The PD1/PDL1 axis, a promising therapeutic target in aggressive breast cancers

Expression of programmed death-ligand 1, IRF1 and CD8 T lymphocyte infiltration in a primary subset of breast cancer patients in Sudan

Objectives

This study aimed to investigate the protein expression of programmed death ligand 1 (PD-L1) in breast cancer (BC) tissues and link this data with estrogen status, the expression of interferon regulatory factor1 (IRF-1), and CD8+T lymphocyte infiltration by immunohistochemistry (IHC). We also attempted to identify the association between PD-L1 expression, the cell proliferation index marker (Ki67), and lymph node involvement.

Methods

One hundred and fifty formalin-fixed and paraffin-embedded (FFPE) blocks of breast tissue were acquired from Sudanese females via The National Public Health Laboratory. FFPE blocks were subjected to antigen/antibody detection by IHC with antibodies raised against PD-L1, IRF1, and CD8. These data were analyzed alongside data extracted from medical records relating to estrogen receptor (ER) status, Ki67 index, and lymph node (LN) status.

Results

IHC analysis revealed a significant association between PD-L1 and CD8 (p = 0.010). In addition, regression analysis indicated the ability of IRF1 to induce PD-L1 expression levels in IRF1-positive cases that were two-fold higher than IRF1-deficient cases (odds ratio [OR]: 2.441 p = 0.035). Analysis also suggested that PD-L1 exerts impact on cell proliferation, as reflected by the Ki67 index. An independent t test showed that higher Ki67 scores were more frequent among PD-L1-positive patients than in PD-L1-negative patients (t = 2.608 p = 0.014). There was an inverse association between PD-L1 and ER status; ER-positive tumors exhibited negative PD-L1 expression and vice versa (p = 0.04). Furthermore, we investigated the prognostic value of PD-L1 by evaluating the association between PD-L1 and LNs dispersed variably with tumor cells; there was no statistically significant relationship between these factors (p > 0.05).

Conclusion

The expression of PD-L1 and IRF-1, along with the infiltration of CD8, represents a potent panel of biomarkers with which to identify BC patients with the highest probabilities of achieving an excellent response to immune therapy, particularly when taking ER status into account, as ER expression levels are known to be high when immune checkpoint blockers (ICBs) generate a poor response.

Hormone Receptor Signaling and Breast Cancer Resistance to Anti-Tumor Immunity

Breast cancers regroup many heterogeneous diseases unevenly responding to currently available therapies. Approximately 70-80% of breast cancers express hormone (estrogen or progesterone) receptors. Patients with these hormone-dependent breast malignancies benefit from therapies targeting endocrine pathways. Nevertheless, metastatic disease remains a major challenge despite available treatments, and relapses frequently ensue. By improving patient survival and quality of life, cancer immunotherapies have sparked considerable enthusiasm and hope in the last decade but have led to only limited success in breast cancers. In addition, only patients with hormone-independent breast cancers seem to benefit from these immune-based approaches. The present review examines and discusses the current literature related to the role of hormone receptor signaling (specifically, an estrogen receptor) and the impact of its modulation on the sensitivity of breast cancer cells to the effector mechanisms of anti-tumor immune responses and on the capability of breast cancers to escape from protective anti-cancer immunity. Future research prospects related to the possibility of promoting the efficacy of immune-based interventions using hormone therapy agents are considered.

IL-17A functions and the therapeutic use of IL-17A and IL-17RA targeted antibodies for cancer treatment

Interleukin 17A (IL-17A) is a major member of the IL-17 cytokine family and is produced mainly by T helper 17 (Th17) cells. Other cells such as CD8+ T cells, γδ T cells, natural killer T cells and innate lymphoid-like cells can also produce IL-17A. In healthy individuals, IL-17A has a host-protective capacity, but excessive elevation of IL-17A is associated with the development of autoimmune diseases and cancer. Monoclonal antibodies (mAbs) targeting IL-17A (e.g., ixekizumab and secukinumab) or IL-17A receptor (IL-17RA) (e.g., brodalumab) would be investigated as potential treatments for these diseases. Currently, the application of IL-17A-targeted drugs in autoimmune diseases will provide new ideas for the treatment of tumors, and its combined application with immune checkpoint inhibitors has become a research hotspot. This article reviews the mechanism of action of IL-17A and the application of anti-IL-17A antibodies, focusing on the research progress on the mechanism of action and therapeutic blockade of IL-17A in various tumors such as colorectal cancer (CRC), lung cancer, gastric cancer and breast cancer. Moreover, we also include the results of therapeutic blockade in the field of cancer as well as recent advances in the regulation of IL-17A signaling.

Aptamer-Based Strategies to Boost Immunotherapy in TNBC

The immune system (IS) may play a crucial role in preventing tumor development and progression, leading, over the last years, to the development of effective cancer immunotherapies. Nevertheless, immune evasion, the capability of tumors to circumvent destructive host immunity, remains one of the main obstacles to overcome for maximizing treatment success. In this context, promising strategies aimed at reshaping the tumor immune microenvironment and promoting antitumor immunity are rapidly emerging. Triple-negative breast cancer (TNBC), an aggressive breast cancer subtype with poor outcomes, is highly immunogenic, suggesting immunotherapy is a viable strategy. As evidence of this, already, two immunotherapies have recently become the standard of care for patients with PD-L1 expressing tumors, which, however, represent a low percentage of patients, making more active immunotherapeutic approaches necessary. Aptamers are short, highly structured, single-stranded oligonucleotides that bind to their protein targets at high affinity and specificity. They are used for therapeutic purposes in the same way as monoclonal antibodies; thus, various aptamer-based strategies are being actively explored to stimulate the IS’s response against cancer cells. The aim of this review is to discuss the potential of the recently reported aptamer-based approaches to boost the IS to fight TNBC.

