Ex vivo characterization of tumor-derived melanoma antigen encoding gene-specific CD8+cells in patients with hepatocellular carcinoma

Immunotherapy and liver transplantation for hepatocellular carcinoma: Current and future challenges

Despite existing curative options like surgical removal, tissue destruction techniques, and liver transplantation for early-stage hepatocellular carcinoma (HCC), the rising incidence and mortality rates of this global health burden necessitate continuous exploration of novel therapeutic strategies. This review critically assesses the dynamic treatment panorama for HCC, focusing specifically on the burgeoning role of immunotherapy in two key contexts: early-stage HCC and downstaging advanced HCC to facilitate liver transplant candidacy. It delves into the unique immunobiology of the liver and HCC, highlighting tumor-mediated immune evasion mechanisms. Analyzing the diverse immunotherapeutic approaches including checkpoint inhibitors, cytokine modulators, vaccines, oncolytic viruses, antigen-targeting antibodies, and adoptive cell therapy, this review acknowledges the limitations of current diagnostic markers alpha-fetoprotein and glypican-3 and emphasizes the need for novel biomarkers for patient selection and treatment monitoring. Exploring the rationale for neoadjuvant and adjuvant immunotherapy in early-stage HCC, current research is actively exploring the safety and effectiveness of diverse immunotherapeutic approaches through ongoing clinical trials. The review further explores the potential benefits and challenges of combining immunotherapy and liver transplant, highlighting the need for careful patient selection, meticulous monitoring, and novel strategies to mitigate post-transplant complications. Finally, this review delves into the latest findings from the clinical research landscape and future directions in HCC management, paving the way for optimizing treatment strategies and improving long-term survival rates for patients with this challenging malignancy.

First-in-human dose escalation trial to evaluate the clinical safety and efficacy of an anti-MAGEA1 autologous TCR-transgenic T cell therapy in relapsed and refractory solid tumors

RATIONALE OF THE TRIAL

Although the use of engineered T cells in cancer immunotherapy has greatly advanced the treatment of hematological malignancies, reaching meaningful clinical responses in the treatment of solid tumors is still challenging. We investigated the safety and tolerability of IMA202 in a first-in-human, dose escalation basket trial in human leucocyte antigen A*02:01 positive patients with melanoma-associated antigen A1 (MAGEA1)-positive advanced solid tumors.

TRIAL DESIGN

The 2+2 trial design was an algorithmic design based on a maximally acceptable dose-limiting toxicity (DLT) rate of 25% and the sample size was driven by the algorithmic design with a maximum of 16 patients. IMA202 consists of autologous genetically modified cytotoxic CD8+ T cells expressing a T cell receptor (TCR), which is specific for a nine amino acid peptide derived from MAGEA1. Eligible patients underwent leukapheresis, T cells were isolated, transduced with lentiviral vector carrying MAGEA1-specific TCR and following lymphodepletion (fludarabine/cyclophosphamide), infused with a median of 1.4×109 specific T cells (range, 0.086×109-2.57×109) followed by interleukin 2. SAFETY OF IMA202: No DLT was observed. The most common grade 3-4 adverse events were cytopenias, that is, neutropenia (81.3%), lymphopenia (75.0%), anemia (50.0%), thrombocytopenia (50.0%) and leukopenia (25.0%). 13 patients experienced cytokine release syndrome, including one grade 3 event. Immune effector cell-associated neurotoxicity syndrome was observed in two patients and was grade 1 in both. EFFICACY OF IMA202: Of the 16 patients dosed, 11 (68.8%) patients had stable disease (SD) as their best overall response (Response Evaluation Criteria in Solid Tumors V.1.1). Five patients had initial tumor shrinkage in target lesions and one patient with SD experienced continued shrinkage in target lesions for 3 months in total but had to be classified as progressive disease due to progressive non-target lesions. IMA202 T cells were persistent in peripheral blood for several weeks to months and were also detectable in tumor tissue. Peak persistence was higher in patients who received higher doses.

CONCLUSION

In conclusion, IMA202 had a manageable safety profile, and it was associated with biological and potential clinical activity of MAGEA1-targeting genetically engineered TCR-T cells in a poor prognosis, multi-indication solid tumor cohort.

TRIAL REGISTRATION NUMBERS

NCT04639245, NCT05430555.

Therapeutic Vaccines against Hepatocellular Carcinoma in the Immune Checkpoint Inhibitor Era: Time for Neoantigens?

Immune checkpoint inhibitors (ICI) have been used as immunotherapy for hepatocellular carcinoma (HCC) with promising but still limited results. Identification of immune elements in the tumor microenvironment of individual HCC patients may help to understand the correlations of responses, as well as to design personalized therapies for non-responder patients. Immune-enhancing strategies, such as vaccination, would complement ICI in those individuals with poorly infiltrated tumors. The prominent role of responses against mutated tumor antigens (neoAgs) in ICI-based therapies suggests that boosting responses against these epitopes may specifically target tumor cells. In this review we summarize clinical vaccination trials carried out in HCC, the available information on potentially immunogenic neoAgs in HCC patients, and the most recent results of neoAg-based vaccines in other tumors. Despite the low/intermediate mutational burden observed in HCC, data obtained from neoAg-based vaccines in other tumors indicate that vaccines directed against these tumor-specific antigens would complement ICI in a subset of HCC patients.

Novel Cellular Therapies for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer related death worldwide. Most patients present with advanced disease, and current gold-standard management using tyrosine kinase inhibitors or immune checkpoint inhibitors (ICIs) offers modest clinical benefit. Cellular immune therapies targeting HCC are currently being tested in the laboratory and in clinical trials. Here, we review the landscape of cellular immunotherapy for HCC, defining antigenic targets, outlining the range of cell therapy products being applied in HCC (such as CAR-T and TCR-T), and exploring how advanced engineering solutions may further enhance this therapeutic approach.

Nanomedicine Approach to Immunotherapy of Hepatocellular Carcinoma

In recent years, the growing studies focused on the immunotherapy of hepatocellular carcinoma and proved the preclinical and clinical promises of host antitumor immune response. However, there were still various obstacles in meeting satisfactory clinic need, such as low response rate, primary resistance and secondary resistance to immunotherapy. Tackling these barriers required a deeper understanding of immune underpinnings and a broader understanding of advanced technology. This review described immune microenvironment of liver and HCC which naturally decided the complexity of immunotherapy, and summarized recent immunotherapy focusing on different points. The ever-growing clues indicated that the instant killing of tumor cell and the subsequent relive of immunosuppressive microenvironment were both indis- pensables. The nanotechnology applied in immunotherapy and the combination with intervention technology was also discussed.

Hepatocellular Carcinoma Immune Landscape and the Potential of Immunotherapies

Hepatocellular carcinoma (HCC) is the most common liver tumor and among the deadliest cancers worldwide. Advanced HCC overall survival is meager and has not improved over the last decade despite approval of several tyrosine kinase inhibitors (TKi) for first and second-line treatments. The recent approval of immune checkpoint inhibitors (ICI) has revolutionized HCC palliative care. Unfortunately, the majority of HCC patients fail to respond to these therapies. Here, we elaborate on the immune landscapes of the normal and cirrhotic livers and of the unique HCC tumor microenvironment. We describe the molecular and immunological classifications of HCC, discuss the role of specific immune cell subsets in this cancer, with a focus on myeloid cells and pathways in anti-tumor immunity, tumor promotion and immune evasion. We also describe the challenges and opportunities of immunotherapies in HCC and discuss new avenues based on harnessing the anti-tumor activity of myeloid, NK and γδ T cells, vaccines, chimeric antigen receptors (CAR)-T or -NK cells, oncolytic viruses, and combination therapies.

