Tumor-induced escape mechanisms and their association with resistance to checkpoint inhibitor therapy

The evolving role of immune checkpoint inhibitors in cervical and endometrial cancer

The introduction of immune checkpoint inhibitors (ICIs) has revolutionized the treatment landscape for numerous tumor types, including cervical and endometrial cancers. Multiple ICIs against programmed cell death-1 (PD-1), programmed death-ligand 1 (PD-L1), and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) have demonstrated encouraging outcomes in controlled clinical studies for advanced cervical and endometrial cancers. For advanced cervical cancer, approved ICIs as second-line treatment include cemiplimab, nivolumab, and pembrolizumab as single agents. In the first-line treatment setting, options include pembrolizumab alone or in combination with bevacizumab, as well as atezolizumab combined with a backbone platinum-based chemotherapy plus bevacizumab. Additionally, for locally advanced cervical cancer, pembrolizumab is recommended alongside concurrent chemoradiotherapy. For endometrial cancer, pembrolizumab monotherapy, pembrolizumab in combination with lenvatinib, and dostarlimab are currently approved as second-line treatment options. Moreover, either dostarlimab or pembrolizumab can be added to first-line platinum-based chemotherapy for mismatch repair deficient malignancies. Although the inclusion of these agents in clinical practice has led to improved overall response rates and survival outcomes, many patients still lack benefits, possibly due to multiple intrinsic and adaptive resistance mechanisms to immunotherapy. This review aims to highlight the rationale for utilizing ICIs and their current role, while also delineating the proposed mechanisms of resistance to ICIs in cervical and endometrial cancer.

Determinants of gastric cancer immune escape identified from non-coding immune-landscape quantitative trait loci

The landscape of non-coding mutations in cancer progression and immune evasion is largely unexplored. Here, we identify transcrptome-wide somatic and germline 3' untranslated region (3'-UTR) variants from 375 gastric cancer patients from The Cancer Genome Atlas. By performing gene expression quantitative trait loci (eQTL) and immune landscape QTL (ilQTL) analysis, we discover 3'-UTR variants with cis effects on expression and immune landscape phenotypes, such as immune cell infiltration and T cell receptor diversity. Using a massively parallel reporter assay, we distinguish between causal and correlative effects of 3'-UTR eQTLs in immune-related genes. Our approach identifies numerous 3'-UTR eQTLs and ilQTLs, providing a unique resource for the identification of immunotherapeutic targets and biomarkers. A prioritized ilQTL variant signature predicts response to immunotherapy better than standard-of-care PD-L1 expression in independent patient cohorts, showcasing the untapped potential of non-coding mutations in cancer.

Cancer Immunology: Immune Escape of Tumors-Expression and Regulation of HLA Class I Molecules and Its Role in Immunotherapies

The addition of "avoiding immune destruction" to the hallmarks of cancer demonstrated the importance of cancer immunology and in particular the role of immune surveillance and escape from malignancies. However, the underlying mechanisms contributing to immune impairment and immune responses are diverse. Loss or reduced expression of the HLA class I molecules are major characteristics of human cancers resulting in an impaired recognition of tumor cells by CD8 + cytotoxic T lymphocytes. This is of clinical relevance and associated with worse patients outcome and limited efficacy of T-cell-based immunotherapies. Here, we summarize the role of HLA class I antigens in cancers by focusing on the underlying molecular mechanisms responsible for HLA class I defects, which are caused by either structural alterations or deregulation at the transcriptional, posttranscriptional, and posttranslational levels. In addition, the influence of HLA class I abnormalities to adaptive and acquired immunotherapy resistances will be described. The in-depth knowledge of the different strategies of malignancies leading to HLA class I defects can be applied to design more effective cancer immunotherapies.

PD-L1 and MHC Class I Expression in High-grade Ovarian Cancers, Including Platinum-resistant Recurrences Treated With Checkpoint Inhibitor Therapy

Immune-modulating therapies targeting the programmed cell death-1/programmed cell death ligand-1 (PD-L1) immunosuppressive system have been used successfully in many solid tumor types. There is evidence that biomarkers such as PD-L1 and major histocompatibility complex (MHC) class I help identify candidates for anti-programmed cell death-1/PD-L1 checkpoint inhibition, though the evidence is limited in ovarian malignancies. PD-L1 and MHC Class I immunostaining was performed on pretreatment whole tissue sections in 30 cases of high-grade ovarian carcinoma. The PD-L1 combined positive score was calculated (a score of ≥1 is considered positive). MHC class I status was categorized as an intact or subclonal loss. In patients who received immunotherapy, drug response was assessed using RECIST criteria. PD-L1 was positive in 26 of 30 cases (87%; combined positive score: 1 to 100). Seven of 30 patients showed subclonal loss of MHC class I (23%), and this occurred in both PD-L1 negative (3/4; 75%) and PD-L1 positive (4/26; 15%) cases. Only 1 of 17 patients who received immunotherapy in the setting of a platinum-resistant recurrence responded to the addition of immunotherapy, and all 17 died of disease. In the setting of recurrent disease, patients did not respond to immunotherapy regardless of PD-L1/MHC class I status, suggesting that these immunostains may not be effective predictive biomarkers in this setting. Subclonal loss of expression of MHC class I occurs in ovarian carcinoma, including in PD-L1 positive cases, suggesting that the 2 pathways of immune evasion may not be mutually exclusive and that it may be important to interrogate MHC class I status in PD-L1 positive tumors to identify additional immune evasion mechanisms in these tumors.

Boosting Checkpoint Immunotherapy with Biomaterials

The immune checkpoint blockade (ICB) therapy has revolutionized the field of cancer treatment, while low response rates and systemic toxicity limit its clinical outcomes. With the rapid advances in nanotechnology and materials science, various types of biomaterials have been developed to maximize therapeutic efficacy while minimizing side effects by increasing tumor antigenicity, reversing immunosuppressive microenvironment, amplifying antitumor immune response, and reducing extratumoral distribution of checkpoint inhibitors as well as enhancing their retention within target sites. In this review, we reviewed current design strategies for different types of biomaterials to augment ICB therapy effectively and then discussed present representative biomaterial-assisted immune modulation and targeted delivery of checkpoint inhibitors to boost ICB therapy. Current challenges and future development prospects for expanding the ICB with biomaterials were also summarized. We anticipate this review will be helpful for developing emerging biomaterials for ICB therapy and promoting the clinical application of ICB therapy.

An update on the biological characteristics and functions of tuft cells in the gut

The intestine is a powerful digestive system and one of the most sophisticated immunological organs. Evidence shows that tuft cells (TCs), a kind of epithelial cell with distinct morphological characteristics, play a significant role in various physiological processes. TCs can be broadly categorized into different subtypes depending on different molecular criteria. In this review, we discuss its biological properties and role in maintaining homeostasis in the gastrointestinal tract. We also emphasize its relevance to the immune system and highlight its powerful influence on intestinal diseases, including inflammations and tumors. In addition, we provide fresh insights into future clinical diagnostic and therapeutic strategies related to TCs.

Biology of cancer; from cellular and molecular mechanisms to developmental processes and adaptation

Cancer research has been largely focused on the cellular and molecular levels of investigation. Recent data show that not only the cell but also the extracellular matrix plays a major role in the progression of malignancy. In this way, the cells and the extracellular matrix create a specific local microenvironment that supports malignant development. At the same time, cancer implies a systemic evolution which is closely related to developmental processes and adaptation. Consequently, there is currently a real gap between the local investigation of cancer at the microenvironmental level, and the pathophysiological approach to cancer as a systemic disease. In fact, the cells and the matrix are not only complementary structures but also interdependent components that act synergistically. Such relationships lead to cell-matrix integration, a supracellular form of biological organization that supports tissue development. The emergence of this supracellular level of organization, as a structure, leads to the emergence of the supracellular control of proliferation, as a supracellular function. In humans, proliferation is generally involved in developmental processes and adaptation. These processes suppose a specific configuration at the systemic level, which generates high-order guidance for local supracellular control of proliferation. In conclusion, the supracellular control of proliferation act as an interface between the downstream level of cell division and differentiation, and upstream level of developmental processes and adaptation. Understanding these processes and their disorders is useful not only to complete the big picture of malignancy as a systemic disease, but also to open new treatment perspectives in the form of etiopathogenic (supracellular or informational) therapies.

