Inverse correlation of HER2 with MHC class I expression on oesophageal squamous cell carcinoma

Expression and correlation of PD-L1 and HER2 in oesophageal squamous cell carcinoma

AIMS

In recent years, patients with programmed cell death-Ligand 1 (PD-L1)-positive oesophageal squamous cell carcinoma (OSCC) have been able to benefit from immunotherapy. However, method for improving the treatment efficacy of PD-L1-positive patients is a problem that needs further consideration. Studies on the relationship between human epidermal growth factor receptor 2 (HER2) and PD-L1 expression have recently been reported in certain cancers, but the relationship between PD-L1 and HER2 expression in OSCC is still unclear.

METHODS

A total of 263 patients with OSCC were included in the study. PD-L1 protein expression and HER2 protein expression were analysed by immunohistochemistry (IHC), and fluorescence in situ hybridisation (FISH) was performed to assess HER2 gene amplification. The significance of differences between HER2 status, PD-L1 status and clinicopathological parameters was assessed. The relationship between PD-L1 status and HER2 status was examined.

RESULTS

Of the 263 OSCC cases, the PD-L1-positive expression rates were 39.2% and 77.2% in OSCC for Tumour Proportion Score (TPS) and Combined Positive Score (CPS), respectively, and PD-L1 expression was associated with the degree of tumour differentiation. The HER2 expression was positive in 24% (63/263) of cases based on IHC and FISH. HER2 expression was not significantly associated with clinicopathological characteristics. PD-L1 TPS expression and CPS expression were significantly positively correlated with HER2 expression in OSCC.

CONCLUSIONS

PD-L1 expression was significantly positively correlated with HER2 expression in OSCC. The results provide valuable insight for the future application of HER2-targeted therapy combined with immunotherapy in OSCC.

HER2 Alterations in Non-Small Cell Lung Cancer: Biologico-Clinical Consequences and Interest in Therapeutic Strategies

Lung cancer stands as the first cause of death by cancer in the world. Despite the improvement in patients' outcomes in the past decades through the development of personalized medicine approaches, a substantial portion of patients remains ineligible for targeted therapies due to the lack of a "druggable" molecular target. HER2, a receptor tyrosine kinase member of the EGFR/ErbB family, is known to show oncogenic properties. In this review, we focus on the different HER2 dysregulation mechanisms that have been observed in non-small cell lung cancer (NSCLC): gene mutation, gene amplification, protein overexpression and protein hyper-phosphorylation, the latter suggesting that HER2 dysregulation can occur independently of any molecular aberration. These HER2 alterations inevitably have consequences on tumor biology. Here, we discuss how they are not only involved in abnormal proliferation and survival of cancer cells but also potentially in increased angiogenic properties, mesenchymal features and tumor immune escape. Finally, we review the impact of these HER2 alterations in various therapeutic approaches. While standard chemotherapy and groundbreaking immunotherapy seem rather ineffective for HER2-altered NSCLCs, the development of HER2-targeted therapies such as tyrosine kinase inhibitors, anti-HER2 antibodies and especially antibody-drug conjugates could provide new hopes for patients.

Preclinical and Clinical Observations Implying Combination Therapy to Enhance the Efficacy of the Her-2/neu B-Cell Peptide-Based Vaccine HER-Vaxx and to Prevent Immune Evasion

Her-2/neu-targeting therapy by passive application with trastuzumab is associated with acquired resistance and subsequent metastasis development, which is attributed to the upregulation of tumoral PD-L1 expression and the downregulation of Her-2/neu. We aimed to investigate this association, following active immunization with our recently constructed B-cell peptide-based Her-2/neu vaccines in both preclinical and clinical settings. Immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and combined positive score (CPS) were applied to evaluate Her-2/neu and PD-L1 expression using a murine syngeneic tumor model for Her-2/neu lung metastases and tumor biopsies from a gastric cancer patient with disease progression. A significant and concomitant reduction in Her-2/neu and the upregulation of PD-L1 expression was observed in vaccinated mice after 45 days, but not after 30 days, of metastases development. A significant increase in tumor-infiltrating B lymphocytes was observed at both time points. The downregulation of Her-2/neu and the upregulation of PD-L1 were observed in a patient's primary tumor at the disease progression time point but not prior to vaccination (Her-2/neu IHC: 3 to 0, FISH: 4.98 to 1.63; PD-L1 CPS: 0% to 5%). Our results further underline the need for combination therapy by targeting PD-L1 to prevent metastasis formation and immune evasion of Her-2/neu-positive and PD-L1-negative tumor cells.

Cancer cell-intrinsic mechanisms driving acquired immune tolerance

Immune evasion is a hallmark of cancer, enabling tumors to survive contact with the host immune system and evade the cycle of immune recognition and destruction. Here, we review the current understanding of the cancer cell-intrinsic factors driving immune evasion. We focus on T cells as key effectors of anti-cancer immunity and argue that cancer cells evade immune destruction by gaining control over pathways that usually serve to maintain physiological tolerance to self. Using this framework, we place recent mechanistic advances in the understanding of cancer immune evasion into broad categories of control over T cell localization, antigen recognition, and acquisition of optimal effector function. We discuss the redundancy in the pathways involved and identify knowledge gaps that must be overcome to better target immune evasion, including the need for better, routinely available tools that incorporate the growing understanding of evasion mechanisms to stratify patients for therapy and trials.