Programmed cell death 1 and programmed cell death ligand 1 expression in invasive breast carcinoma using CAL10 and NAT105 immunostaining

Increased incidence of breast cancer has stimulated development of new diagnostic and therapeutic methods. The programmed cell death 1 (PD1) pathway and its inhibitors are promising avenues for investigation. PD1 includes PD ligands 1 (PDL1) and 2 (PDL2). We investigated the expression of PD1 and PDL1 in invasive breast carcinomas using immunohistochemical staining. We used 171 invasive breast carcinoma specimens from which tissue microarray blocks were created. Immunohistochemical staining of PD1 using NAT105, and PDL1 using CAL10 was performed on tissue microarray sections. NAT105 and CAL10 are useful clones for detecting expression of PD1 and PDL1. PD1 and PDL1 immunostaining was significantly stronger in carcinomas with basal-like phenotype compared to other molecular breast cancer types. PD1 and PDL1 expression also was associated with a high histologic grade and a high Ki-67 index. PD1 expression also was associated with lymphovascular invasion and axillary metastasis. PD1 and PDL1 expression is associated with aggressive tumor behavior and a basal-like phenotype in breast cancer. We suggest that inhibition of the PD1/PDL1 pathway, particularly in triple negative breast carcinomas with basal-like phenotype, might be useful for targeted immunotherapy.

High Expression of RAI14 in Triple-Negative Breast Cancer Participates in Immune Recruitment and Implies Poor Prognosis Through Bioinformatics Analyses

Objective: The purpose of current research is to explore the function of retinoic acid-induced protein 14 (RAI14), being a reciprocal protein of carboxypeptidase N1 (CPN1), and as a biomarker for prognosis and immunoregulatory effects in breast cancers.

Methods: Interacting proteins of CPN1 were characterized by co-immunoprecipitation (CO-IP) and mass spectrometry. We evaluated RAI14 expression and related clinical prognosis based on bioinformatics methods. The level of relevance between RAI14 and infiltrating immune cells biomarkers was investigated by using TIMER and certificated by immunohistochemical staining and cytology experiments.

Results: RAI14 is an interacting protein of CPN1. Higher RAI14 expression in TNBC was significantly correlated with poor prognosis in TNBC, especially (RFS: HR = 1.32, p = 0.015; DFS: HR = 1.18, p = 0.035). The estrogen receptor (ER), P53 status, and histological types and triple-negative status were observed and correlated with RAI14 expression. Moreover, the level of RAI14 was positive in relation with the expression of CD163 (M2 macrophages marker, r = 0.393, p = 1.89e-06) and PD-1 (T-cell exhaustion marker, r = 0.626, p = 4.82e-03), indicating RAI14 levels were mainly related to M2 macrophages and T-cell exhaustion infiltration in TNBC. Furthermore, CPN1 overexpression was accompanied by RAI14 and PD-L1 upregulation, and a correlation was found among them.

Conclusions: RAI14 is a potential downstream molecule of CPN1, which may be a potential prognostic biomarker and identification of an immunosuppressive tumor microenvironment in TNBC.

Tumor Microenvironment: Key Players in Triple Negative Breast Cancer Immunomodulation

Simple Summary

The tumor microenvironment (TME) is a complicated network composed of various cells, signaling molecules, and extra cellular matrix. TME plays a crucial role in triple negative breast cancer (TNBC) immunomodulation and tumor progression, paradoxically, acting as an immunosuppressive as well as immunoreactive factor. Research regarding tumor immune microenvironment has contributed to a better understanding of TNBC subtype classification. Shall we treat patients precisely according to specific subtype classification? Moving beyond traditional chemotherapy, multiple clinical trials have recently implied the potential benefits of immunotherapy combined with chemotherapy. In this review, we aimed to elucidate the paradoxical role of TME in TNBC immunomodulation, summarize the subtype classification methods for TNBC, and explore the synergistic mechanism of chemotherapy plus immunotherapy. Our study may provide a new direction for the development of combined treatment strategies for TNBC.

Abstract

Triple negative breast cancer (TNBC) is a heterogeneous disease and is highly related to immunomodulation. As we know, the most effective approach to treat TNBC so far is still chemotherapy. Chemotherapy can induce immunogenic cell death, release of damage-associated molecular patterns (DAMPs), and tumor microenvironment (TME) remodeling; therefore, it will be interesting to investigate the relationship between chemotherapy-induced TME changes and TNBC immunomodulation. In this review, we focus on the immunosuppressive and immunoreactive role of TME in TNBC immunomodulation and the contribution of TME constituents to TNBC subtype classification. Further, we also discuss the role of chemotherapy-induced TME remodeling in modulating TNBC immune response and tumor progression with emphasis on DAMPs-associated molecules including high mobility group box1 (HMGB1), exosomes, and sphingosine-1-phosphate receptor 1 (S1PR1), which may provide us with new clues to explore effective combined treatment options for TNBC.

HER2-targeted antibody-drug conjugate induces host immunity against cancer stem cells

We previously tested HER2-targeted antibody-drug conjugates (ADCs) in immunocompromised (SCID) mice, precluding evaluation of host immunity, impact on cancer stem cells (CSCs), and potential benefit when combined with PD-L1 blockade. In this study, we tested HER2-targeted ADC in two immunocompetent mouse tumor models. HER2-targeted ADC specifically inhibited the growth of HER2-expressing tumors, prolonged animal survival, and reduced HER2⁺ and PD-L1⁺ cells. ADC + anti-PD-L1 antibody augmented therapeutic efficacy, modulated immune gene signatures, increased the number and function of CD3⁺ and CD19⁺ tumor-infiltrating lymphocytes (TILs), induced tumor antigen-specific immunological memory, stimulated B cell activation, differentiation, and IgG1 production both systemically and in the tumor microenvironment. In addition, ADC therapy modulated T cell subsets and their activation in TILs. Furthermore, HER2-targeted ADC reduced the number and tumorigenicity of ALDH^hi CSCs. This study demonstrates that HER2-targeted ADC effectively targets ALDH^hi CSCs and this effect is augmented by co-administration of anti-PD-L1 antibody.

