Revisiting cancer immunoediting by understanding cancer immune complexity

A Comprehensive Review of Long Non-Coding RNAs in the Cancer-Immunity Cycle: Mechanisms and Therapeutic Implications

Long non-coding RNAs (lncRNAs) have emerged as pivotal regulators of the dynamic interplay between cancer progression and immune responses. This review explored their influence on key processes of the cancer-immunity cycle, such as immune cell differentiation, antigen presentation, and tumor immunogenicity. By modulating tumor escape from the immune response, therapeutic resistance, and tumor-stroma interactions, lncRNAs actively shape the tumor microenvironment. Due to their growing knowledge in the area of immune suppression, directly intervening in the induction of regulatory T cells (Tregs), M2 macrophages, and regulating immune checkpoint pathways such as PD-L1, CTLA-4, and others, lncRNAs can be considered promising therapeutic targets. Advances in single-cell technologies and immunotherapy have significantly expanded our understanding of lncRNA-driven regulatory networks, paving the way for novel precision medicine approaches. Ultimately, we discussed how targeting lncRNAs could enhance cancer immunotherapy, offering new avenues for biomarker discovery and therapeutic intervention.

Breast Cancer Xenograft Murine Models

Mice are used as model organisms to understand the pathological basis of a variety of human diseases, including breast cancer. Both immunocompetent and immunocompromised mouse models are used depending on the scope of the study. Immunocompetent models allow the study of the impact of the immune system in murine models of mammary cancer, while immunodeficient mice serve as ideal host organisms to understand the behavior of human breast cancers within a biological system. Xenografting of human breast cancer cells into immunocompromised mouse models continues to be the most used fundamental animal model in preclinical breast cancer research. These in vivo models allow critical understanding of tumor biology and assessment of novel treatments, a necessary prelude to testing new drugs in the clinic. In this chapter, we provide detailed methodology for the use of non-obese diabetic (NOD) severe combined immunodeficient (SCID) mice in several breast cancer xenografting procedures, including established cell lines and patient-derived xenografts (PDXs).

The Comprehensive "Omics" Approach from Metabolomics to Advanced Omics for Development of Immune Checkpoint Inhibitors: Potential Strategies for Next Generation of Cancer Immunotherapy

In the past decade, immunotherapies have been emerging as an effective way to treat cancer. Among several categories of immunotherapies, immune checkpoint inhibitors (ICIs) are the most well-known and widely used options for cancer treatment. Although several studies continue, this treatment option has yet to be developed into a precise application in the clinical setting. Recently, omics as a high-throughput technique for understanding the genome, transcriptome, proteome, and metabolome has revolutionized medical research and led to integrative interpretation to advance our understanding of biological systems. Advanced omics techniques, such as multi-omics, single-cell omics, and typical omics approaches, have been adopted to investigate various cancer immunotherapies. In this review, we highlight metabolomic studies regarding the development of ICIs involved in the discovery of targets or mechanisms of action and assessment of clinical outcomes, including drug response and resistance and propose biomarkers. Furthermore, we also discuss the genomics, proteomics, and advanced omics studies providing insights and comprehensive or novel approaches for ICI development. The overview of ICI studies suggests potential strategies for the development of other cancer immunotherapies using omics techniques in future studies.

Manipulation of the Immune System for Cancer Defeat: A Focus on the T Cell Inhibitory Checkpoint Molecules