A novel risk score based on immune-related genes for hepatocellular carcinoma as a reliable prognostic biomarker and correlated with immune infiltration

BACKGROUND

Immunological-related genes (IRGs) play a critical role in the immune microenvironment of tumors. Our study aimed to develop an IRG-based survival prediction model for hepatocellular carcinoma (HCC) patients and to investigate the impact of IRGs on the immune microenvironment.

METHODS

Differentially expressed IRGs were obtained from The Genomic Data Commons Data Portal (TCGA) and the immunology database and analysis portal (ImmPort). The univariate Cox regression was used to identify the IRGs linked to overall survival (OS), and a Lasso-regularized Cox proportional hazard model was constructed. The International Cancer Genome Consortium (ICGC) database was used to verify the prediction model. ESTIMATE and CIBERSORT were used to estimate immune cell infiltration in the tumor immune microenvironment (TIME). RNA sequencing was performed on HCC tissue specimens to confirm mRNA expression.

RESULTS

A total of 401 differentially expressed IRGs were identified, and 63 IRGs were found related to OS on the 237 up-regulated IRGs by univariate Cox regression analyses. Finally, five IRGs were selected by the LASSO Cox model, including SPP1, BIRC5, STC2, GLP1R, and RAET1E. This prognostic model demonstrated satisfactory predictive value in the ICGC dataset. The risk score was an independent predictive predictor for OS in HCC patients. Immune-related analysis showed that the immune infiltration level in the high-risk group was higher, suggesting that the 5-IRG signature may play an important role in mediating immune escape and immune resistance in the TIME of HCC. Finally, we confirmed the 5-IRG signature is highly expressed in 65 HCC patients with good predictive power.

CONCLUSION

We established and verified a new prognosis model for HCC patients based on survival-related IRGs, and the signature could provide new insights into the prognosis of HCC.

The Human Leukocyte Antigen G as an Immune Escape Mechanism and Novel Therapeutic Target in Urological Tumors

The non-classical human leukocyte antigen G (HLA-G) is a potent regulatory protein involved in the induction of immunological tolerance. This is based on the binding of membrane-bound as well as soluble HLA-G to inhibitory receptors expressed on various immune effector cells, in particular NK cells and T cells, leading to their attenuated functions. Despite its restricted expression on immune-privileged tissues under physiological conditions, HLA-G expression has been frequently detected in solid and hematopoietic malignancies including urological cancers, such as renal cell and urothelial bladder carcinoma and has been associated with progression of urological cancers and poor outcome of patients: HLA-G expression protects tumor cells from anti-tumor immunity upon interaction with its inhibitory receptors by modulating both the phenotype and function of immune cells leading to immune evasion. This review will discuss the expression, regulation, functional and clinical relevance of HLA-G expression in urological tumors as well as its use as a putative biomarker and/or potential therapeutic target for the treatment of renal cell carcinoma as well as urothelial bladder cancer.

Cancer-Associated Fibroblasts Promote the Upregulation of PD-L1 Expression Through Akt Phosphorylation in Colorectal Cancer

Upregulation of immune checkpoint proteins is one of the main mechanisms for tumor immune escape. The expression of programmed death ligand-1 (PD-L1) in colorectal cancer (CRC) is higher than in normal colorectal epithelial tissue, and patients with higher PD-L1 expression have a poorer prognosis. Additionally, PD-L1 expression in CRC is affected by the tumor microenvironment (TME). As a major component of the TME, cancer-associated fibroblasts (CAFs) can act as immune regulators and generate an immunosuppressive tumor microenvironment. Therefore, we speculated that CAFs may be related to the upregulation of PD-L1 in CRC, which leads to tumor immune escape. We found that CAFs upregulate PD-L1 expression in CRC cells through AKT phosphorylation, thereby reducing the killing of CRC cells by peripheral blood mononuclear cells. The ratio of CAFs to CRC cells was positively correlated with AKT phosphorylation and the expression of PD-L1 in CRC in vitro. Consistent with the in vitro results, high CAF content and high expression of PD-L1 were negatively correlated with disease-free survival (DFS) of CRC patients. These results indicate that the upregulation of PD-L1 expression in CRC by CAFs through the activation of Akt is one of the molecular mechanisms of tumor immune escape. Thus, targeted anti-CAF therapy may help improve the efficacy of immunotherapy.

State-of-the-Art: Exosomes in Colorectal Cancer

Colorectal cancer (CRC) has a high prevalence and mortality rate, globally. To date, the progression mechanisms of CRC are still elusive. Exosomes (~100 nm in diameter) correspond to a subset of extracellular vesicles formed by an array of cancerous cells and stromal cells. These particular nanovesicles carry and transmit bioactive molecules, like proteins, lipids, and genetic materials, which mediate the crosstalk between cancer cells and the microenvironment. Accumulating evidence has shown the decisive functions of exosomes in the development, metastasis, and therapy resistance of CRC. Furthermore, some recent studies have also revealed the abilities of exosomes to function as either biomarkers or therapeutic targets for CRC. This review focuses on the specific mechanisms of exosomes in regulating CRC progression, and summarizes the potential clinical applications of exosomes in the diagnosis and therapy of CRC.

Protein Kinase D3 Promotes the Reconstruction of OSCC Immune Escape Niche Via Regulating MHC-I and Immune Inhibit Molecules Expression

Protein kinase D3 (PKD3) has been involved in various aspects of tumorigenesis and progression in many kinds of cancer types. However, whether PKD3 regulates immune escape in tumor microenvironment is rarely reported. Here, we explored the function and mechanism of PKD3 in reconstructing the immune escape niche of oral squamous cell carcinoma (OSCC). Both the Western blotting analysis in OSCC cells and the gene expression correlation analysis from The Cancer Genome Atlas shows that the expression of Fas and programmed cell death-ligand 1 (PD-L1) was positively correlated with PKD3, while major histocompatibility complex-I (MHC-I) was negatively correlated with PKD3. Knockdown of PKD3 significantly decreased the expression of Fas and PD-L1 and increased the expression of MHC-I. Furthermore, when PKD3 was overexpressed in oral precancerous cells, Fas, PD-L1, and MHC-I showed an opposite trend to that observed when PKD3 was knocked down. In addition, PKD3 knockdown decreased the secretion of transforming growth factor β, CC-chemokine ligand 21, interleukin-10 by OSCC cells. Finally, the tumor cell antigen, which was extracted from PKD3 knockdown OSCC cells, significantly induced the growth and activation of T lymphocytes. These results demonstrate that PKD3 promotes the immune escape of OSCC cells by regulating the expression of Fas, PD-L1, MHC-I, transforming growth factor β, CC-chemokine ligand 21, interleukin-10, and plays a key role in reconstructing the tumor immune escape niche.

PD-L1 and Mismatch Repair Status in Uterine Carcinosarcomas

Uterine carcinosarcomas have few adjuvant treatment options. Programmed cell death ligand-1 (PD-L1) expression in these tumors may predict response to checkpoint inhibitor therapies. An increase in PD-L1 expression has been shown in endometrial carcinomas with mismatch repair (MMR) deficiencies; however, few studies have evaluated PD-L1 expression in uterine carcinosarcomas. We examined PD-L1 expression in 41 cases of uterine carcinosarcoma using combined positive scores (CPS) and tumor proportion scores (TPS), and correlated with MMR status, p53 expression, and epithelial histotype. In addition to confirming the diagnosis of carcinosarcoma, the epithelial components were stratified based on endometrioid versus serous histology. Thirty-three cases (80%) were positive for PD-L1, defined as a CPS score of ≥1 or a TPS score of ≥1%. Twelve cases (29%) showed high expression of PD-L1, defined as a CPS score of ≥10 or a TPS score of ≥10%. The majority of the morphologically adjudicated carcinosarcomas had a serous epithelial component (83%) rather than endometrioid (17%), which was reinforced by aberrant p53 staining predominantly within cases with serous morphology. The majority of carcinosarcomas showed at least focal PD-L1 expression, predominantly in tumor-associated immune cells. Carcinosarcomas with endometrioid morphology were significantly more likely to have high-level PD-L1 (5/7 vs. 7/34; P=0.015). MMR-deficient carcinosarcomas were also more likely to have high-level PD-L1 (2/3 vs. 10/28); however, this did not reach statistical significance (P=0.2) and overall MMR-deficiency was uncommon (3 cases, 7%). These findings suggest that PD-L1 may be additive to MMR testing as a predictive biomarker for checkpoint inhibitor vulnerability in carcinosarcomas.