Biomarkers for Inflammatory Breast Cancer: Diagnostic and Therapeutic Utility

Inflammatory breast cancer (IBC) is a rare and highly aggressive subtype of advanced breast cancer. The aggressive behavior, resistance to chemotherapy, angiogenesis, and high metastatic potential are key intrinsic characteristics of IBC caused by many specific factors. Pathogenesis and behavior of IBC are closely related to tumor surrounding inflammatory and immune cells, blood vessels, and extracellular matrix, which are all components of the tumor microenvironment (TME). The tumor microenvironment has a crucial role in the local immune r09esponse. The communication between intrinsic and extrinsic components of IBC and the abundance of cytokines and chemokines in the TME strongly contribute to the aggressiveness and high angiogenic potential of this tumor. Critical modes of interaction are cytokine-mediated communication and direct intercellular contact between cancer cells and tumor microenvironment with a variety of pathway crosstalk. This review aimed to summarize current knowledge of predictive and prognostic biomarkers in IBC.

Liquid Biopsies to Evaluate Immunogenicity of Gynecological/Breast Tumors: On the Way to Blood-Based Biomarkers for Immunotherapies

BACKGROUND

Despite the assumption of breast cancer (BC) as a cold, non-immunogenic tumor, immune checkpoint inhibitor (ICI) therapy is favorable for a subgroup of patients. Immunohistochemical assessment of the programmed cell death ligand 1 (PD-L1) is the only approved companion diagnostic for anti-PD-L1 therapy in metastatic triple-negative BC; however, challenges regarding the standardization of PD-L1 scoring in tumor tissue still remain. Consequently, to select patients most likely to respond to ICI, blood-based biomarkers are urgently needed.

SUMMARY AND KEY MESSAGES

Liquid biopsy, comprising circulating immune cells, circulating tumor cells and extracellular vesicles, as well as their surface proteins, is of high potential, and these analytes were already shown to be molecular correlates or regulators of the evasion from antitumoral immune reaction. Liquid biopsy, also enabling the evaluation of tumor mutational burden (TMB), microsatellite instability, and the T-cell receptor repertoire, allows serial sampling for monitoring purposes and reflects intra-tumoral heterogeneity which qualifies as marker for immunogenicity. Only a very few studies have already elucidated the potential of these analytes as biomarkers under ICI therapy. Nonetheless, the topic is of growing interest and has high relevance for the future. However, for clinical implementation, these multifarious analytes first need to pass robust standardization and validation procedures.

Estrogen Receptor Downregulates Expression of PD-1/PD-L1 and Infiltration of CD8+ T Cells by Inhibiting IL-17 Signaling Transduction in Breast Cancer

Background: The relationship between the interleukin 17 (IL-17) family of cytokines and breast cancer has been widely studied in recent years. Many studies have revealed increased levels of the cytokine IL-17A in estrogen receptor (ER)-negative or triple-negative breast cancer. Upregulation of IL-17A signaling is associated with increased expression of programmed cell death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1) in breast cancer with low ER expression and may elevate the infiltration of CD8⁺ T cells in tumor tissue. This study aims to determine whether ER downregulates the expression of PD-1/PD-L1, reduces the infiltration of CD8⁺ T cells, and affects the immune microenvironment by decreasing T-helper 17 (Th17) cell infiltration and inhibiting IL-17 signaling in breast cancer.

Methods: Samples in The Cancer Genome Atlas Breast Cancer dataset were grouped by ER status and the PAM50 intrinsic subtype. The expression of IL-17 family cytokines and Th17 cell signature cytokines were compared between groups. IL-17 signaling pathway-related genes that were differentially expressed according to the ER level were identified. The PD-1 and PD-L1 levels were compared between breast cancer samples with different ER statuses and IL-17A/IL-17F expression levels. Correlation analyses of the expression of PD-1/PD-L1 and IL-17 signaling pathway-related genes were performed. The associations of the expression of IL-17 signaling pathway-related genes with the immune microenvironment were investigated.

Results: High levels of ER decreased the expression of IL-17A, IL-17C, and IL-17F but increased the expression of IL-17E (IL25), which acts as a suppressor of IL-17 signaling. The expression levels of Th17 cell signature cytokines were significantly increased in ER-negative breast cancer. The expression levels of genes encoding downstream products of IL-17A/IL-17F signaling were downregulated in breast cancer with high ER expression. Increased expression of PD-1/PD-L1 was associated with ER-negative status, IL-17A-positive status, IL-17F-positive status, and upregulation of IL-17 signaling pathway-related genes in breast cancer. Enhanced IL-17 signal transduction was associated with the elevation of CD8⁺ T cell infiltration and variation of the immune microenvironment of breast cancer.

Conclusion: High estrogen receptor levels decrease PD-1/PD-L1 expression and CD8⁺ T cell infiltration by suppressing Th17 cell infiltration and IL-17 signal transduction in breast cancer.

SIRT7 Is a Prognostic Biomarker Associated With Immune Infiltration in Luminal Breast Cancer

Background: Sirtuin 7 (SIRT7), a protein-coding gene whose abnormal expression and function are associated with carcinogenesis. However, the prognosis of SIRT7 in different breast cancer subtypes and its correlation with tumor-infiltrating lymphocytes remain unclear.

Methods: The expression and survival data of SIRT7 in patients with breast cancer were analyzed using Tumor Immune Estimation Resource (TIMER), Gene Expression Profiling Interaction Analysis (GEPIA), The Human Protein Atlas (HPA), UALCAN, Breast Cancer Gene-Expression Miner (BC-GenExMiner), and Kaplan-Meier plotter databases. Also, the expression correlations between SIRT7 and immune infiltration gene markers were analyzed using TIMER and further verified the results using immunohistochemistry.

Results: SIRT7 exhibited higher expression levels in breast cancer tissues than the adjacent normal tissues. SIRT7 expression was significantly correlated with sample type, subclass, cancer stage, menopause status, age, nodal status, estrogen receptor (ER), progesterone receptor (PR), and triple-negative status. High SIRT7 expression was associated with poor prognosis in breast cancer-luminal A [overall survival (OS): hazard ratio (HR) = 1.54, p = 1.70e-02; distant metastasis-free survival (DMFS): HR = 1.56, p = 2.60e-03]. Moreover, the expression of SIRT7 was positively correlated with the expression of IRF5 (M1 macrophages marker, r = 0.165, p = 1.13e-04) and PD1 (T cell exhaustion marker, r = 0.134, p = 1.74e-03). These results suggested that the expression of SIRT7 was related to M1 macrophages and T cell exhaustion infiltration in breast cancer-luminal.