The immune system actively counteracts the tumorigenesis process; a breakout of the immune system function, or its ability to recognize transformed cells, can favor cancer development. Cancer becomes able to escape from immune system control by using multiple mechanisms, which are only in part known at a cellular and molecular level. Among these mechanisms, in the last decade, the role played by the so-called "inhibitory immune checkpoints" is emerging as pivotal in preventing the tumor attack by the immune system. Physiologically, the inhibitory immune checkpoints work to maintain the self-tolerance and attenuate the tissue injury caused by pathogenic infections. Cancer cell exploits such immune-inhibitory molecules to contrast the immune intervention and induce tumor tolerance. Molecular agents that target these checkpoints represent the new frontier for cancer treatment. Despite the heterogeneity and multiplicity of molecular alterations among the tumors, the immune checkpoint targeted therapy has been shown to be helpful in selected and even histologically different types of cancer, and are currently being adopted against an increasing variety of tumors. The most frequently used is the moAb-based immunotherapy that targets the Programmed Cell Death 1 protein (PD-1), the PD-1 Ligand (PD-L1) or the cytotoxic T lymphocyte antigen-4 (CTLA4). However, new therapeutic approaches are currently in development, along with the discovery of new immune checkpoints exploited by the cancer cell. This article aims to review the inhibitory checkpoints, which are known up to now, along with the mechanisms of cancer immunoediting. An outline of the immune checkpoint targeting approaches, also including combined immunotherapies and the existing trials, is also provided. Notwithstanding the great efforts devoted by researchers in the field of biomarkers of response, to date, no validated FDA-approved immunological biomarkers exist for cancer patients. We highlight relevant studies on predictive biomarkers and attempt to discuss the challenges in this field, due to the complex and largely unknown dynamic mechanisms that drive the tumor immune tolerance.

DKK2 blockage-mediated immunotherapy enhances anti-angiogenic therapy of Kras mutated colorectal cancer

There are limited options for targeted therapies for colorectal cancer (CRC). Anti-EGFR therapy is limited to CRC without KRAS mutations. Even worse, most of CRC are refractory to currently immune checkpoint blockade. DKK2, which is upregulated in CRC, was recently found to suppress host immune responses, and its blockage effectively impeded tumor progression in benign genetic CRC models in our previous study. Here, our recent study demonstrated that in human CRC tumor samples expressing high levels of DKK2, DKK2 blockade caused stronger activation of tumor infiltrating CD8⁺ T cells in ex vivo culture. Intriguingly, we observed a correlation of high DKK2 expression with increased lymph node metastasis prevalence in these CRC patients as well. Furthermore, in a mouse genetic CRC model with mutations in APC and KRAS, which more closely mimics advanced human CRC, we confirmed the tumor inhibitory effect of DKK2 blockade, which significantly retarded tumor progression and extended survival, with increased immune effector cell activation and reduced angiogenesis. Based on this, we performed a combined administration of DKK2 blockade with sub-optimal anti-VEGFR treatment and observed a synergetic effect on suppressing tumor angiogenesis and progression, as well as extending survival, better than those of every single therapy. Thus, this study provides further evidence for the potential therapeutic application of DKK2 blockade in the clinical treatment of human CRC.

Have Cells Harboring the HIV Reservoir Been Immunoedited?

Immunoediting is an important concept in oncology, delineating the mechanisms through which tumors are selected for resistance to immune-mediated elimination. The recent emergence of immunotherapies, such as checkpoint inhibitors, as pillars of cancer therapy has intensified interest in immunoediting as a constraint limiting the efficacy of these approaches. Immunoediting manifests at a number of levels for different cancers, for example through the establishment of immunosuppressive microenvironments within solid tumors. Of particular interest to the current review, selection also occurs at the cellular level; and recent studies have revealed novel mechanisms by which tumor cells acquire intrinsic resistance to immune recognition and elimination. While the selection of escape mutations in viral epitopes by HIV-specific T cells, which is a hallmark of chronic HIV infection, can be considered a form of immunoediting, few studies have considered the possibility that HIV-infected cells themselves may parallel tumors in having differential intrinsic susceptibilities to immune-mediated elimination. Such selection, on the level of an infected cell, may not play a significant role in untreated HIV, where infection is propagated by high levels of cell-free virus produced by cells that quickly succumb to viral cytopathicity. However, it may play an unappreciated role in individuals treated with effective antiretroviral therapy where viral replication is abrogated. In this context, an "HIV reservoir" persists, comprising long-lived infected cells which undergo extensive and dynamic clonal expansion. The ability of these cells to persist in infected individuals has generally been attributed to viral latency, thought to render them invisible to immune recognition, and/or to their compartmentalization in anatomical sites that are poorly accessible to immune effectors. Recent data from ex vivo studies have led us to propose that reservoir-harboring cells may additionally have been selected for intrinsic resistance to CD8+ T cells, limiting their elimination even in the context of antigen expression. Here, we draw on knowledge from tumor immunoediting to discuss potential mechanisms by which clones of HIV reservoir-harboring cells may resist elimination by CD8+ T cells. The establishment of such parallels may provide a premise for testing therapeutics designed to sensitize tumor cells to immune-mediated elimination as novel approaches aimed at curing HIV infection.

