CTLA-4 positive breast cancer cells suppress dendritic cells maturation and function

Advances in immunotherapy for breast cancer and feline mammary carcinoma: From molecular basis to novel therapeutic targets

The role of inflammation in cancer is a topic that has been investigated for many years. As established, inflammation emerges as a defining characteristic of cancer, presenting itself as a compelling target for therapeutic interventions in the realm of oncology. Controlling the tumor microenvironment (TME) has gained paramount significance, modifying not only the effectiveness of immunotherapy but also modulating the outcomes and prognoses of standard chemotherapy and other anticancer treatments. Immunotherapy has surfaced as a central focus within the domain of tumor treatments, using immune checkpoint inhibitors as cancer therapy. Immune checkpoints and their influence on the tumor microenvironment dynamic are presently under investigation, aiming to ascertain their viability as therapeutic interventions across several cancer types. Cancer presents a significant challenge in humans and cats, where female breast cancer ranks as the most prevalent malignancy and feline mammary carcinoma stands as the third most frequent. This review seeks to summarize the data about the immune checkpoints cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), lymphocyte activation gene-3 (LAG-3), programmed cell death protein-1 (PD-1), V-domain Ig suppressor of T cell activation (VISTA), and T-cell immunoglobulin and mucin domain 3 (TIM-3) respective ongoing investigations as prospective targets for therapy for human breast cancer, while also outlining findings from studies reported on feline mammary carcinoma (FMC), strengthening the rationale for employing FMC as a representative model in the exploration of human breast cancer.

Dysfunction of dendritic cells in tumor microenvironment and immunotherapy

Dendritic cells (DCs) comprise diverse cell populations that play critical roles in antigen presentation and triggering immune responses in the body. However, several factors impair the immune function of DCs and may promote immune evasion in cancer. Understanding the mechanism of DC dysfunction and the diverse functions of heterogeneous DCs in the tumor microenvironment (TME) is critical for designing effective strategies for cancer immunotherapy. Clinical applications targeting DCs summarized in this report aim to improve immune infiltration and enhance the biological function of DCs to modulate the TME to prevent cancer cells from evading the immune system. Herein, factors in the TME that induce DC dysfunction, such as cytokines, hypoxic environment, tumor exosomes and metabolites, and co-inhibitory molecules, have been described. Furthermore, several key signaling pathways involved in DC dysfunction and signal-relevant drugs evaluated in clinical trials were identified. Finally, this review provides an overview of current clinical immunotherapies targeting DCs, especially therapies with proven clinical outcomes, and explores future developments in DC immunotherapies.

Identification of Two Distinct Immune Subtypes in Hepatitis B Virus (HBV)-Associated Hepatocellular Carcinoma (HCC)

HBV is the most common risk factor for HCC development, accounting for almost 50% of cases worldwide. Despite significant advances in immunotherapy, there is limited information on the HBV-HCC tumor microenvironment (TME), which may influence the response to checkpoint inhibitors. Here, we characterize the TME in a unique series of liver specimens from HBV-HCC patients to identify who might benefit from immunotherapy. By combining an extensive immunohistochemistry analysis with the transcriptomic profile of paired liver samples (tumor vs. nontumorous tissue) from 12 well-characterized Caucasian patients with HBV-HCC, we identified two distinct tumor subtypes that we defined immune-high and immune-low. The immune-high subtype, seen in half of the patients, is characterized by a high number of infiltrating B and T cells in association with stromal activation and a transcriptomic profile featuring inhibition of antigen presentation and CTL activation. All the immune-high tumors expressed high levels of CTLA-4 and low levels of PD-1, while PD-L1 was present only in four of six cases. In contrast, the immune-low subtype shows significantly lower lymphocyte infiltration and stromal activation. By whole exome sequencing, we documented that four out of six individuals with the immune-low subtype had missense mutations in the CTNNB1 gene, while only one patient had mutations in this gene in the immune-high subtype. Outside the tumor, there were no differences between the two subtypes. This study identifies two distinctive immune subtypes in HBV-associated HCC, regardless of the microenvironment observed in the surrounding nontumorous tissue, providing new insights into pathogenesis. These findings may be instrumental in the identification of patients who might benefit from immunotherapy.

Dual silencing of tumor-intrinsic VISTA and CTLA-4 stimulates T-cell mediated immune responses and inhibits MCF7 breast cancer development

BACKGROUND

As inhibitory immune checkpoint molecules, cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) and V-domain Ig suppressor of T-cell activation (VISTA) can be expressed in tumoral cells and facilitate immune evasion of tumoral cells. Herein, we studied the significance of tumor-intrinsic CTLA-4 and VISTA silencing in tumor development and inflammatory factors expression in a co-culture system with MCF7 and T-cells.

METHODS

MCF7 cells were transfected with 60 pmol of CTLA-siRNA, VISTA-siRNA, and dual VISTA-/CTLA-4-siRNA. The MTT assay was performed to study the effect of CTLA-4 and VISTA knockdown on the viability of MCF7 cells. Colony formation and wound-healing assays were performed to investigate the effect of CTLA-4 and VISTA silencing on the clonogenicity and migration of MCF7 cells. Flow cytometry was used to study the significance of CTLA-4 and VISTA knockdown on the apoptosis and cell cycle of MCF7 cells. Also, a co-culture system with MCF7 and T-cells was developed to study the expression levels of IL-2, IFN-γ, TNF-α, TGF-β, and IL-10 following CTLA-4 and VISTA knockdown. The expression levels of caspase3, Bax, Bcl2, and MMP-9 were also investigated using quantitative real-time PCR. Finally, the TCGA Breast Cancer and GSE45827 datasets were analyzed to study the potential prognostic values of VISTA and CTLA-4, their expression difference in luminal A breast cancer and non-tumoral tissues, and their correlation in luminal A breast cancer tissues.

RESULTS

Combined knockdown of tumor-intrinsic VISTA and CTLA-4 is superior in upregulating IL-2, IFN-γ, and TNF-α, downregulating TGF-β and IL-10 in T lymphocytes. Also, the combined silencing arrests the cell cycle at the sub-G1 phase, decreases migration, inhibits clonogenicity, and reduces cell viability of MCF7 cells. This combined treatment upregulates caspase 9 and BAX and downregulates MMP-9 in MCF7 cells. Our in-silico results have demonstrated a significant positive correlation between CTLA-4 and VISTA in luminal A breast cancer.

CONCLUSION

The additive effect of the combined knockdown of tumor-intrinsic VISTA and CTLA-4 can substantially upregulate pro-inflammatory factors, downregulate anti-inflammatory factors, and inhibit tumor development in MCF7 cells. The significant positive correlation between VISTA and CTLA-4 in luminal A breast cancer might support the idea that a network of inhibitory immune checkpoint molecules regulates anti-tumoral immune responses; thus, combinational immune checkpoint molecules blockade can be suggested.

Rapid turnover of CTLA4 is associated with a complex architecture of reversible ubiquitylation

The immune checkpoint regulator CTLA4 is an unusually short-lived membrane protein. Here we show that its lysosomal degradation is dependent on ubiquitylation at Lysine residues 203 and 213. Inhibition of the v-ATPase partially restores CTLA4 levels following cycloheximide treatment, but also reveals a fraction that is secreted in exosomes. The endosomal deubiquitylase, USP8, interacts with CTLA4 and its loss enhances CTLA4 ubiquitylation in cancer cells, mouse CD4+ T cells and in cancer cell-derived exosomes. Depletion of the USP8 adapter protein, HD-PTP, but not ESCRT-0 recapitulates this cellular phenotype, but shows distinct properties vis-à-vis exosome incorporation. Re-expression of wild-type USP8, but neither a catalytically inactive, nor a localization-compromised ΔMIT domain mutant can rescue delayed degradation of CTLA4, or counteract its accumulation in clustered endosomes. UbiCRest analysis of CTLA4-associated ubiquitin chain linkages identifies a complex mixture of conventional Lys63- and more unusual Lys27- and Lys29-linked polyubiquitin chains that may underly the rapidity of protein turnover.