Conclusions: These findings demonstrate that the high expression of SIRT7 indicates poor prognosis in breast cancer as well as increased immune infiltration levels of M1 macrophages and T cell exhaustion in breast cancer-luminal. Thus, SIRT7 may serve as a candidate prognostic biomarker for determining prognosis associated with immune infiltration in breast cancer-luminal.

Crosstalk between HER2 and PD-1/PD-L1 in Breast Cancer: From Clinical Applications to Mathematical Models

Breast cancer is one of the major causes of mortality in women worldwide. The most aggressive breast cancer subtypes are human epidermal growth factor receptor-positive (HER2+) and triple-negative breast cancers. Therapies targeting HER2 receptors have significantly improved HER2+ breast cancer patient outcomes. However, several recent studies have pointed out the deficiency of existing treatment protocols in combatting disease relapse and improving response rates to treatment. Overriding the inherent actions of the immune system to detect and annihilate cancer via the immune checkpoint pathways is one of the important hallmarks of cancer. Thus, restoration of these pathways by various means of immunomodulation has shown beneficial effects in the management of various types of cancers, including breast. We herein review the recent progress in the management of HER2+ breast cancer via HER2-targeted therapies, and its association with the programmed death receptor-1 (PD-1)/programmed death ligand-1 (PD-L1) axis. In order to link research in the areas of medicine and mathematics and point out specific opportunities for providing efficient theoretical analysis related to HER2+ breast cancer management, we also review mathematical models pertaining to the dynamics of HER2+ breast cancer and immune checkpoint inhibitors.

Programmed Cell Death Ligand 1 in Breast Cancer: Technical Aspects, Prognostic Implications, and Predictive Value

In the light of recent advances in the immunotherapy field for breast cancer (BC) treatment, especially in the triple-negative subtype, the identification of reliable biomarkers capable of improving patient selection is paramount, because only a portion of patients seem to derive benefit from this appealing treatment strategy. In this context, the role of programmed cell death ligand 1 (PD-L1) as a potential prognostic and/or predictive biomarker has been intensively explored, with controversial results. The aim of the present review is to collect available evidence on the biological relevance and clinical utility of PD-L1 expression in BC, with particular emphasis on technical aspects, prognostic implications, and predictive value of this promising biomarker. IMPLICATIONS FOR PRACTICE: In the light of the promising results coming from trials of immune checkpoint inhibitors for breast cancer treatment, the potential predictive and/or prognostic role of programmed cell death ligand 1 (PD-L1) in breast cancer has gained increasing interest. This review provides clinicians with an overview of the available clinical evidence regarding PD-L1 as a biomarker in breast cancer, focusing on both data with a possible direct impact on clinic and methodological pitfalls that need to be addressed in order to optimize PD-L1 implementation as a clinically useful tool for breast cancer management.

Pathological and molecular characteristics of inflammatory breast cancer

Inflammatory breast cancer (IBC) is a rare and aggressive form of breast cancer characterized by the presence of many dermal tumor emboli in the papillary and reticular dermis of the skin overlying the breast. IBC patients, compared to other breast cancer patients, have more frequently metastatic axillary lymph nodes. IBC is often high grade, negative for hormone receptors and presents with amplification of the HER2 gene. Invasive IBC is frequently of ductal phenotype, even if a specific histological distinction for these lesions has not been described. The pathogenesis and evolution of IBC are strongly dependent upon tumor microenvironment, characterized by several macrophages/monocytes and lymphocytes. The tumor and microenvironment cells are well molecularly characterized, showing the main contributor of inflammatory pathways in tumor biology of IBC. In addition, several molecular alterations are described in this tumor, such as mutations of ERBB2, KRAS, BRAF, EGFR, PIK3CA, PTEN, AKT1, and AKT3 genes that could suggest a therapeutic stratification of IBC patients with the combination of different biological target therapies.

The Complex Interaction between the Tumor Micro-Environment and Immune Checkpoints in Breast Cancer

The progression of breast cancer and its association with clinical outcome and treatment remain largely unexplored. Accumulating data has highlighted the interaction between cells of the immune system and the tumor microenvironment in cancer progression, and although studies have identified multiple facets of cancer progression within the development of the tumor microenvironment (TME) and its constituents, there is lack of research into the associations between breast cancer subtype and staging. Current literature has provided insight into the cells and pathways associated with breast cancer progression through expression analysis. However, there is lack of co-expression studies between immune pathways and cells of the TME that form pro-tumorigenic relationships contributing to immune-evasion. We focus on the immune checkpoint and TME elements that influence cancer progression, particularly studies in molecular subtypes of breast cancer.

Primary tumor resection for initially staged IV breast cancer: An emphasis on programmed death-ligand 1 expression, promoter methylation status, and survival

Conventional therapy modalities for advanced breast cancer are problematic, whereas checkpoint blockade immunotherapy has been considered as a promising approach. This study aims to determine programmed death-ligand 1 (PD-L1) expression and methylation status of PD-L1 promoter in primary tumor tissue and metastatic foci of patients with stage IV breast cancer.Clinicopathological data and survival rates of 57 breast cancer patients, who were initially staged IV, and operated for intact tumors, were retrospectively analyzed. Immunohistochemical analysis of PD-L1 using 57 primary tumors, 33 paired metastatic lymph nodes, and 14 paired distant metastases was performed. Additionally, the methylation rate of the PD-L1 gene promoter region was determined with real-time polymerase chain reaction (PCR) analysis in 38 samples.Overall PD-L1 expression in primary tumors was 23.1% (12/52). PD-L1 positivity was reduced in lymph nodes by 15.2% (5/33) and in distant metastases by 21.4% (3/14). PD-L1 expression diverged between primary and metastatic foci in a subset of cases (18.2% for lymph node and 33.3% for distant metastasis). In general, the PD-L1 promoter was not methylated, and mean methylation rates were low (min. 0%-max. 21%). We observed no correlation between PD-L1 expression, promoter methylation, and survival.Neither the expression nor the methylation status of PD-L1 in patients, who were presented with stage IV breast cancer and operated for an intact primary tumor, had a statistically significant relation with survival. Discordance in PD-L1 expression between primary tumor and metastasis should be considered during pathological and clinical management of patients who would undergo checkpoint blockade therapy.