Mechanisms driving the immunoregulatory function of cancer cells

Tumours display an astonishing variation in the spatial distribution, composition and activation state of immune cells, which impacts their progression and response to immunotherapy. Shedding light on the mechanisms that govern the diversity and function of immune cells in the tumour microenvironment will pave the way for the development of more tailored immunomodulatory strategies for the benefit of patients with cancer. Cancer cells, by virtue of their paracrine and juxtacrine communication mechanisms, are key contributors to intertumour heterogeneity in immune contextures. In this Review, we discuss how cancer cell-intrinsic features, including (epi)genetic aberrations, signalling pathway deregulation and altered metabolism, play a key role in orchestrating the composition and functional state of the immune landscape, and influence the therapeutic benefit of immunomodulatory strategies. Moreover, we highlight how targeting cancer cell-intrinsic parameters or their downstream immunoregulatory pathways is a viable strategy to manipulate the tumour immune milieu in favour of antitumour immunity.

Single-cell mapping of N6-methyladenosine in esophageal squamous cell carcinoma and exploration of the risk model for immune infiltration

BACKGROUND

N6-methyladenosine (m6A) modification is the most common RNA modification, but its potential role in the development of esophageal cancer and its specific mechanisms still need to be further investigated.

METHODS

Bulk RNA-seq of 174 patients with esophageal squamous carcinoma from the TCGA-ESCC cohort, GSE53625, and single-cell sequencing data from patients with esophageal squamous carcinoma from GSE188900 were included in this study. Single-cell analysis of scRNA-seq data from GSE188900 of 4 esophageal squamous carcinoma samples and calculation of PROGENy scores. Demonstrate the scoring of tumor-associated pathways for different cell populations. Cell Chat was calculated for cell populations. thereafter, m6A-related differential genes were sought and risk models were constructed to analyze the relevant biological functions and impact pathways of potential m6A genes and their impact on immune infiltration and tumor treatment sensitivity in ESCC was investigated.

RESULTS

By umap downscaling analysis, ESCC single-cell data were labelled into clusters of seven immune cell classes. Cellchat analysis showed that the network interactions of four signaling pathways, MIF, AFF, FN1 and CD99, all showed different cell type interactions. The prognostic risk model constructed by screening for m6A-related differential genes was of significant value in the prognostic stratification of ESCC patients and had a significant impact on immune infiltration and chemotherapy sensitivity in ESCC patients.

CONCLUSION

In our study, we explored a blueprint for the distribution of single cells in ESCC based on m6A methylation and constructed a risk model for immune infiltration analysis and tumor efficacy stratification in ESCC on this basis. This may provide important potential guidance for revealing the role of m6A in immune escape and treatment resistance in esophageal cancer.

Active immunization with a Her-2/neu-targeting Multi-peptide B cell vaccine prevents lung metastases formation from Her-2/neu breast cancer in a mouse model

•

Trastuzumab and Pertuzumab extend the overall survival of breast cancer patients.

•

Unlike monoclonal antibodies B cell peptides induce immunological memory.

•

A multi-peptide B cell-based vaccination prevents Her-2/neu lung metastasis in mice.

•

The vaccination results in Her-2/neu-negative tumors, with increased PD-L1 expression.

•

A combination/alternating therapy for a total remission of metastases is suggested.

In pre-clinical and clinical settings, active immunization with a Her-2/neu vaccine (HerVaxx), comprising B-cell peptide from Trastuzumab binding site, has been shown to reduce primary tumor growth via induction of polyclonal anti-tumor immune responses and immunological memory. Here, we tested the combination of HerVaxx and the recently identified B-cell epitope/mimotope of Pertuzumab, i.e. a multi-peptide B-cell vaccine, for preventing Her-2/neu lung metastases formation in a mouse model. Active immunization with the multi-peptide vaccine was associated with decreased lung weights, and histological evaluation of the lungs showed that the significant reduction of lung metastases was associated with increased CD4⁺ and CD8⁺ T cell infiltration. Notably, along with the overall reduction of lungs weights and Her-2 positive metastases, a formation of Her-2/neu-negative tumors but with increased PD-L1 expression was observed. Our results might pave the way to a multi-peptide B-cell Her-2/neu vaccine serving as a secondary intervention in adjuvant settings to prevent tumor recurrence and spread. Moreover, combination therapy targeting PD-L1 may result in total remission of metastases. Such a therapy may be used clinically to alternately target Her-2/neu and PD-L1 in metastatic breast cancer.

Downregulation of PD‐L1 and HLA‐I in non‐small cell lung cancer with ALK fusion

Background

Early clinical trials indicate that patients with anaplastic lymphoma kinase (ALK)‐driven non‐small cell lung cancer (NSCLC) have a lower response rate to programmed cell death protein 1 (PD‐1) antibody therapy. However, the specific mechanism underlying this remains unclear. To further explore the characteristics of the tumor microenvironment and determine the potential mechanism of immunotherapy resistance in patients with ALK, we selected another important immune‐related molecule, major histocompatibility complex class I (HLA‐I), as the focus of our study.

