FOXP3-positive regulatory T lymphocytes and epithelial FOXP3 expression in synchronous normal, ductal carcinoma in situ, and invasive cancer of the breast

Detailed Profiling of the Tumor Microenvironment in Ethnic Breast Cancer, Using Tissue Microarrays and Multiplex Immunofluorescence

Breast cancer poses a global health challenge, yet the influence of ethnicity on the tumor microenvironment (TME) remains understudied. In this investigation, we examined immune cell infiltration in 230 breast cancer samples, emphasizing diverse ethnic populations. Leveraging tissue microarrays (TMAs) and core samples, we applied multiplex immunofluorescence (mIF) to dissect immune cell subtypes across TME regions. Our analysis revealed distinct immune cell distribution patterns, particularly enriched in aggressive molecular subtypes triple-negative and HER2-positive tumors. We observed significant correlations between immune cell abundance and key clinicopathological parameters, including tumor size, lymph node involvement, and patient overall survival. Notably, immune cell location within different TME regions showed varying correlations with clinicopathologic parameters. Additionally, ethnicities exhibited diverse distributions of cells, with certain ethnicities showing higher abundance compared to others. In TMA samples, patients of Chinese and Caribbean origin displayed significantly lower numbers of B cells, TAMs, and FOXP3-positive cells. These findings highlight the intricate interplay between immune cells and breast cancer progression, with implications for personalized treatment strategies. Moving forward, integrating advanced imaging techniques, and exploring immune cell heterogeneity in diverse ethnic cohorts can uncover novel immune signatures and guide tailored immunotherapeutic interventions, ultimately improving breast cancer management.

Progression from ductal carcinoma in situ to invasive breast cancer: molecular features and clinical significance

Ductal carcinoma in situ (DCIS) represents pre-invasive breast carcinoma. In untreated cases, 25-60% DCIS progress to invasive ductal carcinoma (IDC). The challenge lies in distinguishing between non-progressive and progressive DCIS, often resulting in over- or under-treatment in many cases. With increasing screen-detected DCIS in these years, the nature of DCIS has aroused worldwide attention. A deeper understanding of the biological nature of DCIS and the molecular journey of the DCIS-IDC transition is crucial for more effective clinical management. Here, we reviewed the key signaling pathways in breast cancer that may contribute to DCIS initiation and progression. We also explored the molecular features of DCIS and IDC, shedding light on the progression of DCIS through both inherent changes within tumor cells and alterations in the tumor microenvironment. In addition, valuable research tools utilized in studying DCIS including preclinical models and newer advanced technologies such as single-cell sequencing, spatial transcriptomics and artificial intelligence, have been systematically summarized. Further, we thoroughly discussed the clinical advancements in DCIS and IDC, including prognostic biomarkers and clinical managements, with the aim of facilitating more personalized treatment strategies in the future. Research on DCIS has already yielded significant insights into breast carcinogenesis and will continue to pave the way for practical clinical applications.

The Possible Role of Anti- and Protumor-Infiltrating Lymphocytes in Pathologic Complete Response in Early Breast Cancer Patients Treated with Neoadjuvant Systemic Therapy

The tumor microenvironment, composed of pro- and antitumor immune cells, affects cancer cell behavior. We aimed to evaluate whether tumor-infiltrating lymphocyte (TIL) density and TIL subtypes in core biopsies at the diagnosis of breast cancer patients could predict a pathologic complete response (pCR; ypT0/is ypN0) from neoadjuvant systemic therapy (NST). The TIL subtypes were determined based on the proportions of presumably antitumor (CD8+, CXCL13+) and protumor (PD-1+, FOXP3+) immune cells. A prospective, noninterventional study, including 171 participants undergoing NST, was performed. The median TIL density for the entire cohort was 10% (IQR: 3.5-23.8), and 59 (35%) patients achieved pCR. TIL density was positively associated with pCR (univariately and multivariably). In the multivariable logistic regression model, TIL density was an independent predictor of pCR (p = 0.012, OR 1.27; 95% CI 1.05-1.54) when controlled for age (p = 0.232), Ki-67 (p = 0.001), node-negative status (p = 0.024), and HER2+/triple negative vs. luminal B-like subtype (p < 0.001). In our sample, higher proportions of PD-1+ TILs and FOXP3+ TILs were associated with a higher probability of pCR but the association was not statistically significant and we could not make any conclusions on the direction of associations in the model with all four biomarkers. In the exploratory multivariable analysis, we showed that only higher CD8+ TILs were associated with pCR. In conclusion, TIL density and its subtypes are associated with pCR.