PD-1/PD-L1 Targeting in Breast Cancer: The First Clinical Evidences Are Emerging. A Literature Review

Recently, the development of immunotherapy through the immune checkpoint blockade led to long-lasting responses in several types of cancers that are refractory to conventional treatments, such as melanoma or non-small cell lung cancer. Immunotherapy has also demonstrated significant improvements in various other types of cancers. However, breast cancer remains one of the tumors that have not experienced the explosion of immunotherapy yet. Indeed, breast cancer was traditionally considered as being weakly immunogenic with a lower mutational load compared to other tumor types. In the last few years, anti-PD1/PD-L1 (Programmed death-ligand 1) agents have been evaluated in breast cancer, particularly in the triple negative subtype, with promising results observed when delivered as monotherapy or in combination with conventional treatments. In this review, we will report the results of the most recent studies evaluating immune checkpoint inhibitors in breast cancer. In addition, we will discuss the concomitant development of possible biomarkers, which is required for improving the selection of patients with the highest probability of benefiting from these agents.

Expression of PD-1 and PD-L1 in Extramammary Paget Disease: Implications for Immune-Targeted Therapy

Extramammary Paget disease (EMPD) is a locally aggressive cutaneous malignancy that usually arises in anogenital or axillary skin. Immune checkpoint inhibitors targeting programmed cell death receptor (PD-1) and/or its ligand (PD-L1) are approved for the treatment of several types of cancer, and response to these generally correlates with increased PD-L1 expression by tumor cells. The expression of PD-L1 and composition and density of the tumor-associated immune infiltrate in EMPD have been little studied. To determine whether EMPD might be amenable to immune checkpoint blockade, we analyzed the expression of PD-1 and PD-L1 and the composition and density of the tumor-associated immune infiltrate in EMPD and evaluated associations between biomarker expression and clinicopathologic parameters. Twenty-one EMPD tumors were evaluated for tumor cell PD-L1 expression and for relative expression and distribution of CD3, CD8, PD-1, and PD-L1 in the tumor-associated immune infiltrate by using a combination of visual and image analysis (Aperio ImageScope). In addition, PD-L1 expression was assessed in 10 cases of mammary Paget disease (MPD). In EMPD cases, PD-L1 was expressed by tumor cells (3/21; 14%) and the tumor-associated immune infiltrate (15/21; 71%), and PD-1 was expressed by the tumor-associated immune infiltrate in all cases analyzed (18/18). However, PD-L1 expression by EMPD tumor cells did not correlate with the density of CD3-, CD8-, or PD-1-positive cells in the tumor-associated immune infiltrate or other clinicopathologic parameters. Furthermore, the density of CD3, CD8, PD-1, and PD-L1 in the tumor-associated immune infiltrate did not correlate with any clinicopathologic parameters evaluated with the exception that CD3 positive values were significantly higher in patients who were still alive (median, 1310 cells/mm²; range, 543–2115;) than in those who died (median, 611 cells/mm²; range, 481–908; p = 0.049). In all MPD cases, PD-L1 was absent in tumor cells but present in the tumor-associated immune infiltrate, and PD-L1 expression in lymphocytes was lower in patients with HER2/neu-positive than in those with HER2/neu-negative disease (p = 0.07). Our findings raise the possibility of therapeutic targeting of the PD-1/PD-L1 axis in EMPD.

Immunotherapy in breast cancer: Current status and future directions

Breast cancer, one of the leading causes of death in women in the United States, challenges therapeutic success in patients due to tumor heterogeneity, treatment resistance, metastasis and disease recurrence. Knowledge of immune system involvement in normal breast development and breast cancer has led to extensive research into the immune landscape of breast cancer and multiple immunotherapy clinical trials in breast cancer patients. However, poor immunogenicity and T-cell infiltration along with heightened immunosuppression in the tumor microenvironment have been identified as potential challenges to the success of immunotherapy in breast cancer. Oncodrivers, owing to their enhanced expression and stimulation of tumor cell proliferation and survival, present an excellent choice for targeted immunotherapy development in breast cancer. Loss of anti-tumor immune response specific to oncodrivers has been reported in breast cancer patients as well. Dendritic cell vaccines have been tested for their efficacy in generating anti-tumor T-cell response against specific tumor-associated antigens and oncodrivers and have shown improved survival outcome in patients. Here, we review the current status of immunotherapy in breast cancer, focusing on dendritic cell vaccines and their therapeutic application in breast cancer. We further discuss future directions of breast cancer immunotherapy and potential combination strategies involving dendritic cell vaccines and existing chemotherapeutics for improved efficacy and better survival outcome in breast cancer.

Prediction of pathological complete response and prognosis in patients with neoadjuvant treatment for triple-negative breast cancer

Background

It has been reported that pathological complete response is an important surrogate marker for disease-free survival and overall survival in patients with triple-negative breast cancer. This study investigates predictors of the response to neoadjuvant platinum-based or anthracycline-based treatment, and of the prognosis, in patients with triple-negative breast cancer.

Methods

A total of 121 patients with triple-negative breast cancer received neoadjuvant treatment with either platinum or anthracycline between 2008 and 2013. Pathological complete response was assessed relative to different treatments using logistic regression models with age, clinical tumor stage, grading, and Ki-67 as predictors and interaction terms, to obtain adjusted and subgroup-specific results. The impact of the pathological complete response rate on disease-free survival and overall survival was also analyzed.