Metabolic Symbiosis and Immunomodulation: How Tumor Cell-Derived Lactate May Disturb Innate and Adaptive Immune Responses

The tumor microenvironment (TME) is composed by cellular and non-cellular components. Examples include the following: (i) bone marrow-derived inflammatory cells, (ii) fibroblasts, (iii) blood vessels, (iv) immune cells, and (v) extracellular matrix components. In most cases, this combination of components may result in an inhospitable environment, in which a significant retrenchment in nutrients and oxygen considerably disturbs cell metabolism. Cancer cells are characterized by an enhanced uptake and utilization of glucose, a phenomenon described by Otto Warburg over 90 years ago. One of the main products of this reprogrammed cell metabolism is lactate. "Lactagenic" or lactate-producing cancer cells are characterized by their immunomodulatory properties, since lactate, the end product of the aerobic glycolysis, besides acting as an inducer of cellular signaling phenomena to influence cellular fate, might also play a role as an immunosuppressive metabolite. Over the last 10 years, it has been well accepted that in the TME, the lactate secreted by transformed cells is able to compromise the function and/or assembly of an effective immune response against tumors. Herein, we will discuss recent advances regarding the deleterious effect of high concentrations of lactate on the tumor-infiltrating immune cells, which might characterize an innovative way of understanding the tumor-immune privilege.

Human leukocyte antigen-G overexpression predicts poor clinical outcomes in low-grade gliomas

Overexpression of human leukocyte antigen-G (HLA-G), a non-classical major histocompatibility complex class-I molecule associated with immunosuppression, has been reported in various human malignancies. In the present study, we examined the role of HLA-G in gliomas. Clinical characteristics, mRNA expression microarrays and follow-up data pertaining to 293 patients with histologically confirmed gliomas were analyzed. The expression levels of HLA-G were compared between different grades of gliomas and correlated with progression-free survival (PFS) and overall survival (OS) to evaluate its prognostic value. We found that HLA-G was overexpressed in gliomas as compared to that in normal brain tissue samples (-1.288±0.265). The highest expression levels were in glioblastomas (GBMs), anaplastic gliomas (AGs) and low-grade gliomas (LGGs), in that order (0.328±0.778, 0.176±0.881, -0.388±0.686, respectively). Significant inter-group differences were observed between low-grade and high-grade glioma tissues (p<0.001 and p<0.001, t-test, AGs and GBMs, respectively). More astrocytoma patients exhibited increased HLA-G expression as compared to other LGG patients (p=0.004, Chi-square test). Significant differences were observed with respect to PFS and OS (p=0.009 and 0.032, log-rank test, for PFS and OS, respectively) between the high- and low-expression subgroups in patients with LGGs. On Cox regression analysis, overexpression of HLA-G appeared to be an independent predictor of clinical outcomes (p=0.007 and 0.026, for PFS and OS, respectively). Our results suggest that HLA-G expression may serve as a potential biomarker for predicting aggressive tumor grades of gliomas and for histological subtype of LGGs. Elevated HLA-G expression could serve as an independent predictor of poor clinical outcomes in patients with low-grade gliomas.