Methods

We collected the biopsy samples of 140 patients with NSCLC. The number of CD8+ T cells and HLA‐I/programmed cell death 1 ligand 1 (PD‐L1) expression were determined by immunohistochemistry. Disease‐free survival (DFS) and overall survival (OS) were analyzed using the Kaplan–Meier method, and their relationship with patient clinical characteristics analyzed using Cox proportional hazards regression. In addition, we treated ALK‐positive lung cancer cells with ALK inhibitors in vitro to observe changes of HLA‐I.

Results

ALK positivity was associated with low membrane PD‐L1 and HLA‐I expression. However, these two indicators were not associated with the prognosis of patients with stage I–IIIa NSCLC. Inhibition of ALK could upregulate HLA‐I membrane expression to a certain extent.

Conclusion

Patients with ALK fusion showed downregulation of PD‐L1 and HLA‐I expression on the tumor cell membrane. Inhibition of ALK and its downstream signaling pathway can reverse it. These results suggest that the appropriate combination therapy should be considered for patients with ALK fusion and using targeted therapy at the proper time may increase patient benefits.

HLA class I antigen processing machinery defects in antitumor immunity and immunotherapy

Human leukocyte antigen (HLA) class I antigen-processing machinery (APM) plays a crucial role in the synthesis and expression of HLA class I tumor antigen-derived peptide complexes; the latter mediate the recognition and elimination of malignant cells by cognate T cells. Defects in HLA class I APM component expression and/or function are frequently found in cancer cells, providing them with an immune escape mechanism that has relevance in the clinical course of the disease and in the response to T-cell-based immunotherapy. The majority of HLA class I APM defects (>75%) are caused by epigenetic mechanisms or dysregulated signaling and therefore can be corrected by strategies that counteract the underlying mechanisms. Their application in oncology is likely to improve responses to T-cell-based immunotherapies, including checkpoint inhibition.

The effects of T-DXd on the expression of HLA class I and chemokines CXCL9/10/11 in HER2-overexpressing gastric cancer cells

Trastuzumab deruxtecan (T-DXd), a HER2-targeting antibody–drug conjugate with a topoisomerase I inhibitor deruxtecan (DXd), exhibits an excellent anti-tumor effect in previously treated HER2-positive tumors. A recent study demonstrated that T-DXd not only suppressed tumor growth but also enhanced anti-tumor immunity through increasing the number of tumor-infiltrating CD8⁺ T cells and enhancement of major-histocompatibility-complex class I expression on tumor cells in a mouse model. However, the effect of T-DXd on anti-tumor immune responses in human cancers is largely unknown. We investigated the effect of T-DXd on the expression of HLA class I and CXCL9/10/11, T-cell chemoattractants, in HER2-positive human gastric cancer (GC) cells. We found that T-DXd significantly inhibited GC cell proliferation in a HER2-dependent manner, while it slightly increased the expression of HLA class I in HER2-positive GC cells. Moreover, we revealed that T-DXd significantly induced mRNA expression of CXCL9/10/11 in HER2-positive GC cells. T-DXd-triggered up-regulation of these chemokines was mediated through the activation of DNA damage signaling pathways. These results suggest that T-DXd triggers anti-tumor immune responses at least in part through induction of the expression of HLA class I and CXCL9/10/11 on HER2-positive GC cells, resulting in the enhancement of anti-tumor immunity in human GC.

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

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

Cancer Immune Evasion Through Loss of MHC Class I Antigen Presentation

Major histocompatibility class I (MHC I) molecules bind peptides derived from a cell's expressed genes and then transport and display this antigenic information on the cell surface. This allows CD8 T cells to identify pathological cells that are synthesizing abnormal proteins, such as cancers that are expressing mutated proteins. In order for many cancers to arise and progress, they need to evolve mechanisms to avoid elimination by CD8 T cells. MHC I molecules are not essential for cell survival and therefore one mechanism by which cancers can evade immune control is by losing MHC I antigen presentation machinery (APM). Not only will this impair the ability of natural immune responses to control cancers, but also frustrate immunotherapies that work by re-invigorating anti-tumor CD8 T cells, such as checkpoint blockade. Here we review the evidence that loss of MHC I antigen presentation is a frequent occurrence in many cancers. We discuss new insights into some common underlying mechanisms through which some cancers inactivate the MHC I pathway and consider some possible strategies to overcome this limitation in ways that could restore immune control of tumors and improve immunotherapy.

A Functional Screening Strategy for Engineering Chimeric Antigen Receptors with Reduced On-Target, Off-Tumor Activation

In recent years, chimeric antigen receptor (CAR) T cell cancer immunotherapies have advanced substantially in the clinic. However, challenges related to safety persist; one major concern occurs when CARs trigger a response to antigen present on healthy cells (on-target, off-tumor response). A strategy to ameliorate this relies on the complex relationship between receptor affinity and signaling, such that one can engineer a CAR that is only activated by tumor cells expressing high antigen levels. Here, we developed a CAR T cell display platform with stable genomic expression and rapid functional screening based on interleukin-2 signaling. Starting with a CAR with high affinity toward its target antigen, we combined CRISPR-Cas9 genome editing and deep mutational scanning to generate a library of antigen-binding domain variants. This library was subjected to multiple rounds of selection based on either antigen binding or cell signaling. Deep sequencing of the resulting libraries and a comparative analysis revealed the enrichment and depletion of specific variants from which we selected CARs that were selectively activated by tumor cells based on antigen expression levels. Our platform demonstrates how directed evolution based on functional screening and deep sequencing-guided selection can be combined to enhance the selectivity and safety of CARs.