CD8+ T Cell Responses during HCV Infection and HCC

Chronic hepatitis C virus (cHCV) infection is a major global health burden and the leading cause of hepatocellular carcinoma (HCC) in the Western world. The course and outcome of HCV infection is centrally influenced by CD8⁺ T cell responses. Indeed, strong virus-specific CD8⁺ T cell responses are associated with spontaneous viral clearance while failure of these responses, e.g., caused by viral escape and T cell exhaustion, is associated with the development of chronic infection. Recently, heterogeneity within the exhausted HCV-specific CD8⁺ T cells has been observed with implications for immunotherapeutic approaches also for other diseases. In HCC, the presence of tumor-infiltrating and peripheral CD8⁺ T cell responses correlates with a favorable prognosis. Thus, tumor-associated and tumor-specific CD8⁺ T cells are considered suitable targets for immunotherapeutic strategies. Here, we review the current knowledge of CD8+ T cell responses in chronic HCV infection and HCC and their respective failure with the potential consequences for T cell-associated immunotherapeutic approaches.

Immunotherapy for Hepatocellular Carcinoma: A 2021 Update

Hepatocellular carcinoma (HCC) is one of one of the most frequent liver cancers and the fourth leading cause of cancer-related mortality worldwide. Current treatment options such as surgery, neoadjuvant chemoradiotherapy, liver transplantation, and radiofrequency ablation will benefit only a very small percentage of patients. Immunotherapy is a novel treatment approach representing an effective and promising option against several types of cancer. The aim of our study is to present the currently ongoing clinical trials and to evaluate the efficacy of immunotherapy in HCC. In this paper, we demonstrate that combination of different immunotherapies or immunotherapy with other modalities results in better overall survival (OS) and progression-free survival (PFS) compared to single immunotherapy agent. Another objective of this paper is to demonstrate and highlight the importance of tumor microenvironment as a predictive and prognostic marker and its clinical implications in immunotherapy response.

Inefficient induction of circulating TAA-specific CD8+ T-cell responses in hepatocellular carcinoma

Background & Aims: In hepatocellular carcinoma (HCC), CD8+ T-cell responses targeting tumor-associated antigens (TAA) are considered to be beneficial. However, the molecular profile of TAA-specific CD8+ T cells in HCC is not well defined due to their low frequency.

Results: In this study, we demonstrate that TAA-specific CD8+ T-cell responses are not efficiently induced in the peripheral blood of HCC patients as supported by the following observations: First, in HCC patients, frequencies of TAA-specific CD8+ T cells were not increased compared to healthy donors (HD) or patients with liver cirrhosis. Second, a remarkable proportion of TAA-specific CD8+ T cells were naïve despite the presence of antigen within the tumor tissue. Third, antigen-experienced TAA-specific CD8+ T cells lack the characteristic transcriptional regulation of exhausted CD8+ T cells, namely Eomes^hiTbet^dim, and express inhibitory receptors only on a minor proportion of cells. This suggests restricted antigen recognition and further supports the hypothesis of inefficient induction and activation.

Methods: By applying peptide/MHCI tetramer-based enrichment, a method of high sensitivity, we now could define the heterogeneity of circulating TAA-specific CD8+ T cells targeting glypican-3, NY-ESO-1, MAGE-A1 and MAGE-A3. We focused on therapy-naïve HCC patients of which the majority underwent transarterial chemoembolization (TACE).

Conclusion: Our analysis reveals that circulating TAA-specific CD8+ T cells targeting 4 different immunodominant epitopes are not properly induced in therapy-naïve HCC patients thereby unravelling new and unexpected insights into TAA-specific CD8+ T-cell biology in HCC. This clearly highlights severe limitations of these potentially anti-tumoral T cells that may hamper their biological and clinical relevance in HCC.

Immune cell therapy for hepatocellular carcinoma

Given the success of immune checkpoint inhibitors and chimeric antigen receptor (CAR) T cells in clinical settings, the host immune system plays an important role in the recognition and targeting of tumor cells in cancer immunotherapy. As a result, there have been numerous advancements in immune cell therapy using human immune cells. However, recent evidence suggests that one type of immunotherapy alone is not effective for the treatment of cancer, particularly solid tumors. Thus, effective immunotherapy combinations, such as the combination of checkpoint inhibitors and immune cell therapy, are needed. This review focuses on hepatocellular carcinoma among other solid tumors and discusses the current status and future of immune cell therapy in cancer immunotherapy.

Characteristics of Immune Response to Tumor-Associated Antigens and Immune Cell Profile in Patients With Hepatocellular Carcinoma

Host antitumor immune responses may be different between hepatocellular carcinoma (HCC) caused by metabolic disorders and HCC associated with hepatitis virus infection. In this study, we examined the immune response of tumor-associated antigen (TAA)-specific T cells and immune cell profile in patients with HCC separated by cause. Thirty-two patients with hepatitis B virus (HBV)-related HCC, 42 patients with hepatitis C virus-related HCC, and 18 patients with nonalcoholic steatohepatitis (NASH)-related HCC were analyzed. The frequencies of TAA-specific T cells, the expression levels of surface markers on each immune cell, and the expression of each TAA in HCC tissue were measured. The immune response to TAA and immune cell profile were markedly different among the three groups. The immune response to TAA in the NASH-related HCC group was weaker than the responses in the other two groups. In patients with NASH-related HCC, the frequencies of effector regulatory T cells (eTregs) and cluster of differentiation 8-positive (CD8⁺ ) T cells strongly expressing cytotoxic T-lymphocyte antigen (CTLA)-4 were high. The frequency of CD8⁺ T cells strongly expressing programmed cell death 1 was the highest in patients with HBV-related HCC. Among these immune cell profiles, the frequencies of C-X-C motif chemokine receptor 3⁺ eTregs and CTLA-4⁺ CD8⁺ T cells were inversely correlated with the strength of the TAA-specific T-cell immune response, and the restoration of TAA-specific T-cell responses by anti-CTLA-4 antibody was observed. Conclusion: The immune response to TAA were markedly different among the three groups, and a correlation with the immune cell profile was observed, suggesting that development of immunotherapy based on the etiology of HCC may lead to more effective treatment outcomes.

Immune response to human telomerase reverse transcriptase-derived helper T cell epitopes in hepatocellular carcinoma patients

BACKGROUND AND AIMS

Human telomerase reverse transcriptase is a catalytic enzyme involved in telomere elongation. It is expressed in many tumours, including hepatocellular carcinoma. The purpose of the present study was to identify major histocompatibility complex class II-restricted helper T cell epitopes derived from human telomerase reverse transcriptase in patients with hepatocellular carcinoma.

METHODS

TEPITOPE software was used to predict helper T cell epitopes based on the entire amino acid sequence of human telomerase reverse transcriptase, and peptides were synthesized based on the predicted sequence. Interferon (IFN)-γ enzyme linked immunospot assay was performed to examine the T cell response to each of the synthesized peptides in peripheral blood mononuclear cells. Furthermore, the peptides were labelled with fluorescein isothiocyanate to test their binding affinity for major histocompatibility complex class II molecules. Lastly, the association between patient characteristics and the level of immune response to these epitopes was examined.

