Novel insights into the molecular mechanisms of HLA class I abnormalities

The molecular mechanism of actions and clinical utilities of tumor infiltrating lymphocytes in gastrointestinal cancers: a comprehensive review and future prospects toward personalized medicine

Gastrointestinal (GI) cancers remain a significant global health burden, accounting for a substantial number of cases and deaths. Regrettably, the inadequacy of dependable biomarkers hinders the precise forecasting of patient prognosis and the selection of appropriate therapeutic sequencing for individuals with GI cancers, leading to suboptimal outcomes for numerous patients. The intricate interplay between tumor-infiltrating lymphocytes (TILs) and the tumor immune microenvironment (TIME) has been shown to be a pivotal determinant of response to anti-cancer therapy and consequential clinical outcomes across a multitude of cancer types. Therefore, the assessment of TILs has garnered global interest as a promising prognostic biomarker in oncology, with the potential to improve clinical decision-making substantially. Moreover, recent discoveries in immunotherapy have progressively changed the landscape of cancer treatment and significantly prolonged the survival of patients with advanced cancers. Nonetheless, the response rate remains constrained within solid tumor sufferers, even when TIL landscapes appear comparable, which calls for the development of our understanding of cellular and molecular cross-talk between TIME and tumor. Hence, this comprehensive review encapsulates the extant literature elucidating the TILs' underlying molecular pathogenesis, prognostic significance, and their relevance in the realm of immunotherapy for patients afflicted by GI tract cancers. Within this review, we demonstrate that the type, density, and spatial distribution of distinct TIL subpopulations carries pivotal implications for the prediction of anti-cancer treatment responses and patient survival. Furthermore, this review underscores the indispensable role of TILs in modulating therapeutic responses within distinct molecular subtypes, such as those characterized by microsatellite stability or programmed cell death ligand-1 expression in GI tract cancers. The review concludes by outlining future directions in TIL-based personalized medicine, including integrating TIL-based approaches into existing treatment regimens and developing novel therapeutic strategies that exploit the unique properties of TILs and their potential as a promising avenue for personalized cancer treatment.

Curcuphenol possesses an unusual histone deacetylase enhancing activity that counters immune escape in metastatic tumours

Curcuphenol, a common component of the culinary spices, naturally found in marine invertebrates and plants, has been identified as a novel candidate for reversing immune escape by restoring expression of the antigen presentation machinery (APM) in invasive cancers, thereby resurrecting the immune recognition of metastatic tumours. Two synthetic curcuphenol analogues, were prepared by informed design that demonstrated consistent induction of APM expression in metastatic prostate and lung carcinoma cells. Both analogues were subsequently found to possess a previously undescribed histone deacetylase (HDAC)-enhancing activity. Remarkably, the H3K27ac ChIPseq analysis of curcuphenol-treated cells reveals that the induced epigenomic marks closely resemble the changes in genome-wide pattern observed with interferon-γ, a cytokine instrumental for orchestrating innate and adaptive immunity. These observations link dietary components to modifying epigenetic programs that modulate gene expression guiding poised immunity.

Understanding the squamous cell carcinoma immune microenvironment

Primary cutaneous squamous cell carcinoma (cSCC) is the second most common human cancer with a rising incidence of about 1.8 million in the United States annually. Primary cSCC is usually curable by surgery; however, in some cases, cSCC eventuates in nodal metastasis and death from disease specific death. cSCC results in up to 15,000 deaths each year in the United States. Until recently, non-surgical options for treatment of locally advanced or metastatic cSCC were largely ineffective. With the advent of checkpoint inhibitor immunotherapy, including cemiplimab and pembrolizumab, response rates climbed to 50%, representing a vast improvement over chemotherapeutic agents used previously. Herein, we discuss the phenotype and function of SCC associated Langerhans cells, dendritic cells, macrophages, myeloid derived suppressor cells and T cells as well as SCC-associated lymphatics and blood vessels. Possible role(s) of SCC-associated cytokines in progression and invasion are reviewed. We also discuss the SCC immune microenvironment in the context of currently available and pipeline therapeutics.

Genetic Modification of T Cells for the Immunotherapy of Cancer

Immunotherapy is a beneficial treatment approach for multiple cancers, however, current therapies are effective only in a small subset of patients. Adoptive cell transfer (ACT) is a facet of immunotherapy where T cells targeting the tumor cells are transferred to the patient with several primary forms, utilizing unmodified or modified T cells: tumor-infiltrating lymphocytes (TIL), genetically modified T cell receptor transduced T cells, and chimeric antigen receptor (CAR) transduced T cells. Many clinical trials are underway investigating the efficacy and safety of these different subsets of ACT, as well as trials that combine one of these subsets with another type of immunotherapy. The main challenges existing with ACT are improving clinical responses and decreasing adverse events. Current research focuses on identifying novel tumor targeting T cell receptors, improving safety and efficacy, and investigating ACT in combination with other immunotherapies.

Prognostic value of Dickkopf-1 and ß-catenin expression according to the antitumor immunity of CD8-positive tumor-infiltrating lymphocytes in biliary tract cancer

The role of β-catenin and Dickkopf-1 (DKK1) is dependent on the specific immunobiology of T cell inflammation in biliary tract cancer (BTC). We aimed to analyze the role of DKK1 or β-catenin as a prognostic factor in BTC, and determine the clinical associations of ß-catenin and DKK1 with CD8+ tumor-infiltrating lymphocytes (TIL). We used data from The Cancer Genome Atlas Research Network and the clinicopathological data of 145 patients with BTC who had undergone primary radical resection between 2006 and 2016. CD8+ TIL expression was a significant predictor of favorable overall survival (OS) and relapse-free survival (RFS) (median OS, 34.9 months in high-TIL, 16.7 months in low-TIL, P < 0.0001 respectively; median RFS, 27.1 months in high-TIL, 10.0 months in low-TIL, P < 0.0001 respectively). In the high-CD8+ TIL BTC group, the tumor expression of β-catenin and DKK1 had a significant negative impact on either OS or RFS. In the low-TIL BTC group, there were no differences according to ß-catenin and DKK1 expression. Cox regression multivariate analysis demonstrated that CD8+ TIL and β-catenin retained significant association with OS. Among patients with resected BTC, the β-catenin and DKK1 protein and high CD8+ TIL levels were associated with poor and good clinical outcomes, respectively.

Tumor microenvironment and immune evasion in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC), an aggressive malignancy, is characterized by high morbidity and low survival rates with limited therapeutic options outside of regional surgery, conventional cytotoxic chemotherapy, and irradiation. Increasing studies have supported the synergistic role of the tumor microenvironment (TME) in cancer advancement. The immune system, in particular, plays a key role in surveillance against the initiation, development, and progression of HNSCC. The understanding of how neoplastic cells evolve and evade the immune system whether through self-immunogenicity manipulation, or expression of immunosuppressive mediators, provides the foundation for the development of advanced therapies. Furthermore, the crosstalk between cancer cells and the host immune system have a detrimental effect on the TME promoting angiogenesis, proliferation, and metastasis. This review provides a recent insight into the role of the key inflammatory cells infiltrating the TME, with a focus on reviewing immunological principles related to HNSCC, as cancer immunosurveillance and immune escape, including a brief overview of current immunotherapeutic strategies and ongoing clinical trials.