Immunotherapy for Head and Neck Squamous Cell Carcinoma

Although head and neck squamous cell carcinoma has traditionally been considered to be a very immunosuppressive, or at least nonimmunogenic, tumor type, recent results from clinical studies of immune checkpoint blockade strategies have led to resurgence in the enthusiasm for immunotherapeutic approaches. Additional strategies for immunotherapy that are under active investigation include enhancement of cetuximab-mediated antibody-dependent cell-mediated cytotoxicity, tumor vaccines, and engineered T cells for adoptive therapy. All of these studies have early-phase clinical trials under way, and the next several years will be exciting as the results of these studies are reported.

Targeting Epigenetic Processes in Photodynamic Therapy-Induced Anticancer Immunity

Photodynamic therapy (PDT) of cancer is an approved therapeutic procedure that generates oxidative stress leading to cell death of tumor and stromal cells. Cell death resulting from oxidative damage to intracellular components leads to the release of damage-associated molecular patterns (DAMPs) that trigger robust inflammatory response and creates local conditions for effective sampling of tumor-associated antigens (TAA) by antigen-presenting cells. The latter can trigger development of TAA-specific adaptive immune response. However, due to a number of mechanisms, including epigenetic regulation of TAA expression, tumor cells evade immune recognition. Therefore, numerous approaches are being developed to combine PDT with immunotherapies to allow development of systemic immunity. In this review, we describe immunoregulatory mechanisms of epigenetic treatments that were shown to restore the expression of epigenetically silenced or down-regulated major histocompatibility complex molecules as well as TAA. We also discuss the results of our recent studies showing that epigenetic treatments based on administration of methyltransferase inhibitors in combination with PDT can release effective mechanisms leading to development of antitumor immunity and potentiated antitumor effects.

Intratumoral INF-γ triggers an antiviral state in GL261 tumor cells: a major hurdle to overcome for oncolytic vaccinia virus therapy of cancer

Oncolytic vaccinia virus (VACV) therapy is an alternative treatment option for glioblastoma multiforme. Here, we used a comparison of different tumor locations and different immunologic and genetic backgrounds to determine the replication efficacy and oncolytic potential of the VACV LIVP 1.1.1, an attenuated wild-type isolate of the Lister strain, in murine GL261 glioma models. With this approach, we expected to identify microenvironmental factors, which may be decisive for failure or success of oncolytic VACV therapy. We found that GL261 glioma cells implanted subcutaneously or orthotopically into Balb/c athymic, C57BL/6 athymic, or C57BL/6 wild-type mice formed individual tumors that respond to oncolytic VACV therapy with different outcomes. Surprisingly, only Balb/c athymic mice with subcutaneous tumors supported viral replication. We identified intratumoral IFN-γ expression levels that upregulate MHCII expression on GL261 cells in C57BL/6 wild-type mice associated with a non-permissive status of the tumor cells. Moreover, this IFN-γ-induced tumor cell phenotype was reversible.

The pro-metastatic role of bone marrow-derived cells: a focus on MSCs and regulatory T cells

Several bone marrow-derived cells have been shown to promote tumour growth and progression. These cells can home to the primary tumour and become active components of the tumour microenvironment. Recent studies have also identified bone marrow-derived cells—such as mesenchymal stem cells and regulatory T cells—as contributors to cancer metastasis. The innate versatility of these cells provides diverse functional aid to promote malignancy, ranging from structural support to signal-mediated suppression of the host immune response. Here, we review the role of mesenchymal stem cells and regulatory T cells in cancer metastasis. A better understanding of the bipolar nature of these bone marrow-derived cells in physiological and malignant contexts could pave the way for new therapeutics against metastatic disease.

Antitumor and immunostimulatory activity of a polysaccharide-protein complex from Scolopendra subspinipes mutilans L. Koch in tumor-bearing mice