Regulating the regulatory T cells as cell therapies in autoimmunity and cancer

Regulatory T cells (Tregs), possess a pivotal function in the maintenance of immune homeostasis. The dysregulated activity of Tregs has been associated with the onset of autoimmune diseases and cancer. Hence, Tregs are promising targets for interventions aimed at steering the immune response toward the desired path, either by augmenting the immune system to eliminate infected and cancerous cells or by dampening it to curtail the damage to self-tissues in autoimmune disorders. The activation of Tregs has been observed to have a potent immunosuppressive effect against T cells that respond to self-antigens, thus safeguarding our body against autoimmunity. Therefore, promoting Treg cell stability presents a promising strategy for preventing or managing chronic inflammation that results from various autoimmune diseases. On the other hand, Tregs have been found to be overactivated in several forms of cancer, and their role as immune response regulators with immunosuppressive properties poses a significant impediment to the successful implementation of cancer immunotherapy. However, the targeting of Tregs in a systemic manner may lead to the onset of severe inflammation and autoimmune toxicity. It is imperative to develop more selective methods for targeting the function of Tregs in tumors. In this review, our objective is to elucidate the function of Tregs in tumors and autoimmunity while also delving into numerous therapeutic strategies for reprogramming their function. Our focus is on reprogramming Tregs in a highly activated phenotype driven by the activation of key surface receptors and metabolic reprogramming. Furthermore, we examine Treg-based therapies in autoimmunity, with a specific emphasis on Chimeric Antigen Receptor (CAR)-Treg therapy and T-cell receptor (TCR)-Treg therapy. Finally, we discuss key challenges and the future steps in reprogramming Tregs that could lead to the development of novel and effective cancer immunotherapies.

Identification of differentially expressed HERV-K(HML-2) loci in colorectal cancer

Colorectal cancer is one of the malignant tumors with the highest mortality rate in the world. Survival rates vary significantly among patients at various stages of the disease. A biomarker capable of early diagnosis is required to facilitate the early detection and treatment of colorectal cancer. Human endogenous retroviruses (HERVs) are abnormally expressed in various diseases, including cancer, and have been involved in cancer development. Real-time quantitative PCR was used to detect the transcript levels of HERV-K(HML-2) gag, pol, and env in colorectal cancer to systematically investigate the connection between HERV-K(HML-2) and colorectal cancer. The results showed that HERV-K(HML-2) transcript expression was significantly higher than healthy controls and was consistent at the population and cell levels. We also used next-generation sequencing to identify and characterize HERV-K(HML-2) loci that were differentially expressed between colorectal cancer patients and healthy individuals. The analysis revealed that these loci were concentrated in immune response signaling pathways, implying that HERV-K impacts the tumor-associated immune response. Our results indicated that HERV-K might serve as a screening tumor marker and a target for tumor immunotherapy in colorectal cancer.

Metabolomic Signatures of Scarff-Bloom-Richardson (SBR) Grade in Non-Metastatic Breast Cancer

PURPOSE

Identification of metabolomic biomarkers of high SBR grade in non-metastatic breast cancer.

METHODS

This retrospective bicentric metabolomic analysis included a training set (n = 51) and a validation set (n = 49) of breast cancer tumors, all classified as high-grade (grade III) or low-grade (grade I-II). Metabolomes of tissue samples were studied by liquid chromatography coupled with mass spectrometry.

RESULTS

A molecular signature of the top 12 metabolites was identified from a database of 602 frequently predicted metabolites. Partial least squares discriminant analyses showed that accuracies were 0.81 and 0.82, the R2 scores were 0.57 and 0.55, and the Q2 scores were 0.44431 and 0.40147 for the training set and validation set, respectively; areas under the curve for the Receiver Operating Characteristic Curve were 0.882 and 0.886. The most relevant metabolite was diacetylspermine. Metabolite set enrichment analyses and metabolic pathway analyses highlighted the tryptophan metabolism pathway, but the concentration of individual metabolites varied between tumor samples.

CONCLUSIONS

This study indicates that high-grade invasive tumors are related to diacetylspermine and tryptophan metabolism, both involved in the inhibition of the immune response. Targeting these pathways could restore anti-tumor immunity and have a synergistic effect with immunotherapy. Recent studies could not demonstrate the effectiveness of this strategy, but the use of theragnostic metabolomic signatures should allow better selection of patients.