Investigation of HER-2 Expression an Its Correlation with Clinicopathological Parameters and Overall Survival of Esophageal Squamous Cell Carcinoma Patients

Background & Objective:

Human epidermal growth factor receptor 2 (HER-2) exhibits a vast range of expression in esophageal squamous cell carcinoma (ESCC) patients as a biomarker. This paper aimed to investigate HER-2 expression and clinicopathological parameters of esophageal SCC.

Methods:

HER-2 expression was assessed in 102 ESCC patients by immunohistochemistry. The HER-2 staining intensity , according to the Gastric HER2 Biomarker1.0.0.1 version of the college of American pathologists (CAP) protocol for gastric and gastroesophageal junction cancers, was graded as 0 (no reactivity in any of the cancer cells’ membranes); 1+ (pale or hardly noticeable reactivity in the membrane of cancer cells’ cluster [≥ 5 neoplastic cells] regardless of the positive cancer cells’ percentage); 2+ (weak-to-moderate complete, basolateral, or lateral membranous reactivity regardless of the positive cancer cells’ percentage); and 3+ ( strong complete, basolateral, or lateral reactivity in the membrane of the cancer cell cluster regardless of the positive cancer cells’ percentage).In this regard, 3+ scored samples were considered as positive. If HER-2 expression was scored 2+, an additional fluorescence in situ hybridization (FISH) was performed. Fisher's exact test was employed for investigating the correlation of HER-2 expression status with patients’ clinicopathological characteristics (including age, gender, tumor location, stage, grade, infiltration level, venous invasion, lymphatic invasion, and tumor recurrence). Kaplan-Meier analysis was done for the patients’ survival assessments.

Results:

Five patients (~5%) were HER-2 positive and no significant association was observed between HER-2 expression and clinicopathological properties. In addition, HER-2 expression status exhibited no significant association with the patients’ overall survival (P=0.9299).

Conclusion:

HER-2 is not a suitable prognostic biomarker for Iranian ESCC patients.

MHC Class I Downregulation in Cancer: Underlying Mechanisms and Potential Targets for Cancer Immunotherapy

In recent years, major advances have been made in cancer immunotherapy. This has led to significant improvement in prognosis of cancer patients, especially in the hematological setting. Nonetheless, translation of these successes to solid tumors was found difficult. One major mechanism through which solid tumors can avoid anti-tumor immunity is the downregulation of major histocompatibility complex class I (MHC-I), which causes reduced recognition by- and cytotoxicity of CD8⁺ T-cells. Downregulation of MHC-I has been described in 40-90% of human tumors, often correlating with worse prognosis. Epigenetic and (post-)transcriptional dysregulations relevant in the stabilization of NFkB, IRFs, and NLRC5 are often responsible for MHC-I downregulation in cancer. The intrinsic reversible nature of these dysregulations provides an opportunity to restore MHC-I expression and facilitate adaptive anti-tumor immunity. In this review, we provide an overview of the mechanisms underlying reversible MHC-I downregulation and describe potential strategies to counteract this reduction in MHC-I antigen presentation in cancer.

In vitro cytotoxic effect of Trastuzumab in combination with Pertuzumab in breast cancer cells is improved by interleukin-2 activated NK cells

Targeting erb-b2 receptor tyrosine kinase 2 (ERBB2) using the combination of Trastuzumab and Pertuzumab has demonstrated promising results in breast cancer therapy. It has further been revealed that interleukin-2 (IL-2) can activate Natural Killer cells (NK cells) and elevate their cytotoxic potency against tumor cells. In this study, we explored the cytotoxic effect of recombinant human IL-2 in combination with Trastuzumab and Pertuzumab on the ERBB2 positive (SK-BR-3) and negative (MDA-MB-231) breast cancer cell lines. The cytotoxicity level of IL-2 activated NK cells (approximately 75%) were significantly higher than untreated cells (approximately 55%) in the presence of Trastuzumab and Pertuzumab against SK-BR-3 cells, while no difference was observed in the case of MDA-MB-231 cells (about 15%).

Biglycan-mediated upregulation of MHC class I expression in HER-2/neu-transformed cells

The extracellular matrix protein biglycan (BGN) has oncogenic or tumor suppressive potential depending on the cellular origin. HER-2/neu overexpression in murine fibroblasts and human model systems is inversely correlated with BGN expression. Upon its restoration BGN^high HER-2/neu⁺ fibroblasts were less tumorigenic in immune competent mice when compared to BGN^low/neg HER-2/neu⁺ cells, which was associated with enhanced immune cell responses and higher frequencies of immune effector cells in tumors and peripheral blood. The increased immunogenicity of BGN^high HER-2/neu⁺ fibroblasts appears to be due to upregulated MHC class I surface antigens and reduced expression levels of transforming growth factor (TGF)-β isoforms and the TGF-β receptor 1 suggesting a link between BGN, TGF-β pathway and HER-2/neu-mediated downregulation of MHC class I antigens. Treatment of BGN^low/neg HER-2/neu⁺ cells with recombinant BGN or an inhibitor of TGF-β enhanced MHC class I surface antigens in BGN^low/neg HER-2/neu-overexpressing murine fibroblasts, which was mediated by a transcriptional upregulation of major MHC class I antigen processing components. Furthermore, BGN expression in HER-2/neu⁺ cells was accompanied by an increased expression of the proteoglycan decorin (DCN). Since recombinant DCN also elevated MHC class I surface expression in BGN^low/neg HER-2/neu⁺ cells, both proteoglycans might act synergistically. This was in accordance with in silico analyses of mRNA data obtained from The Cancer Genome Atlas (TCGA) dataset available for breast cancer (BC) patients. Thus, our data provide for the first time evidence that proteoglycan signatures are modulated by HER-2/neu and linked to MHC class I-mediated immune escape associated with an altered TGF-β pathway.

