Increased frequencies of CD8+ T lymphocytes recognizing wild-type p53-derived epitopes in peripheral blood correlate with presence of epitope loss tumor variants in patients with hepatocellular carcinoma

Targeting Immune Cells in the Tumor Microenvironment of HCC: New Opportunities and Challenges

Immune associated cells in the microenvironment have a significant impact on the development and progression of hepatocellular carcinoma (HCC) and have received more and more attention. Different types of immune-associated cells play different roles, including promoting/inhibiting HCC and several different types that are controversial. It is well known that immune escape of HCC has become a difficult problem in tumor therapy. Therefore, in recent years, a large number of studies have focused on the immune microenvironment of HCC, explored many mechanisms worth identifying tumor immunosuppression, and developed a variety of immunotherapy methods as targets, laying the foundation for the final victory in the fight against HCC. This paper reviews recent studies on the immune microenvironment of HCC that are more reliable and important, and provides a more comprehensive view of the investigation of the immune microenvironment of HCC and the development of more immunotherapeutic approaches based on the relevant summaries of different immune cells.

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.

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.

Prospects for immunotherapy as a novel therapeutic strategy against hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly aggressive malignant disease, with a poor clinical prognosis. Many standard therapies are often considered for HCC treatment today; however, these conventional therapies often fail to achieve sufficiently effective clinical results. Today, HCC therapy is set to undergo a major revolution, owing to rapid developments in cancer immunotherapy, particularly immune checkpoint inhibitor therapy. Cancer immunotherapy is a novel and promising treatment strategy that differs significantly from conventional therapies in its approach to achieve antitumor effects. In fact, many cancer immunotherapies have been tested worldwide and shown to be effective against various types of cancer; HCC is no exception to this trend. For example, we identified a specific cancer antigen called glypican-3 (GPC3) and performed clinical trials of GPC3-targeted peptide vaccine immunotherapy in patients with HCC. Here, we present an overview of the immune mechanisms for development and progression of HCC, our GPC3-based immunotherapy, and immune checkpoint inhibitor therapy against HCC. Finally, we discuss the future prospects of cancer immunotherapy against HCC. We believe that this review and discussion of cancer immunotherapy against HCC could stimulate more interest in this promising strategy for cancer therapy and help in its further development.

Immunotherapy for hepatocellular carcinoma patients: is it ready for prime time?

Hepatocellular carcinoma (HCC) is the most common primary liver malignancy and the second most common cause of cancer death worldwide. Current treatment options for patients with intermediate and advanced HCC are limited, and there is an unmet need for novel therapeutic approaches. HCC is an attractive target for immunomodulation therapy, since it arises in an inflammatory milieu due to hepatitis B and C infections and cirrhosis. However, a major barrier to the development and success of immunotherapy in patients with HCC is the liver's inherent immunosuppressive function. Recent advances in the field of cancer immunology allowed further characterization of immune cell subsets and function, and created new opportunities for therapeutic modulation of the immune system. In this review, we present the different immune cell subsets involved in potential immune modulation of HCC, discuss their function and clinical relevance, review the variety of immune therapeutic agents currently under investigation in clinical trials, and outline future research directions.

Immunotherapy of patient with hepatocellular carcinoma using cytotoxic T lymphocytes ex vivo activated with tumor antigen-pulsed dendritic cells

Purpose The aim of this study was to evaluate the clinical response of immunotherapy with dendritic cell-cytotoxic T lymphocytes (DC-CTLs) in patients with hepatocellular carcinoma (HCC).

Method Sixty-eight patients with a confirmed diagnosis of HCC and who received follow-up until December 2015 were enrolled. We measured immune phenotypes of DCs and activated T cells using flow cytometry and clinical indexes using an electrochemiluminescence method.