Investigating T Cell Immunity in Cancer: Achievements and Prospects

T cells play a key role in tumour surveillance, both identifying and eliminating transformed cells. However, as tumours become established they form their own suppressive microenvironments capable of shutting down T cell function, and allowing tumours to persist and grow. To further understand the tumour microenvironment, including the interplay between different immune cells and their role in anti-tumour immune responses, a number of studies from mouse models to clinical trials have been performed. In this review, we examine mechanisms utilized by tumour cells to reduce their visibility to CD8⁺ Cytotoxic T lymphocytes (CTL), as well as therapeutic strategies trialled to overcome these tumour-evasion mechanisms. Next, we summarize recent advances in approaches to enhance CAR T cell activity and persistence over the past 10 years, including bispecific CAR T cell design and early evidence of efficacy. Lastly, we examine mechanisms of T cell infiltration and tumour regression, and discuss the strengths and weaknesses of different strategies to investigate T cell function in murine tumour models.

Tumor Microenvironment, HLA Class I and APM Expression in HPV-Negative Oral Squamous Cell Carcinoma

Simple Summary

Oral squamous cell carcinoma has developed different strategies to escape from T-cell-mediated immune surveillance, which is mediated by changes in the composition of cellular and soluble components of the tumor microenvironment as well as an impaired expression of molecules of the antigen processing machinery leading to a downregulation of HLA class I surface antigens. In depth characterization of these escape mechanisms might help to develop strategies to overcome this tolerance. In this study, human papilloma virus negative oral squamous cell carcinoma lesions were analyzed regarding the protein expression of major components of the HLA class I antigen processing/presentation pathway in correlation to the intra-tumoral immune cell composition, IFN-γ signaling and clinical parameters, which was further confirmed by bioinformatics analyses of datasets obtained from The Cancer Genome Atlas. This novel knowledge could be used for optimizing the design of immunotherapeutic approaches of this disease.

Abstract

Progression of oral squamous cell carcinoma (OSCC) has been associated with an escape of tumor cells from the host immune surveillance due to an increased knowledge of its underlying molecular mechanisms and its modulation by the tumor microenvironment and immune cell repertoire. In this study, the expression of HLA class I (HLA-I) antigens and of components of the antigen processing machinery (APM) was analyzed in 160 pathologically classified human papilloma virus (HPV)-negative OSCC lesions and correlated to the intra-tumoral immune cell response, IFN-γ signaling and to the patient’s outcome. A heterogeneous but predominantly lower constitutive protein expression of HLA-I APM components was found in OSCC sections when compared to non-neoplastic cells. Tumoral HLA-I APM component expression was further categorized into the three major phenotypes HLA-I^high/APM^high, HLA-I^low/APM^low and HLA-I^{discordant high/low}/APM^high. In the HLA-I^high/APM^high group, the highest frequency of intra-tumoral CD8⁺ T cells and lowest number of CD8⁺ T cells close to FoxP3⁺ cells were found. Patients within this group presented the most unfavorable survival, which was significantly evident in stage T2 tumors. Despite a correlation with the number of intra-tumoral CD8⁺ T cells, tumoral JAK1 expression as a surrogate marker for IFN-γ signaling was not associated with HLA-I/APM expression. Thus, the presented findings strongly indicate the presence of additional factors involved in the immunomodulatory process of HPV-negative OSCC with a possible tumor-burden-dependent complex network of immune escape mechanisms beyond HLA-I/APM components and T cell infiltration in this tumor entity.

Identification of microRNAs Targeting the Transporter Associated with Antigen Processing TAP1 in Melanoma

The underlying molecular mechanisms of the aberrant expression of components of the HLA class I antigen processing and presentation machinery (APM) in tumors leading to evasion from T cell-mediated immune surveillance could be due to posttranscriptional regulation mediated by microRNAs (miRs). So far, some miRs controlling the expression of different APM components have been identified. Using in silico analysis and an miR enrichment protocol in combination with small RNA sequencing, miR-26b-5p and miR-21-3p were postulated to target the 3′ untranslated region (UTR) of the peptide transporter TAP1, which was confirmed by high free binding energy and dual luciferase reporter assays. Overexpression of miR-26b-5p and miR-21-3p in melanoma cells downregulated the TAP1 protein and reduced expression of HLA class I cell surface antigens, which could be reverted by miR inhibitors. Moreover, miR-26b-5p overexpression induced a decreased T cell recognition. Furthermore, an inverse expression of miR-26b-5p and miR-21-3p with TAP1 was found in primary melanoma lesions, which was linked with the frequency of CD8⁺ T cell infiltration. Thus, miR-26-5p and miR-21-3p are involved in the HLA class I-mediated immune escape and might be used as biomarkers or therapeutic targets for HLA class I^low melanoma cells.

MHC class I transactivator NLRC5 in host immunity, cancer and beyond

The presentation of antigenic peptides by major histocompatibility complex (MHC) class I and class II molecules is crucial for activation of the adaptive immune system. The nucleotide-binding domain and leucine-rich repeat receptor family members CIITA and NLRC5 function as the major transcriptional activators of MHC class II and class I gene expression, respectively. Since the identification of NLRC5 as the master regulator of MHC class I and class-I-related genes, there have been major advances in understanding the function of NLRC5 in infectious diseases and cancer. Here, we discuss the biological significance and mechanism of NLRC5-dependent MHC class I expression.

HLA Class I Allele Expression and Clinical Outcome in De Novo Metastatic Prostate Cancer

The prognostic value of human leukocyte antigen (HLA) class I molecules in prostate cancer (PCa) remains unclear. Herein, we investigated the prognostic relevance of the most frequently expressed HLA-A alleles in Greece (A*02:01 and HLA-A*24:02) in de novo metastatic hormone-sensitive PCa (mPCa), which is a rare and aggressive disease characterized by a rapid progression to castration-resistance (CR) and poor overall survival (OS), contributing to almost 50% of PCa-related deaths. We identified 56 patients who had either progressed to CR (these patients were retrospectively analyzed for the time to the progression of CR and prospectively for OS) or had at least three months’ follow-up postdiagnosis without CR progression and, thus, were prospectively analyzed for both CR and OS. Patients expressing HLA-A*02:01 showed poor clinical outcomes vs. HLA-A*02:01⁻negative patients. HLA-A*24:02⁻positive patients progressed slower to CR and had increased OS. Homozygous HLA-A*02:01 patients progressed severely to CR, with very short OS. Multivariate analyses ascribed to both HLA alleles significant prognostic values for the time to progression (TTP) to CR and OS. The presence of HLA-A*02:01 and HLA-A*24:02 alleles in de novo mPCa patients are significantly and independently associated with unfavorable or favorable clinical outcomes, respectively, suggesting their possible prognostic relevance for treatment decision-making in the context of precision medicine.