Epstein-Barr Virus-Associated Malignancies and Immune Escape: The Role of the Tumor Microenvironment and Tumor Cell Evasion Strategies

Simple Summary

The Epstein–Barr virus, also termed human herpes virus 4, is a human pathogenic double-stranded DNA virus. It is highly prevalent and has been linked to the development of 1–2% of cancers worldwide. EBV-associated malignancies encompass various structural and epigenetic alterations. In addition, EBV-encoded gene products and microRNAs interfere with innate and adaptive immunity and modulate the tumor microenvironment. This review provides an overview of the characteristic features of EBV with a focus on the intrinsic and extrinsic immune evasion strategies, which contribute to EBV-associated malignancies.

Abstract

The detailed mechanisms of Epstein–Barr virus (EBV) infection in the initiation and progression of EBV-associated malignancies are not yet completely understood. During the last years, new insights into the mechanisms of malignant transformation of EBV-infected cells including somatic mutations and epigenetic modifications, their impact on the microenvironment and resulting unique immune signatures related to immune system functional status and immune escape strategies have been reported. In this context, there exists increasing evidence that EBV-infected tumor cells can influence the tumor microenvironment to their own benefit by establishing an immune-suppressive surrounding. The identified mechanisms include EBV gene integration and latent expression of EBV-infection-triggered cytokines by tumor and/or bystander cells, e.g., cancer-associated fibroblasts with effects on the composition and spatial distribution of the immune cell subpopulations next to the infected cells, stroma constituents and extracellular vesicles. This review summarizes (i) the typical stages of the viral life cycle and EBV-associated transformation, (ii) strategies to detect EBV genome and activity and to differentiate various latency types, (iii) the role of the tumor microenvironment in EBV-associated malignancies, (iv) the different immune escape mechanisms and (v) their clinical relevance. This gained information will enhance the development of therapies against EBV-mediated diseases to improve patient outcome.

Molecular mechanisms of human herpes viruses inferring with host immune surveillance

Several human herpes viruses (HHVs) exert oncogenic potential leading to malignant transformation of infected cells and/or tissues. The molecular processes induced by viral-encoded molecules including microRNAs, peptides, and proteins contributing to immune evasion of the infected host cells are equal to the molecular processes of immune evasion mediated by tumor cells independently of viral infections. Such major immune evasion strategies include (1) the downregulation of proinflammatory cytokines/chemokines as well as the induction of anti-inflammatory cytokines/chemokines, (2) the downregulation of major histocompatibility complex (MHC) class Ia directly as well as indirectly by downregulation of the components involved in the antigen processing, and (3) the downregulation of stress-induced ligands for activating receptors on immune effector cells with NKG2D leading the way. Furthermore, (4) immune modulatory molecules like MHC class Ib molecules and programmed cell death1 ligand 1 can be upregulated on infections with certain herpes viruses. This review article focuses on the known molecular mechanisms of HHVs modulating the above-mentioned possibilities for immune surveillance and even postulates a temporal order linking regular tumor immunology with basic virology and offering putatively novel insights for targeting HHVs.

NOD2 deficiency confers a pro-tumorigenic macrophage phenotype to promote lung adenocarcinoma progression

Nucleotide‐binding and oligomerization domain‐containing protein 2 (NOD2) was a member of the NOD‐like receptor family and played an important role in the innate immune response. Dysregulated NOD2 had been reported to contribute to tumorigenesis and progression. Here, we investigated that decreased NOD2 expressions could affect the phenotypic polarization of tumour‐associated macrophages and thus lead to the poor prognosis of lung adenocarcinoma patients. We clustered the patients by the single‐sample gene set enrichment analysis of tumour microenvironment and 13 prognostic differentially expressed immune‐related genes (PDEIRGs) were obtained based on prognostic analyses. After multiple assessments on the 13 PDEIRGs, NOD2 was considered to be the central immune gene and had a strong effect on suppressing tumour progression. Decreased NOD2 expression could be induced by cancer cells and lead to the phenotypic polarization of macrophages from protective M1 phenotype to pro‐tumorigenic M2 subtype which might be attributed to the down‐regulating of NF‐κB signalling pathway. This study draw attention to the role of inhibited innate immune function mediated by depletion of NOD2 in the TME. Our work also points to a potential strategy of NOD2‐mediated TAM‐targeted immunotherapy.

Polymorphisms in MHC class I molecules influence their interactions with components of the antigen processing and presentation pathway

MHC class I (MHC-I) molecules undergo an intricate folding process in order to pick up antigenic peptide to present to the immune system. In recent years, the discovery of a new peptide editor for MHC-I has added an extra level of complexity in our understanding of how peptide presentation is regulated. On top of this, the incredible diversity in MHC-I molecules leads to significant variation in the interaction between MHC-I and components of the antigen processing and presentation pathway. Here, we review our current understanding regarding how polymorphisms in human leukocyte antigen class I molecules influence their interactions with key components of the antigen processing and presentation pathway. A deeper understanding of this may offer new insights regarding how apparently subtle variation in MHC-I can have a significant impact on susceptibility to disease.

Playing hide and seek: Tumor cells in control of MHC class I antigen presentation

MHC class I (MHC-I) molecules present a blueprint of the intracellular proteome to T cells allowing them to control infection or malignant transformation. As a response, pathogens and tumor cells often downmodulate MHC-I mediated antigen presentation to escape from immune surveillance. Although the fundamental rules of antigen presentation are known in detail, the players in this system are not saturated and new modules of regulation have recently been uncovered. Here, we update the understanding of antigen presentation by MHC-I molecules and how this can be exploited by tumors to prevent exposure of the intracellular proteome. This knowledge can provide new ways to improve immune responses against tumors and pathogens.

The landscape of bispecific T cell engager in cancer treatment

T cell-based immunotherapies have revolutionized treatment paradigms in various cancers, however, limited response rates secondary to lack of significant T-cell infiltration in the tumor site remain a major problem. To address this limitation, strategies for redirecting T cells to treat cancer are being intensively investigated, while the bispecific T cell engager (BiTE) therapy constitutes one of the most promising therapeutic approaches. BiTE is a bispecific antibody construct with a unique function, simultaneously binding an antigen on tumor cells and a surface molecule on T cells to induce tumor lysis. BiTE therapy represented by blinatumomab has achieved impressive efficacy in the treatment of B cell malignancies. However, major mechanisms of resistance to BiTE therapy are associated with antigen loss and immunosuppressive factors such as the upregulation of immune checkpoints. Thus, modification of antibody constructs and searching for combination strategies designed to further enhance treatment efficacy as well as reduce toxicity has become an urgent issue, especially for solid tumors in which response to BiTE therapy is always poor. In particular, immunotherapies focusing on innate immunity have attracted increasing interest and have shown promising anti-tumor activity by engaging innate cells or innate-like cells, which can be used alone or complement current therapies. In this review, we depict the landscape of BiTE therapy, including clinical advances with potential response predictors, challenges of treatment toxicity and resistance, and developments of novel immune cell-based engager therapy.