Results DCs exhibited up-regulation of the maturation markers CD83, CD80, CD11c, and CD86 on day8. Levels of IFN-γ and TNF-α were higher in the DCs pulsed with tumor-associated antigens (TAAs) than in DCs with a non-proliferative recombinant adenovirus. The percentage of regulatory T cells (Tregs) decreased in patients after DC-CTLs therapy. In addition, serum levels of AFP, AFP-L3, ALT, and CA19-9 were significantly reduced in these patients. Quality of life was improved, especially on physical functioning scales. Median overall survival (OS) and progression-free survival (PFS) were 8.2 months and 4.3 months, respectively, for the control group and 12.8 months and 9 months, respectively, for the DC-CTL group. Patients treated with DC-CTLs therapy showed a statistically significant PFS and OS curve (OS: p=0.016; PFS: p<0.0001). In addition, no serious adverse reactions were observed.

Conclusion This study indicated that Tregs, as well as serum levels of AFP, AFP-L3, ALT, and CA19-9, which were correlated with a poor prognosis, decreased after DC-CTL treatments. The OS, PFS and the quality of life of HCC patients partially improved.

Potentiality of immunotherapy against hepatocellular carcinoma

Hepatocellular carcinoma (HCC), the predominant form of primary liver cancer, is the fifth most common cancer worldwide and the second leading cause of cancer-related death. Despite the high incidence, treatment options remain limited for advanced HCC, and as a result prognosis continues to be poor. Current therapeutic options, surgery, chemotherapy and radiotherapy, have only modest efficacy. New treatment modalities to prolong survival and to minimize the risk of adverse response are desperately needed for patients with advanced HCC. Tumor immunotherapy is a promising, novel treatment strategy that may lead to improvements in both treatment-associated toxicity and outcome. The strategies have developed in part through genomic studies that have yielded candidate target molecules and in part through basic biology studies that have defined the pathways and cell types regulating immune response. Here, we summarize the various types of HCC immunotherapy and argue that the newfound field of HCC immunotherapy might provide critical advantages in the effort to improve prognosis of patients with advanced HCC. Already several immunotherapies, such as tumor-associated antigen therapy, immune checkpoint inhibitors and cell transfer immunotherapy, have demonstrated safety and feasibility in HCC patients. Unfortunately, immunotherapy currently has low efficacy in advanced stage HCC patients; overcoming this challenge will place immunotherapy at the forefront of HCC treatment, possibly in the near future.

Immune Regulation by Self-Recognition: Novel Possibilities for Anticancer Immunotherapy

Circulating T cells that specifically target normal self-proteins expressed by regulatory immune cells were first described in patients with cancer, but can also be detected in healthy individuals. The adaptive immune system is distinguished for its ability to differentiate between self-antigens and foreign antigens. Thus, it was remarkable to discover T cells that apparently lacked tolerance to important self-proteins, eg, IDO, PD-L1, and FoxP3, expressed in regulatory immune cells. The ability of self-reactive T cells to react to and eliminate regulatory immune cells can influence general immune reactions. This suggests that they may be involved in immune homeostasis. It is here proposed that these T cells should be termed antiregulatory T cells (anti-Tregs). The role of anti-Tregs in immune-regulatory networks may be diverse. For example, pro-inflammatory self-reactive T cells that react to regulatory immune cells may enhance local inflammation and inhibit local immune suppression. Further exploration is warranted to investigate their potential role under different malignant conditions and the therapeutic possibilities they possess. Utilizing anti-Tregs for anticancer immunotherapy implies the direct targeting of cancer cells in addition to regulatory immune cells. Anti-Tregs provide the immune system with yet another level of immune regulation and contradict the notion that immune cells involved in the adjustment of immune responses only act as suppressor cells.

Prognostic impact of programmed cell death 1 ligand 1 expression in human leukocyte antigen class I-positive hepatocellular carcinoma after curative hepatectomy

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common solid tumors worldwide. Surgery is potentially curative, but high recurrence rates worsen patient prognosis. The interaction between the proteins programmed cell death 1 (PD-1) and programmed cell death 1 ligand 1 (PD-L1) is an important immune checkpoint. The significance of PD-L1 expression and human leukocyte antigen class I (HLA class I), recognized by CD8 T cells, in the prognosis of patients with HCC remains to be determined.

METHODS

We assessed the levels of PD-L1 and HLA class I expression on HCC samples from 80 patients who had undergone hepatectomy at our institution, and evaluated the correlations between PD-L1 and HLA class I expression and patient prognosis.