Identification of miR-200a-5p targeting the peptide transporter TAP1 and its association with the clinical outcome of melanoma patients

Tumor escape is often associated with abnormalities in the surface expression of the human leukocyte antigen class I (HLA-I) antigens thereby limiting CD8+ cytotoxic T cell responses. This impaired HLA-I surface expression can be mediated by deficient expression of components of the antigen processing and presentation machinery (APM) due to epigenetic, transcriptional and/or post-transcriptional processes. Since a discordant mRNA and protein expression pattern of APM components including the peptide transporter associated with antigen processing 1 (TAP1) has been frequently described in tumors of distinct origin, a post-transcriptional control of APM components caused by microRNAs (miR) was suggested. Using an in silico approach, miR-200a-5p has been identified as a candidate miR binding to the 3' untranslated region (UTR) of TAP1. Luciferase reporter assays demonstrated a specific binding of miR-200a-5p to the TAP1 3'-UTR. Furthermore, the miR-200a-5p expression is inversely correlated with the TAP1 protein expression in HEK293T cells and in a panel of melanoma cell lines as well as in primary melanoma lesions. High levels of miR-200a-5p expression were associated with a shorter overall survival of melanoma patients. Overexpression of miR-200a-5p reduced TAP1 levels, which was accompanied by a decreased HLA-I surface expression and an enhanced NK cell sensitivity of melanoma cells. These data show for the first time a miR-mediated control of the peptide transporter subunit TAP1 in melanoma thereby leading to a reduced HLA-I surface expression accompanied by an altered immune recognition and reduced patients' survival.

Abbreviations

Ab: antibody; ACTB: β-actin; APM: antigen processing and presentation machinery; ATCC: American tissue culture collection; β2-m: β2-microglobulin; BSA: bovine serum albumin; CTL: cytotoxic T lymphocyte; FCS: fetal calf serum; FFL: firefly luciferase; FFPE: formalin-fixed paraffin-embedded; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; HC: heavy chain; HLA: human leukocyte antigen; HLA-I: HLA class I; HRP: horseradish peroxidase; IFN: interferon; im-miR: immune modulatory miRNA; LMP: low molecular weight protein; luc: luciferase; MFI: mean fluorescence intensity; MHC: major histocompatibility complex; miR: microRNA; NC: negative control; NK: natural killer; NSCLC: non-small cell lung carcinoma; OS: overall survival; PBMC: peripheral blood mononuclear cells; RBP: RNA-binding proteins; RL: Renilla; RLU: relative light units; TAP: transporter associated with antigen processing; tpn: tapasin; UTR: untranslated region.

NLRC5: new cancer buster?

Recent decades, there is significant progress in understanding the mechanisms of tumor progression and immune evasion. The newly discovered protein NLRC5 is demonstrated to participate in regulating cancer immune escape through enhancing MHC class I genes expression in certain tumors. Nevertheless, increasing evidence has revealed that NLRC5 is up-regulated in some other tumors and promote tumor development and progression. The purpose of this review is to describe the role of NLRC5 in tumors and discuss whether NLRC5 can be a potential target in cancer treatment.

HLA Class I Antigen Processing Machinery Defects in Cancer Cells-Frequency, Functional Significance, and Clinical Relevance with Special Emphasis on Their Role in T Cell-Based Immunotherapy of Malignant Disease

MHC class I antigen abnormalities have been shown to be one of the major immune escape mechanisms murine and human cancer cells utilize to avoid recognition and destruction by host immune system. This mechanism has clinical relevance, since it is associated with poor prognosis and/or reduced patients' survival in many types of malignant diseases. The recent impressive clinical responses to T cell-based immunotherapies triggered by checkpoint inhibitors have rekindled tumor immunologists and clinical oncologists' interest in the analysis of the human leukocyte antigen (HLA) class I antigen processing machinery (APM) expression and function in malignant cells. Abnormalities in the expression, regulation and/or function of components of this machinery have been associated with the development of resistances to T cell-based immunotherapies. In this review, following the description of the human leukocyte antigen (HLA) class I APM organization and function, the information related to the frequency of defects in HLA class I APM component expression in various types of cancer and the underlying molecular mechanisms is summarized. Then the impact of these defects on clinical response to T cell-based immunotherapies and strategies to revert this immune escape process are discussed.

Human leucocyte antigen class I in hormone receptor-positive, HER2-negative breast cancer: association with response and survival after neoadjuvant chemotherapy

Background

Clinical application of cancer immunotherapy requires a better understanding of tumor immunogenicity and the tumor microenvironment. HLA class I molecules present antigens to CD8⁺ cytotoxic cells. Their loss or downregulation is frequently found in tumors resulting in reduced T cell responses and worse prognosis.

Methods

We evaluated HLA class I heavy chain expression by immunohistochemistry in 863 biopsies (GeparTrio trial). Patients received neoadjuvant chemotherapy and adjuvant endocrine treatment if tumors were hormone receptor-positive (HR+). In parallel, the expression of HLA-A was analyzed using a microarray cohort of 320 breast cancer patients from the MD Anderson Cancer Center. We evaluated its association with clinical outcome, tumor-infiltrating lymphocytes (TILs), and immune cell metagenes.

Results

In HR+/HER2− breast cancer, HLA class I heavy chain expression was associated with increased TILs and better response to chemotherapy (7% vs. 14% pCR rate, P = 0.029), but worse disease-free survival (hazard ratio (HR) 1.6 (1.1–2.4); P = 0.024). The effect was significant in a multivariate model adjusted for clinical and pathological variables (HR 1.7 (1.1–2.6); P = 0.016) and was confirmed by analysis of HLA-A in a microarray cohort. HLA-A was correlated to most immune cell metagenes. There was no association with response or survival in triple-negative or HER2+ disease.

Conclusions

The study confirms the negative prognostic role of lymphocytes in HR+ breast cancer and points at a complex interaction between chemotherapy, endocrine treatment, and tumor immunogenicity. The results point at a subtype-specific and potentially treatment-specific role of tumor-immunological processes in breast cancer with different implications in triple-negative and hormone receptor-positive disease.

Influence of mutagenic versus non-mutagenic pre-operative chemotherapy on the immune infiltration of residual breast cancer

Background: Chemotherapeutic agents are often mutagenic. Induction of mutation associated neo-epitopes is one of the mechanisms by which chemotherapy is thought to increase the number of tumor-infiltrating lymphocytes. It is not known, however, whether treatment with various chemotherapeutic agents with different mutagenic capacity induce a significantly different number of stromal tumor-infiltrating lymphocytes (StrTIL) in residual cancer.Methods: One hundred and twenty breast carcinoma cases with residual disease that were treated with one of three types of pre-operative chemotherapy regimens were selected for the study. The percentage of StrTIL was evaluated in pretreatment core biopsies (pre-StrTIL) and post-treatment surgical tumor samples (post-StrTIL). TIL changes (ΔStrTIL) were calculated from the difference between post-StrTIL and pre-StrTIL.Results: When analyzing the pre-StrTIL and post-StrTIL among the three treatment groups, we detected significant StrTIL increase independently of the treatment applied. Based on distant metastases-free survival analysis, both post-StrTIL and ΔStrTIL was found to be independent prognostic factor in HR negative cases. Conclusions: Significant increase of StrTIL in the residual disease was observed in patients treated with the highly (platinum), moderately (cyclophosphamide) and marginally mutagenic chemotherapeutic agents (taxane, anthracycline). Increase in StrTIL in residual cancer compared to pretreatment tumor tissue is associated with improved distant metastasis-free survival in cases with HR negative breast carcinoma.