A novel role for an old target: CD45 for breast cancer immunotherapy

Breast cancer subtypes have not shown significant response to current immunomodulatory therapies. Although most subtypes are treatable, triple negative breast cancer (TNBC), an aggressive highly metastatic cancer, comprising 10-20% of breast cancers, remains an unmet medical need. New strategies are needed in order to overcome flaws in the responsiveness to current TNBC therapies. Our aims were: first, to determine the efficacy of a novel immunomodulatory peptide, C24D, on TNBC and second, to elucidate the molecular mechanism by which C24D induces immune-modulating tumor killing. Using mass spectrometry analysis, we identified CD45 as the C24D binding receptor. In vitro and in vivo TNBC models were used to assess the efficacy of C24D in reversing TNBC-induced immunosuppression and in triggering immune-modulated tumor cell killing. The CD45 signal transduction pathway was evaluated by western blot and FACS analyses. We revealed that addition of PBMCs from healthy female donors to TNBC cells results in a cascade of suppressive CD45 intracellular signals. On binding to CD45's extra-cellular domain on TNBC-suppressed leukocytes, the C24D peptide re-activates the Src family of tyrosine kinases, resulting in specific tumor immune response. In vitro, immune reactivation by C24D results in an increase of CD69+ T and CD69+ NK cells, triggering specific killing of TNBC cells. In vivo, C24D induced CD8+ and activated CD56+ tumor infiltrated cells, resulting in tumor apoptosis. Our results should renew interest in molecules targeting CD45, such as the C24D peptide, as a novel strategy for TNBC immunotherapy.

MHC Class I Loss in Triple-negative Breast Cancer: A Potential Barrier to PD-1/PD-L1 Checkpoint Inhibitors

Suppression of the immune system is intimately linked to the development and progression of malignancy, and immune modulating treatment options have shown promise in a variety of tumor types, including some triple-negative breast cancers (TNBC). The most dramatic therapeutic success has been seen with immune checkpoint inhibitors targeting programmed cell death protein 1 (PD-1) and its ligand, PD-L1. Difficulty remains, however, in appropriate patient selection for treatment, as many PD-L1-positive cancers fail to show durable responses to PD-1/PD-L1 inhibition. Checkpoint inhibitor targeting of the adaptive immune response relies on the presence of major histocompatibility complex (MHC) class I molecules on the tumor cell surface for tumor antigen presentation. MHC class I loss has been previously described in breast cancer and represents a putative mechanism of immunotherapeutic resistance in this tumor type. One hundred seventeen invasive primary breast carcinomas with a range of histologic subtypes were evaluated on tissue microarrays containing formalin-fixed paraffin-embedded tissue. Loss of MHC class I expression was common among breast cancers, with greater than half of cases demonstrating either subclonal or diffuse loss. Fifty-nine percent of TNBC demonstrated loss of MHC class I, including 46% of those meeting the Food and Drug Administration-approved threshold of 1% for tumor-associated immune cell PD-L1 expression. MHC class I loss was particularly common in the apocrine subtype of TNBC (78%). MHC class I's employment as a predictive biomarker should be considered, as its loss may represent a barrier to successful enhancement of the antitumor adaptive immune response by PD-1/PD-L1 inhibition.

Innovative Approaches in the Battle Against Cancer Recurrence: Novel Strategies to Combat Dormant Disseminated Tumor Cells

Cancer recurrence remains a great fear for many cancer survivors following their initial, apparently successful, therapy. Despite significant improvement in the overall survival of many types of cancer, metastasis accounts for ~90% of all cancer mortality. There is a growing understanding that future therapeutic practices must accommodate this unmet medical need in preventing metastatic recurrence. Accumulating evidence supports dormant disseminated tumor cells (DTCs) as a source of cancer recurrence and recognizes the need for novel strategies to target these tumor cells. This review presents strategies to target dormant quiescent DTCs that reside at secondary sites. These strategies aim to prevent recurrence by maintaining dormant DTCs at bay, or eradicating them. Various approaches are presented, including: reinforcing the niche where dormant DTCs reside in order to keep dormant DTCs at bay; promoting cell intrinsic mechanisms to induce dormancy; preventing the engagement of dormant DTCs with their supportive niche in order to prevent their reactivation; targeting cell-intrinsic mechanisms mediating long-term survival of dormant DTCs; sensitizing dormant DTCs to chemotherapy treatments; and, inhibiting the immune evasion of dormant DTCs, leading to their demise. Various therapeutic approaches, some of which utilize drugs that are already approved, or have been tested in clinical trials and may be considered for repurposing, will be discussed. In addition, clinical evidence for the presence of dormant DTCs will be reviewed, along with potential prognostic biomarkers to enable the identification and stratification of patients who are at high risk of recurrence, and who could benefit from novel dormant DTCs targeting therapies. Finally, we will address the shortcomings of current trial designs for determining activity against dormant DTCs and provide novel approaches.

Honey and its protein components: Effects in the cancer immunology

The immune system plays an important role in cancer development, but some tumor cells can evade or inhibit the processes of innate and adaptive immunity. This review made a description of honey and its proteins effect on diverse mediators from the immune system. Scientific evidence reported that many types of honey (jungle, manuka, pasture, and others) and some isolated proteins enhanced the release of reactive oxygen species (O₂ ^- and H₂ O₂ ) and cytokines (mostly IL-1β, IL-6, and TNF-α) by innate immune system cells. Furthermore, honey elicited proliferation and functions of T lymphocytes, cells related to specific adaptive immune responses. These studies have established a precedent over the honey and its properties on the immune system, demonstrating that it can promote the innate and adaptive immunity. PRACTICAL APPLICATIONS: Cancer is a genetic illness that represents a world health problem. Recognizing the potential of diet therapy in the prevention and treatment of chronic diseases, the present work summarizes the effects of honey on the immune system and mediators involved in cancer elimination processes, establishing the importance of this natural product as a future anticancer agent.

Nanotechnology assisted photo- and sonodynamic therapy for overcoming drug resistance

Drug resistance is considered the most important reason for the clinical failure of cancer chemotherapy. Circumventing drug resistance and improving the efficacy of anticancer agents remains a major challenge. Over the past several decades, photodynamic therapy (PDT) and sonodynamic therapy (SDT) have attracted substantial attention for their efficacy in cancer treatment, and have been combined with chemotherapy to overcome drug resistance. However, simultaneously delivering sensitizers and chemotherapy drugs to same tumor cell remains challenging, thus greatly limiting this combinational therapy. The rapid development of nanotechnology provides a new approach to solve this problem. Nano-based drug delivery systems can not only improve the targeted delivery of agents but also co-deliver multiple drug components in single nanoparticles to achieve optimal synergistic effects. In this review, we briefly summarize the mechanisms of drug resistance, discuss the advantages and disadvantages of PDT and SDT in reversing drug resistance, and describe state-of-the-art research using nano-mediated PDT and SDT to solve these refractory problems. This review also highlights the clinical translational potential for this combinational therapy.

Development and validation of a robust immune-related risk signature for hepatocellular carcinoma

BACKGROUND

Increasing evidence has indicated immune-related genes (IRGs) play a key role in the development of hepatocellular carcinoma (HCC). Whereas, there have been no investigations proposing a reliable prognostic signature in terms of IRGs. This study aimed to develop a robust signature based on IRGs in HCC. A total of 597 HCC patients from The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) databases were enrolled in this study.

METHODS

The TCGA cohort was utilized for discovery, and the ICGC cohort was utilized for validation. Multiple algorithms were implemented to identify key prognostic IRGs and establish an immune-related risk signature. Bioinformatics analysis and R soft tools were utilized to annotate underlying biological functions.