Results

The pathological complete response rate was higher after platinum/taxane treatment compared with anthracycline/taxane (50.0% vs. 41.8%), but this was not significant in the adjusted analysis (OR 1.44; 95% CI, 0.68 to 3.09). A high histological grade (G3) was a predictor for higher pathological complete response in platinum-based therapy (OR 2.27; 95% CI, 1.00 to 5.30). The effect of neoadjuvant chemotherapy on pathological complete response was significantly different for G1–2 vs. G3 (P_interaction = 0.013), and additional subgroup-specific differences were noted. Pathological complete response was a predictor for improved disease-free survival and overall survival in both treatment groups, with and without platinum chemotherapy.

Conclusions

This retrospective study of patients with triple-negative breast cancer adds to the evidence that the treatment effect of platinum may be greatest particularly in G3 tumors. In addition, the effect of pathological complete response on the prognosis does not depend on the treatment used.

Diagnostic value of PD-1 mRNA expression combined with breast ultrasound in breast cancer patients

Introduction

This study explored the value of measuring programmed death 1 (PD-1) in peripheral blood, combined with breast ultrasound using the Breast Imaging Reporting and Data System (BI-RADS) classification, for differentiation between benign and malignant breast tumors.

Materials and methods

We enrolled 113 patients with breast cancer and 66 patients with benign breast tumors who were admitted to Hangzhou First People’s Hospital from September 2014 to August 2017. The mRNA level of PD-1 was detected by quantitative real-time polymerase chain reaction.

Results

The mRNA levels of PD-1 were significantly higher in the peripheral blood of patients with breast cancer than those in patients with benign breast tumors. The diagnostic sensitivity of PD-1 mRNA expression was 0.805, the specificity was 0.788, and the area under the curve (AUC) was 0.848 (P < 0.001); the sensitivity of breast ultrasound-based BI-RADS classification was 0.752, the specificity was 0.909, and the AUC was 0.906 (P < 0.001); and the combined sensitivity, specificity, and AUC of the two assays were 0.920, 0.879, and 0.938, respectively (P < 0.001). Progesterone receptor-positive breast cancer patients exhibited high levels of PD-1 expression (P < 0.001).

Conclusion

This study suggests that the measurement of PD-1 combined with breast ultrasound-based BI-RADS classification represents a significant improvement for breast cancer diagnosis compared with diagnoses based on either method alone.

Characterization of Pattern Recognition Receptor Expression and Functionality in Liver Primary Cells and Derived Cell Lines

Different liver cell types are endowed with immunological properties, including cell-intrinsic innate immune functions that are important to initially control pathogen infections. However, a full landscape of expression and functionality of the innate immune signaling pathways in the major human liver cells is still missing. In order to comparatively characterize these pathways, we purified primary human hepatocytes, hepatic stellate cells, liver sinusoidal endothelial cells (LSEC), and Kupffer cells (KC) from human liver resections. We assessed mRNA and protein expression level of the major innate immune sensors, as well as checkpoint-inhibitor ligands in the purified cells, and found Toll-like receptors (TLR), RIG-I-like receptors, as well as several DNA cytosolic sensors to be expressed in the liver microenvironment. Amongst the cells tested, KC were shown to be most broadly active upon stimulation with PRR ligands emphasizing their predominant role in innate immune sensing the liver microenvironment. By KC immortalization, we generated a cell line that retained higher innate immune functionality as compared to THP1 cells, which are routinely used to study monocyte/macrophages functions. Our findings and the establishment of the KC line will help to understand immune mechanisms behind antiviral effects of TLR agonists or checkpoint inhibitors, which are in current preclinical or clinical development.

Possible roles for glucocorticoid signalling in breast cancer

Our understanding of breast cancer biology, and our ability to manipulate breast cancers have grown exponentially in the last 20 years. Much of that expansion has focused on the roles of steroids in driving these neoplasms. Initially this research focused on estrogens and progesterone receptors, and more recently on androgen actions in breast cancers. This review aims to make the case for glucocorticoids as the next essential steroid subclass that contributes significantly to our understanding of steroidogenic regulation of these neoplasms. Glucocorticoids have the potential to play multiple roles in the regulation of breast cancers including their control of cellular differentiation, apoptosis and proliferation. Beyond this they also act as a master integrator of organ homeostats in relation to such as circadian rhythms and stress responses. Therefore a better understanding of glucocorticoids and breast cancer could help to explain some of the epidemiological links between circadian disruption and/or stress and breast cancer development. Finally glucocorticoids are currently used during chemotherapeutic treatment in breast cancer therapy and yet results of various studies suggest that this may have an adverse impact on treatment success. This review aims to summarise the current evidence for glucocorticoids as actors in breast cancer and then suggest future essential approaches in order to determine the roles of glucocorticoids in this disease.

Activated innate lymphoid cell populations accumulate in human tumour tissues

Background

Innate lymphoid cells (ILC) are part of a heterogeneous family of haematopoietic effector cells which lack re-arranged antigen-specific receptors. They promote host defense and contribute to tissue and metabolic homeostasis, wound healing and immune surveillance. Their role in human cancer immunity is less defined, and therefore we aimed to identify the frequency and phenotype of distinct ILC groups in various types of cancer.

Methods

Tissue samples and peripheral blood were collected from patients undergoing surgical resection of gastrointestinal and breast tumours. Single cell suspension of tumour tissue was immediately obtained following surgery using tumour dissociation.

Results

We observed significantly higher frequencies of ILC2 (p value: 0.04) in malignant breast cancer tissue and significantly higher frequencies of group 1 ILC (p value: 0.001) in malignant gastrointestinal tumours. Tumour infiltrating ILC were found to show an activated phenotype with higher expression of MHC-II, KLRG1, early activation marker CD69 and CD44.

Conclusions

Activated innate lymphoid cells infiltrate tumours dependent on tumour type and location.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4262-4) contains supplementary material, which is available to authorized users.

The role of programmed death ligand-1 and tumor-infiltrating lymphocytes in breast cancer overexpressing HER2 gene

PURPOSE

The purpose of the study is to investigate the prognostic significance of programmed death ligand-1 (PD-L1) expression and tumor-infiltrating lymphocytes (TILs) in HER2+ breast cancer (BC).