Functional evaluation of dendritic cells and extracellular vesicles as immunotherapy for breast cancer

Dendritic cells (DCs) play critical roles in recognizing and presenting antigens to T cells. They secrete dendritic cell-derived extracellular vesicles (DC-sEVs), which could mimic the function of DCs. Therefore, we explore the possibility of using DC-sEVs as a potential personalized vaccine in this study. We compared the efficacy of DCs and DC-sEVs on stimulating the immune system to target breast cancer cells and found that DC-sEVs had significantly more MHC molecules on the surface when compared to the parental DCs. In our in vivo and in vitro testing, Dc-sEVs showed significant advantages over DCs, regarding efficacy, safety, storage, and potential delivery advantages. DC-sEVs were able to suppress the growth of immune-cold breast tumors, while DCs failed to do so. These results indicate the strong potential utility of DC-sEVs as a personalized immunotherapy for breast cancer.

The Multifunction Role of Tumor-Associated Mesenchymal Stem Cells and Their Interaction with Immune Cells in Breast Cancer

Mesenchymal stem cells (MSCs) are a heterogeneous group of progenitor cells that play a multifunctional role including tissue regeneration, self-renewal properties, and differentiate into cells of mesodermal lineage such as adipocytes, osteoblasts, and chondrocytes. MSCs come into contact with tumor microenvironment (TME) and differentiate into tumor-associated MSCs (TA-MSCs). Various substances such as chemokines, cytokines, growth factors, and others are released by tumor cells to recruit MSCs. TA-MSCs induced epithelial-mesenchymal transition (EMT) program which mediates tumor growth progression, migration, and invasion. Role of MSCs in the tumor progression, stemness, malignancy, and treatment resistance in the breast cancer TME. Immunomodulation by MSCs is mediated by a combination of cell contact-dependent mechanisms and soluble substances. Monocytes/macrophages, dendritic cells, T cells, B cells, and NK cells all show signs of MSCs' immunomodulatory capability. In a complicated interplay initiated by MSCs, anti-inflammatory monocytes/macrophages and regulatory T cells (Tregs) play a key role, as they unveil their full immunomodulatory potential. MSC- secreted cytokines are commonly blamed for the interaction between MSCs, monocytes, and Tregs. Here, we review the current knowledge of cellular and molecular mechanisms involved in MSC-mediated immunomodulation and focus on the role MSCs play in breast cancer progression and its TME.Abbreviation MSC: Mesenchymal Stem Cells; TME: Tumor Microenvironment; TAMS; Tumour-associated Macrophages; ECM: Extracellular matrix; CAFs: Cancer-associated Fibroblasts; CFUs: Colony-forming unit Fibroblasts; Tregs: T regulatory cells; Bregs; Regulatory B cells; IFN-γ: Interferon-gamma; TNF-α: Tumour Necrosis Factor-alpha; IL: Interleukin; TGF-β: transforming growth factorβ; PGE2: Prostaglandin E2; CXCR: Chemokine Receptor; Blimp-1; B lymphocyte-induced maturation protein-1; CCL: Chemokine motif ligand; EMT: Epithelial-mesenchymal transition.

Recent research and clinical progress of CTLA-4-based immunotherapy for breast cancer

Breast cancer is characterized by a high incidence rate and its treatment challenges, particularly in certain subtypes. Consequently, there is an urgent need for the development of novel therapeutic approaches. Immunotherapy utilizing immune checkpoint inhibitors (ICIs) is currently gaining momentum for the treatment of breast cancer. Substantial progress has been made in clinical studies employing cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) inhibitors for breast cancer, but the cure rates are relatively low. To improve the efficacy of CTLA-4-based therapy for breast cancer, further research is imperative to explore more effective immune-based treatment strategies. In addition to monotherapy, CTLA-4 inhibitors are also being investigated in combination with other ICIs or alternative medications. However, it should be noted that immune-based treatments may cause adverse events. This review focuses on the mechanisms of CTLA-4 inhibitor monotherapy or combination therapy in breast cancer. We systematically summarize the latest research and clinical advances in CTLA-4-based immunotherapy for breast cancer, providing new perspectives on the treatment of breast cancer. In addition, this review highlights the immune-related adverse events (irAEs) associated with CTLA-4 inhibitors, providing insights into the development of appropriate clinical tumor immunotherapy regimens and intervention strategies.

Mechanisms of CD8+ T cell exclusion and dysfunction in cancer resistance to anti-PD-(L)1

CD8⁺ T cells are the front-line defensive cells against cancer. Reduced infiltration and effector function of CD8⁺ T cells occurs in cancer and is contributed to defective immunity and immunotherapy resistance. Exclusion and exhaustion of CD8⁺ T cells are the two key factors associated with reduced durability of immune checkpoint inhibitor (ICI) therapy. Initially activated T cells upon exposure to chronic antigen stimulation or immunosuppressive tumor microenvironment (TME) acquire a hyporesponsive state that progressively lose their effector function. Thus, a key strategy in cancer immunotherapy is to look for factors contributed to defective CD8⁺ T cell infiltration and function. Targeting such factors can define a promising supplementary approach in patients receiving anti-programmed death-1 receptor (PD-1)/anti-programmed death-ligand 1 (PD-L1) therapy. Recently, bispecific antibodies are developed against PD-(L)1 and a dominant factor within TME, representing higher safety profile and exerting more desired outcomes. The focus of this review is to discuss about promoters of deficient infiltration and effector function of CD8⁺ T cells and their addressing in cancer ICI therapy.

Engineering an active immunotherapy for personalized cancer treatment and prevention of recurrence

Breast cancer has been shown to be resistant to immunotherapies. To overcome this challenge, we developed an active immunotherapy for personalized treatment based on a smart nanovesicle. This is achieved by anchoring membrane-bound bioactive interleukin 2 (IL2) and enriching T cell-promoting costimulatory factors on the surface of the dendritic cell-derived small extracellular vesicles. This nanovesicle also displays major histocompatibility complex-bound antigens inherited from tumor lysate-pulsed dendritic cell. When administrated, the surface-bound IL2 is able to guide the nanovesicle to lymphoid organs and activate the IL2 receptor on lymphocytes. Furthermore, it is able to perform antigen presentation in the replacement of professional antigen-presenting cells. This nanovesicle, named IL2-ep13nsEV, induced a strong immune reaction to rescue 50% of the mice in our humanized patient-derived xenografts, sensitized cancer cells to immune checkpoint inhibitor treatment, and prevented the recurrence of resected tumors. This paradigm presents a feasible strategy for the treatment and prevention of metastatic breast cancer.

Cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) as an undetermined tool in tumor cells

In the tumor microenvironment, the function of T cells is a fate-changer for tumor progression. In the meantime, CD28 and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) are vital role players in the controlling activity of T cells as an activator and deactivator, respectively. In T cells in comparison to CD28, the molecular mechanism of CTLA-4 is unclear. In addition, despite the fact that most tumor cell types express CTLA-4, its role in tumor cells is not well understood and only few studies focused on the role of CTLA-4 signaling in tumor cells. It is illustrated that CTLA-4 signaling causes PD-L1 expression in tumor cells. However, numerous characteristics of CTLA-4 signaling in tumor cells are ambiguous and require to be described. In this article, we proposed that the CTLA-4 signaling during immunotherapy with anti-CTLA-4 antibodies may cause poor responses by patients. In addition, we attract attention to several fundamental questions regarding CTLA-4 signaling in tumor cells. Overall, the CTLA-4 signaling function and the related gaps about its role in tumor cells in the present review are challenged.

Variable Intrinsic Expression of Immunoregulatory Biomarkers in Breast Cancer Cell Lines, Mammospheres, and Co-Cultures

Advances in immunotherapy have increased interest in knowing the role of the immune system in breast cancer (BC) pathogenesis. Therefore, immune checkpoints (IC) and other pathways related to immune regulation, such as JAK2 and FoXO1, have emerged as potential targets for BC treatment. However, their intrinsic gene expression in vitro has not been extensively studied in this neoplasia. Thus, we evaluated the mRNA expression of tumor-cell-intrinsic CTLA-4, PDCD1 (PD1), CD274 (PD-L1), PDCD1LG2 (PD-L2), CD276 (B7-H3), JAK2, and FoXO1 in different BC cell lines, derived mammospheres, and co-cultures with peripheral blood mononuclear cells (PBMCs) by real-time quantitative polymerase chain reaction (qRT-PCR). Our results showed that intrinsic CTLA-4, CD274 (PD-L1), and PDCD1LG2 (PD-L2) were highly expressed in triple-negative cell lines, while CD276 was predominantly overexpressed in luminal cell lines. In contrast, JAK2 and FoXO1 were under-expressed. Moreover, high levels of CTLA-4, PDCD1 (PD1), CD274 (PD-L1), PDCD1LG2 (PD-L2), and JAK2 were found after mammosphere formation. Finally, the interaction between BC cell lines and peripheral blood mononuclear cells (PBMCs) stimulates the intrinsic expression of CTLA-4, PCDC1 (PD1), CD274 (PD-L1), and PDCD1LG2 (PD-L2). In conclusion, the intrinsic expression of immunoregulatory genes seems very dynamic, depending on BC phenotype, culture conditions, and tumor-immune cell interactions.