RESULTS

A total of 1416 differentially expressed mRNAs (DEMs) were screened, of which 90 were differentially expressed IRGs (DEIRGs). Using univariate Cox regression analysis, we identified 33 prognostically relevant DEIRGs. Using least absolute shrinkage and selection operator (LASSO) regression and multivariate Cox regression analysis, we extracted 8 optimal DEIRGs to construct a risk signature in the TCGA cohort, and the signature was verified in the ICGC cohort. We also built a nomogram to increase the accuracy of predicting HCC prognosis. By investigating the relationship of the risk score and 8 risk genes from our signature with clinical traits, we found that the aberrant expression of the immune-related risk genes is correlated with the development of HCC. Moreover, the high-risk group was higher than the low-risk group in terms of tumor mutation burden (TMB), immune cell infiltration, and the expression of immune checkpoints (programmed cell death protein 1 [PD-1], programmed cell death ligand 1 [PD-L1], and cytotoxic T-lymphocyte-related protein 4 [CTLA-4]), and functional enrichment analysis indicated the signature enriched an intensive immune phenotype.

CONCLUSION

This study developed a robust immune-related risk signature and built a predictive nomogram that reliably predict overall survival in HCC, which may be helpful for clinical management and personalized immunotherapy decisions.

MHC class I loss in endometrial carcinoma: a potential resistance mechanism to immune checkpoint inhibition

Major histocompatibility complex (MHC) class I is a membrane-bound protein complex expressed on nucleated human cells. MHC class I presents intracellular protein fragments to cytotoxic T cells and triggers an activation cascade upon neoantigen detection by these cells. MHC class I loss by tumor cells decreases tumor neoantigen presentation to the immune system and therefore represents a possible mechanism of immunotherapeutic resistance even among cancers that otherwise appear to be good candidates for checkpoint inhibition, such as mismatch repair (MMR)-deficient and PD-L1-positive malignancies. We herein assess MHC class I expression in a range of endometrial carcinomas, including MMR-deficient and PD-L1-positive cancers. Immunohistochemical staining for combined MHC class I A-, B-, and C-heavy chains was performed on 76 cases of endometrial carcinoma and was classified as present, subclonally lost, or diffusely lost. Tumoral PD-L1 expression, PD-L1 combined positive score, and CD3-positive T lymphocytes were also quantified. Forty-two percent of tumors showed loss of MHC class I expression, either in a subclonal (26%) or diffuse (16%) pattern. This included 46% of MMR-deficient and 25% of PD-L1-positive cancers. These findings suggest that tumoral MHC class I status may be an important factor to consider when selecting endometrial cancer patients for checkpoint inhibition.

Clinical pattern of failure after a durable response to immune check inhibitors in non-small cell lung cancer patients

Although immune checkpoint inhibitors (ICIs) can induce durable responses in non-small-cell lung cancer (NSCLC) patients, a significant proportion of responders still experience progressive disease after a period of response. Limited data are available on the clinical patterns of acquired resistance (AR) to ICIs. Clinical and radiologic data from 125 NSCLC patients treated with anti-PD-1 or PD-L1 antibodies between 2011 and 2018 at two tertiary academic institutions were retrospectively reviewed. Overall, 63 (50.4%) patients experienced AR after ICI treatment in a median of 10.7 months. Among the 13 patients with a partial response with ICI, 12 (32.4%) had only lymph node progression. Most patients (n = 52, 82.5%) had one or two sites with progression (oligo-progression). The median overall survival (OS) after progression was significantly longer in the extrathoracic group than in the thoracic and liver progression groups (30.2 months [95% confidence interval (CI), 13.4 to not reached (NR)], 11.7 months [95% CI, 9.5–21.1], and 5.4 months [95% CI, 2.6-NR], respectively, P < 0.001). Patients with oligo-progression had significantly longer OS after AR than did the multi-progression patients (18.9 months [95% CI, 10.6-NR] vs. 8.8 months [95% CI, 5.7-NR], P = 0.04). No significant difference in progression-free survival was observed between the subsequent chemotherapy and the ICI after AR groups (P = 0.723). Patients with AR after ICI treatment had a unique progression pattern with oligo-progression and high rates of progression only in the lymph nodes. Local treatment and/or continuation of ICIs beyond AR might be an effective option.

The Upregulation of Molecules Related to Tumor Immune Escape in Human Pituitary Adenomas

Human pituitary adenomas are one of the most common intracranial neoplasms. Although most of these tumors are benign and can be treated medically or by transsphenoidal surgery, a subset of these tumors are fast-growing, aggressive, recur, and remain a therapeutic dilemma. Because antibodies against immune checkpoint receptors PD-1 and CLTA-4 are now routinely used for cancer treatment, we quantified the expression of mRNA coding for PD-1, CLTA-4, and their ligands, PD-L1, PD-L2, CD80, and CD86 in human pituitary adenomas and normal pituitary glands, with the ultimate goal of exploiting immune checkpoint therapy in aggressive pituitary adenomas. Aggressive pituitary adenomas demonstrated an increased expression of PD-L2, CD80, and CD86 in compared to that of normal human pituitary glands. Furthermore, aggressive pituitary tumors demonstrated significantly higher levels of CD80 and CD86 compared to non-aggressive tumors. Our results establish a rationale for studying a potential role for immune checkpoint inhibition therapy in the treatment of pituitary adenomas.

Tuft and Cancer Stem Cell Marker DCLK1: A New Target to Enhance Anti-Tumor Immunity in the Tumor Microenvironment

Simple Summary

Doublecortin-like kinase 1 (DCLK1) is a tumor stem cell marker in colon, pancreatic, and potentially other cancers that has received wide attention recently. Aside from its role as a tuft cell marker in normal tissue and as a tumor stem cell marker in cancer, previous studies have demonstrated that silencing DCLK1 functionally reduces stemness, epithelial mesenchymal transition (EMT), and tumorigenesis in cancers. More recently, DCLK1′s role in regulating the inflammatory, pre-cancer, and tumor microenvironment including its ability to modulate immune cell mechanisms has started to come into focus. Importantly, clinically viable therapeutic means of targeting DCLK1 have finally become available in the form of kinase inhibitors, monoclonal antibodies, and chimeric antigen receptor T cells (CAR-T). Herein, we comprehensively review the mechanistic role of DCLK1 in the tumor microenvironment, assess the potential for targeting DCLK1 in colon, pancreatic and renal cancer.

Abstract

Microtubule-associated doublecortin-like kinase 1 (DCLK1) is an accepted marker of tuft cells (TCs) and several kinds of cancer stem cells (CSCs), and emerging evidence suggests that DCLK1-positive TCs participate in the initiation and formation of inflammation-associated cancer. DCLK1-expressing CSCs regulate multiple biological processes in cancer, promote resistance to therapy, and are associated with metastasis. In solid tumor cancers, tumor epithelia, immune cells, cancer-associated fibroblasts, endothelial cells and blood vessels, extracellular matrix, and hypoxia all support a CSC phenotype characterized by drug resistance, recurrence, and metastasis. Recently, studies have shown that DCLK1-positive CSCs are associated with epithelial-mesenchymal transition, angiogenesis, and immune checkpoint. Emerging data concerning targeting DCLK1 with small molecular inhibitors, monoclonal antibodies, and chimeric antigen receptor T-cells shows promising effects on inhibiting tumor growth and regulating the tumor immune microenvironment. Overall, DCLK1 is reaching maturity as an anti-cancer target and therapies directed against it may have potential against CSCs directly, in remodeling the tumor microenvironment, and as immunotherapies.

A prognostic risk model based on immune-related genes predicts overall survival of patients with hepatocellular carcinoma

BACKGROUND AND AIMS

Hepatocellular carcinoma (HCC) is one of the most common heterogeneous tumors that occurs after chronic liver diseases and hepatitis virus infection. Immune-related genes (IRGs) and their ligands regulate the homeostasis of tumor microenvironment, which is essential for the treatment of HCC and its prognosis. This study aimed to investigate the clinical value of IRGs in predicting the prognosis of HCC.

METHODS

We downloaded RNA-seq data and clinical information from TCGA database. Samples were randomly divided into training cohort and testing cohort. The "limma" R package was performed to identify differentially expressed IRGs (DEIRGs) between HCC group and normal group. Prognostic DEIRGs (PDEIRGs) were obtained by univariate Cox analysis. LASSO and multivariate Cox analysis were used, and a prognostic risk model was constructed. In order to better demonstrate the clinical value of our model in predicting overall survival rate, a nomogram was constructed. To further investigate the molecular mechanism of our model, gene set enrichment analysis (GSEA) was performed.