RESULTS

High HLA class I expression was correlated with significantly better recurrence-free survival (RFS), but not overall survival (OS). Multivariate analysis showed that high HLA class I expression was an independent predictor of improved RFS. Low expression of PD-L1 on HCC tended to predict better OS, but the difference was not statistically significant. PD-L1 expression on HCC correlated with the number of CD163-positive macrophages and HLA class I expression with CD3-positive cell infiltration. Univariable and multivariable analyses showed that combined PD-L1 low/HLA class I high expression on HCCs was prognostic for improved OS and RFS.

CONCLUSIONS

PD-L1 status may be a good predictor of prognosis in HCC patients with high HLA class I expression. Novel therapies targeting the PD-L1/PD-1 pathway may improve the prognosis of patients with HCC.

An immunosuppressive subtype of neutrophils identified in patients with hepatocellular carcinoma

Functional disorders of various immune cells have been reported in hepatocellular carcinoma (HCC) patients. Recently, distinct subsets of neutrophils (polymorphonuclear leukocytes, PMN) have been identified in hosts with enhanced or impaired cell-mediated immunity. In this study, therefore, plasma factors and PMN from HCC patients were immunobiologically investigated. Plasma neopterin and CCL17 levels were measured by ELISA in 95 HCC patients. Peripheral PMN were isolated from each HCC patient and tested for CCL2 or CCL3 production by ELISA and flow cytometry. The results showed elevated plasma neopterin levels in HCC patients, while CCL17 levels decreased in correlation with tumor size. PMN from HCC patients produced CCL2, while PMN from healthy subjects did not. Moreover, CCL2 production by PMN was significantly increased in proportion to tumor load. When HCC patients were divided into two groups based on CCL2 produced by PMN, the survival rate of the CCL2 high group was significantly lower than that for other patients. While CCL3 production by PMN was also significantly increased in HCC patients, their CCL3 production did not correlate with tumor load and survival. The CCL2/CCL3 ratio in culture fluids of each PMN was also increased in proportion to tumor size. These results suggest that cell-mediated immunity may be impaired in advanced HCC patients. Moreover, distinct PMN subsets may exist in the peripheral blood of HCC patients. These PMN subsets, especially CCL2-producing PMN, may be involved in tumor extension and the survival outcomes for HCC patients.

Natural immunity to pluripotency antigen OCT4 in humans

OCT4 is a transcription factor critical for the pluripotency of human embryonal stem (ES) and induced pluipotency stem (IPS) cells. OCT4 is commonly expressed in germ-cell tumors as well as putative cancer stem cells in several tumors, and is a key determinant of oncogenic fate in germ-cell tumors. The capacity of the human immune system to recognize this critical stem-cell gene is not known, but has implications for preventing tumors with ES/IPS-based therapies and targeting stem-cell pathways in cancer. Here we show that OCT4-specific T cells can be readily detected in freshly isolated T cells from most (>80%) healthy donors. The reactivity to OCT4-derived peptides resides primarily in the CD45RO(+) memory T-cell compartment and consists predominantly of CD4(+) T cells. T cells reactive against OCT4-derived peptides can be readily expanded in culture using peptide-loaded dendritic cells. In contrast to healthy donors, immunity to OCT4 was detected in only 35% of patients with newly diagnosed germ-cell tumors. However, chemotherapy of germ-cell tumors led to the induction of anti-OCT4 immunity in vivo in patients lacking such responses at baseline. These data demonstrate the surprising lack of immune tolerance to this critical pluripotency antigen in humans. Harnessing natural immunity to this antigen may allow immune-based targeting of pluripotency-related pathways for prevention of cancers, including those in the setting of ES/IPS-based therapies.