PD-L1 overexpression is partially regulated by EGFR/HER2 signaling and associated with poor prognosis in patients with non-small-cell lung cancer

Immunocheckpoint inhibitors targeting the programmed cell death-1 (PD-1) and PD-1 ligand 1 (PD-L1) axis have shown promising results in patients with non-small-cell lung cancer (NSCLC). Recent research has shown that epidermal growth factor receptor (EGFR) signaling affects PD-L1 expression in NSCLC cells; however, the mechanism regulating PD-L1 expression in tumor cells remains unclear. Using immunohistochemistry, we evaluated the impact of expression of PD-L1 and EGF family receptors EGFR and human epidermal growth factor receptor 2 (HER2) in tumor cells from 91 patients with pathological Stage IA-IIIA NSCLC. Overexpression of PD-L1 was observed in 14% of the resected tumors, and associated with poor recurrence-free survival (p = 0.021) and overall survival (p = 0.033). PD-L1 expression is positively correlated with EGFR expression and inversely correlated with HER2. NSCLC cell lines were treated in vitro with the EGFR ligand EGF with or without inhibition of EGFR or HER2, after which PD-L1 expression was evaluated using flow cytometry. Consistent with previous reports, PD-L1 expression was clearly enhanced by EGF. EGFR-tyrosine kinase inhibitors or EGFR small interfering RNA (siRNA) blocked EGF-induced PD-L1 overexpression in NSCLC cell lines, but HER2 siRNA did not. Moreover, our findings suggest that PD-L1 expression could be partially regulated via the PI3K/AKT and JAK/STAT pathways. We conclude that PD-L1 overexpression is associated with poor prognosis and is positively correlated with EGFR expression but inversely correlated with HER2 expression in NSCLC. We also showed that EGFR and HER2 have different effects on EGF-induced PD-L1 expression in NSCLC cell lines.

Inhibition of MHC-I by Brucella abortus is an early event during infection and involves EGFR pathway

Brucella abortus is able to persist inside the host despite the development of potent CD8⁺ T-cell responses. We have recently reported the ability of B. abortus to inhibit the interferon-γ-induced major histocompatibility complex (MHC)-I cell surface expression on human monocytes. This phenomenon was due to the B. abortus-mediated retention of MHC-I molecules within the Golgi apparatus and was dependent on bacterial viability. However, the implications of bacterial virulence or replicative capacity and the signaling pathways remained unknown. Here we demonstrated that the B. abortus mutant strains RB51 and virB10^- are able to inhibit MHC-I expression in the same manner as wild-type B. abortus, even though they are unable to persist inside human monocytes for a long period of time. Consistent with this, the phenomenon was triggered early in time and could be observed at 8 h postinfection. At 24 and 48 h, it was even stronger. Regarding the signaling pathway, targeting epidermal growth factor (EGF) receptor (EGFR), ErbB2 (HER2) or inhibition of tumor necrosis factor-α-converting enzyme, one of the enzymes which generates soluble EGF-like ligands, resulted in partial recovery of MHC-I surface expression. Moreover, recombinant EGF and transforming growth factor-α as well as the combination of both were also able to reproduce the B. abortus-induced MHC-I downmodulation. Finally, when infection was performed in the presence of an extracellular signal-regulated kinase 1/2 (Erk1/2) inhibitor, MHC-I surface expression was significantly recovered. Overall, these results describe how B. abortus evades CD8⁺ T-cell responses early during infection and exploits the EGFR-ERK signaling pathway to escape from the immune system and favor chronicity.

Turning tumour cells into antigen presenting cells: The next step to improve cancer immunotherapy?

Downregulation/loss of the antigen presentation is a major immune escape mechanism in cancer. It allows tumour cells to become 'invisible' and avoid immune attack by antitumour T cells. In tumour harbouring properties of professional antigen presenting cells (i.e. tumour B cells in lymphoma), downregulation/loss of the antigen presentation may also prevent direct priming of naïve T cells by tumour cells. Here, we review treatments that may induce/restore antigen presentation by the tumour cells. These treatments may increase the generation of antitumour T cells and/or their capacity to recognise and eliminate tumour cells. By forcing tumour cells to present their antigens, these treatments may sensitise patients to T cell-based immunotherapies, including checkpoint inhibitors.