RESULTS

Positive T cell response (>10% enzyme linked immunospot positivity) was detected against 4 of 10 peptides. Among all peptides, positive T cell response to the hTERT₆₈ peptide was detected most frequently. While hTERT₆₈ was HLA-DRB1*0405-restricted, it also bound to other MCH class II molecules. Positive helper T cell response was detected most frequently in hepatocellular carcinoma patients with a low serum alpha-foetoprotein level. Several treatments for hepatocellular carcinoma enhanced the immune response against the peptides.

CONCLUSION

Our findings indicate that helper T cell epitopes identified in the present study may be useful to investigate immune responses and for immunotherapy in hepatocellular carcinoma patients.

Downregulation of MAGE family member H1 enhances hepatocellular carcinoma progression and serves as a biomarker for patient prognosis

AIM

The MAGE family member H1 (MAGEH1) belongs to melanoma-associated antigen (MAGE) superfamily. The role of MAGEH1 in hepatocellular carcinoma (HCC) is largely undefined.

MATERIALS & METHODS

We used quantitative reverse transcription PCR and immunohistochemistry to detect MAGEH1 expression in HCC tissues. CCK-8 assay, wound healing migration assay and Transwell Matrigel invasion assay were used to measure HCC cell proliferation, migration and invasion ability.

RESULTS

 MAGEH1 expression was downregulated in HCC tumor tissues compared with adjacent normal liver tissues and in samples from patients with tumor recurrence. MAGEH1 reduced HCC cell proliferation, migration and invasion ability. Low MAGEH1 expression was significantly correlated with poor prognosis in HCC patients.

CONCLUSION

 MAGEH1 may serve as a potential biomarker and a new prognostic factor for HCC.

Cellular Immune Responses for Squamous Cell Carcinoma Antigen Recognized by T Cells 3 in Patients with Hepatocellular Carcinoma

BACKGROUND & AIMS

Squamous cell carcinoma antigen recognized by T cells 3 (SART3), a tumor-associated antigen expressed in many cancers, functions in tumor rejection. In this study, we investigated its usefulness as an immunotherapeutic target in hepatocellular carcinoma (HCC).

METHODS

The expression of SART3 in hepatoma cell lines and HCC tissues was investigated by immunofluorescence and immunohistochemical analyses. Two peptides derived from SART3 (SART3109 and SART3315) were used for immunological analysis. T-cell responses were investigated by interferon-gamma (IFN-γ) enzyme-linked immunospot and cytotoxic T lymphocyte (CTL) assays using peripheral blood mononuclear cells (PBMCs) in 47 patients, and tumor-infiltrating lymphocytes in 8 of 47 patients with HCC. The safety of immunotherapy using a SART3-derived peptide was investigated by vaccinations of SART3109 in 12 patients with HCC (trial registration: UMIN000005677).

RESULTS

The immunofluorescence and immunohistochemical analyses showed that SART3 was expressed in six HCC cell lines, and in HCC tissues including of alpha-fetoprotein-negative individuals. SART3-specific CTLs were generated by stimulating PBMCs with the peptides, and they showed cytotoxicity against HCC cells expressing the protein. Of the 47 HCC patients, 25.5% and 10.6% showed significant responses to SART3109 and SART3315, respectively. The infiltration of SART3109-specific IFN-γ-producing CTLs into the tumor site was confirmed. In the vaccination study, no severe adverse events were observed, and the peptide-specific CTLs were newly induced in four of five patients tested.

CONCLUSIONS

SART3 is an immunotherapeutic candidate, and peptides from this antigen may be applied in HCC immunotherapy.

TRIAL REGISTRATION

UMIN000005677.

Immunotherapy in hepatocellular carcinoma: Primed to make a difference?

Advanced hepatocellular carcinoma (HCC) carries a dismal prognosis and the current treatment is limited to sorafenib, an agent with modest benefit. Preclinical data have indicated that several immunologic mechanisms are at play to promote HCC development and growth while impairing effective antitumor immune surveillance. Several novel approaches geared toward manipulating the immune response to HCC have suggested a therapeutic benefit in early-stage clinical trials, indicating a real potential to augment tumor-specific immunity and improve outcomes in patients with this disease. In the current study, the authors reviewed the barriers to an effective immune response against HCC and contemporary clinical investigations that may be "primed" to alter the natural history of HCC.

Status of and prospects for cancer vaccines against hepatocellular carcinoma in clinical trials

Current therapies to treat advanced hepatocellular carcinoma (HCC) are not satisfactory because of the high rate of recurrence after treatment and because of severe complications after surgery. Cancer vaccines have been studied for decades to achieve effective, micro-invasive, long-lasting anti-tumor action. Cancer vaccines are designed to promote tumor-specific immune responses and increase specific cytotoxic CD8-positive T cells. This review summarizes 16 phase I clinical trials of cancer vaccines against HCC that have been conducted over the past 10 years. According to those trials, the Alpha fetoprotein (AFP), Glypican-3 (GPC3), and Multidrug resistance-associated protein 3 (MRP3) vaccines were well tolerated and safe. Some early clinical trials have shown that vaccination resulted in a large number of T cells activated by a specific tumor-associated antigen in the circulation, but clinical outcomes were not satisfactory. This may be because targets for immunosuppressive agents have yet to be clearly determined in HCC. Therapeutic regimens that combine activative agents and suppressive agents may profoundly improve clinical outcomes for patients with HCC in the future.

The immune system in hepatocellular carcinoma and potential new immunotherapeutic strategies

BACKGROUND

Hepatocellular carcinoma is a major health problem worldwide and the third most common cause of cancer-related death. HCC treatment decisions are complex and dependent upon tumor staging. Several molecular targeted agents have been evaluated in clinical trials in advanced HCC. Despite of only modest objective response rates according to the Response Evaluation Criteria in Solid Tumors, several studies showed encouraging results in terms of prolongation of the time to progression, disease stabilization, and survival. Cellular immunotherapy would improve the immune state and has potential in enhancing the therapeutic outcome for HCC patients.

MATERIALS AND METHODS

A search of the literature was made using cancer literature, the PubMed, Scopus, and Web of Science (WOS) database for the following keywords: "hepatocellular carcinoma," "molecular hepatocarcinogenesis," "targeted therapy," "molecular immunological targets," "tumour-associated antigens," "Tregs," "MDSCs," "immunotherapy."

DISCUSSION AND CONCLUSION

Treatment strategies combining blockade of immunoregulatory cell types such as Tregs and MDSCs and of inhibitory receptors, with vaccine-induced activation of TAA-specific T cells, may be necessary to achieve the most effective therapeutic antitumour activity in HCC. In the future, new therapeutic options will be represented by a blend of immunotherapy-like vaccines and T-cell modulators, supplemented by molecularly targeted inhibitors of tumor signaling pathways.

Circulating tumor and cancer stem cells in hepatitis C virus-associated liver disease

AIM: To assess the role of circulating tumor cells (CTCs) and cancer stem cells (CSCs) in hepatitis C virus (HCV)-associated liver disease.

METHODS: Blood and/or tissue samples were obtained from HCV (genotype 4)-associated hepatocellular carcinoma patients (HCC; n = 120), chronic hepatitis C patients (CH; n = 30) and 33 normal control subjects (n = 33). Serum levels of alpha-fetoprotein (AFP), alkaline phosphatase, and alanine and aspartate aminotransferases were measured. Cytokeratin 19 (CK19) monoclonal antibody was used to enumerate CTCs, and CD133 and CD90 were used to enumerate CSCs by flow cytometry. The expression levels of the CSCs markers (CD133 and CD90) as well as telomerase, melanoma antigen encoding gene 1 (MAGE1) and MAGE3 were assessed by RT-PCR and quantitative real-time polymerase chain reactions. The number of CTCs and/or the expression levels of CK19, CD133, telomerase, MAGE1 and MAGE3 were correlated to the standard clinicopathologic prognostic factors and disease progression.