Scolopendra subspinipes mutilans L. Koch has been used for cancer treatment in traditional Chinese medicine for hundreds of years. In this study, the effects of a polysaccharide-protein complex from Scolopendra subspinipes mutilans L. Koch (SPPC) on the tumor growth and immune function were assessed in sarcoma S180 and hepatoma H22 bearing mice. Results showed that SPPC significantly inhibited the growth of S180 transplanted in mice and prolonged the survival time of H22- bearing mice. In S180-bearing mice, it promoted specific and nonspecific immune response as evidenced by enhancing the activities of natural killer (NK) cells, cytotoxic T lymphocytes (CTL) and the ratio of Th1/Th2 cytokines, and increasing the percentages of CD4(+) T cells, B cells and NK cells. Furthermore, SPPC not only significantly inhibited mRNA expression and production of the immunosuppressive cytokines (IL-10 and TGF-β), but also diminished arachidonic acid (AA)-metabolizing enzymes (COX-2 and CYP4A) and their products (PGE(2) and 20-HETE) in tumor-associated macrophages (TAMs). Taken together, our results indicate that SPPC inhibits tumor growth in vivo by improving antitumor immune responses at least partly via downregulating AA-metabolic pathways in TAMs, and could act as an anti-tumor agent with immunomodulatory activity.

Unfavorable clinical implications of circulating CD44+ lymphocytes in patients with nasopharyngeal carcinoma undergoing radiochemotherapy

BACKGROUND

To evaluate the use of cellular immunity parameters as predictors of therapy response.

METHODS

Circulating lymphocytes were measued by flow cytometry in 94 nasopharyngeal carcinoma (NPC) patients following radiochemotherapy.

RESULTS

Significantly decreased percentage of CD3(+), CD4(+), and CD8(+) lymphocytes, significantly increased proportion of CD44(+), CD25(+), NK lymphocytes, and an increased CD4(+)/CD8(+) ratio were indicated in NPC patients as compared with healthy controls. Circulating CD44(+) lymphocytes in both the N2/N3 and III/IV groups were significantly increased as compared to the N0/N1 and I/II groups, respectively (P<0.05). A significant decrease in CD19(+) lymphocytes was observed in the III/IV group as compared with the I/II group (P<0.05). After radiochemotherapy, NPC patients had significantly (P<0.05) decreased percentages of CD4(+), CD44(+), and CD19(+) lymphocytes and a decreased CD4(+)/CD8(+) ratio, whereas the mean percentages of CD8(+) and NK lymphocytes were significantly (P<0.05) increased. However, compared with the pre-radiochemotherapy values, no significant (P>0.05) changes in CD3(+) or CD25(+) lymphocytes were observed in the NPC-treated group. Follow-up analysis indicated significantly lower DFS for patients with high CD44(+) lymphocytes compared to those with low CD44(+) lymphocytes after radiochemotherapy.

CONCLUSION

Circulating CD44(+) lymphocytes seems to be a promising criterion to predict survival in NPC patients undergoing radiochemotherapy.

An immunologic portrait of cancer

The advent of high-throughput technology challenges the traditional histopathological classification of cancer, and proposes new taxonomies derived from global transcriptional patterns. Although most of these molecular re-classifications did not endure the test of time, they provided bulk of new information that can reframe our understanding of human cancer biology. Here, we focus on an immunologic interpretation of cancer that segregates oncogenic processes independent from their tissue derivation into at least two categories of which one bears the footprints of immune activation. Several observations describe a cancer phenotype where the expression of interferon stimulated genes and immune effector mechanisms reflect patterns commonly observed during the inflammatory response against pathogens, which leads to elimination of infected cells. As these signatures are observed in growing cancers, they are not sufficient to entirely clear the organism of neoplastic cells but they sustain, as in chronic infections, a self-perpetuating inflammatory process. Yet, several studies determined an association between this inflammatory status and a favorable natural history of the disease or a better responsiveness to cancer immune therapy. Moreover, these signatures overlap with those observed during immune-mediated cancer rejection and, more broadly, immune-mediated tissue-specific destruction in other immune pathologies. Thus, a discussion concerning this cancer phenotype is warranted as it remains unknown why it occurs in immune competent hosts. It also remains uncertain whether a genetically determined response of the host to its own cancer, the genetic makeup of the neoplastic process or a combination of both drives the inflammatory process. Here we reflect on commonalities and discrepancies among studies and on the genetic or somatic conditions that may cause this schism in cancer behavior.