Immunocyte Derived Exosomes: Insight into the Potential Chemo-immunotherapeutic Nanocarrier Targeting the Tumor Microenvironment

"Cancer" is a dreadful immune-pathological condition that is characterized by anti-inflammatory and tumorigenic responses, elicited by the infiltrating immune cells in the vicinity of an uncontrollably proliferative tumor in the tumor microenvironment (TME). The TME offers a conducive microenvironment that supports cancer cell survival by modulating the host immune defense. Recent advancement in exosomal research has shown exosomes, originating from immune cells as well as the cancer cells, have immense potential for suppressing cancer progression and survival in the TME. Additionally, exosomes, irrespective of their diverse sources, have been reported to be efficient nanocarriers for cancer therapeutics with the ability for targeted delivery due to their biogenic nature, ease of cellular uptake, and scope for functionalization with biomolecules like peptides, aptamers, targeting ligands, etc. Immune cell-derived exosomes per se have been found efficacious against cancer owing to their immune-stimulant properties (in either naive or antigen primed form) even without loading any of cancer therapeutics or targeting ligand conjugation. Nevertheless, exosomes are being primarily explored as nanovesicular carriers for therapeutic molecules with different loading and targeting strategies, and the synergism between immunotherapeutic behavior of exosomes and the anticancer effect of the therapeutic molecules is yet to be explored. Hence, this review focuses specifically on the possible strategies to modulate the immunological nature of the source immune cells to obtain immune stimulant exosomes and bring these into the spotlight as chemo-immunotherapeutic nanovesicles, that can easily target and modulate the TME.

Contracting triple-negative breast cancer with immunotherapeutic armamentarium: recent advances and clinical prospects

Triple negative breast cancer (TNBC) portraying deficient expression of estrogen receptor (ER), progesterone receptor (PR) and Human epidermal growth factor receptor 2 (HER2) is known to be the most aggressive subtype associated with poor prognosis and interventional strategies limited to chemotherapy and breast conserving surgery. Some TNBC incidences have also been reported with positive circ-HER2 expression thus rendering circ-HER2 a potential immunotherapy target to direct drug development. Resistance and recurrence reported with traditional approaches has led us towards the application of immunotherapeutic interventions owing to their anti-tumor efficacy. This review provides an elaborative insight on potential molecular biomarkers to be targeted by immunotherapy. Additionally, clinical trials proposing the application of immunotherapy in neoadjuvant, adjuvant and metastatic TNBC setting have also been included. The gathered evidence indicates a positive application of immunotherapy in TNBC with therapeutic limitation available only owing to the possibility of adverse events which can be dealt considering risk-to-benefit ratio. Furthermore, potential targets to aim for therapeutic vaccines along with evidence from clinical trials have also been mentioned.

Biological and molecular studies on specific immune cells treated with checkpoint inhibitors for the thera-personal approach of breast cancer patients (ex-vivo study)

Immunotherapy becomes a promising line of treatment for breast cancer (BC) however, its success rate is still limited.

Methods

The study was designed to optimize the condition for producing an effective dendritic cell (DCs) based immunotherapy by using DCs and T lymphocytes together with tumor-infiltrating lymphocytes (TILs) and tumor-infiltrating DCs (TIDCs), treated with anti-PD1 and anti-CTLA4 monoclonal antibodies. This mixture of immune cells was co-cultured with autologous breast cancer cells (BCCs) isolated from 26 BC females.

Results

There was a significant upregulation of CD86 and CD83 on DCs (p = 0.001 and 0.017, respectively), similarly upregulation of CD8, CD4 and CD103 on T cells (p = 0.031, 0.027, and 0.011, respectively). While there was a significant downregulation of FOXP3 and combined CD25.CD8 expression on regulatory T cells (p = 0.014 for both). Increased CD8/Foxp3 ratio (p < 0.001) was also observed. CD133, CD34 and CD44 were downregulated on BCCs (p = 0.01, 0.021, and 0.015, respectively). There was a significant increase in interferon-γ (IFN-γ, p < 0.001), lactate dehydrogenase (LDH, p = 0.02), and a significant decrease in vascular endothelial growth factor (VEGF, p < 0.001) protein levels. Gene expression of FOXP3 and Programmed cell death ligand 1 (PDL-1) were downregulated in BCCs (p < 0.001, for both), similarly cytotoxic T lymphocyte antigen-4 (CTLA4, p = 0.02), Programmed cell death 1 (PD-1, p < 0.001) and FOXP3 (p < 0.001) were significantly downregulated in T cells.

Conclusion

Ex-vivo activation of immune cells (DCs, T cells, TIDCs, and TILs) with immune checkpoint inhibitors could produce a potent and effective BC immunotherapy. However, these data should be validated on an experimental animal model to be transferred to the clinical setting.

Opportunities for Nitric Oxide in Potentiating Cancer Immunotherapy

Despite nearly 30 years of development and recent highlights of nitric oxide (NO) donors and NO delivery systems in anticancer therapy, the limited understanding of exogenous NO's effects on the immune system has prevented their advancement into clinical use. In particular, the effects of exogenously delivered NO differing from that of endogenous NO has obscured how the potential and functions of NO in anticancer therapy may be estimated and exploited despite the accumulating evidence of NO's cancer therapy-potentiating effects on the immune system. After introducing their fundamentals and characteristics, this review discusses the current mechanistic understanding of NO donors and delivery systems in modulating the immunogenicity of cancer cells as well as the differentiation and functions of innate and adaptive immune cells. Lastly, the potential for the complex modulatory effects of NO with the immune system to be leveraged for therapeutic applications is discussed in the context of recent advancements in the implementation of NO delivery systems for anticancer immunotherapy applications. SIGNIFICANCE STATEMENT: Despite a 30-year history and recent highlights of nitric oxide (NO) donors and delivery systems as anticancer therapeutics, their clinical translation has been limited. Increasing evidence of the complex interactions between NO and the immune system has revealed both the potential and hurdles in their clinical translation. This review summarizes the effects of exogenous NO on cancer and immune cells in vitro and elaborates these effects in the context of recent reports exploiting NO delivery systems in vivo in cancer therapy applications.

Dendritic Cells: The Long and Evolving Road towards Successful Targetability in Cancer

Dendritic cells (DCs) are a unique myeloid cell lineage that play a central role in the priming of the adaptive immune response. As such, they are an attractive target for immune oncology based therapeutic approaches. However, targeting these cells has proven challenging with many studies proving inconclusive or of no benefit in a clinical trial setting. In this review, we highlight the known and unknown about this rare but powerful immune cell. As technologies have expanded our understanding of the complexity of DC development, subsets and response features, we are now left to apply this knowledge to the design of new therapeutic strategies in cancer. We propose that utilization of these technologies through a multiomics approach will allow for an improved directed targeting of DCs in a clinical trial setting. In addition, the DC research community should consider a consensus on subset nomenclature to distinguish new subsets from functional or phenotypic changes in response to their environment.

The role of the natural killer (NK) cell modulation in breast cancer incidence and progress

The importance of the immune system on tumor surveillance has been investigated for many years, and its impact on controlling tumor progression has been verified. An important subgroup of the innate immune system is natural killer (NK) cells, whose essential function in modulating tumor behavior and suppressing metastasis and tumor growth has been demonstrated. The first idea of NK cells' crucial biological processes was demonstrated through their potent ability to conduct direct cellular cytotoxicity, even without former sensitization. These properties of NK cells allow them to recognize transformed cells that have attenuated self-ligand and express stress-induced ligands. Furthermore, secretion of various cytokines and chemokines after their activation leads to tumor elimination via either direct cytotoxic effect on malignant cells or activation of the adaptive immune system. In addition, novel immunotherapeutic approaches tend to take advantage of NK cells' ability, leading to antibody-based approaches, the formation of engineered CAR-NK cells, and adoptive cell transfer. However, the restricted functionality of NK cells and the inability to infiltrate tumors are its blind spots in breast cancer patients. In this review, we gathered newly acquired data on the biology and functions of NK cells in breast cancer and proposed ways to employ this knowledge for novel therapeutic approaches in cancers, particularly breast cancer.