RESULTS: Levels of AFP, alkaline phosphatase and aspartate aminotransferase were significantly different among the HCC, CH and control groups (P < 0.001), whereas alanine aminotransferase differed significantly between patient (HCC and CH) and control groups (P < 0.001). At the specified cutoff values determine by flow cytometry, CK19 (49.8), CD90 (400) and CD133 (73) were significantly higher in the blood of HCC patients compared to those in the CH and control groups (P < 0.001). On the other hand, CD133 at a 69.5 cutoff was significantly higher in the CH compared to the control group (P≤ 0.001). Telomerase, MAGE1 and MAGE3 RNA were expressed in 55.71%, 60.00% and 62.86% of the HCC patients, respectively, but were not detected in patients in the CH or control groups, which were statistically significant (Ps < 0.001). The expression levels of telomerase, CD90, MAGE3, CD133 and CK19 were all significantly associated with high tumor grade and advanced stage in HCC patients (all Ps < 0.05).

CONCLUSION: CTC counts and AFP, CK19, telomerase, and MAGE1/MAGE3 expression predict disease progression in patients with HCV, whereas telomerase, MAGE3, CD90, CD133 and CK19 are prognostic markers in HCC.

Immunotherapy of hepatocellular carcinoma

Newer immunotherapy agents may break the barrier that tumors create to evade the attack from the immune system. Dendritic cell vaccination has shown encouraging clinical activity and a favorable safety profile in advanced tumor stages. However, optimal cell maturation status, choice of tumor antigens and route of administration have not been established. Single or multiple peptides derived from tumor-associated antigens may also be used for cancer vaccination. Intratumoral delivery of oncolytic viruses expressing immunostimulating cytokines like GM-CSF have produced stimulating clinical results that need further verification. But it is probably T-cell checkpoint modulation with monoclonal antibodies that has attracted the highest expectations. Promising activity has been reported for tremelimumab, a CTLA-4 inhibitor, and a clinical trial testing the PD-1 antibody nivolumab is underway. Future progress will probably come from a better understanding of the mechanisms of cancer-related immunosuppression, improvement in agents and strategies and combination of the available therapeutic tools.

Clinicopathological analysis of CD8-positive lymphocytes in the tumor parenchyma and stroma of hepatocellular carcinoma

Tumor-infiltrating lymphocytes may be a manifestation of antitumor immunity. In the present study, hepatocellular carcinoma (HCC) and pericancerous non-tumor liver tissues samples were obtained from 86 surgical patients who had not received preoperative treatment. The cellular expression levels of CD4 and CD8 were immunohistochemically examined in the two tissue groups using tissue microarrays, to evaluate their clinicopathological relevance. Immunohistochemically, CD4 and CD8 T cells were observed in the tumor parenchyma and tumor stroma, and the intensity of CD4 and CD8 immunoreactivity was homogeneous in all HCC samples examined. Morphometrically, the average numbers of CD4- and CD8-positive T cells were significantly increased in the tumor stroma, compared with those in the tumor parenchyma (tumor stroma versus tumor parenchyma: 22±3.6 versus 7.4±0.9 in CD4, 32.8±4.2 versus 16±2.5 in CD8; both P<0.01). Furthermore, the average numbers of CD8-positive T cells in the tumor parenchyma and stroma were significantly increased, compared with the average numbers of CD4-positive cells (P<0.05). In addition, in the tumor parenchyma and stroma, the average numbers of CD8 T cells were significantly higher in patients with tumor diameters ≤5 cm compared with those in patients with tumor diameters >5 cm (diameter ≤5 cm versus diameter >5 cm: 18.1±3.3 versus 12.2±3.8 in tumor parenchyma, 36.5±4.8 versus 21.9±8.9 in tumor stroma; both P<0.05). In addition, CD8 expression was significantly enhanced in patients with chronic hepatitis and cirrhosis, compared with paired tumor parenchymal tissues (P<0.01). Furthermore, a significant positive correlation was observed between CD4 and CD8 expression in the tumor parenchyma and stroma (both P<0.001). These observations suggest that tumor parenchyma- or stroma-infiltrating CD8 T cells may be involved in HCC tumor diameter control.

Agonistic anti-CD137 antibody treatment leads to antitumor response in mice with liver cancer

Immunotherapy is a promising strategy against hepatocellular carcinoma (HCC). We assessed the therapeutic effects of stimulating CD137, a member of the TNF receptor family, with agonistic monoclonal antibodies (mAb). Agonistic anti-CD137 mAb treatment was tested on two in situ models of HCC in immunocompetent mice. We also studied the mediators involved at different time points. In an orthotopic HCC the treatment consistently leads to complete tumor regression in 40-60% of animals. The protection is long lasting in the animals responding to the treatment, which can reject a second tumor challenge more than 3 months after treatment and eradication of the first malignancy. The main mediators of the effect are T lymphocytes and NK cells, demonstrated through depletion experiments. In addition, adoptive transfer of splenocytes prepared from anti-CD137 mAb-treated and -cured mice to naive mice allowed them to, in turn, reject the tumor. The efficacy of anti-CD137 mAb treatment is associated with early, sustained recruitment of iNOS-positive macrophages within tumor nodules. Moreover, in the absence of treatment, tumor development is accompanied by infiltration by myeloid derived suppressor cells (MDSC) and regulatory T lymphocytes. In mice responding to the anti-CD137 mAb treatment, this infiltration is very limited, and a combination treatment with a depletion of MDSC leads to the recovery of 80% of the mice. These results demonstrate that agonistic anti-CD137 mAb is a promising therapeutic strategy for anti-tumor immunity stimulation against HCC.

Immunodominance and functional alterations of tumor-associated antigen-specific CD8+ T-cell responses in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common malignancy worldwide with a poor prognosis and limited therapeutic options. To aid the development of novel immunological interventions, we studied the breadth, frequency, and tumor-infiltration of naturally occurring CD8(+) T-cell responses targeting several tumor-associated antigens (TAA). We used overlapping peptides spanning the entire alpha-fetoprotein (AFP), glypican-3 (GPC-3), melanoma-associated gene-A1 (MAGE-A1) and New York-esophageal squamous cell carcinoma-1 (NY-ESO-1) proteins and major-histocompatibility-complex-class-I-tetramers specific for epitopes of MAGE-A1 and NY-ESO-1 to analyze TAA-specific CD8(+) T-cell responses in a large cohort of HCC patients. After nonspecific expansion in vitro, we detected interferon-γ (IFN-γ)-producing CD8(+) T cells specific for all four TAA in the periphery as well as in liver and tumor tissue. These CD8(+) T-cell responses displayed clear immunodominance patterns within each TAA, but no consistent hierarchy was observed between different TAA. Importantly, the response breadth was highest in early-stage HCC and associated with patient survival. After antigen-specific expansion, TAA-specific CD8(+) T cells were detectable by tetramer staining but impaired in their ability to produce IFN-γ. Furthermore, regulatory T cells (Treg) were increased in HCC lesions. Depletion of Treg from cultures improved TAA-specific CD8(+) T-cell proliferation but did not restore IFN-γ-production.