Intravesical BCG: where do we stand? Past, present and future

High and intermediate risk non-muscle invasive bladder cancer poses a real challenge for treatment. Approximately 70% of bladder cancer presents as non-muscle invasive and 20–25% will progress to muscle invasive disease. Recurrences occur in up to 70% but treatment options are limited. Intravesical bacillus Calmette–Guérin is still considered the bladder sparing treatment of choice despite its well documented pitfalls. This review considers how bacillus Calmette–Guérin has become the recommended treatment, its benefits and risks and the alternative options for treatment.

Level of evidence: Not applicable for this multicentre audit.

Clinicopathologic significance of human leukocyte antigen class I expression in patients with stage II and III gastric cancer

Human leukocyte antigen class I (HLA I) molecules composed of alpha (heavy) chain, including HLA-A, -B, or -C encoded by HLA genes, and beta-2-microglobulin (β2M) are membrane proteins on all nucleated cells that display peptide antigens for recognition by CD8-positive cytotoxic T cells. Here, we examined the clinicopathologic signification of HLA I expression in patients with gastric cancer (GC). Immunohistochemistry was performed to detect HLA A/B/C, β2M, CD8, p53, and programmed death-ligand 1 (PD-L1) in the center and invasive margin of the tumor in 395 stage II and III GCs using tissue array method. Additionally, Epstein-Barr virus (EBV) infection and microsatellite instability (MSI) status were investigated. Negative expression of HLA A/B/C and β2M was observed in 258 (65.3%) and 235 (59.5%) of 395 stage II and III GCs, respectively. Negative HLA I expression was significantly associated with aggressive clinicopathologic features. Furthermore, negative expression of HLA A/B/C and β2M was inversely correlated with CD8-positive cytotoxic T cell infiltration, EBV-positivity, and PD-L1 expression (all p < 0.001). Patients with HLA A/B/C-negative GC had worse overall survival (OS) (p = 0.019) and combined analysis with both HLA A/B/C and β2M expression status significantly predicted OS in univariate (p = 0.004) and multivariate survival analysis (p = 0.016). Negative expression of HLA A/B/C and β2M was frequently observed in stage II and III GCs, particularly with the aggressive clinicopathologic features, and correlated with an unfavorable prognosis and host immune response status. These findings contribute to further development of immunotherapy.

Tumor cells endowed with professional antigen-presenting cell functions prime PBLs to generate antitumor CTLs

Intrinsic genetic instability of tumor cells leads to continuous production of mutated proteins referred to as tumor-specific neoantigens. Generally, they are recognized as nonself products by the host immune system. However, an effective adaptive response clearing neoantigen-expressing cells is lost in tumor diseases. Most advanced therapeutic strategies aim at inducing neoantigen-specific immune activation through personalized approaches. They include tumor cell exome sequencing, human leukocyte antigen (HLA) typing, synthesis, and injection of peptides/RNA with adjuvants. Here, we propose an innovative method to induce a CD8⁺ T cytotoxic lymphocyte (CTL) immune response against tumor neoantigens bypassing the steps needed in current therapeutic strategies of personalized vaccination. We assumed that tumor cells can be the most efficient and precise factory of major histocompatibility complex (MHC) class I-associated, tumor neoantigen-derived peptides. Hence, endowing tumor cells with professional antigen-presenting functions would prime CD8⁺ T lymphocytes towards a response against nonself tumor antigens. To explore this possibility, both adenocarcinoma and melanoma human cells were engineered to express both CD80 and CD86 costimulatory molecules. HLA-matched lymphocytes were then primed through cocultivation with the engineered tumor cells. The generation of tumor-specific CD8⁺ T lymphocytes was tested through the combined analysis of cell activation markers, formation of immunologic synapses, generation of tumor antigen-specific CD8⁺ T lymphocytes, and cytotoxic activity. Our data consistently indicate that tumor cells endowed with professional antigen-presenting functions can generate an effective tumor-specific CTL immune response. This finding may open avenues towards the development of innovative antitumor immunotherapies. KEY MESSAGES: We established a novel method to induce antitumor CTLs without a need to identify TAAs and/or tumor neoantigens. This strategy relies on transducing tumor cells with a retroviral vector expressing both CD80 and CD86. In this way, tumor cells prime naïve CD8⁺ T lymphocytes in a way that CTLs killing the same tumor cells are generated. These findings open the way towards preclinical assays in the perspective to introduce this antitumor immunotherapy strategy in clinic.

NLRC5: A paradigm for NLRs in immunological and inflammatory reaction

The nucleotide-binding domain leucine-rich repeat containing (NLR) family of proteins is mainly involved in microbial pathogen recognition, inflammatory responses, and cell death. NLRC5, the largest member of the NLR family, is currently receiving an increasing level of attention. NLRC5 has been demonstrated to be a potent negative regulator of NF-κB signaling pathway-mediated inflammatory response. Moreover, accumulating evidence has indicated that NLRC5 is closely related to pathological processes of various cancers. In this review, we present an overview on NLRC5, addressing its underlying molecular mechanisms and implications in host defense, inflammatory response, and associated cancers.

MHC/HLA Class I Loss in Cancer Cells

In this chapter I describe Tumour Immune Escape mechanisms associated with MHC/HLA class I loss in human and experimental tumours. Different altered HLA class-I phenotypes can be observed that are produced by different molecular mechanisms. Experimental and histological evidences are summarized indicating that at the early stages of tumour development there is an enormous variety of tumour clones with different MHC class I expression patterns. This phase is followed by a strong T cell mediated immune-selection of MHC/HLA class-I negative tumour cells in the primary tumour lesion. This transition period results in a formation of a tumour composed only of HLA-class I negative cells. An updated description of this process observed in a large variety of human tumors is included. In the second section I focus on MHC/HLA class I alterations observed in mouse and human metastases, and describe the generation of different tumor cell clones with altered MHC class I phenotypes, which could be similar or different from the original tumor clone. The biological and immunological relevance of these observations is discussed. Finally, the interesting phenomenon of metastatic dormancy is analyzed in association with a particular MHC class I negative tumor phenotype.