The current status of checkpoint inhibitors in metastatic bladder cancer

For many decades, no significant improvements could be achieved to prolong the survival in metastatic bladder cancer. Recently, systemic immunotherapy with checkpoint inhibitors (anti-PD-L1/anti-CTLA-4) has been introduced as a novel treatment modality for patients with metastatic bladder cancer. We conducted a systematic review according to the PRISMA statement for data published on the clinical efficacy of checkpoint inhibitors in metastatic bladder cancer. Clinical efficacy of anti PD-L1 therapy was investigated in prospective trials in a total of 155 patients. Patients with positive expression for PD-L1 tended towards better overall response rates (ORR) compared to those with negative expression (34/76 vs 10/73, 45 vs 14 %; p = 0.21). Among patients with PD-L1 positive tumors, those with non-visceral metastases exhibited significantly higher ORR compared to those with visceral metastases (82 vs 28 %; p = 0.001). For anti-CTLA4 therapy, there were no data retrievable on clinical efficacy. Although data on clinical efficacy of checkpoint inhibitors in metastatic bladder cancer are currently limited, the efficacy of these drugs might depend mainly on the metastatic volume and immune system integrity. Patients with PD-L1 positive tumors and non-visceral metastases seem to derive the highest benefit from therapy.

Trastuzumab upregulates expression of HLA-ABC and T cell costimulatory molecules through engagement of natural killer cells and stimulation of IFNγ secretion

It is increasingly recognized that trastuzumab, an antibody approved for treating human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer, exerts some of its antitumor effects through enhanced T cell responses. Full activation of CD8⁺ T cells requires both expression of major histocompatibility complex class I molecules (HLA-ABC) and expression of the T cell costimulatory molecule CD80 or CD86; however, the impact of trastuzumab treatment on the expression of HLA-ABC and CD80 and CD86 has not been investigated in HER2-overexpressing breast cancer cells. In this study, we found that, while there is no direct correlation between the expression of HER2 and HLA-ABC in breast cancer, knockdown of HER2 or inhibition of HER2 kinase by lapatinib downregulated HLA-ABC expression. Trastuzumab had no meaningful effects on HLA-ABC expression in HER2-overexpressing breast cancer cells in monoculture; however, treatment of such cells with trastuzumab in co-culture with human peripheral blood mononuclear cells (PBMC) significantly upregulated not only HLA-ABC expression but also CD86 expression. We showed that this upregulation was mediated by interferon gamma (IFNγ) secreted from the natural killer (NK) cells in PBMC as a result of engagement of NK cells by trastuzumab. We further confirmed this effect of trastuzumab in vivo using a mouse mammary tumor model transduced to overexpress human HER2. Together, our data provide evidence that trastuzumab upregulates expression of HLA-ABC and T cell costimulatory molecules in HER2-overexpressing breast cancer cells in the presence of PBMC, which supports the view that T-cell-mediated immune responses are involved in trastuzumab-mediated antitumor effects.

Going back to class I: MHC and immunotherapies for childhood cancer

After decades of unfulfilled promise, immunotherapies for cancer have reached a tipping point, with several FDA approved products now on the market and many more showing promise in both adult and pediatric clinical trials. Tumor cell expression of MHC class I has emerged as a potential determinant of the therapeutic success of many immunotherapy approaches. Here we review current knowledge regarding MHC class I expression in pediatric cancers including a discussion of prognostic significance, the opposing influence of MHC on T-cell versus NK-mediated therapies, and strategies to reverse or circumvent MHC down-regulation.

Expression of MHC Class I on breast cancer cells correlates inversely with HER2 expression

HER2 is a promising target for immunotherapeutic interventions with T cell-based approaches since it is amplified and overexpressed in 20–30% of breast cancers. However, several previous studies including ours showed that HER2-overexpressing tumors may escape cytotoxic T lymphocyte-mediated lysis by downregulating MHC Class I and components of the antigen-processing machinery. The aims of the present study were to analyze the relationship between HER2 and MHC Class I expression and to elucidate the mechanisms underlying MHC Class I downregulation in breast cancer. We explored expression of HER2, MHC Class I, PTEN, Ki67, estrogen and progesterone expression in 70 breast cancer patients by immunohistochemistry (IHC) and analyzed their correlation. We also explored the components of the signal transduction pathway that are involved in the regulation of MHC Class I expression using small-interfering RNAs targeting HER2 as well as an inhibitor of HER2 signaling. HER2 expression in breast cancers correlated inversely with MHC Class I expression analyzed by IHC. HER2 depletion by small-interfering RNAs resulted in MHC Class I upregulation. Moreover, MHC Class I expression on breast cancer cell lines was upregulated by PD98059, an inhibitor of mitogen-associated protein kinases, in a dose-dependent manner. Thus, agents that target the MAPK signaling pathway may increase MHC Class I expression in breast cancer cells.

Inferring alterations in cell-to-cell communication in HER2+ breast cancer using secretome profiling of three cell models

Challenges in demonstrating durable clinical responses to molecular-targeted therapies have sparked a re-emergence in viewing cancer as an evolutionary process. In somatic evolution, cellular variants are introduced through a random process of somatic mutation and are selected for improved fitness through a competition for survival. In contrast to Darwinian evolution, cellular variants that are retained may directly alter the fitness competition. If cell-to-cell communication is important for selection, the biochemical cues secreted by malignant cells that emerge should be altered to bias this fitness competition. To test this hypothesis, we compared the proteins secreted in vitro by two human HER2+ breast cancer cell lines (BT474 and SKBR3) relative to a normal human mammary epithelial cell line (184A1) using a proteomics workflow that leveraged two-dimensional gel electrophoresis (2DE) and MALDI-TOF mass spectrometry. Supported by the 2DE secretome maps and identified proteins, the two breast cancer cell lines exhibited secretome profiles that were similar to each other and, yet, were distinct from the 184A1 secretome. Using protein-protein interaction and pathway inference tools for functional annotation, the results suggest that all three cell lines secrete exosomes, as confirmed by scanning electron microscopy. Interestingly, the HER2+ breast cancer cell line exosomes are enriched in proteins involved in antigen-processing and presentation and glycolytic metabolism. These pathways are associated with two of the emerging hallmarks of cancer: evasion of tumor immunosurveillance and deregulating cellular energetics.