CONCLUSION

Naturally occurring TAA-specific CD8(+) T-cell responses are present in patients with HCC and therefore constitute part of the normal T-cell repertoire. Moreover, the presence of these responses correlates with patient survival. However, the observation of impaired IFN-γ production suggests that the efficacy of such responses is functionally limited. These findings support the development of strategies that aim to enhance the total TAA-specific CD8(+) T-cell response by therapeutic boosting and/or specificity diversification. However, further research will be required to help unlock the full potential of TAA-specific CD8(+) T-cell responses.

Spontaneous and therapeutic immune responses in hepatocellular carcinoma: implications for current and future immunotherapies

Hepatocellular carcinoma (HCC) represents a major health problem in the world, ranking fifth in incidence and third in cancer-related deaths. Due to the unique immunosuppressive microenvironment of the liver, HCC develops in an immunotolerant niche posing an important obstacle to immunotherapy. A number of studies, however, have shown immunogenic properties of HCC by demonstrating spontaneous adaptive immune responses during tumor formation and progression. Furthermore, studies examining immune responses during HCC therapy have revealed that conventional treatments such as surgical resection, locoregional therapy and systemic therapy with antibodies, small molecules or chemotherapy induce adaptive immune responses that contribute to therapeutic effects. These observations have provided a basis for clinical trials involving adoptive transfers of T cells or natural killer cells, peptide and dendritic cell vaccinations or, more recently, virotherapy and inhibition of co-inhibitory molecules. Here, spontaneous and therapeutic immune responses in HCC and their implication for current and future immunotherapies are discussed.

A constructed HLA-A2-restricted pMAGE-A1(278-286) tetramer detects specific cytotoxic T lymphocytes in tumour tissues in situ

OBJECTIVE

To construct a human leucocyte antigen (HLA)-A2-restricted peptide 278-286 of melanoma-associated antigen family A, 1 (pMAGE-A1(278-286)) tetramer to analyse the distribution of cytotoxic T lymphocytes (CTLs) in tumour tissue and tumour-adjacent normal tissue.

METHODS

A HLA-A2-pMAGE-A1(278-286) tetramer was constructed. The distribution of pMAGE-A1(278-286)-specific CTLs was investigated in tumour tissues and tumour-adjacent normal tissues from patients with hepatocellular carcinoma using in situ HLA-A2-pMAGE-A1(278-286) tetramer staining.

RESULTS

Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis indicated that HLA-A2 heavy and light chain proteins were successfully obtained. The successful construction of the HLA-A2-pMAGE-A1(278-286) monomer was confirmed with Western blot analysis using W6/32 antibody. Flow cytometry confirmed the specific binding of HLA-A2-pMAGE-A1(278-286) tetramer to pMAGE-A1(278-286)-specific CTLs. In situ HLA-A2-pMAGE-A1(278-286) tetramer staining demonstrated that the number of pMAGE-A1(278-286)-specific CTLs in tumour tissues was significantly higher than in tumour-adjacent normal tissues.

CONCLUSIONS

The HLA-A2-pMAGE-A1(278-286) tetramer was useful for the detection of pMAGE-A1(278-286)-specific CTLs in both tumour tissues and tumour-adjacent normal tissues. In situ tetramer staining is a powerful tool for investigating the distribution of pMAGE-A1278-286-specific CTLs in the tumour microenvironment.

Identification of a novel HLA-A2-restricted mutated Survivin epitope and induction of specific anti-HCC CTLs that could effectively cross-recognize wild-type Survivin antigen

Peptide vaccine based on tumor-associated antigen (TAA), which usually belongs to self-antigen with poor immunogenicity, has been considered as an attractive option for treatment of malignant tumors. The ideal TAA epitopes should have stable affinity to major histocompatibility complex (MHC) molecules and elicit strong anti-tumor immune response. Although point-mutation technology of TAA peptide may increase the binding capability to MHC molecules, some previous studies have revealed that part of the variant peptides results in lymphocyte not to effectively cross-recognize and kill the target tumor expressed wild-type TAA. Here, we designed a novel HLA-A2-restricted mutated TAA Survivin epitope nonapeptide Sur79L2 (KLSSGCAFL) that showed higher binding ability compared to wild-type peptide Sur79 (KHSSGCAFL) in T2-binding assays. To investigate whether Sur79L2 can induce Survivin-specific anti-hepatocellular carcinoma (HCC) response, we stimulated tumor-associated lymphocytes from a HCC patient with Sur79L2 in vitro. IFN-γ release and cytotoxicity assays showed Sur79L2 could effectively cross-recognize and lysis T2 cell plus peptide Sur79 and HCC cell lines (expression of wild-type Survivin antigen) in an HLA-A2-restricted manner. In contrast, peptide Sur95 (ELTLGEFLKL) that has been reported as a very promising anti-tumor epitope in a variety of tumors except HCC were not able to generate detectable cytotoxic immune responses against HCC in this study. Our results suggest that point-mutated peptide Sur79L2 is a new HLA-A2-restricted CTL epitope and may be useful for the immunotherapy for patients with HCC.

Mechanisms underlying spontaneous regression of hepatocellular carcinoma

We searched MEDLINE and identified 85 cases of spontaneous regression of hepatocellular carcinoma (HCC). Analysis of these cases found that immunity is the most likely cause of spontaneous regression of HCC, and the elimination of immunosuppressive microenvironment may play a key role in this process. Ischemia, ethanol abstinence, and blood transfusion might lead to regression of HCC through the elimination of immunosuppression and activation of antitumor immunity.

Skin delivery of short hairpin RNA of indoleamine 2,3 dioxygenase induces antitumor immunity against orthotopic and metastatic liver cancer

Liver cancer is one of the most malignant cancers in the world and has a high rate of metastasis. Therefore, development of a novel therapy for liver cancer is a critical issue. Indoleamine 2,3-dioxygenase (IDO) is known as a negative immune regulator in dendritic cells. Our previous study demonstrated that skin delivery of IDO short hairpin RNA (shRNA) induced antitumor immunity in subcutaneous bladder and colon tumor models. Because the immunological environment is quite different between skin and liver, it is essential to evaluate whether skin delivery of IDO shRNA is an effective treatment in metastatic and orthotopic animal tumor models. In the present study, IDO shRNA inhibited tumor growth in subcutaneous, metastatic and orthotopic liver tumor models. The cytotoxicity of splenocytes was significantly elevated in mice treated with IDO shRNA in the orthotopic and metastatic tumor models. Interleukin (IL)-12 and interferon (IFN)-gamma mRNA expression were upregulated while IL-10 was downregulated in the inguinal lymph nodes, which were collected from IDO shRNA-treated mice. Similar results were observed in the spleens of mice inoculated with IDO shRNA by gene gun. The results indicate that skin administration of IDO shRNA is an effective therapy in orthotopic and metastatic liver cancer animal models. Indoleamine 2,3-dioxygenase shRNA might be a potential new treatment for liver cancer in the future.