TEIPP antigens for T-cell based immunotherapy of immune-edited HLA class Ilow cancers

T-cell based immunotherapies through checkpoint blockade or adoptive transfer are effective treatments for a wide range of cancers like melanomas and lung carcinomas that harbor a high mutational load. The HLA class I and class II (HLA-I and HLA-II) presented neoantigens arise from genetic mutations in the cancerous cells and are ideal non-self targets for the T cell-based treatments. Although some cancer patients responded with complete regression, many others are irresponsive to checkpoint blockade treatments, or relapse after initial success. One of the mechanisms by which tumors evade T cell recognition is by acquiring deficiencies in the HLA-I antigen-processing pathway, leading to downregulation of HLA-I molecules at the cell surface and thereby creating an 'invisible' tumor phenotype. Interestingly, an alternative antigen repertoire arises on these HLA-I^low cancer cells. We refer to this alternative antigen repertoire as TEIPP: T cell epitopes associated with impaired peptide processing. TEIPP antigens are curious non-mutated peptides from housekeeping proteins that are not presented in homeostasis. In this review, for the first time we recapitulate all our published work on TEIPP antigens, including our recent understanding of the CD8 T cell repertoire. We are convinced that TEIPP-directed T cells will be valuable resources to target immune-edited tumors that have acquired resistance to checkpoint blockade therapy.

Multiparametric immune profiling in HPV- oral squamous cell cancer

Evaluation of T lymphocyte frequency provides prognostic information for patients with oral squamous cell cancer (OSCC). However, the effect of simultaneously evaluating T cell frequency and assessing suppressive elements and defects in antigen-processing machinery (APM) has not been clarified. Simultaneous characterization of CD3+, CD8+, FoxP3+, CD163+, and PD-L1+ cells using multispectral imaging was performed on sections from 119 patients with HPV- OSCC. Expression of β2-microglobulin, MHC class I heavy chain, and large multifunctional peptidase 10 was quantified, and all data were correlated with patient outcome. We found that, consistent with previous reports, high numbers of CD8+ T cells at the invasive margin correlated significantly with prolonged overall survival (OS), while the number of FoxP3+ or PD-L1+ cells did not. Compiling the number of FoxP3+ or PD-L1+ cells within 30 μm of CD8+ T cells identified a significant association with a high number of suppressive elements close to CD8+ T cells and reduced OS. Integrating this information into a cumulative suppression index (CSI) increased correlation with OS. Incorporating tumor expression levels of APM components with CSI further improved prognostic power. This multiparametric immune profiling may be useful for stratifying patients with OSCC for clinical trials.

Identification of Immunogenic Epitopes by MS/MS

The interrogation of cell surface-presented immunogenic epitopes is of great importance to differentiate diseased cells in consequence to malignant transformation or viral infections. On the basis of this knowledge, next-generation immunotherapies against cancers, autoimmunity, or infectious diseases can be developed. The identification of altered peptide repertoires of transformed cells renders mass spectrometry-based analysis indispensable. This is evident considering the low correlation of gene or protein expression alterations, respectively, with changes in the peptide repertoire rendering those analyses less informative. Nevertheless, immunogenicity of peptides appearing to be exclusively found on diseased cells has to be finally proven in T cell-based assays. This review highlights the capabilities and limitations of mass spectrometry in the identification of entire immunopeptidomes, as well as individual potential immunogenic epitopes with a strong focus on cancer. Furthermore, an overview of state-of-the-art immunogenicity screens is presented.

DMBT1 expression in biliary carcinogenesis with correlation of clinicopathological data

AIMS

Deleted in malignant brain tumours 1 (DMBT1) exerts functions in the regulation of epithelial differentiation and inflammation and has been proposed as a tumour suppressor. Because chronic inflammation is a hallmark of cholangiocarcinogenesis, the aim of this study was to investigate the expression of DMBT1 in biliary tract cancer (BTC) and to correlate this expression with clinicopathological data.

METHODS AND RESULTS

The expression of DMBT1 protein was examined immunohistochemically in 157 BTC patients [41 intrahepatic (ICC), 60 extrahepatic cholangiocarcinomas (ECC) and 56 adenocarcinomas of the gallbladder (GBAC)]. Additionally, 56 samples of high-grade biliary intraepithelial neoplasia (BilIN 3) and 92 corresponding samples of histological non-neoplastic biliary tract tissues were included. DMBT1 expression was increased significantly in BilIN 3 compared to normal tissue (P < 0.0001) and BTC (P < 0.0001). BTC showed no significant difference in DMBT1 expression compared to non-neoplastic biliary tissue (P = 0.315). Absent DMBT1 expression in non-neoplastic biliary tissue of BTC patients was associated with poorer survival (P = 0.027). DMBT1 expression was correlated significantly with patients' age (P < 0.001).

CONCLUSION

DMBT1 is expressed differently in cholangiocarcinogenesis and poorer patients' survival rates are associated with absent DMBT1 expression in non-neoplastic biliary tissue, suggesting a tumour-suppressive role of DMBT1 in early cholangiocarcinogenesis.

NLRC5/CITA: A Key Player in Cancer Immune Surveillance

Cancer cells need to escape immune surveillance for successful tumor growth. Loss of MHC class I has been described as a major immune evasion strategy in many cancers. MHC class I transactivator (CITA), NLRC5 [nucleotide-binding domain and leucine-rich repeats containing (NLR) family, caspase activation and recruitment domain (CARD) domain containing 5], is a key transcription coactivator of MHC class I genes. Recent genetic studies have revealed that NLRC5 is a major target for cancer immune evasion mechanisms. The reduced expression or activity of NLRC5 caused by promoter methylation, copy number loss, or somatic mutations is associated with defective MHC class I expression, impaired cytotoxic T cell activation, and poor patient prognosis. Here, we review the role of NLRC5 in cancer immune evasion and the future prospects for cancer research.

Adaptive Resistance to Cancer Immunotherapy

Immunosuppressive mechanisms within the tumor microenvironment have emerged as a major impediment to cancer immunotherapy. While a broad range of secreted factors, receptors/ligands, and cell populations have been described that contribute to the immunosuppression, the involvement of these processes in immune evasion by tumors is typically considered to be an intrinsic property of the tumor. Evidence is now emerging that the processes underlying immune suppression within the tumor are, in fact, triggered by immune attack and reflect a dynamic interplay between the tumor and the host's immune system. The term adaptive resistance has been coined to describe the induction of immune suppressive pathways in the tumor following active attack on the tumor. Adaptive resistance is a scalable process where the magnitude of immune suppression matches the magnitude of the immune attack; the net balance between suppression and attack determines the durability of the anti-tumor response and tumor outcome. In this chapter, we will examine the data supporting adaptive resistance and the opposing roles of T cells in simultaneously promoting both anti-tumor immunity and immune suppression within the tumor microenvironment. The clinical implications of adaptive resistance in the design and application of immunotherapeutic strategies is also discussed.

The impact of interferon-alpha2 on HLA genes in patients with polycythemia vera and related neoplasms

Gene expression profiling in Philadelphia-negative chronic myeloproliferative neoplasms (MPNs) have unraveled significant deregulation of several immune and inflammation genes of potential importance for clonal evolution. Other mechanisms might be downregulation of major histocompatibility class I and II genes used by tumor cells to escape antitumor T-cell-mediated immune responses. Several genes encoding human leukocyte antigen (HLA) class I and II molecules have been shown to be significantly downregulated. Upregulation of HLA genes is considered one of the mechanisms of action of interferon (IFN)-alpha2, but regulation of these genes during IFN-alpha2 treatment in MPNs has never been studied. Our findings show a significant upregulation of several HLA genes of importance for tumor immune surveillance by IFN-alpha2 treatment in MPNs. This mechanism might enhance the cytotoxic potential of immune cells against MPNs and explain the induction of minimal residual disease by IFN-alpha2 treatment in these patients.