Induction of Wnt-inducible signaling protein-1 correlates with invasive breast cancer oncogenesis and reduced type 1 cell-mediated cytotoxic immunity: a retrospective study

Innate and type 1 cell-mediated cytotoxic immunity function as important extracellular control mechanisms that maintain cellular homeostasis. Interleukin-12 (IL12) is an important cytokine that links innate immunity with type 1 cell-mediated cytotoxic immunity. We recently observed in vitro that tumor-derived Wnt-inducible signaling protein-1 (WISP1) exerts paracrine action to suppress IL12 signaling. The objective of this retrospective study was three fold: 1) to determine whether a gene signature associated with type 1 cell-mediated cytotoxic immunity was correlated with overall survival, 2) to determine whether WISP1 expression is increased in invasive breast cancer, and 3) to determine whether a gene signature consistent with inhibition of IL12 signaling correlates with WISP1 expression. Clinical information and mRNA expression for genes associated with anti-tumor immunity were obtained from the invasive breast cancer arm of the Cancer Genome Atlas study. Patient cohorts were identified using hierarchical clustering. The immune signatures associated with the patient cohorts were interpreted using model-based inference of immune polarization. Reverse phase protein array, tissue microarray, and quantitative flow cytometry in breast cancer cell lines were used to validate observed differences in gene expression. We found that type 1 cell-mediated cytotoxic immunity was correlated with increased survival in patients with invasive breast cancer, especially in patients with invasive triple negative breast cancer. Oncogenic transformation in invasive breast cancer was associated with an increase in WISP1. The gene expression signature in invasive breast cancer was consistent with WISP1 as a paracrine inhibitor of type 1 cell-mediated immunity through inhibiting IL12 signaling and promoting type 2 immunity. Moreover, model-based inference helped identify appropriate immune signatures that can be used as design constraints in genetically engineering better pre-clinical models of breast cancer.

Effective anti-tumor immunity is proportional to the number and to the cytotoxic activity of immune cells that enter the tumor microenvironment. Recent advances in cancer immunotherapy stem from increasing the number of tumor-infiltrating immune cells by inhibiting immune checkpoints or adoptive T cell therapy. Here, we used computational methods to identify potential mechanisms present within the tumor microenvironment that limit the efficacy of anti-tumor immunity. Specifically, we found that oncogenic transformation is associated with the induction of tumor-derived biochemical cues, namely Wnt-inducible signaling protein-1, that locally suppress anti-tumor immunity. Moreover, we used model-based inference to demonstrate that a gene signature consistent with effective type 1 cell-mediated cytotoxic immunity is a predictor of overall survival independent of molecular pathology. Interestingly, patients with triple negative breast cancer were more enriched in the cohort associated with type 1 cell-mediated immunity. As this immune gene signature is not present in current genetically engineered mouse models of breast cancer, the results help identify design constraints for engineering better pre-clinical models of breast cancer. Demonstrating efficacy in pre-clinical animal models is a pre-requisite for bringing improved cancer immunotherapies into the clinic.

The MAPK pathway is a predominant regulator of HLA-A expression in esophageal and gastric cancer

Downregulation of HLA class I expression may contribute to a poor prognosis in cancer patients. There is limited information about epigenetic and oncogenic regulation of HLA class I, and multiple mechanisms may be involved. In the current study, we examined the relationship between the HER2-signaling pathway (MAPK and PI3K-Akt) and the expression of HLA class I and Ag-processing machinery (APM) components. A panel of gastric and esophageal cancer cell lines was treated with wortmannin as an Akt-signal inhibitor; the MAPK signal inhibitor PD98059; lapatinib, which inhibits both the epidermal growth factor receptor and HER2 tyrosine kinase; or siRNA for MAPK. The levels of HER2-signaling molecules, APM components, and HLA class I were evaluated by Western blot, quantitative PCR, and flow cytometry. Resected gastric tumor tissues (n = 102) were analyzed for p-Erk and HLA class I expression by immunohistochemistry. As a result, inhibition of the MAPK pathway induced upregulation of HLA-A02 and HLA-A24 expression in parallel with an increase in APM components and enhanced target sensitivity to tumor Ag-specific CTL lysis. HLA-A expression was predominantly regulated by the MAPK pathway, but it was also influenced, in part, by the Akt pathway. There was a strong inverse correlation between p-Erk expression and HLA class I expression in clinical tumor samples. In conclusion, HLA-A expression is predominantly regulated by the MAPK pathway in gastric and esophageal cancer.