Potential Predictive and Prognostic Value of Biomarkers Related to Immune Checkpoint Inhibitor Therapy of Triple-Negative Breast Cancer

As an aggressive subtype of breast cancer, triple-negative breast cancer (TNBC) is associated with poor prognosis and lack of effective therapy, except chemotherapy. In recent years, immunotherapy based on immune checkpoint (IC) inhibition has emerged as a promising therapeutic strategy in TNBC. TNBC has more tumor-infiltrating lymphocytes (TILs) and higher rate of mutation and programmed cell death ligand-1 (PD-L1) expression than other subtypes of breast cancer have. However, previous studies have shown that monotherapy has little efficacy and only some TNBC patients can benefit from immunotherapy. Therefore, it is important to identify biomarkers that can predict the efficacy of IC inhibitors (ICIs) in TNBC. Recently, various biomarkers have been extensively explored, such as PD-L1, TILs and tumor mutational burden (TMB). Clinical trials have shown that PD-L1-positive patients with advanced TNBC benefit from ICIs plus chemotherapy. However, in patients with early TNBC receiving neoadjuvant therapy, PD-L1 cannot predict the efficacy of ICIs. These inconsistent conclusions suggest that PD-L1 is the best to date but an imperfect predictive biomarker for efficacy of ICIs. Other studies have shown that advanced TNBC patients with TMB ≥10 mutations/Mb can achieve clinical benefits from pembrolizumab. TILs also have potential predictive value in TNBC. Here, we select some biomarkers related to ICIs and discuss their potential predictive and prognostic value in TNBC. We hope these biomarkers could help to identify suitable patients and realize precision immunotherapy.

A Novel Attention-Mechanism Based Cox Survival Model by Exploiting Pan-Cancer Empirical Genomic Information

Cancer prognosis is an essential goal for early diagnosis, biomarker selection, and medical therapy. In the past decade, deep learning has successfully solved a variety of biomedical problems. However, due to the high dimensional limitation of human cancer transcriptome data and the small number of training samples, there is still no mature deep learning-based survival analysis model that can completely solve problems in the training process like overfitting and accurate prognosis. Given these problems, we introduced a novel framework called SAVAE-Cox for survival analysis of high-dimensional transcriptome data. This model adopts a novel attention mechanism and takes full advantage of the adversarial transfer learning strategy. We trained the model on 16 types of TCGA cancer RNA-seq data sets. Experiments show that our module outperformed state-of-the-art survival analysis models such as the Cox proportional hazard model (Cox-ph), Cox-lasso, Cox-ridge, Cox-nnet, and VAECox on the concordance index. In addition, we carry out some feature analysis experiments. Based on the experimental results, we concluded that our model is helpful for revealing cancer-related genes and biological functions.

AllergoOncology: Role of immune cells and immune proteins

Background

Immune cells and immune proteins play a pivotal role in host responses to pathogens, allergens and cancer. Understanding the crosstalk between allergic response and cancer, immune surveillance, immunomodulation, role of immunoglobulin E (IgE)‐mediated functions and help to develop novel therapeutic strategies. Allergy and oncology show two opposite scenarios: whereas immune tolerance is desired in allergy, it is detrimental in cancer.

Aim

The current review provides an update on the role of immune cells and immune proteins in allergy and cancer fields.

Methods

Authors investigated the role of relevant immunological markers and the correlation with cancer progression or cancer suppression.

Results

Activated immune cells such as macrophages ‘M1’, dendritic cells (DCs), innate lymphoid cells (ILC2), NK cells, Th1, follicular T helper cells (TFH), TCD8+, B lymphocytes and eosinophils have inhibitory effects on tumourigenesis, while tolerogenic cells such as macrophages ‘M2,’ tolerogenic DCs, ILC3, T and B regulatory lymphocytes appear to favour carcinogenesis. Mastocytes and alarmins can have both effects. RIgE antibodies and CCCL5 chemokine have an anticancer role, whereas IgG4, free light chains, Il‐10, TGF‐β, lipocalin‐2, CCL1 chemokine promote cancer progression. Fundamental is also the contribution of epigenetic changes regulated by the microRNA in cancer progression.

Conclusion

This knowledge represents the key to developing new anticancer therapies.

Immunomodulatory Properties of Immune Checkpoint Inhibitors-More than Boosting T-Cell Responses?

The approval of immune checkpoint inhibitors (ICI) that serve to enhance effector T-cell anti-tumor responses has strongly improved success rates in the treatment of metastatic melanoma and other tumor types. The currently approved ICI constitute monoclonal antibodies blocking cytotoxic T-lymphocyte-associated protein (CTLA)-4 and anti-programmed cell death (PD)-1. By this, the T-cell-inhibitory CTLA-4/CD80/86 and PD-1/PD-1L/2L signaling axes are inhibited. This leads to sustained effector T-cell activity and circumvents the immune evasion of tumor cells, which frequently upregulate PD-L1 expression and modulate immune checkpoint molecule expression on leukocytes. As a result, profound clinical responses are observed in 40-60% of metastatic melanoma patients. Despite the pivotal role of T effector cells for triggering anti-tumor immunity, mounting evidence indicates that ICI efficacy may also be attributable to other cell types than T effector cells. In particular, emerging research has shown that ICI also impacts innate immune cells, such as myeloid cells, natural killer cells and innate lymphoid cells, which may amplify tumoricidal functions beyond triggering T effector cells, and thus improves clinical efficacy. Effects of ICI on non-T cells may additionally explain, in part, the character and extent of adverse effects associated with treatment. Deeper knowledge of these effects is required to further develop ICI treatment in terms of responsiveness of patients to treatment, to overcome resistance to ICI and to alleviate adverse effects. In this review we give an overview into the currently known immunomodulatory effects of ICI treatment in immune cell types other than the T cell compartment.

Thermosensitive hydrogel releasing nitric oxide donor and anti-CTLA-4 micelles for anti-tumor immunotherapy

Due to their autosynchronous roles in shaping the anti-tumor immune response, complex immune regulatory networks acting both locally within the tumor microenvironment as well as in its draining lymph nodes play critical roles in the cancer immunotherapy response. We describe herein a thermosensitive co-polymer hydrogel system formed from biocompatible polymers gelatin and Pluronic^® F127 that are widely used in humans to enable the sustained release of a nitric oxide donor and antibody blocking immune checkpoint cytotoxic T-lymphocyte-associated protein-4 for efficient and durable anti-tumor immunotherapy. By virtue of its unique gel formation and degradation properties that sustain drug retention at the tumor tissue site for triggered release by the tumor microenvironment and formation of in situ micelles optimum in size for lymphatic uptake, this rationally designed thermosensitive hydrogel facilitates modulation of two orthogonal immune signaling networks relevant to the regulation of the anti-tumor immune response to improve local and abscopal effects of cancer immunotherapy.

Dendritic cell-based cancer immunotherapy in the era of immune checkpoint inhibitors: From bench to bedside

Dendritic cells (DCs) can present tumoral antigens to T-cells and stimulate T-cell-mediated anti-tumoral immune responses. In addition to uptaking, processing, and presenting tumoral antigens to T-cells, co-stimulatory signals have to be established between DCs with T-cells to develop anti-tumoral immune responses. However, most of the tumor-infiltrated immune cells are immunosuppressive in the tumor microenvironment (TME), paving the way for immune evasion of tumor cells. This immunosuppressive TME has also been implicated in suppressing the DC-mediated anti-tumoral immune responses, as well. Various factors, i.e., immunoregulatory cells, metabolic factors, tumor-derived immunosuppressive factors, and inhibitory immune checkpoint molecules, have been implicated in developing the immunosuppressive TME. Herein, we aimed to review the biology of DCs in developing T-cell-mediated anti-tumoral immune responses, the significance of immunoregulatory cells in the TME, metabolic barriers contributing to DCs dysfunction in the TME, tumor-derived immunosuppressive factors, and inhibitory immune checkpoint molecules in DC-based cell therapy outcomes. With reviewing the ongoing clinical trials, we also proposed a novel therapeutic strategy to increase the efficacy of DC-based cell therapy. Indeed, the combination of DC-based cell therapy with monoclonal antibodies against novel immune checkpoint molecules can be a promising strategy to increase the response rate of patients with cancers.