Development of a Listeria monocytogenes-based vaccine against hepatocellular carcinoma

Live attenuated Listeria monocytogenes (LM) is a promising bacterial vector able to induce a T-cell response to tumor-associated antigens and demonstrates great potential for use in vaccine development. A novel recombinant LM-based vaccine (Lmdd (LM ΔdalΔdat)-MPFG (multiple peptide fusing genes)) was developed with the ability to express and secrete hepatocellular carcinoma (HCC)-related tumor-associated antigens fragments due to the insertion of hepatitis B virus (HBV)-X protein (HBx)-derived epitopes HBx(52-60) and HBx(140-148), the universal T-helper epitope, alpha-fetoprotein (AFP) epitope AFP(158-166), and melanoma antigen gene (MAGE)-3(271-279) into the HBV core protein. Following immunization with the Lmdd-MPFG vaccine, macrophages exhibited uptake of the bacteria; the vaccine was then nearly cleared 3 days after the first administration. It disappeared even more quickly following subsequent vaccinations. However, recombinant Lmdd-MPFG allowed for the full development of an antitumor response towards the human leukocyte antigen (HLA)-A0201 epitopes of MPFG. Each epitope stimulated an augmented T-cell proliferation and enhanced the supernatant level of interferon (IFN)-γ in vitro. In addition, IFN-γ-producing CD8(+) T cells as well as in vivo cytolytic activity were significantly increased in HLA-A2 transgenic mice. Additionally, the Lmdd-MPFG developed a strong antitumor response, as indicated by the significant resistance of immunized mice to MPFG-positive Hepa1-6 cell challenge in both a prophylactic and therapeutic setting. Tumor regression was accompanied by an enhanced cytotoxic T lymphocyte response and a decrease of regulatory T cells in the tumor. Collectively, these results suggest that utilizing attenuated LM as a vaccine vector, able to carry the MPFG gene, presents a potentially feasible strategy for prevention of HCC.

Comparative analysis of various tumor-associated antigen-specific t-cell responses in patients with hepatocellular carcinoma

Many tumor-associated antigens (TAAs) recognized by cytotoxic T cells (CTLs) have been identified during the last two decades and some of them have been used in clinical trials. However, there are very few in the field of immunotherapy for hepatocellular carcinoma (HCC) because there have not been comparative data regarding CTL responses to various TAAs. In the present study, using 27 peptides derived from 14 different TAAs, we performed comparative analysis of various TAA-specific T-cell responses in 31 HCC patients to select useful antigens for immunotherapy and examined the factors that affect the immune responses to determine a strategy for more effective therapy. Twenty-four of 31 (77.4%) HCC patients showed positive responses to at least one TAA-derived peptide in enzyme-linked immunospot assay. The TAAs consisting of cyclophilin B, squamous cell carcinoma antigen recognized by T cells (SART) 2, SART3, p53, multidrug resistance-associated protein (MRP) 3, alpha-fetoprotein (AFP) and human telomerase reverse transcriptase (hTERT) were frequently recognized by T cells and these TAA-derived peptides were capable of generating peptide-specific CTLs in HCC patients, which suggested that these TAAs are immunogenic. HCC treatments enhanced TAA-specific immune responses with an increased number of memory T cells and induced de novo T-cell responses to lymphocyte-specific protein tyrosine kinase, human epidermal growth factor receptor type 2, p53, and hTERT. Blocking cytotoxic T-lymphocyte antigen-4 (CTLA-4) resulted in unmasking of TAA-specific immune responses by changing cytokine and chemokine profiles of peripheral blood mononuclear cells stimulated by TAA-derived peptides.

CONCLUSION

Cyclophilin B, SART2, SART3, p53, MRP3, AFP, and hTERT were immunogenic targets for HCC immunotherapy. TAA-specific immunotherapy combined with HCC treatments and anti-CTLA-4 antibody has the possibility to produce stronger tumor-specific immune responses.

Potential of immunotherapy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide with limited therapeutic options. Since HCC has been shown to be immunogenic, T cell-based immunotherapy is considered a promising treatment. In this review, we summarize current knowledge of T cell responses against tumour-associated antigens, as well as the mechanisms underlying the poor quality of these responses in patients with HCC. Insights into these important aspects of HCC immunology are crucial for the further development of novel immunotherapies.

Novel soluble HLA-A2/MELAN-A complexes selectively stain a differentiation defective subpopulation of CD8+ T cells in patients with melanoma

Multimeric MHC I-peptide complexes containing phycoerythrin-streptavidin are widely used to detect and investigate antigen-specific CD8+ (and CD4+) T cells. Because such reagents are heterogeneous, we compared their binding characteristics with those of monodisperse dimeric, tetrameric and octameric complexes containing linkers of variable length and flexibility on Melan-A-specific CD8+ T cell clones and peripheral blood mononuclear cells (PBMC) from HLA-A*0201(+) melanoma patients. Striking binding differences were observed for different defined A2/Melan-A(26-35) complexes on T cells depending on their differentiation stage. In particular, short dimeric but not octameric A2/Melan-A(26-35) complexes selectively and avidly stained incompletely differentiated effector-memory T cells clones and populations expressing CD27 and CD28 and low levels of cytolytic mediators (granzymes and perforin). This subpopulation was found in PBMC from all six melanoma patients analyzed and proliferated on peptide stimulation with only modest phenotypic changes. By contrast influenza matrix(58-66) -specific CD8+ PBMC from nine HLA-A*0201(+) healthy donors were efficiently stained by A2/Flu matrix(58-61) multimers, but not dimer and upon peptide stimulation proliferated and differentiated from memory into effector T cells. Thus PBMC from melanoma patients contain a differentiation defective sub-population of Melan-A-specific CD8+ T cells that can be selectively and efficiently stained by short dimeric A2/Melan- A(26-35) complexes, which makes them directly accessible for longitudinal monitoring and further investigation.

Cell-mediated immune responses to alpha-fetoprotein and other antigens in hepatocellular carcinoma

Cell-mediated immune responses play an important role in the control of tumour growth. CD4 and CD8 T cells recognise tumour antigens presented via major histocompatibility complex molecules of antigen presenting cells and develop into effector cells with the ability to identify and kill tumour cells. Here, we re-examine the adaptive immune response to tumour antigens expressed by hepatocellular carcinoma (HCC) and discuss approaches that could be applied in future T-cell-based immunotherapy schedules to induce a potent and effective antitumour immunity. Moreover, we discuss cytotoxic T lymphocyte and Th1 responses to tumour antigens in patients with HCC and evaluate the effects of conventional treatments on antitumour T-cell responses.

Quantitative expression and immunogenicity of MAGE-3 and -6 in upper aerodigestive tract cancer

The MAGE antigens are frequently expressed cancer vaccine targets. However, quantitative analysis of MAGE expression in upper aerodigestive tract (UADT) tumor cells and its association with T-cell recognition has not been performed, hindering the selection of appropriate candidates for MAGE-specific immunotherapy. Using quantitative RT-PCR (QRT-PCR), we evaluated the expression of MAGE-3/6 in 65 UADT cancers, 48 normal samples from tumor matched sites and 7 HLA-A*0201+ squamous cell carcinoma of the head and neck (SCCHN) cell lines. Expression results were confirmed using Western blot. HLA-A*0201:MAGE-3- (271-279) specific cytotoxic T lymphocytes (MAGE-CTL) from SCCHN patients and healthy donors showed that MAGE-3/6 expression was highly associated with CTL recognition in vitro. On the basis of the MAGE-3/6 expression, we could identify 31 (47%) of the 65 UADT tumors, which appeared to express MAGE-3/6 at levels that correlated with efficient CTL recognition. To confirm that the level of MAGE-3 expression was responsible for CTL recognition, 2 MAGE-3/6 mRNA(high) SCCHN cell lines, PCI-13 and PCI-30, were subjected to MAGE-3/6-specific knockdown. RNAi-transfected cells showed that MAGE expression and MAGE-CTL recognition were significantly reduced. Furthermore, treatment of cells expressing low MAGE-3/6 mRNA with a demethylating agent, 5-aza-2'-deoxycytidine (DAC), increased the expression of MAGE-3/6 and CTL recognition. Thus, using QRT-PCR UADT cancers frequently express MAGE-3/6 at levels sufficient for CTL recognition, supporting the use of a QRT-PCR-based assay for the selection of candidates likely to respond to MAGE-3/6 immunotherapy. Demethylating agents could increase the number of patients amenable for targeting epigenetically modified tumor antigens in vaccine trials.