Molecular mechanisms of HLA class I-mediated immune evasion of human tumors and their role in resistance to immunotherapies

Although the human immune system can recognize and eradicate tumor cells, tumors have also been shown to develop different strategies to escape immune surveillance, which has been described for the first time in different mouse models. The evasion of immune recognition was often associated with a poor prognosis and reduced survival of patients. During the last years the molecular mechanisms, which protect tumor cells from this immune attack, have been identified and appear to be more complex than initially expected. However, next to the composition of cellular, soluble and physical components of the tumor microenvironment, the tumor cells changes to limit immune responses. Of particular importance are classical and non-classical human leukocyte antigen (HLA) class I antigens, which often showed a deregulated expression in cancers of distinct origin. Furthermore, HLA class I abnormalities were linked to defects in the interferon signaling, which have both been shown to be essential for mounting immune responses and are involved in resistances to T cell-based immunotherapies. Therefore this review summarizes the expression, regulation, function and clinical relevance of HLA class I antigens in association with the interferon signal transduction pathway and its role in adaptive resistances to immunotherapies.

NLRC5, a promising new entry in tumor immunology

The recent use of T cell-based cancer immunotherapies, such as adoptive T-cell transfer and checkpoint blockade, yields increasing clinical benefit to patients with different cancer types. However, decrease of MHC class I expression is a common mechanism transformed cells take advantage of to evade CD8(+) T cell-mediated antitumor responses, negatively impacting on the outcome of immunotherapies. Hence, there is an urgent need to develop novel approaches to overcome this limitation. NLRC5 has been recently described as a key transcriptional regulator controlling expression of MHC class I molecules. In this commentary, we summarize and put into perspective a study by Rodriguez and colleagues recently published in Oncoimmunology, addressing the role of NLRC5 in melanoma. The authors demonstrate that NLRC5 overexpression in B16 melanoma allows to recover MHC class I expression, rising tumor immunogenicity and counteracting immune evasion. Possible ways of manipulating NLRC5 activity in tumors will be discussed. Highlighting the therapeutic potential of modulating NLRC5 levels, this publication also encourages evaluation of NLRC5, and by extension MHC class I pathway, as clinical biomarker to select personalized immunotherapeutic strategies.

Clinical relevance of the tumor microenvironment and immune escape of oral squamous cell carcinoma

BACKGROUND

Changes in the tumor microenvironment and immune surveillance represent crucial hallmarks of various kinds of cancer, including oral squamous cell carcinoma (OSCC), and a close crosstalk of hypoxia regulating genes, an activation of chemokines and immune cells has been described.

METHODS

A review about the pivotal role of HIF-1, its crosstalk to various cornerstones in OSCC tumorigenesis is presented.

RESULTS

Hypoxia is a frequent event in OSCC and leads to a reprogramming of the cellular metabolism in order to prevent cell death. Hypoxic OSCC cells induce different adaptive changes such as anaerobic glycolysis, pH stabilisation and alterations of the gene and protein expression profile. This complex metabolic program is orchestrated by the hypoxia inducible factor (HIF)-1, the master regulator of early tumor progression. Hypoxia-dependent and -independent alterations in immune surveillance lead to different immune evasion strategies, which are partially mediated by alterations of the tumor cells, changes in the frequency, activity and repertoire of immune cell infiltrates and of soluble and environmental factors of the tumor micromilieu with consecutive generation of an immune escape phenotype, progression of disease and poor clinical outcome of OSCC patients.

CONCLUSIONS

This review focusses on the importance of HIF-1 in the adaption and reprogramming of the metabolic system to reduced oxygen values as well as on the role of the tumor microenvironment for evasion of OSCC from immune recognition and destruction.

Vaccines for established cancer: overcoming the challenges posed by immune evasion

Therapeutic vaccines preferentially stimulate T cells against tumour-specific epitopes that are created by DNA mutations or oncogenic viruses. In the setting of premalignant disease, carcinoma in situ or minimal residual disease, therapeutic vaccination can be clinically successful as monotherapy; however, in established cancers, therapeutic vaccines will require co-treatments to overcome immune evasion and to become fully effective. In this Review, we discuss the progress that has been made in overcoming immune evasion controlled by tumour cell-intrinsic factors and the tumour microenvironment. We summarize how therapeutic benefit can be maximized in patients with established cancers by improving vaccine design and by using vaccines to increase the effects of standard chemotherapies, to establish and/or maintain tumour-specific T cells that are re-energized by checkpoint blockade and other therapies, and to sustain the antitumour response of adoptively transferred T cells.

NLRC5 elicits antitumor immunity by enhancing processing and presentation of tumor antigens to CD8(+) T lymphocytes

Cancers can escape immunesurveillance by diminishing the expression of MHC class-I molecules (MHC-I) and components of the antigen-processing machinery (APM). Developing new approaches to reverse these defects could boost the efforts to restore antitumor immunity. Recent studies have shown that the expression of MHC-I and antigen-processing molecules is transcriptionally regulated by NOD-like receptor CARD domain containing 5 (NLRC5). To investigate whether NLRC5 could be used to improve tumor immunogenicity, we established stable lines of B16-F10 melanoma cells expressing NLRC5 (B16-5), the T cell co-stimulatory molecule CD80 (B16-CD80) or both (B16-5/80). Cells harboring NLRC5 constitutively expressed MHC-I and LMP2, LMP7 and TAP1 genes of the APM. The B16-5 cells efficiently presented the melanoma antigenic peptide gp100_25–33 to Pmel-1 TCR transgenic CD8⁺ T cells and induced their proliferation. In the presence of CD80, B16-5 cells stimulated Pmel-1 cells even without the addition of gp100 peptide, indicating that NLRC5 facilitated the processing and presentation of endogenous tumor antigen. Upon subcutaneous implantation, B16-5 cells showed markedly reduced tumor growth in C57BL/6 hosts but not in immunodeficient hosts, indicating that the NLRC5-expressing tumor cells elicited antitumor immunity. Following intravenous injection, B16-5 and B16-5/80 cells formed fewer lung tumor foci compared to control cells. In mice depleted of CD8⁺ T cells, B16-5 cells formed large subcutaneous and lung tumors. Finally, immunization with irradiated B16-5 cells conferred protection against challenge by parental B16 cells. Collectively, our findings indicate that NLRC5 could be exploited to restore tumor immunogenicity and to stimulate protective antitumor immunity.