(Im)maturity in Tumor Ecosystem

Tumors have special features that make them distinct from their normal counterparts. Immature cells in a tumor mass and their critical contributions to the tumorigenesis will open new windows toward cancer therapy. Incomplete cellular development brings versatile and unique functionality in the cellular tumor ecosystem, such as what is seen for highly potential embryonic cells. There is evidence that maturation of certain types of cells in this ecosystem can recover the sensitivity of the tumor. Therefore, understanding more about the mechanisms that contributed to this immaturity will render new therapeutic approaches in cancer therapy. Targeting such mechanisms can be exploited as a supplementary to the current immunotherapeutic treatment schedules, such as immune checkpoint inhibitor (ICI) therapy. The key focus of this review is to discuss the impact of (im)maturity in cellular tumor ecosystems on cancer progression, focusing mainly on immaturity in the immune cell compartment of the tumor, as well as on the stemness of tumor cells.

The impact of hypoxia on immune state in cancer

Hypoxia is a known feature of solid tumors and a critical promoter of tumor hallmarks. Hypoxia influences tumor immunity in a way favoring immune evasion and resistance. Extreme hypoxia and aberrant hypoxia-inducible factor-1 (HIF-1) activity in tumor microenvironment (TME) is a drawback for effective immunotherapy. Infiltration and activity of CD8⁺ T cells is reduced in such condition, whereas regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) show high activities. Highly hypoxic TME also impairs maturation and activity of dendritic cell (DCs) and natural killer (NK) cells. In addition, the hypoxic TME positively is linked positively with metabolic changes in cells of immune system. These alterations are indicative of a need for hypoxia modulation as a complementary targeting strategy to go with immune checkpoint inhibitor (ICI) therapy.

The application of immune checkpoint blockade in breast cancer and the emerging role of nanoparticle

Breast cancer is the most common malignancy in the female population with a high mortality rate. Despite the satisfying depth of studies evaluating the contributory role of immune checkpoints in this malignancy, few articles have reviewed the pros and cons of immune checkpoint blockades (ICBs). In the current review, we provide an overview of immune-related inhibitory molecules and also discuss the original data obtained from international research laboratories on the aberrant expression of T and non-T cell-associated immune checkpoints in breast cancer. Then, we especially focus on recent studies that utilized ICBs as the treatment strategy in breast cancer and provide their efficiency reports. As there are always costs and benefits, we discuss the limitations and challenges toward ICB therapy such as adverse events and drug resistance. In the last section, we allocate an overview of the recent data concerning the application of nanoparticle systems for cancer immunotherapy and propose that nano-based ICB approaches may overcome the challenges related to ICB therapy in breast cancer. In conclusion, it seems it is time for nanoscience to more rapidly move forward into clinical trials and illuminates the breast cancer treatment area with its potent features for the target delivery of ICBs.

Differential Response of MDA-MB-231 and MCF-7 Breast Cancer Cells to In Vitro Inhibition with CTLA-4 and PD-1 through Cancer-Immune Cells Modified Interactions

Drugs targeting immune checkpoint molecules have been found effective in melanoma, lung cancer, and other malignancies treatment. Recent studies on breast cancer demonstrated the significance of inhibitory anti-CTLA-4 and anti-PD-1 in the regulation of disease progression. However, seemingly the same types of breast cancer do not always respond unambiguously to immunotherapy. Thus, here we set out to analyze the in vitro effects of inhibiting CTLA-4 and PD-1 on interactions between co-cultured lymphocytes and two selected breast adenocarcinoma cell lines. Breast cancer cells were co-cultured with lymphocytes to evaluate the effects of CTLA-4 and PD-1 inhibition. Proliferation, cell cycle, and viability assessment were measured in cancer cells. IFN-gamma, IL-10, perforin, granzyme B production, and CTLA-4 and PD-1 expression were analyzed in lymphocytes. We found that administration of anti-CTLA-4 improved the anti-cancer activity of T cells with reduced proliferation and viability of MDA-MB-231. Lack of response was observed in the context of MCF-7. In addition, differential expression of checkpoint proteins was found between studied cancer cells lines. Inhibition of molecules was followed by IL-10 and IFN-gamma decrease in lymphocytes co-cultured with MDA-MB-231, not demonstrated in reference to MCF-7. Furthermore, CTLA-4 blockage was associated with reduction of CTLA-4+ and PD-1+ lymphocytes in MDA-MB-231, with a significant increase in MCF-7, reduced by anti-PD-1. Altogether, our study revealed that anti-CTLA-4 and anti-PD-1 treatment can improve lymphocytes effects on breast cancer cells. Favorable effects seemed to be related to breast cancer cells features as differential responses were reported. Novel blocking antibodies strategies should be tested for more effective cancer inhibition.

CD11b+CTLA4+ myeloid cells are a key driver of tumor evasion in colorectal cancer

Background

Tumor metastasis is the major cause of death of colorectal cancer (CRC), and metastatic CRC remains incurable in many cases despite great advances in genetic and molecular profiling, and clinical development of numerous drugs, including immune checkpoint inhibitors. Thus, more effective treatments are urgently needed for the patients in clinical settings.

Methods

We used mouse CRC metastasis models that murine Colon26 cells were subcutaneously and intravenously implanted and attempted to elucidate the tumor biological and immunological mechanisms underlying cancer metastasis. Then, we evaluated in vivo antitumor efficacy induced by agents targeting the identified molecular mechanisms using the mouse models. We validated the clinical relevancy of the findings using peripheral blood mononuclear cells obtained from stage IV metastatic CRC patients.

Results

CD11b⁺CTLA4⁺ myeloid cells were systemically expanded in the metastatic settings and facilitated tumor progression and metastasis directly via generating lipid droplets in tumor cells and indirectly via inducing immune exhaustion. These events were mediated by IL1B produced via the CTLA4 signaling from the increased myeloid cells. Blocking CTLA4 and IL1B with the specific mAbs significantly suppressed tumor progression and metastasis in the mouse models resistant to anti-PD1 therapy, and the therapeutic efficacy was optimized by blocking cyclooxygenases with aspirin.

Conclusions

The CD11b⁺CTLA4⁺ cells are a key driver of tumor evasion, and targeting the CTLA4-IL1B axis could be a promising strategy for treating metastatic CRC. The triple combination regimen with anti-CTLA4/IL1B mAbs and aspirin may be useful in clinical settings.

CTLA-4 Expression and Its Clinical Significance in Breast Cancer

Breast cancer is the leading cause of women's death among all cancers. The main reason associated with this is the development of metastasis and therapy-resistant breast carcinoma (BC), which pose the main challenge of oncology nowadays. Evidence suggest that these tumors seem to have inhibitory mechanisms that may favor their progression and surveillance. Cancer cells can evade antitumor T cell responses by expressing some immune inhibitory molecules such as the cytotoxic T-lymphocyte antigen-4 (CTLA-4), whose clinical meaning has emerged in the last few years and is poorly understood in the BC context. This systematic literature review aims at identifying studies on CTLA-4 expression in BC, and address what is known about its clinical meaning. A literature search was performed in PubMed and LILACS databases, using the MESH terms "breast cancer"; "CTLA-4 Antigen/antagonists and inhibitors"; and "Lymphocytes, Tumor-Infiltrating/immunology", published in the last 10 years. In total, 12 studies were included in this review. Systematic review used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Despite the small number of eligible studies, the literature reports some associations between CTLA-4 expression in the tumor microenvironment and worse BC outcomes, regardless of its molecular subtype. CTLA-4 expression in BC is a putative marker of clinical significance and a rationale therapeutic target in the emerging field of immunotherapy.

