO expression is higher than IDO, PD-L1 correlates only with IDO but not TDO. Immune effector (Granzyme B) and suppressive (PD-1 and TGF-β) genes correlate with IDO and B7-1, B7-H5, PD-L2. Identification of the in situ correlation of PD-L1, PD-L2 and IDO suggest their cumulative immuno suppressive role in HCC. The distinct correlations among B7-1, B7-2, B7-H2, and B7-H3, correlation of PD-1 with non-cognate ligands such as B7-1 and B7-H5, and correlation of tumor lytic enzyme Granzyme B with IDO and PD-L2 suggest that HCC microenvironment is complexly orchestrated with both stimulatory and inhibitory molecules which together neutralize and blunt anti-HCC immunity. Functional assays demonstrate that both PDL-1 and IDO synergistically inhibit T cell responses. Altogether, the present data suggest the usage of combined immune checkpoint blocking strategies targeting co-inhibitory B7 molecules and IDO for HCC management.

Clinical immunology and immunotherapy for hepatocellular carcinoma: current progress and challenges

At the time of hepatocellular carcinoma (HCC) diagnosis, patients are most often at an advanced stage; however, the current treatment regimens remain unsatisfactory. Thus, novel and more powerful therapeutic approaches for advanced HCC are urgently required. Exacerbation of immunotolerant signals and/or escaping immunosurveillance leads to the development of HCC, which appears to be a rational reason to use immunotherapy to restore anticancer immunity. Several novel immunotherapeutic methods, including the use of immune checkpoint inhibitors, new types of immune cell adoption [e.g., chimeric antigen receptor T cell (CAR-T), TCR gene-modified T cells and stem cells], and microRNAs have been used in clinical trials for the treatment of HCC. However, some crucial issues remain to be addressed for such novel immunotherapy techniques. Finally, immunotherapy is now standing on the threshold of great advances in the fight against HCC.

Hepatocellular carcinoma: Therapeutic advances in signaling, epigenetic and immune targets

Hepatocellular carcinoma (HCC) remains a global medical burden with rising incidence due to chronic viral hepatitis and non-alcoholic fatty liver diseases. Treatment of advanced disease stages is still unsatisfying. Besides first and second generation tyrosine kinase inhibitors, immune checkpoint inhibitors have become central for the treatment of HCC. New modalities like epigenetic therapy using histone deacetylase inhibitors (HDACi) and cell therapy approaches with chimeric antigen receptor T cells (CAR-T cells) are currently under investigation in clinical trials. Development of such novel drugs is closely linked to the availability and improvement of novel preclinical and animal models and the identification of predictive biomarkers. The current status of treatment options for advanced HCC, emerging novel therapeutic approaches and different preclinical models for HCC drug discovery and development are reviewed here.