RESULTS

Compared with the low-risk group, the high-risk group had a significantly worse prognosis. Moreover, our prognostic risk model can accurately stratify tumor grade and TNM stage. Importantly, in our model, not only immune checkpoint genes were well predicted, but also human leucocyte antigen-I molecules were revealed. GSEA suggested that "MAPK signaling pathway," "mTOR signaling pathway," "NOD like receptor signaling pathway," "Toll like receptor signaling pathway," "VEGF signaling pathway," "WNT signaling pathway" had significant correlations with the high-risk group.

CONCLUSION

Overall, our study showed that our prognostic risk model can be used to assess prognosis of HCC, which may provide a certain basis for the survival rate of patients with HCC.

Identification of an Immune-Related Prognostic Predictor in Hepatocellular Carcinoma

Liver hepatocellular carcinoma (LIHC) is the most prevalent primary cancer of the liver, and immune-related genes (IRGs) regulate its development. So far, there is still no precise biomarker that predicts response to immunotherapy in LIHC. Therefore, this research seeks to identify immunogenic prognostic biomarkers and explore potential predictors for the efficacy of anti-PD-1/PD-L1 therapies in LIHC. The clinical data and gene expression profiles of patients diagnosed with LIHC were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Moreover, IRGs were obtained from the ImmPort database. We discovered 35 IRGs that were differentially expressed between LIHC tissues and corresponding normal tissues. Through univariate Cox regression analysis, eight prognostic differentially expressed IRGs (PDEIRGs) were identified. Further, three optimal PDEIRGs (BIRC5, LPA, and ROBO1) were identified and used to construct a prognostic risk signature of LIHC patients via multivariate Cox regression analysis. The signature was validated by ROC curves. Subsequently, based on gene set enrichment analysis (GSEA) analysis, two out of the three optimal PDEIRGs (BIRC5 and LPA) were significantly enriched in the mismatch repair (MMR) pathway. Moreover, the two PDEIRGs (BIRC5 and LPA) were significantly correlated with the expression of genes related to mismatch repair (MLH1, MSH2, MSH6, and PMS2). Furthermore, correlations between the two PDEIRGs (BIRC5 and LPA) and immune checkpoints of cancer treatment (such as CTLA4, PD-1, and PD-L1) were demonstrated. Hyperprogressive disease (HPD) is a novel pattern of tumor progression which has a close relationship with immune checkpoint inhibitors (ICIs) utilization. MDM2 family amplification might promote the HPD phenomenon. Finally, we found a positive regulatory relationship between HPD related gene (MDM2) and BIRC5. Notably, MDM2 can either interact directly with BIRC5 or indirectly via downstream transcription factors of BIRC5. Overall, our study uncovered a novel 3-immune-related prognostic genes in LIHC.

Loss of MHC Class I Expression in HPV-associated Cervical and Vulvar Neoplasia: A Potential Mechanism of Resistance to Checkpoint Inhibition

Tumor cell expression of major histocompatibility complex (MHC) class I is required for antigen presentation and adaptive immune recognition. Absent or diminished MHC class I expression is thought to contribute to immunotherapeutic resistance in some epithelial tumors but has not been previously studied in cervical and vulvar carcinoma. Given that anti-programmed cell death 1 (PD-1) checkpoint inhibition is deployed for programmed cell death ligand 1 (PD-L1)-positive recurrent and metastatic cervical squamous carcinomas, identifying tumors with loss of MHC class I is of clinical interest to optimize the selection of immunotherapeutic candidates. Immunohistochemistry for PD-L1 and MHC class I combined A, B, and C heavy chains (MHC class I) was assessed in 58 human papillomavirus-associated cervical and vulvar lesions, including 27 squamous intraepithelial lesions (SILs) and 31 invasive squamous cell carcinoma (SCC). Although 84% of SCC and 22% of SIL were PD-L1-positive, 35.5% (11/31) of SCC and 18.5% (5/27) of SIL also showed clonal or complete loss of MHC class I. Loss of MHC class I expression was more common in PD-L1-positive (10/26, 38%) versus PD-L1-negative SCC (1/5, 20%). In summary, over one third of human papillomavirus-associated cervical and vulvar SCC show clonal or complete loss of MHC class I expression, including many PD-L1-positive cases. This suggests that the efficacy of checkpoint inhibitors targeting the PD-1/PD-L1 axis may be limited in a subset of cervical and vulvar squamous neoplasms due to an impaired ability to engage with the adaptive immune system related to loss of MHC class I expression.

Gene signature of antigen processing and presentation machinery predicts response to checkpoint blockade in non-small cell lung cancer (NSCLC) and melanoma

Background

Limited data exist on the role of alterations in HLA Class I antigen processing and presentation machinery in mediating response to immune checkpoint blockade (ICB).

Methods

This retrospective cohort study analyzed transcriptional profiles from pre-treatment tumor samples of 51 chemotherapy-refractory advanced non-small cell lung cancer (NSCLC) patients and two independent melanoma cohorts treated with ICB. An antigen processing machinery (APM) score was generated utilizing eight genes associated with APM (B2M, CALR, NLRC5, PSMB9, PSME1, PSME3, RFX5, and HSP90AB1). Associations were made for therapeutic response, progression-free survival (PFS) and overall survival (OS).

Results

In NSCLC, the APM score was significantly higher in responders compared with non-responders (p=0.0001). An APM score above the median value for the cohort was associated with improved PFS (HR 0.34 (0.18 to 0.64), p=0.001) and OS (HR 0.44 (0.23 to 0.83), p=0.006). The APM score was correlated with an inflammation score based on the established T-cell-inflamed resistance gene expression profile (Pearson’s r=0.58, p<0.0001). However, the APM score better predicted response to ICB relative to the inflammation score with area under a receiving operating characteristics curve of 0.84 and 0.70 for PFS and OS, respectively. In a cohort of 14 high-risk resectable stage III/IV melanoma patients treated with neoadjuvant anti-PD1 ICB, a higher APM score was associated with improved disease-free survival (HR: 0.08 (0.01 to 0.50), p=0.0065). In an additional independent melanoma cohort of 27 metastatic patients treated with ICB, a higher APM score was associated with improved OS (HR 0.29 (0.09 to 0.89), p=0.044).

Conclusion

Our data demonstrate that defects in antigen presentation may be an important feature in predicting outcomes to ICB in both lung cancer and melanoma.

Activated melanoma vessels: A sticky point for successful immunotherapy

Metastatic melanoma is a devastating disease with a marginal-albeit increasing-hope for cure. Melanoma has a high mutation rate which correlates to the expression of numerous neo-antigens and thus is associated with the potential to induce and strengthen effective antitumoral immunity. However, the incomplete and potentially insufficient response to established immunotherapies (response rates usually do not markedly exceed 60%) already points to the need of further studies to improve treatment strategies. Multiple tumor escape mechanisms that allow melanoma to evade from antitumoral immune responses have been characterized and must be overcome to achieve a better clinical efficacy of immunotherapies. Recently, promising progress has been made in targeting tumor vasculature to control and increase the infiltration of tumors with effector lymphocytes. It has been hypothesized that amplified lymphocytic infiltrates in melanoma metastases result in a switch of the tumor microenvironment from a non-inflammatory to an inflammatory state. In this view point essay, we discuss the requirements for successful homing of lymphocytes to melanoma tissue and we present a mouse melanoma xenograft model that allows the investigation of human tumor vessels in vivo. Furthermore, current clinical studies dealing with the activation of melanoma vasculature for enhanced effectiveness of immunotherapy protocols are presented and open questions for routine clinical application are addressed.