Boosting immune system against cancer by resveratrol

Modulation of the immune system is a critical part of anticancer therapies including immunotherapy, chemotherapy, and radiotherapy. The aim of immunomodulation in cancer therapy is boosting immune system cells including CD8+ T lymphocytes and natural killer (NK) cells, as well as suppression of immunosuppressive responses by macrophages and regulatory T cells (Tregs). Usually, using single or dual modality can induce immune system responses against cancer. However, immunosuppressive responses attenuate antitumor immunity following cancer therapy. Using some agents to boost immune system's function against cancer can increase therapeutic efficiency of anticancer therapy. Resveratrol, as a natural agent, has shown ability to modulate the immune system to potentiate antitumor immunity. Resveratrol has been shown to induce the release of anticancer cytokines such as IFN-γ and TNF-α and also inhibits the release of TGF-β. It also can stimulate the polarization of CD4+ T cells and macrophages toward anticancer cells and reduce infiltration and polarization of immunosuppressive cells. Furthermore, resveratrol can sensitize cancer cells to the released dead signals by anticancer immune cells. This review explains how resveratrol can boost the immune system against cancer via modulation of immune cell responses within tumor.

Immune checkpoint inhibitors: review of the existing evidence and challenges in breast cancer

Cancer initiation and progression are associated with immune system responses. Tumor cells use various tricks to scape of immune system, such as activating immune checkpoint pathways that induce immunosuppressive functions. Among the different immune checkpoint receptors, CTLA-4 and PD-1/PD-L1 are prominent therapeutic targets in different cancers. Although the US FDA has approved some immune checkpoint inhibitors for several cancers, concerning breast cancer still different clinical trials are looking for optimizing efficacy and decreasing immune-related adverse events. This review will discuss the existing body of knowledge with regard to cross-talk between immune system and tumor cells and then explore immune checkpoint-related signaling pathways in the context of breast tumors. Finally, we highlight the application of different immune checkpoint blockers in breast cancer patients.

Tumor microenvironment characterization in triple-negative breast cancer identifies prognostic gene signature

We aimed to elucidate the landscape of tumor microenvironment (TME) in triple-negative breast cancer (TNBC). Cohorts from Gene Expression Omnibus database (N = 107) and METABRIC (N = 299) were used as the training set and validation set, respectively. TME was evaluated via single-sample gene set enrichment analysis, and unsupervised clustering was used for cluster identification. Consequently, TNBC was classified into two distinct TME clusters (Cluster 1 and Cluster 2) according to predefined immune-related terms. Cluster 1 was characterized by low immune infiltration with poor prognosis; whereas, Cluster 2 was characterized by high immune infiltration with better survival probability. Further, Cluster 1 had larger tumor volumes, while Cluster 2 had smaller tumor volumes. Finally, a TME signature for prognosis stratification in TNBC was developed and validated. In summary, we comprehensively evaluated the TME of TNBC and constructed a TME signature that correlated with prognosis. Our results provide new insights for the immunotherapy of TNBC.

Single-cell landscape of the ecosystem in early-relapse hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has high relapse and low 5-year survival rates. Single-cell profiling in relapsed HCC may aid in the design of effective anticancer therapies, including immunotherapies. We profiled the transcriptomes of ∼17,000 cells from 18 primary or early-relapse HCC cases. Early-relapse tumors have reduced levels of regulatory T cells, increased dendritic cells (DCs), and increased infiltrated CD8⁺ T cells, compared with primary tumors, in two independent cohorts. Remarkably, CD8⁺ T cells in recurrent tumors overexpressed KLRB1 (CD161) and displayed an innate-like low cytotoxic state, with low clonal expansion, unlike the classical exhausted state observed in primary HCC. The enrichment of these cells was associated with a worse prognosis. Differential gene expression and interaction analyses revealed potential immune evasion mechanisms in recurrent tumor cells that dampen DC antigen presentation and recruit innate-like CD8⁺ T cells. Our comprehensive picture of the HCC ecosystem provides deeper insights into immune evasion mechanisms associated with tumor relapse.

Beyond T-Cells: Functional Characterization of CTLA-4 Expression in Immune and Non-Immune Cell Types

The immune response consists of a finely-tuned program, the activation of which must be coupled with inhibitory mechanisms whenever initiated. This ensures tight control of beneficial anti-pathogen and anti-tumor responses while preserving tissue integrity, promoting tissue repair, and safeguarding against autoimmunity. A cogent example of this binary response is in the mobilization of co-stimulatory and co-inhibitory signaling in regulating the strength and type of a T-cell response. Of particular importance is the costimulatory molecule CD28 which is countered by CTLA-4. While the role of CD28 in the immune response has been thoroughly elucidated, many aspects of CTLA-4 biology remain controversial. The expression of CD28 is largely constrained to constitutive expression in T-cells and as such, teasing out its function has been somewhat simplified by a limited and specific expression profile. The expression of CTLA-4, on the other hand, while reported predominantly in T-cells, has also been described on a diverse repertoire of cells within both lymphoid and myeloid lineages as well as on the surface of tumors. Nonetheless, the function of CTLA-4 has been mostly described within the context of T-cell biology. The focus on T-cell biology may be a direct result of the high degree of amino acid sequence homology and the co-expression pattern of CD28 and CTLA-4, which initially led to the discovery of CTLA-4 as a counter receptor to CD28 (for which a T-cell-activating role had already been described). Furthermore, observations of the outsized role of CTLA-4 in T_reg-mediated immune suppression and the striking phenotype of T-cell hyperproliferation and resultant disease in CTLA-4^−/− mice contribute to an appropriate T-cell-centric focus in the study of CTLA-4. Complete elucidation of CTLA-4 biology, however, may require a more nuanced understanding of its role in a context other than that of T-cells. This makes particular sense in light of the remarkable, yet limited utility of anti-CTLA-4 antibodies in the treatment of cancers and of CTLA-4-Ig in autoimmune disorders like rheumatoid arthritis. By fully deducing the biology of CTLA-4-regulated immune homeostasis, bottlenecks that hinder the widespread applicability of CTLA-4-based immunotherapies can be resolved.

Impact of anatomic site on antigen-presenting cells in cancer

Checkpoint blockade immunotherapy (CBT) can induce long-term clinical benefits in patients with advanced cancer; however, response rates to CBT vary by cancer type. Cancers of the skin, lung, and kidney are largely responsive to CBT, while cancers of the pancreas, ovary, breast, and metastatic lesions to the liver respond poorly. The impact of tissue-resident immune cells on antitumor immunity is an emerging area of investigation. Recent evidence indicates that antitumor immune responses and efficacy of CBT depend on the tissue site of the tumor lesion. As myeloid cells are predominantly tissue-resident and can shape tumor-reactive T cell responses, it is conceivable that tissue-specific differences in their function underlie the tissue-site-dependent variability in CBT responses. Understanding the roles of tissue-specific myeloid cells in antitumor immunity can open new avenues for treatment design. In this review, we discuss the roles of tissue-specific antigen-presenting cells (APCs) in governing antitumor immune responses, with a particular focus on the contributions of tissue-specific dendritic cells. Using the framework of the Cancer-Immunity Cycle, we examine the contributions of tissue-specific APC in CBT-sensitive and CBT-resistant carcinomas, highlight how these cells can be therapeutically modulated, and identify gaps in knowledge that remain to be addressed.

Bispecific anti-PD-1/CTLA-4 antibody for advanced solid tumors

PD-1 and CTLA-4 are checkpoint inhibitors of the immune response in cancer, making them the target molecules for the development of therapeutic antibodies. US2019161548 patent describes a bispecific antibody capable of specifically binding to PD-1 and CTLA-4 that induced the proliferation and activation of CD8⁺ cells, as well as the expression of induclble co-stimulator in CD4⁺ T cells. Clinical trials to evaluate safety, dose-limiting toxicities and maximum tolerated/administered dose are still in the patient recruitment phase, but it will be of great interest to the scientific and medical community to know if the first bispecific anti-PD-1/CLTA-4 antibody, exceeds expectations and exceeds action of the combination of nivolumab and epilimumab in the treatment of cancer.

How Different Are the Molecular Mechanisms of Nodal and Distant Metastasis in Luminal A Breast Cancer?

Lymph node status is one of the best prognostic factors in breast cancer, however, its association with distant metastasis is not straightforward. Here we compare molecular mechanisms of nodal and distant metastasis in molecular subtypes of breast cancer, with major focus on luminal A patients. We analyze a new cohort of 706 patients (MMCI_706) as well as an independent cohort of 836 primary tumors with full gene expression information (SUPERTAM_HGU133A). We evaluate the risk of distant metastasis, analyze targetable molecular mechanisms in Gene Set Enrichment Analysis and identify relevant inhibitors. Lymph node positivity is generally associated with NF-κB and Src pathways and is related to high risk (OR: 5.062 and 2.401 in MMCI_706 and SUPERTAM_HGU133A, respectively, p < 0.05) of distant metastasis in luminal A patients. However, a part (≤15%) of lymph node negative tumors at the diagnosis develop the distant metastasis which is related to cell proliferation control and thrombolysis. Distant metastasis of lymph node positive patients is mostly associated with immune response. These pro-metastatic mechanisms further vary in other molecular subtypes. Our data indicate that the management of breast cancer and prevention of distant metastasis requires stratified approach based on targeted strategies.