Immunization with a P53 synthetic long peptide vaccine induces P53-specific immune responses in ovarian cancer patients, a phase II trial

The prognosis of ovarian cancer, the primary cause of death from gynecological malignancies, has only modestly improved over the last decades. Immunotherapy is one of the new treatment modalities explored for this disease. To investigate safety, tolerability, immunogenicity and obtain an impression of clinical activity of a p53 synthetic long peptide (p53-SLP) vaccine, twenty patients with recurrent elevation of CA-125 were included, eighteen of whom were immunized 4 times with 10 overlapping p53-SLP in Montanide ISA51. The first 5 patients were extensively monitored for toxicity, but showed no > or = grade 3 toxicity, thus accrual was continued. Overall, toxicity was limited to grade 1 and 2, mostly locoregional, inflammatory reactions. IFN-gamma producing p53-specific T-cell responses were induced in all patients who received all 4 immunizations as measured by IFN-gamma ELISPOT. An IFN-gamma secretion assay showed that vaccine-induced p53-specific T-cells were CD4(+), produced both Th1 and Th2 cytokines as analyzed by cytokine bead array. Notably, Th2 cytokines dominated the p53-specific response. P53-specific T-cells were present in a biopsy of the last immunization site of at least 9/17 (53%) patients, reflecting the migratory capacity of p53-specific T-cells. As best clinical response, stable disease evaluated by CA-125 levels and CT-scans, was observed in 2/20 (10%) patients, but no relationship was found with vaccine-induced immunity. This study shows that the p53-SLP vaccine is safe, well tolerated and induces p53-specific T-cell responses in ovarian cancer patients. Upcoming trials will focus on improving T helper-1 polarization and clinical efficacy.

Healthy individuals have T-cell and antibody responses to the tumor antigen cyclin B1 that when elicited in mice protect from cancer

We previously identified the aberrantly expressed cell cycle regulator cyclin B1 as a tumor antigen recognized by antibodies and T cells from patients with breast, lung, and head and neck cancers. Ordinarily expressed only transiently in the G2/M stage of the cell cycle in normal cells, cyclin B1 is constitutively expressed at high levels in the cytoplasm of these and many other tumor types, leading to its recognition by the cancer patient's immune system. We report here an unexpected observation that cyclin B1-specific antibody and memory CD4 and CD8 T cells are also found in many healthy individuals who have no history of cancer. Moreover, young as well as older healthy people have these responses suggesting that events other than cancer, which occur either early in life or throughout life, may lead to aberrant cyclin B1 expression and anti-cyclin B1 immunity. The role, if any, of immunity to this tumor-associated antigen is not known. We wanted to determine specifically whether immunity to cyclin B1 might be important in the immunosurveillance of cyclin B1+ tumors. We therefore tested in mice the effectiveness of vaccine-elicited anti-cyclin B1 immunity against a cyclin B1+ mouse tumor that was chosen based on our published observation that cyclin B1 overexpression is associated with the lack of p53 function. We found that cyclin B1 DNA prime-protein boost vaccine protected mice from a challenge with a tumor cell line that was established from a tumor arising in the p53(-/-) mouse that spontaneously overexpresses cyclin B1.

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.

Intratumoral T cells, tumor-associated macrophages, and regulatory T cells: association with p53 mutations, circulating tumor DNA and survival in women with ovarian cancer

OBJECTIVES

Forty percent of women with ovarian cancer have circulating free tumor DNA. We sought to determine if the tumor immune infiltrate varied based on tumor p53 mutation status or presence of circulating tumor DNA.

METHODS

We performed immunohistochemistry on 119 ovarian cancer specimens with CD3 and CD8 (Intratumoral T cells (TILs)), CD68 (tumor-associated macrophages (TAMs)), and FoxP3 (T regulatory cells (Tregs)). Tumors had been previously sequenced for mutations in exons 4-10 of p53, and plasma from women characterized for free tumor DNA.

RESULTS

TIL and TAM levels were positively correlated (P<0.0001). High levels of TILs were identified in 54 of 119 tumors (45.4%). No survival difference was identified according to the presence of TILs or TAMs. Patients with greater TILs were more likely to be optimally cytoreduced (P=0.005). p53 mutations were associated with more TILs (P=0.008). The presence of circulating tumor DNA did not correlate with TILs, TAMs, or Tregs. In the subgroup with a low host antitumor immune response, the intermediate response Tregs group did have a survival advantage (P=0.049).