Characterization of the expression and immunological impact of the transcriptional activator CREB in renal cell carcinoma

Background

The non-classical human leukocyte antigen (HLA)-G is a strong immunomodulatory molecule. Under physiological conditions, HLA-G induces immunological tolerance in immune privileged tissues, while under pathophysiological situations it contributes to immune escape mechanisms. Therefore, HLA-G could act as a potential immune checkpoint for future anti-cancer immunotherapies. Recent data suggest an aberrant expression of the cAMP response element binding protein (CREB) in clear cell renal cell carcinoma (ccRCC), which is correlated with tumor grade and stage. Furthermore, preliminary reports demonstrated a connection of CREB as a control variable of HLA-G transcription due to CREB binding sites in the HLA-G promoter region. This study investigates the interaction between CREB and HLA-G in different renal cell carcinoma (RCC) subtypes and its correlation to clinical parameters.

Methods

The direct interaction of CREB with the HLA-G promoter was investigated by chromatin immunoprecipitation in RCC cell systems. Furthermore, the expression of CREB and HLA-G was determined by immunohistochemistry using a tissue microarray (TMA) consisting of 453 RCC samples of distinct subtypes. Staining results were assessed for correlations to clinical parameters as well as to the composition of the immune cell infiltrate.

Results

There exists a distinct expression pattern of HLA-G and CREB in the three main RCC subtypes. HLA-G and CREB expression were the lowest in chromophobe RCC lesions. However, the clinical relevance of CREB and HLA-G expression differed. Unlike HLA-G, high levels of CREB expression were positively associated to the overall survival of RCC patients. A slightly, but significantly elevated number of tumor infiltrating regulatory T cells was observed in tumors of high CREB expression. Whether this small increase is of clinical relevance has to be further investigated.

Conclusions

An interaction of CREB with the HLA-G promoter could be validated in RCC cell lines. Thus, for the first time the expression of CREB and its interaction with the HLA-G in human RCCs has been shown, which might be of clinical relevance.

Role of Oral Bacteria in the Development of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is an invasive epithelial neoplasm that is influenced by various risk factors, with a low survival rate and an increasing death rate. In the past few years, with the verification of the close relationship between different types of cancers and the microbiome, research has focused on the compositional changes of oral bacteria and their role in OSCC. Generally, oral bacteria can participate in OSCC development by promoting cell proliferation and angiogenesis, influencing normal apoptosis, facilitating invasion and metastasis, and assisting cancer stem cells. The study findings on the association between oral bacteria and OSCC may provide new insight into methods for early diagnosis and treatment development.

A few good peptides: MHC class I-based cancer immunosurveillance and immunoevasion

The remarkable success of immune checkpoint inhibitors demonstrates the potential of tumour-specific CD8⁺ T cells to prevent and treat cancer. Although the number of lives saved by immunotherapy mounts, only a relatively small fraction of patients are cured. Here, we review two of the factors that limit the application of CD8⁺ T cell immunotherapies: difficulties in identifying tumour-specific peptides presented by MHC class I molecules and the ability of tumour cells to impair antigen presentation as they evolve under T cell selection. We describe recent advances in understanding how peptides are generated from non-canonical translation of defective ribosomal products, relate this to the dysregulated translation that is a feature of carcinogenesis and propose dysregulated translation as an important new source of tumour-specific peptides. We discuss how the synthesis and function of components of the antigen-processing and presentation pathway, including the recently described immunoribosome, are manipulated by tumours for immunoevasion and point to common druggable targets that may enhance immunotherapy.

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.

The Role of the RNA-Binding Protein Family MEX-3 in Tumorigenesis

The muscle excess 3 (MEX-3) protein was first identified in Caenorhabditis elegans (C. elegans), and its respective homologues were also observed in vertebrates, including humans. It is a RNA-binding protein (RBP) with an additional ubiquitin E3 ligase function, which further acts as a post-transcriptional repressor through unknown mechanisms. In humans, MEX-3 proteins post-transcriptionally regulate a number of biological processes, including tumor immunological relevant ones. These have been shown to be involved in various diseases, including tumor diseases of distinct origins. This review provides information on the expression and function of the human MEX-3 family in healthy tissues, as well after malignant transformation. Indeed, the MEX-3 expression was shown to be deregulated in several cancers and to affect tumor biological functions, including apoptosis regulation, antigen processing, and presentation, thereby, contributing to the immune evasion of tumor cells. Furthermore, current research suggests MEX-3 proteins as putative markers for prognosis and as novel targets for the anti-cancer treatment.

Heme oxygenase-1 orchestrates the immunosuppressive program of tumor-associated macrophages

Tumor-associated macrophages (TAMs) contribute to the maintenance of a strong immunosuppressive environment, supporting tumor progression and resistance to treatment. To date, the mechanisms that drive acquisition of these immunosuppressive features are still poorly defined. Heme oxygenase-1 (HO-1) is the rate-limiting enzyme that catabolizes free heme. It displays important cytoprotective, antiinflammatory, and antioxidant properties. A growing body of evidence suggests that HO-1 may also promote tumor development. Herein, we show that HO-1 is highly expressed in monocytic cells in the tumor microenvironment (TME) once they differentiate into TAMs. Deletion of HO-1 in the myeloid compartment enhances the beneficial effects of a therapeutic antitumor vaccine by restoring CD8+ T cell proliferation and cytotoxicity. We further show that induction of HO-1 plays a major role in monocyte education by tumor cells by modulating their transcriptional and epigenetic programs. These results identify HO-1 as a valuable therapeutic target to reprogram the TME and synergize with current cancer therapies to facilitate antitumor response.

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.

CD19-targeting fusion protein combined with PD1 antibody enhances anti-tumor immunity in mouse models

In our previous studies, using a B cell vaccine (scFv-Her2), the targeting of tumor-associated antigen Her2 (human epidermal growth factor receptor-2) to B cells via the anti-CD19 single chain variable fragment (scFv) was shown to augment tumor-specific immunity, which enhanced tumor control in the prophylactic and therapeutic setting. However, the fusion protein displayed limited activity against established tumors, and local relapses often occurred following scFv-Her2 treatment, indicating that scFv-Her2-induced responses are inadequate to maintain anti-tumor immunity. In this study, targeting the IV region (D4) of the extracellular region of Her2 to B cells via CD19 molecules (scFv-Her2_D4) was found to enhance IFN-γ-producing-CD8⁺ T cell infiltration in tumor tissues and reduced the number of tumor-infiltrating myeloid-derived suppressor cells (MDSCs). However, negative co-stimulatory molecules such as programmed cell death protein-1 (PD-1), CD160, and LAG-3 on T cells and programmed death protein ligand-1 (PD-L1) on tumor cells were upregulated in the tumor microenvironment after scFv-Her2_D4 treatment. Further, anti-PD1 administration enhanced the efficacy of scFv-Her2_D4 and anti-tumor immunity, as evidenced by the reversal of tumor-infiltrating CD8⁺ T cell exhaustion and the reduction of MDSCs and Treg cells, which suppress T cells and alter the tumor immune microenvironment. Moreover, combining this with anti-PD1 antibodies promoted complete tumor rejection. Our data provide evidence of a close interaction among tumor vaccines, T cells, and the PD-L1/PD-1 axis and establish a basis for the rational design of combination therapy with immune modulators and tumor vaccine therapy.

From cellular microbiology to bacteria-based next generations of cancer immunotherapies

Pioneer work by Prof. Cossart among others, studying the interactions between pathogenic bacteria and host cells (this discipline was termed Cellular Microbiology), was fundamental to determine the bacterial infection processes and to improve our knowledge of different cellular mechanisms. The study of bacteria-host interactions also involves in vivo host immune responses, which can be manipulated by bacteria, being these last potent tools for different immunotherapies. During the last years, tumour immunotherapies, mainly the use of antibodies that target immune checkpoints [checkpoint inhibitors (CPI)], have been a revolution in oncology, allowing the treatment of tumours otherwise with very bad prognosis. In the same direction, bacteria inoculations have been used from long to treat some cancers; for example, non-muscle-invasive bladder cancer can be successfully treated with the bacterium Bacillus Calmette Guerin (BCG). More recently, it has been shown that microbiota could determine the success of CPI immunotherapies and intense research is being performed in order to use bacteria as immunotherapy tools due to their ability to activate the immune system. In this context, to expand the knowledge of the bacteria-immune system interactions will be fundamental to improve tumour immunotherapies.