The Role of the Tumor Microenvironment in Developing Successful Therapeutic and Secondary Prophylactic Breast Cancer Vaccines

Breast cancer affects roughly one in eight women over their lifetime and is a leading cause of cancer-related death in women. While outcomes have improved in recent years, prognosis remains poor for patients who present with either disseminated disease or aggressive molecular subtypes. Cancer immunotherapy has revolutionized the treatment of several cancers, with therapeutic vaccines aiming to direct the cytotoxic immune program against tumor cells showing particular promise. However, these results have yet to translate to breast cancer, which remains largely refractory from such approaches. Recent evidence suggests that the breast tumor microenvironment (TME) is an important and long understudied barrier to the efficacy of therapeutic vaccines. Through an improved understanding of the complex and biologically diverse breast TME, it may be possible to advance new combination strategies to render breast carcinomas sensitive to the effects of therapeutic vaccines. Here, we discuss past and present efforts to advance therapeutic vaccines in the treatment of breast cancer, the molecular mechanisms through which the TME contributes to the failure of such approaches, as well as the potential means through which these can be overcome.

Understanding the Role of Innate Immune Cells and Identifying Genes in Breast Cancer Microenvironment

The innate immune system is the first line of defense against invading pathogens and has a major role in clearing transformed cells, besides its essential role in activating the adaptive immune system. Macrophages, dendritic cells, NK cells, and granulocytes are part of the innate immune system that accumulate in the tumor microenvironment such as breast cancer. These cells induce inflammation in situ by secreting cytokines and chemokines that promote tumor growth and progression, in addition to orchestrating the activities of other immune cells. In breast cancer microenvironment, innate immune cells are skewed towards immunosuppression that may lead to tumor evasion. However, the mechanisms by which immune cells could interact with breast cancer cells are complex and not fully understood. Therefore, the importance of the mammary tumor microenvironment in the development, growth, and progression of cancer is widely recognized. With the advances of using bioinformatics and analyzing data from gene banks, several genes involved in NK cells of breast cancer individuals have been identified. In this review, we discuss the activities of certain genes involved in the cross-talk among NK cells and breast cancer. Consequently, altering tumor immune microenvironment can make breast tumors more responsive to immunotherapy.

Isolation of Two Novel Human Anti-CTLA-4 mAbs with Intriguing Biological Properties on Tumor and NK Cells

The cytotoxic T lymphocyte-antigen 4 (CTLA-4) has been considered an IC exclusively expressed on T cells, where it counteracts the co-stimulatory CD28 receptor, by competing for its binding to CD-80 and CD-86. We recently found that it is expressed also on tumor and NK cells, suggesting other possible unknown roles of CTLA-4. To shed light on these novel aspects of CTLA-4, we used Ipilimumab, the first FDA approved human antibody targeting CTLA-4, in parallel studies with two novel human mAbs we isolated by using an efficient phage display selection strategy on live activated lymphocytes and purified mouse and human CTLA-4. The selection for cross-reactive mAbs was guaranteed by a high throughput sequencing to identify the sequences commonly enriched by two parallel pannings on human and mouse CTLA-4. Two isolated antibodies were found to bind with high affinity to both human and mouse CTLA-4 and lymphocytes, showing nanomolar or sub-nanomolar Kd values. They were able to kill Treg cells by ADCC, and to activate both human and mouse PBMCs, by strongly increasing cytokines secretion. Interestingly, they activated NK cells, exhibited cytotoxicity against cancer cells by inducing ADCC and inhibited tumor cell growth by affecting CTLA-4 downstream pathways in a similar fashion to CD-80 and CD-86 ligands and differently from Ipilimumab. Moreover, the novel mAbs showed a reduced ability to interfere in the binding of CD-80 ligands to CTLA-4 on T cells with respect to Ipilimumab, suggesting that they could allow for anti-tumor effects without the irAEs associated with the potent antagonistic activity of Ipilimumab.

Biological Landscape of Triple Negative Breast Cancers Expressing CTLA-4

Patients with triple-negative breast cancer (TNBC) have a poor prognosis, partly because of the absence of targeted therapies. Recognition of the key role of immune responses against cancer has allowed the advent of immunotherapy, focused on the inhibition of negative immune checkpoints, such as CTLA-4. CTLA-4 is also expressed in some cancer cells, but its activity in tumor cells is not completely understood. Thus, the aim of the present work was to determine the biological landscape and functions of CTLA-4 expressed in TNBC cells through preclinical and in silico analysis. Exploration of CTLA-4 by immunohistochemistry in 50 TNBC tumors revealed membrane and cytoplasmic expression at different intensities. Preclinical experiments, using TNBC cell lines, showed that stimulation of CTLA-4 with CD80 enhances activation of the ERK1/2 signaling pathway, while CTLA-4 blockade by Ipilimumab induces the activation of AKT and reduces cell proliferation in vitro. We then developed an analytic pipeline to define the effects of CTLA-4 in available public data that allowed us to identify four distinct tumor clusters associated with CTLA-4 activation, which are characterized by enrichment of distinctive pathways associated with cell adhesion, MAPK signaling, TGF-ß, VEGF, TNF-α, drug metabolism, ion and amino acid transport, and KRAS signaling, among others. In addition, blockade of CTLA-4 induced increased secretion of IL-2 by tumor cells, suggesting that the receptor regulates cellular functions that may impact the immune microenvironment. This is relevant because a deep characterization of immune infiltrate, conducted using public data to estimate the abundancies of immune-cell types, showed that CTLA-4-activated-like tumors present a conditional immune state similar to an escape phenotype exploited by cancer cells. Finally, by interrogating transcriptional predictors of immunotherapy response, we defined that CTLA-4 activation correlates with high immune scores related to good clinical predicted responses to anti-CTLA-4 therapy. This work sheds new light on the roles of activated CLTA-4 in the tumor compartment and suggests an important interplay between tumor CLTA-4-activated portraits and immune-infiltrating cell populations.

Prognostic impacts of tumoral expression and serum levels of PD-L1 and CTLA-4 in colorectal cancer patients

BACKGROUND

Programmed cell death ligand-1 (PD-L1) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) play a pivotal role in cancer immunotherapy. Each of these molecules has a membrane-bound receptor form (mPD-L1/mCTLA-4) and a soluble form (sPD-L1/sCTLA-4). However, these prognostic impacts in colorectal cancer (CRC) remain unclear.

METHODS

We immunohistochemically scored tumoral mPD-L1/mCTLA-4 expression and quantified preoperative circulating sPD-L1/sCTLA-4 levels using matched serum specimens from 131 patients with pStage I-III CRC. We also examined the association between these statuses and tumor infiltrating lymphocytes (TILs) in these patients.

RESULTS

Elevated levels of mPD-L1, mCTLA-4, sPD-L1 and sCTLA-4 were significantly correlated with poor overall survival (OS) and disease-free survival (DFS). Co-high expression of tumoral mPD-L1 and mCTLA-4 or co-elevated levels of serum sPD-L1 and sCTLA-4 were strongly correlated with poor OS and DFS. Multivariate analysis revealed that both statuses were negative independent prognostic factors for OS [hazard ratio (HR) 3.86, 95% confidence interval (95% CI) 1.71-8.51, p = 0.001; HR 5.72, 95% CI 1.87-14.54, p = 0.004, respectively] and DFS (HR 2.53, 95% CI 1.23-4.95, p = 0.01; HR 6.88, 95% CI 2.42-17.13, p = 0.0008, respectively). Although low expression of tumoral mCTLA-4 was significantly correlated with increased CD8(+) TILs, there was no correlation in any other combination.

CONCLUSIONS

We verified the prognostic impacts of mPD-L1, mCTLA-4, sPD-L1 and sCTLA-4 in pStage I-III CRC patients. Dual evaluation of immune checkpoint molecules in primary tissues or preoperative serum could identify a patient population with poor prognosis in these patients.