Future directions in bladder cancer immunotherapy: towards adaptive immunity

The clinical management of bladder cancer has not changed significantly in several decades. In particular, intravesical bacillus Calmette-Guérin (BCG) immunotherapy has been a mainstay for high-risk nonmuscle invasive bladder cancer since the late 1970s/early 1980s. This is despite the fact that bladder cancer has the highest recurrence rates of any cancer and BCG immunotherapy has not been shown to induce a tumor-specific immune response. We and others have hypothesized that immunotherapies capable of inducing tumor-specific adaptive immunity are needed to impact bladder cancer morbidity and mortality. This article summarizes the preclinical and clinical development of bladder cancer immunotherapies with an emphasis on the last 5 years. Expected progress in the near future is also discussed.

The urgent need to recover MHC class I in cancers for effective immunotherapy

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Tumor immune escape compromises the efficacy of cancer immunotherapy.

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Loss of MHC class I expression is a frequent event in cancer cells.

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Three tumor phenotypes determine cancer fate: escape, rejection and dormancy.

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Recovery of MHC class I expression is required to improve cancer immunotherapy.

Immune escape strategies aimed to avoid T-cell recognition, including the loss of tumor MHC class I expression, are commonly found in malignant cells. Tumor immune escape has proven to have a negative effect on the clinical outcome of cancer immunotherapy, including treatment with antibodies blocking immune checkpoint molecules. Hence, there is an urgent need to develop novel approaches to overcome tumor immune evasion. MHC class I antigen presentation is often affected in human cancers and the capacity to induce upregulation of MHC class I cell surface expression is a critical step in the induction of tumor rejection. This review focuses on characterization of rejection, escape, and dormant profiles of tumors and its microenvironment with a special emphasis on the tumor MHC class I expression. We also discuss possible approaches to recover MHC class I expression on tumor cells harboring reversible/‘soft’ or irreversible/‘hard’ genetic lesions. Such MHC class I recovery approaches might well synergize with complementary forms of immunotherapy.

Clinical Role of Human Leukocyte Antigen in Health and Disease

Most of the genes in the major histocompatibility complex (MHC) region express high polymorphism that is fundamental for their function. The most important function of human leukocyte antigen (HLA) molecule is in the induction, regulation of immune responses and the selection of the T cell repertoire. A clinician's attention is normally drawn to a system only when it malfunctions. The HLA system is no exception in this regard, but in contrast to other systems, it also arouses interest when it functions well - too well, in fact. Population studies carried out over the last several decades have identified a long list of human diseases that are significantly more common among individuals that carry particular HLA alleles including inflammatory, autoimmune and malignant disorders. HLA-disease association is the name of this phenomenon, and the mechanism underlying is still a subject of hot debate. Social behaviours are affected by HLA genes and preference for HLA disparate mates may provide 'good genes' for an individual's offspring. Also, certain HLA genes may be associated with shorter life and others with longer lifespan, but the effects depend both on the genetic background and on the environmental conditions. The following is a general overview of the important functional aspects of HLA in health and diseases.

Major histocompatibility complex class I expression impacts on patient survival and type and density of immune cells in biliary tract cancer

BACKGROUND

Biliary tract cancers (BTC) are rare malignant tumours with a poor prognosis. Previously, we have presented a detailed characterisation of the inflammatory infiltrate in BTC. Here, we analysed the impact of the expression of major histocompatibility complex class I (MHC I) on patient survival and the quantity, as well as the quality of tumour-infiltrating immune cell types in BTC.

METHODS

MHC I expression was assessed semi-quantitatively in 334 BTC, including extrahepatic (n=129) and intrahepatic cholangiocarcinomas (n=146), as well as adenocarcinomas of the gallbladder (n=59). In addition, 71 high-grade biliary intraepithelial lesions (BilIN 3) were included. Results were correlated with data on antitumour inflammation and investigated with respect to their association with clinicopathological variables and patient survival.

RESULTS

BTC showed a wide spectrum of different MHC I expression patterns ranging from complete negativity in some tumours to strong homogenous expression in others. In BilIN 3, significantly higher MHC I expression levels were seen compared to invasive tumours (P=0.004). Patients with strong tumoural MHC I expression had a significantly higher overall survival probability (median survival benefit: 8 months; P=0.006). MHC I expression strongly correlated with the number of tumour-infiltrating T-lymphocytes (CD4(+) and CD8(+)) and macrophages.

CONCLUSIONS

Differences of MHC I expression predict patient outcome and show correlations with specific components of the inflammatory infiltrate in BTC. These findings contribute to a better understanding of immune response and immune escape phenomena in cholangiocarcinogenesis.

Epigenetic changes within the promoter regions of antigen processing machinery family genes in Kazakh primary esophageal squamous cell carcinoma

The esophageal squamous cell carcinoma (ESCC) is thought to develop through a multi-stage process. Epigenetic gene silencing constitutes an alternative or complementary mechanism to mutational events in tumorigenesis. Posttranscriptional regulation of human leukocyte antigen class I (HLA-I) and antigen processing machinery (APM) proteins expression may be associated with novel epigenetic modifications in cancer development. In the present study, we determined the expression levels of HLA-I antigen and APM components by immunohistochemistry. Then by a bisulfite-sequencing PCR (BSP) approach, we identified target CpG islands methylated at the gene promoter region of APM family genes in a ESCC cell line (ECa109), and further quantitative analysis of CpG site specific methylation of these genes in cases of Kazakh primary ESCCs with corresponding non-cancerous esophageal tissues using the Sequenom MassARRAY platform. Here we showed that the development of ESCCs was accompanied by partial or total loss of protein expression of HLA-B, TAP2, LMP7, tapasin and ERp57. The results demonstrated that although no statistical significance was found of global target CpG fragment methylation level sof HLA-B, TAP2, tapasin and ERp57 genes between ESCC and corresponding non-cancerous esophageal tissues, there was significant differences in the methylation level of several single sites between the two groups. Of thesse only the global methylation level of LMP7 gene target fragments was statistically higher (0.0517±0.0357) in Kazakh esophageal cancer than in neighboring normal tissues (0.0380±0.0214, p<0.05). Our results suggest that multiple CpG sites, but not methylation of every site leads to down regulation or deletion of gene expression. Only some of them result in genetic transcription, and silencing of HLA-B, ERp57, and LMP7 expression through hypermethylation of the promoters or other mechanisms may contribute to mechanisms of tumor escape from immune surveillance in Kazakh esophageal carcinogenesis.

Epigenetic regulations in the IFNγ signalling pathway: IFNγ-mediated MHC class I upregulation on tumour cells is associated with DNA demethylation of antigen-presenting machinery genes

Downregulation of MHC class I expression on tumour cells, a common mechanism by which tumour cells can escape from specific immune responses, can be associated with coordinated silencing of antigen-presenting machinery genes. The expression of these genes can be restored by IFNγ. In this study we documented association of DNA demethylation of selected antigen-presenting machinery genes located in the MHC genomic locus (TAP-1, TAP-2, LMP-2, LMP-7) upon IFNγ treatment with MHC class I upregulation on tumour cells in several MHC class I-deficient murine tumour cell lines (TC-1/A9, TRAMP-C2, MK16 and MC15). Our data also documented higher methylation levels in these genes in TC-1/A9 cells, as compared to their parental MHC class I-positive TC-1 cells. IFNγ-mediated DNA demethylation was relatively fast in comparison with demethylation induced by DNA methyltransferase inhibitor 5-azacytidine, and associated with increased histone H3 acetylation in the promoter regions of APM genes. Comparative transcriptome analysis in distinct MHC class I-deficient cell lines upon their treatment with either IFNγ or epigenetic agents revealed that a set of genes, significantly enriched for the antigen presentation pathway, was regulated in the same manner. Our data demonstrate that IFNγ acts as an epigenetic modifier when upregulating the expression of antigen-presenting machinery genes.