Association of Soluble HLA-G Plasma Level and HLA-G Genetic Polymorphism With Pregnancy Outcome of Patients Undergoing in vitro Fertilization Embryo Transfer

Infertility is currently a growing problem observed around the world and is estimated to affect between 8 and 12% of reproductive-aged couples worldwide. Artificial reproductive techniques are the last chance for couples seeking their own child. Human leukocyte antigen (HLA)-G expression has been suggested as an immunomodulatory molecule that influences pregnancy outcome. The HLA-G gene encodes either membrane-bound or/and soluble proteins. The aim of this study was the evaluation of the role of soluble HLA-G (sHLA-G) and its gene polymorphism in successful implantation after in vitro fertilization embryo transfers (IVF-ETs) in different clinical protocols. We tested the HLA-G polymorphism in three positions: rs1632947: c.-964G>A; rs1233334: c.-725G>C/T in promoter region; rs371194629: c.^*65_^*66insATTTGTTCATGCCT in 3′ untranslated region of exon 8, in 389 patients who underwent IVF-ETs and 320 women with healthy children born after natural conception. Among the patient group, 239 women were with recurrent implantation failure and 117 women had an ongoing pregnancy or a child born after IVF-ET. We found that certain rs1632947-rs1233334-rs371194629 HLA-G haplotypes and diplotypes were associated with infertility, while others were protective. The lowest secretors of sHLA-G were G-C-ins haplotype carriers (37.21 IU/ml), while the highest -G-C-del carriers (73.80 IU/ml). Other haplotype carriers were intermediate secretors. In our study, regardless of possessed haplotype by the patient, 59.73 IU/ml sHLA-G was the threshold value with the best sensitivity (58.82%) and specificity (66.10%) to discriminate patients who achieved and maintained pregnancy from those who did not conceive or they had miscarriage (p = 0.0085; likelihood ratio, 1.74; 95% CI = 0.55–0.78). However, we do not exclude that factors other than sHLA-G may also contribute to complications in pregnancy. In addition, we found that IVF patients in cycles when frozen/thawed embryo was transferred secreted higher soluble HLA-G levels than patients with fresh embryo transferred (p = 0.021). Moreover, correlation analysis of sHLA-G concentration measured before and after embryo transfer for particular patients indicated short ovarian stimulation with gonadotropin-releasing hormone antagonist as more beneficial than long protocol with gonadotropin-releasing hormone agonist. Our study confirms a role of HLA-G polymorphism in infertility and soluble HLA-G in the early stages of pregnancy.

miR-19 regulates the expression of interferon-induced genes and MHC class I genes in human cancer cells

MicroRNA-19 (miR-19) is identified as the key oncogenic component of the miR-17-92 cluster. When we explored the functions of the dysregulated miR-19 in lung cancer, microarray-based data unexpectedly demonstrated that some immune and inflammatory response genes (i.e., IL32, IFI6 and IFIT1) were generally down-regulated by miR-19 overexpression in A549 cells, which prompted us to fully investigate whether the miR-19 family (i.e., miR-19a and miR-19b-1) was implicated in regulating the expression of immune and inflammatory response genes in cancer cells. In the present study, we observed that miR-19a or miR-19b-1 overexpression by miRNA mimics in the A549, HCC827 and CNE2 cells significantly downregulated the expression of interferon (IFN)-regulated genes (i.e., IRF7, IFI6, IFIT1, IFITM1, IFI27 and IFI44L). Furthermore, the ectopic miR-19a or miR-19b-1 expression in the A549, HCC827, CNE2 and HONE1 cells led to a general downward trend in the expression profile of major histocompatibility complex (MHC) class I genes (such as HLA-B, HLA-E, HLA-F or HLA-G); conversely, miR-19a or miR-19b-1 inhibition by the miRNA inhibitor upregulated the aforementioned MHC Class I gene expression, suggesting that miR-19a or miR-19b-1 negatively modulates MHC Class I gene expression. The miR-19a or miR-19b-1 mimics reduced the expression of interleukin (IL)-related genes (i.e., IL1B, IL11RA and IL6) in the A549, HCC827, CNE2 or HONE1 cells. The ectopic expression of miR-19a or miR-19b-1 downregulated IL32 expression in the A549 and HCC827 cells and upregulated IL32 expression in CNE2 and HONE1 cells. In addition, enforced miR-19a or miR-19b-1 expression suppressed IL-6 production by lung cancer and nasopharyngeal carcinoma (NPC) cells. Taken together, these findings demonstrate, for the first time, that miR-19 can modulate the expression of IFN-induced genes and MHC class I genes in human cancer cells, suggesting a novel role of miR-19 in linking inflammation and cancer, which remains to be fully characterized.

Prognostic value of immune-related genes in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common pathological subtype of renal cell carcinoma, and immune-related genes (IRGs) are key contributors to its development. In this study, the gene expression profiles and clinical data of ccRCC patients were downloaded from The Cancer Genome Atlas database and the cBioPortal database, respectively. IRGs were obtained from the ImmPort database. We analyzed the expression of IRGs in ccRCC, and discovered 681 that were differentially expressed between ccRCC and normal kidney tissues. Univariate Cox regression analysis was used to identify prognostic differentially expressed IRGs (PDEIRGs). Using Lasso regression and multivariate Cox regression analyses, we detected seven optimal PDEIRGs (PLAU, ISG15, IRF9, ARG2, RNASE2, SEMA3G and UCN) and used them to construct a risk model to predict the prognosis of ccRCC patients. This model accurately stratified patients with different survival outcomes and precisely identified patients with different mutation burdens. Our findings suggest the seven PDEIRGs identified in this study are valuable prognostic predictors in ccRCC patients. These genes could be used to investigate the developmental mechanisms of ccRCC and to design individualized treatments for ccRCC patients.

Implications for Tumor Microenvironment and Epithelial Crosstalk in the Management of Gastrointestinal Cancers

Rapid advances in technology are revealing previously unknown organization, cooperation, and limitations within the population of nontumor cells surrounding the tumor epithelium known as the tumor microenvironment (TME). Nowhere are these findings more pertinent than in the gastrointestinal (GI) tract where exquisite cell specialization supports a complex microenvironmental niche characterized by rapid stemness-associated cell turnover, pathogen sensing, epithelial orchestration of immune signaling, and other facets that maintain the complex balance between homeostasis, inflammation, and disease. Here, we summarize and discuss select emerging concepts in the precancerous microenvironment, TME, and tumor epithelial-TME crosstalk as well as their implications for the management of GI cancers.

A Pan-Cancer Approach to Predict Responsiveness to Immune Checkpoint Inhibitors by Machine Learning

Immunotherapy by using immune checkpoint inhibitors (ICI) has dramatically improved the treatment options in various cancers, increasing survival rates for treated patients. Nevertheless, there are heterogeneous response rates to ICI among different cancer types, and even in the context of patients affected by a specific cancer. Thus, it becomes crucial to identify factors that predict the response to immunotherapeutic approaches. A comprehensive investigation of the mutational and immunological aspects of the tumor can be useful to obtain a robust prediction. By performing a pan-cancer analysis on gene expression data from the Cancer Genome Atlas (TCGA, 8055 cases and 29 cancer types), we set up and validated a machine learning approach to predict the potential for positive response to ICI. Support vector machines (SVM) and extreme gradient boosting (XGboost) models were developed with a 10×5-fold cross-validation schema on 80% of TCGA cases to predict ICI responsiveness defined by a score combining tumor mutational burden and TGF- β signaling. On the remaining 20% validation subset, our SVM model scored 0.88 accuracy and 0.27 Matthews Correlation Coefficient. The proposed machine learning approach could be useful to predict the putative response to ICI treatment by expression data of primary tumors.