Profile of tumor antigen-specific CD8 T cells in patients with hepatitis B virus-related hepatocellular carcinoma

BACKGROUND & AIMS

Tumor and viral antigens are expressed by hepatocellular carcinoma (HCC) in patients with chronic hepatitis B, but little is known about the immunodominance and function of tumor- and virus-specific CD8+ T cells in these patients.

METHODS

HLA-A2-restricted T-cell responses to 16 tumor antigens and hepatitis B virus (HBV) proteins were tested using 49 previously described epitopes. Cells from 30 HLA-A2+, HBV-infected patients (10 with HCC, 10 with HBV cirrhosis, and 10 HBV but no cirrhosis) were analyzed, after expansion, by enzyme-linked immunosorbent spot (ELISPOT). Interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-2 production, as well as expression of the degranulation marker CD107a on tumor-specific CD8+ T cells, were evaluated.

RESULTS

Cells from all groups had tumor-specific responses. The tumor antigens NY-ESO-1 and SSX-2 were most frequently targeted and were immunogenic in the HLA-A2 subtypes that are characteristic of Asian ethnicity. Tumor-specific T cells had low affinities; T cells from non-HCC patients were polyfunctional (IFN-gamma+, TNF-alpha+, CD107a+) and those from HCC patients displayed an exhausted phenotype (IFN-gamma+, CD107a+). Programmed Death 1 (PD-1) was expressed at higher levels on T cells from tumor and liver than peripheral blood from HCC patients and might contribute to T-cell exhaustion. Blocking PD-1/PD-L1 increased the frequency of tumor-specific T cells in HCC patients but did not restore T cell function.

CONCLUSIONS

Patients with or without HCC have a quantitative and functional hierarchy of tumor-specific T cells. HLA-A2-restricted T cells from HCC patients target NY-ESO-1, but exist in an exhausted state that might require additional activation to restore function.

The immunosuppressive tumor microenvironment in hepatocellular carcinoma

Increasing evidence indicates the immunosuppressive nature of the local environment in tumor. The present study was focused on analyzing the immune status within hepatocellular carcinoma. In contrast to the increasing number of CD4(+) T cells, CD8(+), CD3(-)CD56(+), CD3(+)CD56(+), and gammadeltaT cells were all found to be under-represented in tumor infiltrating lymphocytes. Notably, the relative abundance of CD3(+)CD56(+) cells appeared to be correlated with patient survival. Functional analysis demonstrated that CD4(+) cells in the tumor tended to produce more IL-10 but less IFN-gamma, whereas CD8(+) cells showed impaired capacity for the production of both IFN-gamma and perforin. Consistent with previous reports, we observed a significant increase of Foxp3(+) cells in the tumor tissue. Intriguingly, although over 90% of CD4(+)CD25(high) cells were found to be Foxp3(+), the majority of Foxp3(+) cells were identified in the CD4(+)CD25(medium) and CD4(+)CD25(-) subsets. In support of its role as a negative regulator, CD4(+)CD25(high) cells suppressed the proliferation of CD4(+)CD25(-) cells isolated from the same tissues in an APC dependent manner. In conclusion, the tumor microenvironment of hepatocellular carcinoma is featured by the presence of multiple immunosuppressive factors.

Strategies for Successful Vaccination against Hepatocellular Carcinoma

Current therapies against hepatocellular carcinoma (HCC) are not curative in the majority of patients. In the past, immunotherapy approaches aimed to non-specifically stimulate immune response were quite ineffective. New treatments based on stimulation of specific anti-tumor immune response are currently proposed and appear more promising. Tumor-specific antigens identified in HCC demonstrated immunogenicity both in preclinical and clinical trials. Effectiveness in animal studies raised interest in the clinical applicability of non-specific adoptive immunotherapy that prevented disease recurrence after tumor resection. Dendritic cell (DC)-based tumor vaccines achieved encouraging results, and cellular vaccines based on DCs have already entered clinical trials. Preventive and therapeutic DNA vaccination have been proposed, all based on tumor-associated antigens (TAAs), either modified or not, an example being alpha-fetoprotein (AFP). The concomitant expression of co-stimulatory molecules and cytokines was used to increase tumor immunogenicity. Syngeneic or nude mice models indicated that immunotherapy for HCC could stimulate an anti-tumor T-cell response leading to clinical benefit devoid of significant toxicity. The use of DNA-based vaccination raises exciting possibilities in preventing HCC in high-risk individuals such as those with cirrhosis. Novel immunotherapy strategies may contribute in the future to prevention and treatment of HCC.

Frequent expression of the novel cancer testis antigen MAGE-C2/CT-10 in hepatocellular carcinoma

Cancer testis (CT) antigens are attractive targets for immunotherapy in cancer patients. Immunohistochemistry was used to study the expression of the CT antigens MAGE-C2/CT-10, MAGE-C1/CT-7, GAGE, MAGE-A4 and NY-ESO-1 in 146 hepatocellular carcinomas, 13 intrahepatic cholangiocarcinomas, 37 extrahepatic cholangiocarcinomas and 32 gallbladder carcinomas. Immunopositivity was correlated with clinicopathological parameters, MHC Class 1 expression, intratumoral CD4+, CD8+ and FOXP3+ T cells and CD163+ antigen-presenting cells. Of the 146 hepatocellular carcinomas, 34% were positive for MAGE-C2/CT-10, 12% for MAGE-C1/CT-7, 11% for GAGE and 2% for NY-ESO-1, respectively. MHC Class 1 coexpression was identified in almost all CT antigen-positive tumors. The number of intratumoral FOXP3+ regulatory T cells was increased in CT antigen-positive hepatocellular carcinomas (p<0.004), suggesting inhibition of immune response in such tumors. Furthermore, MAGE-C1/CT-7 and GAGE positivity was correlated with reduced overall survival in patients with hepatocellular carcinoma (p=0.03 and 0.01, respectively). Four (13%) gallbladder carcinomas stained positive for MAGE-C2/CT-10, of which 1 tumor (3%) was also positive for NY-ESO-1 and GAGE. CT antigens were not expressed in intra- and extrahepatic cholangiocarcinomas. Our results suggest that MAGE-C2/CT-10 may be a good candidate for peptide vaccination in patients with hepatocellular carcinoma.

Expression of multidrug resistance-associated protein 3 and cytotoxic T cell responses in patients with hepatocellular carcinoma

BACKGROUND/AIMS

Multidrug resistance-associated protein 3 (MRP3) is a carrier-type transport protein belonging to the ABC transporters. It is expressed in normal tissues, and enhanced expression in many cancers has been reported. In this study, we investigated the usefulness of MRP3 as a target antigen in immunotherapy for hepatocellular carcinoma (HCC).

METHODS

The MRP3 expression level in HCC tissue was measured by quantitative PCR. MRP3-specific T cell responses were investigated by several immunological techniques using peripheral blood mononuclear cells or tumor-infiltrating lymphocytes.