Enhanced phenotypic alterations of alveolar type II cells in response to Aflatoxin G1 -induced lung inflammation

Recently, we discovered that Aflatoxin G1 (AFG1 ) induces chronic lung inflammatory responses, which may contribute to lung tumorigenesis in Balb/C mice. The cancer cells originate from alveolar type II cells (AT-II cells). The activated AT-II cells express high levels of MHC-II and COX-2, may exhibit altered phenotypes, and likely inhibit antitumor immunity by triggering regulatory T cells (Tregs). However, the mechanism underlying phenotypic alterations of AT-II cells caused by AFG1 -induced inflammation remains unknown. In this study, increased MHC-II expression in alveolar epithelium was observed and associated with enhanced Treg infiltration in mouse lung tissues with AFG1 -induced inflammation. This provides a link between phenotypically altered AT-II cells and Treg activity in the AFG1 -induced inflammatory microenvironment. AFG1 -activated AT-II cells underwent phenotypic maturation since AFG1 upregulated MHC-II expression on A549 cells and primary human AT-II cells in vitro. However, mature AT-II cells may exhibit insufficient antigen presentation, which is necessary to activate effector T cells, due to the absence of CD80 and CD86. Furthermore, we treated A549 cells with AFG1 and TNF-α together to mimic an AFG1 -induced inflammatory response in vitro, and we found that TNF-α and AFG1 coordinately enhanced MHC-II, CD54, COX-2, IL-10, and TGF-β expression levels in A549 cells compared to AFG1 alone. The phenotypic alterations of A549 cells in response to the combination of TNF-α and AFG1 were mainly regulated by TNF-α-mediated induction of the NF-κB pathway. Thus, enhanced phenotypic alterations of AT-II cells were induced in response to AFG1 -induced inflammation. Thus, AT-II cells are likely to suppress anti-tumor immunity by triggering Treg activity.

Reduced Expression of the Antigen Processing Machinery Components TAP2, LMP2, and LMP7 in Tonsillar and Base of Tongue Cancer and Implications for Clinical Outcome

OBJECTIVES: Patients with human papillomavirus (HPV)–positive tonsillar squamous cell carcinoma (TSCC) and base of tongue squamous cell carcinoma (BOTSCC) have a better clinical outcome than those with corresponding HPV-negative tumors. Moreover, there is a strong positive correlation between absent/low as opposed to strong HLA class I expression and favorable clinical outcome for HPV-positive tumors, while the reverse applies to HPV-negative tumors. The expression of the antigen processing machinery (APM) components TAP1, TAP2, LMP2, and LMP7 in these tumors in relation to HPV status, HLA class I expression, each other, and clinical outcome was therefore investigated. MATERIAL AND METHODS: Formalin-fixed paraffin-embedded TSCC and BOTSCC, derived from 151 patients and previously analyzed for HPV DNA, HLA class I, and LMP10 expression were stained by immunohistochemistry for TAP1, TAP2, LMP2, and LMP7. RESULTS: Absent/low TAP2, LMP2, and LMP7 expression, similar to HLA class I and LMP10, was common in TSCC and BOTSCC, irrespective of HPV status. Expression of TAP1 and TAP2 was correlated, as was LMP2 to LMP7. LMP2 and LMP7 expression was also associated to HLA class I expression. Moreover, absence of LMP7 was linked to increased disease-free survival in both HPV-positive and HPV-negative cases. CONCLUSION: Reduced expression of TAP2, LMP2, and LMP7 was frequent in TSCC and BOTSCC and their expression as well as that of TAP1 was often interrelated. Furthermore, low LMP7 expression correlated to better clinical outcome and may, together with HPV status, potentially be used for prediction of treatment response.

Trials of vaccines for pancreatic ductal adenocarcinoma: Is there any hope of an improved prognosis?

Pancreatic tumors are chemoresistant and malignant, and there are very few therapeutic options for pancreatic cancer, as the disease is normally diagnosed at an advanced stage. Although attempts have been made to develop vaccine therapies for pancreatic cancer for a couple of decades, none of the resultant protocols or regimens have succeeded in improving the clinical outcomes of patients. We herein review vaccines tested within the past few years, including peptide, biological and multiple vaccines, and describe the three sets of criteria used to evaluate the therapeutic activity of vaccines in solid tumors.

Opposing consequences of signaling through EGF family members: Escape from CTLs could be a bait for NK cells

Oncogenes have been traditionally viewed as molecular drivers for tumor growth and survival. Recent evidence indicates that oncogenes may facilitate the escape of malignant cells from immune recognition and elimination. In this article, we discuss the implications of the overexpression of epidermal growth factor receptor (EGFR) family members on immune escape of tumors and immunotherapy.

Myeloid-derived suppressor cells in malignant melanoma

Melanoma is known for its rapid progression, metastasis to distant organs and therapeutic resistance. Despite high melanoma immunogenicity, the results of immunotherapeutic clinical studies are mostly unsatisfactory. One explanation is the development of strong immunosuppression mediated by highly immunosuppressive regulatory leukocytes, in particular, myeloid-derived suppressor cells (MDSCs). These cells were found to be enriched and activated in the melanoma microenvironment, inducing a profound impairment of anti-tumor immune responses and leading to the tumor progression. Therefore, understanding the mechanisms of MDSC generation, migration to the tumor site and activation as well as their targeting is important for the development of novel strategies for effective melanoma immunotherapy. We suggest that such therapeutic approaches should involve the inhibition of MDSC-mediated immunosuppressive melanoma microenvironment combined with other immunologic treatments.

Therapeutic cancer vaccines: a long and winding road to success

Harnessing the immune system to achieve therapeutic efficacy in cancer has been a milestone in immuno-oncology. Tumor-induced suppression works as an obstacle for the effectiveness of immunotherapies. Advances in our understanding of the interrelationship between cancer immunoediting and immunotherapy led to successful manipulation of anticancer immunity; this provided the platform for combining cancer vaccines with chemotherapies counteracting, to some extent, tumor-induced suppressive entities and demonstrating clinical efficacy. Targeting co-inhibitory and co-stimulatory receptors with immunostimulatory antibodies has also shown clinical promise and its combined use with vaccines is a promising new approach of immunotherapy for cancer. Recent evidence supporting vaccine administration in patients with early and less aggressive disease should be additionally placed to select the appropriate patient population and to identify earlier markers of clinical benefit and immunological parameters that correlate with survival. This review focuses on promising vaccination platforms and essential perspectives in the treatment of cancer.