CONCLUSIONS

p53 mutations are associated with higher levels of TILs. The ratio of Tregs to TILS may be more important than absolute levels. A brisk T cell response within the tumor predicts adequacy of cytoreduction, suggesting successful cytoreduction may be partially due to underlying tumor biology and host response.

Vaccination with p53 peptide-pulsed dendritic cells is associated with disease stabilization in patients with p53 expressing advanced breast cancer; monitoring of serum YKL-40 and IL-6 as response biomarkers

p53 Mutations are found in up to 30% of breast cancers and peptides derived from over-expressed p53 protein are presented by class I HLA molecules and may act as tumor-associated epitopes in cancer vaccines. A dendritic cell (DC) based p53 targeting vaccine was analyzed in HLA-A2+ patients with progressive advanced breast cancer. DCs were loaded with 3 wild-type and 3 P2 anchor modified HLA-A2 binding p53 peptides. Patients received up to 10 sc vaccinations with 5 x 10(6) p53-peptide loaded DC with 1-2 weeks interval. Concomitantly, 6 MIU/m(2) interleukine-2 was administered sc. Results from a phase II trial including 26 patients with verified progressive breast cancer are presented. Seven patients discontinued treatment after only 2-3 vaccination weeks due to rapid disease progression or death. Nineteen patients were available for first evaluation after 6 vaccinations; 8/19 evaluable patients attained stable disease (SD) or minor regression while 11/19 patients had progressive disease (PD), indicating an effect of p53-specific immune therapy. This was supported by: (1) a positive correlation between p53 expression of tumor and observed SD, (2) therapy induced p53 specific T cells in 4/7 patients with SD but only in 2/9 patients with PD, and (3) significant response associated changes in serum YKL-40 and IL-6 levels identifying these biomarkers as possible candidates for monitoring of response in connection with DC based cancer immunotherapy. In conclusion, a significant fraction of breast cancer patients obtained SD during p53-targeting DC therapy. Data encourage initiation of a randomized trial in p53 positive patients evaluating the impact on progression free survival.

Direct detection of cytolytic T lymphocyte-mediated cytotoxicity on antigen-transfected cell microarray

CD8(+) T lymphocytes are capable of recognizing and destroying cancer cells or virally infected cells and can thus offer protection from cellular malignant transformation and pathogenic challenges. With large numbers of genes discovered in genome analyses, rapid identification of cancer or viral antigens would facilitate better exploitation of CD8(+) T lymphocyte-mediated immune protection. Reverse transfection microarray technology allows expression of individual cDNAs at defined positions in a cell monolayer and direct detection of corresponding phenotypic changes of transfected cells at specific locations. In this study, we have integrated reverse transfection with image-based fluorometric detection of antigen-specific CTL-mediated cytotoxicity on transfected cell microarrays. As a result, the antigen recognition of cloned CTL cells has been successfully detected on the cell microarray, in which the specific or non-specific mini-gene DNA in the expression vector or vector alone was spotted. Moreover, the cellular capability of antigen processing and presentation on microarray has also been evaluated by using chimeric DNA constructs containing the antigen-encoding mini-gene sequence. This novel approach may facilitate high throughput screens of cancer cell or virus cDNA libraries to identify individual cDNAs that encode targets for immune intervention.

Tumor immunoediting and immunosculpting pathways to cancer progression

Recent studies have suggested that a natural function of the immune system is to respond and destroy aberrant, dysfunctional cells by a process called immunosurveillance. These studies also suggest that the tumors that arise despite immunosurveillance have been immunosculpted by the immune system. The purported abilities of tumors to induce immune tolerance and suppression, the increased pathogenic behavior of the tumor cells following exposure to immune effectors and the loss of immunogenicity (i.e. immunoediting) often observed in advanced stage tumors could be the result of immunosculpting. In some cases, these immunosculpting features may be permanent and irreversible. However, in other cases, reversible epigenetic mechanisms may underlie the immune resistant tumor phenotype. Regardless, these immune-induced alterations could contribute to cancer pathogenesis. Understanding the mechanisms by which tumors evade immunity will be important for disease prevention and therapeutics.