RESULTS

The MRP3 expression level in HCC tissue was significantly higher than that in non-cancerous tissue (P<0.05). MRP3-specific cytotoxic T cells (CTLs) could be induced regardless of liver function, the presence or absence of HCV infection, the blood AFP level, and the stage of HCC. The CTLs showed cytotoxicity against HCC cells overexpressing MRP3. A negative correlation was present between the MRP3 expression level in HCC tissue and the frequency of MRP3-specific CTLs. The frequency of MRP3-specific CTLs increased after HCC treatment, such as transcatheter arterial embolization and radiofrequency ablation.

CONCLUSIONS

Our study demonstrates that MRP3 is a potential candidate for tumor antigen with strong immunogenicity in HCC immunotherapy.

Comprehensive analysis of the alpha-fetoprotein-specific CD8+ T cell responses in patients with hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common malignancy worldwide, with a poor prognosis and limited therapeutic options. Therefore, the development of novel therapeutic strategies is of high priority. alpha-Fetoprotein (AFP) is overexpressed in the majority of HCCs. Priming of immune responses against AFP results in significant protective antitumoral T cell responses in the mouse model. Little information is available about the hierarchy, breadth, frequency, and peripheral versus intrahepatic distribution of AFP-specific CD8(+) T cell responses in patients with HCC. To address these important issues we comprehensively analyzed CD8(+) T cell responses against full-length AFP in peripheral blood, tumor liver tissue, and nontumor liver tissue from patients with HCC using overlapping AFP peptides. The AFP-specific CD8(+) T cell response was also tested in peripheral blood and liver from patients chronically infected with hepatitis C virus (HCV) and compared to the HCV-specific CD8(+) T cell response. The majority of patients with HCC showed AFP-specific responses, with many responses directed against previously unreported epitopes. These responses were primarily detectable in the HCC tissue and mainly targeted the C-terminus of AFP. Interestingly, AFP-specific T cells were not only found in patients with HCC but also in patients with chronic HCV infection, other liver diseases, and less frequently in healthy subjects.

CONCLUSION

In patients with HCC, a high frequency of AFP-specific CD8(+) T cells directed against different epitopes suggest that AFP has a strong and broad immunogenicity. Further, CD8(+) T cells specific for the self-antigen AFP are present in the normal T cell repertoire and are not centrally or peripherally deleted. Our results provide support for strategies to boost AFP-specific CD8(+) T cell responses in patients with HCC but also demonstrate a diversity of immune responses that may be needed for protection.

Increased immunostimulatory activity conferred to antigen-presenting cells by exposure to antigen extract from hepatocellular carcinoma after radiofrequency thermal ablation

Radiofrequency thermal ablation represents an effective treatment for hepatocellular carcinoma (HCC) and it can also exert an "adjuvant" effect on spontaneous antitumor T-cell responses, as suggested by human and animal studies. The adjuvant effect is thought to depend on the huge amount of necrotic tumor antigen made available to the immune system by HCC thermal ablation. In addition, radiofrequency thermal ablation may result in the release of local stimuli responsible for activation and maturation of antigen-presenting cells (APCs). To test this hypothesis, we studied APC maturation and function in 19 patients undergoing thermal ablation for HCC. Patients' monocytes induced to differentiate with granulocyte macrophage colony-stimulating factor (GM-CSF), or GM-CSF plus IL-4, were cocultured in vitro with tumor debris generated by radiofrequency thermal ablation. Expression of costimulatory molecules, lymphnode homing chemokine receptor, antigen presentation, and cytokine secretion were enhanced by incubation with HCC treated tissue as compared with untreated HCC and nontumor liver tissue. Moreover, HCC-specific T-cell responses could be induced by monocytes activated with GM-CSF and incubated with thermally ablated HCC tissue. HCC thermal ablation can create an antigenic source along with stimuli appropriate for maturation of APCs to induce HCC-specific T-cell responses. These results contribute to explain at least in part the adjuvant effect of HCC thermal ablation and suggest a novel strategy to induce maturation of APCs and their loading with HCC antigens for active immunotherapy protocols aimed at reducing HCC recurrence after thermal ablation.

Alpha-fetoprotein and other tumour-associated antigens for immunotherapy of hepatocellular cancer

BACKGROUND

Hepatocellular carcinoma (HCC) is a leading cause of cancer death, with few treatment options for advanced disease.

OBJECTIVES

Here, we review the aetiology of HCC and focus on recent data on tumour-associated antigens (TAA) for HCC, their functions and potential use as immunological targets for immune-based therapy for HCC. In addition, we examine some aspects of antigen presentation within the liver.

RESULTS/CONCLUSIONS

alpha-Fetoprotein (AFP) has been investigated for many years as a TAA, and has been tested in recent clinical trials. More recently, additional TAA have been identified and new therapeutic approaches have been investigated which may be testable clinically in this difficult disease setting.

Specific CD8(+ )T cell responses to HLA-A2 restricted MAGE-A3 p271-279 peptide in hepatocellular carcinoma patients without vaccination

The MAGE-A3 protein, one of the promising tumor antigens for immunotherapy, is highly expressed in human hepatocellular carcinoma (HCC). In this study, we estimated the specific CD8(+) T cell immune response to MAGE-A3 p271-279 peptide (M3(271)) in the peripheral blood of HCC patients without antigen vaccination in order to evaluate its immunotherapeutic potential in these patients. After expansion in vitro, the functional IFN-gamma producing M3(271) specific CD8(+) T cells were detected in 30.8% (8/26) of HLA-A2(+)MAGE-A3(+) HCC patients. The effector CD8(+ )T cells could release cytotoxic molecules of granzyme B and perforin after restimulation with natural HLA-A2(+)MAGE-A3(+) HCC cell lines in the samples tested. The functional supertype of HLA-A2 in the presentation of HLA-A*0201 restricted M3(271) peptide has been identified in the Chinese HCC patients of Han ethnicity, that widely expanded the applicability of this tumor peptide vaccine in Chinese HCC patients. Thus, the functionally detectable pre-existence of M3(271)-specific CD8(+) T cells in HCC patients makes M3(271) a potential target for immunotherapy in these patients. The responsive CD8(+ )T cells to both NY-ESO-1 and MAGE-A3 antigens provide a rationale for the application of a bivalent vaccine in HCC patients with tumors expressing both antigens.

Toward the development of multi-epitope p53 cancer vaccines: an in vitro assessment of CD8(+) T cell responses to HLA class I-restricted wild-type sequence p53 peptides

Wild-type sequence (wt) p53 peptides are attractive candidates for broadly applicable cancer vaccines. Six HLA-A2 or HLA-A24-restricted wt p53 peptides were evaluated for their ex vivo immunogenicity and their potential for use in cancer vaccines. Peripheral blood mononuclear cells (PBMC) obtained from HLA-A*0201(+) and/or HLA-A*2402(+) normal donors and subjects with squamous cell carcinoma of the head and neck (SCCHN) were analyzed for p53 peptide-specific reactivity in ELISPOT IFN-gamma assays. CD8(+) T cells in 7/10 normal donors (HD) and 11/23 subjects with SCCHN responded to at least one of the wt p53 peptides. CD8(+) T cell precursors responsive to wt p53 epitopes were detected in the circulation of most subjects with early disease, and an elevated blood Tc(1)/Tc(2) ratio distinguished wt p53 peptide responders from non-responders. The identification of multiple wt p53 peptides able to induce cytolytic T lymphocytes in most subjects with cancer promotes the development of multi-epitope p53 vaccines.