METHODS

HER2+ BC cases (n  = 191) were collected between 1996 and 2013. Tissue microarray (TMA) slides were stained with two clones of PD-L1 antibodies (28-8 and 22C3) and the percentage of positive membranous staining was scored. TILs of the full sections were also scored using percentage scale.

RESULTS

Clone 28-8 had expression in ≥ 1% of the tumor cells in 25.7% of the cases, while clone 22C3 in ≥ 1% of the tumor cells was expressed in 11.5% of the cases. In the multivariate analysis, higher expression of PD-L1 (clone 28-8) in tumor correlated with lower risk of tumor recurrence, with HR of 0.4 (p = 0.033). Higher level of TILs (> 15%) predicts better overall survival (OS) in all patients with HR of 0.35 (p  = 0.0046). In the group of patients who were treated with trastuzumab-based adjuvant chemotherapy, lower PD-L1 (clone 28-8) expression in TILs correlated with tumor recurrence (p  = 0.034). In the group of patients who were treated with non-trastuzumab-based adjuvant chemotherapy, lower TILs and lower PD-L1 (clone 28-8) expression in tumor had borderline statistical significance in association with tumor recurrence (p  = 0.064 and 0.083, respectively). In the group of patients who were treated with trastuzumab-based adjuvant chemotherapy, PD-L1 or TILs was not statistically significant to predict 5-year survival. In the group of patients who were treated with non-trastuzumab-based adjuvant chemotherapy, low TILs (p = 0.009) correlated with 5-year death due to disease.

CONCLUSION

We conclude that PD-L1 may have prognostic significance in HER2+ BCs.

Targeting of interleukin (IL)-17A inhibits PDL1 expression in tumor cells and induces anticancer immunity in an estrogen receptor-negative murine model of breast cancer

The expression of IL-17A and programmed death ligand 1 (PDL1) is increased in estrogen receptor-negative breast cancer. IL-17A promotes tumor cell survival and invasiveness and inhibits the antitumor immune response. The PDL1-PD1 (programmed death protein 1) signaling pathway promotes escape from immune surveillance in tumor cells. The pro-tumor properties of IL-17A and PDL1 in various cancers have been previously examined; however, the relationship and roles of IL-17A and PDL1 in ER-negative breast cancer have not been evaluated. Therefore, we assessed whether IL-17A promotes PDL1 expression in tumor cells and whether targeting of IL-17A could inhibit ER-negative breast cancer progression in a murine model. Our study revealed that IL-17A promoted PDL1 expression in human and mouse cells. In the murine cancer model, targeting of IL-17A inhibited PDL1 expression in the tumor microenvironment, decreased the percentage of Treg cells in tumor-infiltrating lymphocytes, and promoted CD4+ and CD8+ T cells to secrete interferon gamma. More importantly, treatment with combined anti-IL-17A and anti-PDL1 antibodies enhanced antitumor effects in favor of tumor eradication. Thus, our study established a pro-tumor role of IL-17A in promoting tumor immune escape and supports the development of a novel cytokine immunotherapy against breast cancer.

Expression of Programmed Death Ligand 1 (PD-L1) in Posttreatment Primary Inflammatory Breast Cancers and Clinical Implications

OBJECTIVES

Inflammatory breast carcinoma (IBC) is rare but is the most lethal type of breast cancer. Programmed death ligand 1 (PD-L1) expression in IBCs has been understudied.

METHODS

In this study, tissue microarrays of 68 IBCs were immunostained with a PD-L1 antibody using an antibody clone (28-8) and detection system approved by the US Food and Drug Administration for selecting patients with non-small cell lung cancer and melanoma for anti-PD-L1 therapy.

RESULTS

Positive PD-L1 expression was found in 25 (36.8%) of 68 samples but was not significantly associated with the clinicopathologic variables examined. Univariate analysis of overall survival (OS) revealed that worse OS was significantly associated with positive PD-L1, negative estrogen receptor, and triple-negative status. The 5-year OS rate was 36.4% for patients with PD-L1-positive IBC and 47.3% for those with PD-L1-negative IBC. In multivariate analyses, PD-L1 status remained a statistically independent predictor of OS.

CONCLUSIONS

These findings indicate that PD-L1 inhibitors could potentially improve the clinical outcome of patients with PD-L1-positive IBC.

PD1 protein expression in tumor infiltrated lymphocytes rather than PDL1 in tumor cells predicts survival in triple-negative breast cancer

To determine PD1/PDL1 expression status in triple-negative breast cancer (TNBC) at both protein and mRNA levels, and to analyze the relationship between their expression and clinical parameters of the TNBC patients. Immunohistochemistry and RNAscope were used to semi quantitively evaluate PD1/PDL1 protein and mRNA expression in 195 TNBC cases on tissue microarrays. Tumor infiltrating lymphocyte (TILs) abundance was assessed using hematoxylin-eosin staining. Both tumor cells and TILs expressed PDL1. PDL1 protein and mRNA positivity was 6.7% and 74.4% respectively in tumor cells, and 31.3% and 50.9% respectively in TILs. PDL1 protein and mRNA expressions had no significant association with patient prognosis. PD1 protein was only detected in TILs (70.3% positivity). PD1 protein expression was significantly related to PDL1 expression, higher TIL abundance, Ki-67 index, basal-like subtypes, and distant metastasis. Furthermore, it was significantly associated with longer disease free survival (P<0.001) and overall survival (P = 0.004). There was no significant association between PD1 mRNA expression and clinicopathological characteristics. PD1/PDL1 protein and mRNA expressions were inconsistent (kappa = 0.705 and 0.061, respectively). PD1 protein expression in TILs, but not PDL1 in tumor cells, was a favorable prognostic factor in TNBC. PD1/PDL1 mRNA and protein expressions were inconsistent.