The two sides of HER2/neu: immune escape versus surveillance

The oncogene HER2 is one of the prototypes for targeted immunotherapy of cancer using both monoclonal antibodies as well as T cell based immunotherapies. Effective humoral and cellular immune responses against HER2 can be induced, but these responses can be influenced by the effects of this oncogene on the target tumor cells. The processes involved in HER2-mediated adaptive and innate immunity and the molecular mechanisms underlying the escape of HER2-expressing tumor cells from immune surveillance, particularly from cytotoxic T cells, are discussed. Implementing this knowledge in clinical trials to revert immune evasion may help optimize immunotherapies directed against HER2-expressing tumors.

An evolutionary perspective on anti-tumor immunity

The challenges associated with demonstrating a durable response using molecular-targeted therapies in cancer has sparked a renewed interest in viewing cancer from an evolutionary perspective. Evolutionary processes have three common traits: heterogeneity, dynamics, and a selective fitness landscape. Mutagens randomly alter the genome of host cells creating a population of cells that contain different somatic mutations. This genomic rearrangement perturbs cellular homeostasis through changing how cells interact with their tissue microenvironment. To counterbalance the ability of mutated cells to outcompete for limited resources, control structures are encoded within the cell and within the organ system, such as innate and adaptive immunity, to restore cellular homeostasis. These control structures shape the selective fitness landscape and determine whether a cell that harbors particular somatic mutations is retained or eliminated from a cell population. While next-generation sequencing has revealed the complexity and heterogeneity of oncogenic transformation, understanding the dynamics of oncogenesis and how cancer cells alter the selective fitness landscape remain unclear. In this technology review, we will summarize how recent advances in technology have impacted our understanding of these three attributes of cancer as an evolutionary process. In particular, we will focus on how advances in genome sequencing have enabled quantifying cellular heterogeneity, advances in computational power have enabled explicit testing of postulated intra- and intercellular control structures against the available data using simulation, and advances in proteomics have enabled identifying novel mechanisms of cellular cross-talk that cancer cells use to alter the fitness landscape.

The tumour suppressor Fhit positively regulates MHC class I expression on cancer cells

MHC class I (MHC-I) molecules are ubiquitously expressed on the cells of an organism. Study of the regulation of these molecules in normal and disease conditions is important. In tumour cells, the expression of MHC-I molecules is very frequently lost, allowing these cells to evade the immune response. Cancers of different histology have shown total loss of MHC-I molecule expression, due to a coordinated transcriptional down-regulation of various antigen-processing machinery (APM) components and/or MHC-I heavy chains. The mechanisms responsible for these alterations remain unclear. We determined the possible genes involved by comparing MHC-I-positive with MHC-I-negative murine metastases derived from the same fibrosarcoma tumour clone. MHC-I-negative metastases showed transcriptional down-regulation of APM and MHC-I heavy chains. The use of microarrays and subtraction cDNA libraries revealed four candidate genes responsible for this alteration, but two of them were ruled out by real-time RT-PCR analyses. The other two genes, AP-2α and Fhit tumour suppressors, were studied by using siRNA to silence their expression in a MHC-I-positive metastatic cell line. AP-2α inhibition did not modify transcriptional expression of APM components or MHC-I heavy chains or surface expression of MHC-I. In contrast, silencing of the Fhit gene produced the transcriptional down-regulation of APM components and MHC-I heavy chains and decreased MHC-I surface expression. Moreover, transfection of Fhit in MHC-I-negative tumour cell lines restored MHC-I cell surface expression. These data indicate that defects in Fhit expression may promote MHC-I down-regulation in cancer cells and allow escape from immunosurveillance(#).

Metformin rescues cell surface major histocompatibility complex class I (MHC-I) deficiency caused by oncogenic transformation

Active avoidance by tumor cells from attack and elimination by immune cells is an emerging cancer hallmark that is achieved primarily through decreasing the levels of major histocompatibility complex class I (MHC-I) at the cancer cells' surface. Deficiencies in MHC-I antigen-restricted immunosurveillance may be intertwined with an altered, Warburg-like cancer cell-intrinsic metabolism, another emerging hallmark of cancer that involves a switch from mitochondrial respiration to glycolysis to efficiently support large-scale biosynthetic programs that are required for active cell proliferation. We recently envisioned that intervention strategies aimed at reversing the bioenergetic signature of cancer cells (e.g., the antidiabetic biguanide metformin) should correct oncogene (e.g., HER2)-driven MHC-I defects, thus preventing immune escape of oncogene transformants. First, we explored how metformin treatment impacted mitochondrial biogenesis in cultured breast cancer cells overexpressing the membrane tyrosine kinase receptor HER2, the best-characterized downregulator of MHC-I. Metformin exposure was found to dose-dependently increase the expression levels of cytochrome c oxidase I and mitochondrial succinate dehydrogenase, which are encoded by mitochondrial and nuclear DNA, respectively. Second, we explored whether metformin-enhanced mitochondrial biogenesis might significantly alter the MHC-I status in breast carcinoma cells. MHC-I expression, as assessed by flow cytometry using an anti-HLA-ABC monoclonal antibody, was fully restored (up to ~25-fold upregulation) in MHC-I-negative HER2 gene-amplified carcinoma cells. These findings may help delineate a previously unrecognized mechanism through which metformin (and metformin-like drugs) may enable a cancer patient's own immune system to mount an efficient anti-metastasis response that can prevent or delay disease recurrence. Restored antigenicity and immunogenicity of tumor cells may represent a previously unrecognized primary mode of action underlying the cancer-preventive effects of metformin.