Tumor microenvironment-related dendritic cell deficiency: a target to enhance tumor immunotherapy

Dendritic cells (DCs), as specialized antigen-presenting cells, are essential for the initiation of specific T cell responses in innate antitumor immunity and, in certain cases, support humoral responses to inhibit tumor development. Mounting evidence suggests that the DC system displays a broad spectrum of dysfunctional status in the tumor microenvironment (TME), which ultimately affects antitumor immune responses. DC-based therapy can restore the function of DCs in the TME, thus showing a promising potential in tumor therapy. In this review, we provide an overview of the DC deficiency caused by various factors in the TME and discuss proposed strategies to reverse DC deficiency and the applications of novel combinatorial DC-based therapy for immune normalization of the tumor.

microRNAs in the Antitumor Immune Response and in Bone Metastasis of Breast Cancer: From Biological Mechanisms to Therapeutics

Breast cancer is the most common type of cancer in women, and the occurrence of metastasis drastically worsens the prognosis and reduces overall survival. Understanding the biological mechanisms that regulate the transformation of malignant cells, the consequent metastatic transformation, and the immune surveillance in the tumor progression would contribute to the development of more effective and targeted treatments. In this context, microRNAs (miRNAs) have proven to be key regulators of the tumor-immune cells crosstalk for the hijack of the immunosurveillance to promote tumor cells immune escape and cancer progression, as well as modulators of the metastasis formation process, ranging from the preparation of the metastatic site to the transformation into the migrating phenotype of tumor cells. In particular, their deregulated expression has been linked to the aberrant expression of oncogenes and tumor suppressor genes to promote tumorigenesis. This review aims at summarizing the role and functions of miRNAs involved in antitumor immune response and in the metastasis formation process in breast cancer. Additionally, miRNAs are promising targets for gene therapy as their modulation has the potential to support or inhibit specific mechanisms to negatively affect tumorigenesis. With this perspective, the most recent strategies developed for miRNA-based therapeutics are illustrated.

Ipilimumab and Its Derived EGFR Aptamer-Based Conjugate Induce Efficient NK Cell Activation against Cancer Cells

The immune checkpoint CTLA-4 (cytotoxic T-lymphocyte-antigen 4), which inhibits the co-stimulatory CD28 signal on T cells, has been recently found expressed on other cell populations, such as tumor and natural killer (NK) cells. We tested for the first time the effects of ipilimumab, the human anti-CTLA4 mAb in clinical use, on these cells and found that it inhibits the growth of tumor cells expressing CTLA-4 also in the absence of lymphocytes, and efficiently activates NK cells, thus suggesting an important unexplored role of NK cells in ipilimumab-modulated immune responses. Interestingly, the epidermal growth factor receptor (EGFR) has been shown to play a key role in tumor cell escape from immune surveillance, and in cytotoxic T lymphocyte inhibition. Thus, we tested combinatorial treatments of ipilimumab with an anti-EGFR aptamer endowed with anti-tumor activity, and constructed for the first time a novel bispecific immunoconjugate, made up of these two compounds. The novel immunoconjugate binds to the target cells, induces the activation of lymphocytes, including NK cells, and inhibits the growth of tumor target cells more efficiently than the parental compounds, by strongly enhancing the cytotoxic activity of both human peripheral blood mononuclear cells and NK cells against tumor cells.

Cell-mediated immune resistance in cancer

The genetic and epigenetic aberrations that underlie immune resistance lead to tumors that are refractory to clinically established and experimental immunotherapies, including monoclonal antibodies and T cell-based therapies. From various forms of cytotoxic T cells to small molecule inhibitors that revamp the tumor microenvironment, these therapies have demonstrated notable responses in cancer models and a resistant subset of cancer patients, used both alone and in combination. However, even current approaches, such as those targeting checkpoint molecules, tumor ligands, and involving gene-related therapies, present a challenge in non-responding patients. In this perspective, we discuss the most common mechanisms of immune resistance, including tumor heterogeneity, tumor ligand and major histocompatibility complex modulation, anti-apoptotic pathways, checkpoint inhibitory ligands, immunosuppressive cells and factors in the tumor microenvironment, and activation-induced cell death. In addition, we discuss the strategies designed to circumvent these resistance pathways to showcase the potential of emerging technologies in battling the rise of resistance.

Tumor microenvironmental influences on dendritic cell and T cell function: A focus on clinically relevant immunologic and metabolic checkpoints

Cancer immunotherapy is fast becoming one of the most promising means of treating malignant disease. Cancer vaccines, adoptive cell transfer therapies, and immune checkpoint blockade have all shown varying levels of success in the clinical management of several cancer types in recent years. However, despite the clinical benefits often achieved by these regimens, an ongoing problem for many patients is the inherent or acquired resistance of their cancer to immunotherapy. It is now appreciated that dendritic cells and T lymphocytes both play key roles in antitumor immune responses and that the tumor microenvironment presents a number of barriers to the function of these cells that can ultimately limit the success of immunotherapy. In particular, the engagement of several immunologic and metabolic checkpoints within the hostile tumor microenvironment can severely compromise the antitumor functions of these important immune populations. This review highlights work from both preclinical and clinical studies that has shaped our understanding of the tumor microenvironment and its influence on dendritic cell and T cell function. It focuses on clinically relevant targeted and immunotherapeutic strategies that have emerged from these studies in an effort to prevent or overcome immune subversion within the tumor microenvironment. Emphasis is also placed on the potential of next-generation combinatorial regimens that target metabolic and immunologic impediments to dendritic cell and T lymphocyte function as strategies to improve antitumor immune reactivity and the clinical outcome of cancer immunotherapy going forward.

Immunopathogenesis of Immune Checkpoint Inhibitor-Related Adverse Events: Roles of the Intestinal Microbiome and Th17 Cells

The advent of novel, innovative, and effective anti-cancer immunotherapies has engendered an era of renewed optimism among cancer specialists and their patients. Foremost among these successful immunotherapies are monoclonal antibodies (MAbs) which target immune checkpoint inhibitor (ICI) molecules, most prominently cytotoxic T-lymphocyte-associated protein (CTLA-4) and programmed cell death protein-1 (PD-1) and its major ligand, PD-L1. These immunotherapeutic agents are, however, often associated with the occurrence of immune-mediated toxicities known as immune-related adverse events (IRAEs). The incidence of severe toxicities increases substantially when these agents are used together, particularly with CTLA-4 in combination with PD-1 or PD-L1 antagonists. Accordingly, dissociating the beneficial anti-tumor therapeutic activity of these agents from the emergence of IRAEs represents a significant challenge to attaining the optimum efficacy of ICI-targeted immunotherapy of cancer. This situation is compounded by an increasing awareness, possibly unsurprising, that both the beneficial and harmful effects of ICI-targeted therapies appear to result from an over-reactive immune system. Nevertheless, this challenge may not be insurmountable. This contention is based on acquisition of recent insights into the role of the gut microbiome and its products as determinants of the efficacy of ICI-targeted immunotherapy, as well as an increasing realization of the enigmatic involvement of Th17 cells in both anti-tumor activity and the pathogenesis of some types of IRAEs. Evidence linking the beneficial and harmful activities of ICI-targeted immunotherapy, recent mechanistic insights focusing on the gut microbiome and Th17 cells, as well as strategies to attenuate IRAEs in the setting of retention of therapeutic activity, therefore represent the major thrusts of this review.

OX40 (CD134) and OX40 ligand, important immune checkpoints in cancer

Immunotherapy has shown promising results in cancer treatment. Research shows that most patients might be resistant to these therapies. So, new immune therapies are needed. OX40 (CD134) and OX40 ligand (OX40L), costimulatory molecules, express on different types of immune cells. The interaction between OX40 and OX40L (OX40/OX40L) induces the expansion and proliferation of T cells and decreases the immunosuppression of regulatory T (Treg) cells to enhance the immune response to the specific antigen. For the important role OX40 takes in the process of immunity, many clinical trials are focusing on OX40 to find out whether it may have active effects in clinical cancer treatment. The results of clinical trials are still not enough. So, we reviewed the OX40 and its ligand (OX40L) function in cancer, clinical trials with OX40/OX40L and the correlation between OX40/OX40L and other immune checkpoints to add more ideas to tumor feasible treatment.