The Role of Immune Escape and Immune Cell Infiltration in Breast Cancer

While detailed analysis of aberrant cancer cell signaling pathways and changes in cancer cell DNA has dominated the field of breast cancer biology for years, there now exists increasing evidence that the tumor microenvironment (TME) including tumor-infiltrating immune cells support the growth and development of breast cancer and further facilitate invasion and metastasis formation as well as sensitivity to drug therapy. Furthermore, breast cancer cells have developed different strategies to escape surveillance from the adaptive and innate immune system. These include loss of expression of immunostimulatory molecules, gain of expression of immunoinhibitory molecules such as PD-L1 and HLA-G, and altered expression of components involved in apoptosis. Furthermore, the composition of the TME plays a key role in breast cancer development and treatment response. In this review we will focus on i) the different immune evasion mechanisms used by breast cancer cells, ii) the role of immune cell infiltration in this disease, and (iii) implication for breast cancer-based immunotherapies.

The Protective and Immunomodulatory Effects of Fucoidan Against 7,12-Dimethyl benz[a]anthracene-Induced Experimental Mammary Carcinogenesis Through the PD1/PDL1 Signaling Pathway in Rats

Fucoidan is a sulfated polysaccharide that is extracted from brown algae seaweed. This study was designed to evaluate the protective and immunomodulatory effects of dietary fucoidan on 7,12-dimethyl benz[a]anthracene (DMBA)-induced experimental mammary carcinogenesis in rats. Sixty Sprague-Dawley rats were randomly assigned to four equal groups: the control group (control group), the cancer model group (model group), and the F1 and F2 groups, which were fed fucoidan at concentrations of 200 and 400 mg/kg·body weight, respectively. We found that fucoidan treatment decreased the tumor incidence and mean tumor weight and prolonged the tumor latency. Flow cytometric analyses revealed that the number of blood natural killer cells was higher after fucoidan treatment and that the proportions of CD4 and CD8 T cells were also increased. The serum levels of interleukin (IL)-6, IL-12p40, and interferon (IFN)-γ were higher in the rats treated with fucoidan compared to those of model rats. Moreover, the percentage of CD3+ Foxp3+ regulatory T cells in the blood and the levels of IL-10 and transforming growth factor β in the serum were lower in the rats treated with fucoidan. Furthermore, fucoidan treatment decreased the expression of Foxp3 and programmed cell death 1 ligand 1 (PDL1) in tumor tissues. The levels of p-phosphatidyl inositol kinase 3 and p-AKT in tumor tissues were also lower than those of model rats. These results suggest that a fucoidan-supplemented diet can inhibit DMBA-induced tumors in rats. This study provides experimental evidence toward elucidating the immune enhancement induced by fucoidan through the programmed cell death 1/PDL1 signaling pathway. The immunomodulatory effect is one of the possible mechanisms of the protective effect of fucoidan against mammary carcinogenesis.

Mechanism of immune evasion in breast cancer

Breast cancer (BC) is the most common malignant tumor among women, with high morbidity and mortality. Its onset, development, metastasis, and prognosis vary among individuals due to the interactions between tumors and host immunity. Many diverse mechanisms have been associated with BC, with immune evasion being the most widely studied to date. Tumor cells can escape from the body’s immune response, which targets abnormal components and foreign bodies, using different approaches including modification of surface antigens and modulation of the surrounding environment. In this review, we summarize the mechanisms and factors that impact the immunoediting process and analyze their functions in detail.

PDL1 expression is a poor-prognosis factor in soft-tissue sarcomas

Soft-tissue sarcomas (STS) are a group of rare, heterogeneous, and aggressive tumors, with high metastatic risk and relatively few efficient systemic therapies. In the quest for new treatments, the immune system represents an attractive therapeutic target. Recently, PD1/PDL1 inhibitors showed very promising results in patients with solid tumors. PDL1 expression has been rarely studied in STS, in small series only, by using immunohistochemistry (IHC), and with non-concordant prognostic implications. Here, we have analyzed PDL1 mRNA expression in 758 clinical STS samples retrospectively profiled using DNA microarrays and RNAseq, and searched for correlations with clinicopathological variables including metastasis-free survival (MFS) after surgery. PDL1 expression was heterogeneous across the samples. PDL1-high samples (41%) were more frequently leiomyosarcomas and liposarcomas, and showed more frequently a complex genetic profile and a high-risk CINSARC signature. No correlation existed with other clinicopathological features such as tumor site, depth, and pathological tumor grade and size. In multivariate prognostic analysis, the PDL1-high class was associated with shorter MFS, independently of the pathological type and the CINSARC signature. Analysis of correlations with biological factors suggested the existence in tumors of the PDL1-high class of a strong and efficient cytotoxic T-cell response, however associated with some degree of T-cell exhaustion and negative regulation. In conclusion, we show that PDL1 expression refines the prediction of metastatic relapse in operated localized STS, and that PD1/PDL1 blockade holds potential to improve patient survival by reactivating inhibited T cells to increase the antitumor immune in PDL1-high tumors.

Strategies to modulate the immune system in breast cancer: checkpoint inhibitors and beyond

Is breast cancer (BC) immunogenic? Many data suggest that it is. Many observations demonstrated the prognostic role of tumor-infiltrating lymphocytes (TILs) in triple negative (TN) and human epidermal growth factor receptor 2 (HER-2)-positive BC. TNBCs are poorly differentiated tumors with high genetic instability and very high heterogeneity. This heterogeneity enhances the 'danger signals' and select clone variants that could be more antigenic or, in other words, that could more strongly stimulate a host immune antitumor response. The response to chemotherapy is at least partly dependent on an immunological reaction against those tumor cells that are dying during the chemotherapy. One of the mechanisms whereby chemotherapy can stimulate the immune system to recognize and destroy malignant cells is commonly known as immunogenic cell death (ICD). ICD elicits an adaptive immune response. Which are the clinical implications of all 'immunome' data produced in the last years? First, validate prognostic or predictive role of TILs. Second, validate immune genomic signatures that may be predictive and prognostic in patients with TN disease. Third, incorporate an 'immunoscore' into traditional classification of BC, thus providing an essential prognostic and potentially predictive tool in the pathology report. Fourth, implement clinical trials for BC in the metastatic setting with drugs that target immune-cell-intrinsic checkpoints. Blockade of one of these checkpoints, cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) or the programmed cell death 1 (PD-1) receptor may provide proof of concepts for the activity of an immune-modulation approach in the treatment of a BC.