Spatial interplay of tissue hypoxia and T-cell regulation in ductal carcinoma in situ

Hypoxia promotes aggressive tumor phenotypes and mediates the recruitment of suppressive T cells in invasive breast carcinomas. We investigated the role of hypoxia in relation to T-cell regulation in ductal carcinoma in situ (DCIS). We designed a deep learning system tailored for the tissue architecture complexity of DCIS, and compared pure DCIS cases with the synchronous DCIS and invasive components within invasive ductal carcinoma cases. Single-cell classification was applied in tandem with a new method for DCIS ductal segmentation in dual-stained CA9 and FOXP3, whole-tumor section digital pathology images. Pure DCIS typically has an intermediate level of colocalization of FOXP3+ and CA9+ cells, but in invasive carcinoma cases, the FOXP3+ (T-regulatory) cells may have relocated from the DCIS and into the invasive parts of the tumor, leading to high levels of colocalization in the invasive parts but low levels in the synchronous DCIS component. This may be due to invasive, hypoxic tumors evolving to recruit T-regulatory cells in order to evade immune predation. Our data support the notion that hypoxia promotes immune tolerance through recruitment of T-regulatory cells, and furthermore indicate a spatial pattern of relocalization of T-regulatory cells from DCIS to hypoxic tumor cells. Spatial colocalization of hypoxic and T-regulatory cells may be a key event and useful marker of DCIS progression.

Ductal Carcinoma in Situ: Molecular Changes Accompanying Disease Progression

Ductal carcinoma in situ (DCIS) is a non-obligate precursor of invasive ductal carcinoma (IDC), whereby if left untreated, approximately 12% of patients develop invasive disease. The current standard of care is surgical removal of the lesion, to prevent potential progression, and radiotherapy to reduce risk of recurrence. There is substantial overtreatment of DCIS patients, considering not all DCIS lesions progress to invasive disease. Hence, there is a critical imperative to better predict which DCIS lesions are destined for poor outcome and which are not, allowing for tailored treatment. Active surveillance is currently being trialed as an alternative management practice, but this approach relies on accurately identifying cases that are at low risk of progression to invasive disease. Two DCIS-specific genomic profiling assays that attempt to distinguish low and high-risk patients have emerged, but imperfections in risk stratification coupled with a high price tag warrant the continued search for more robust and accessible prognostic biomarkers. This search has largely turned researchers toward the tumor microenvironment. Recent evidence suggests that a spectrum of cell types within the DCIS microenvironment are genetically and phenotypically altered compared to normal tissue and play critical roles in disease progression. Uncovering the molecular mechanisms contributing to DCIS progression has provided optimism for the search for well-validated prognostic biomarkers that can accurately predict the risk for a patient developing IDC. The discovery of such markers would modernize DCIS management and allow tailored treatment plans. This review will summarize the current literature regarding DCIS diagnosis, treatment, and pathology.

The role of stromal immune microenvironment in the progression of ductal carcinoma in situ (DCIS) to invasive breast cancer

Aim

The first aim of the study was to compare the scores and types of stromal immune cells in 30 patients with primary DCIS and in the same patients after invasive breast recurrence in order to assess possible differences in both during tumor progression. The second aim was to evaluate possible differences in stromal cells of 30 patients with primary DCIS before progression and in the control group of 11 DCIS patients without recurrence during long-term follow-up.

Material and methods

Evaluation of tumor-infiltrating lymphocytes (TILs) and immunohistochemical stains for immune cell markers CD4, CD8, CD20, CD138, FOXP3, CD163 and TGF beta was performed on the stroma of primary DCIS before progression, invasive breast cancer of the same patients after progression and DCIS without progression.

Results

The comparison of stromal cells in 30 patients with initial DCIS and its invasive recurrence revealed an increased level of CD20 + immune cells (median score 5% vs. 17%, respectively, p < 0.001) and CD163 + cells (median score 1% vs. 5%, respectively, p < 0.001) in invasive breast cancer. The comparison of stromal cells in 30 patients with initial DCIS before recurrence and the control group of 11 patients with DCIS without recurrence showed statistically significant difference for CD138 + cells, which were more prevalent in patients with worse prognosis (median score 0 vs. 2%, respectively, p < 0.001). No similar relationship was found for the other tested cells as well as for TGF-beta.

Conclusions

CD138 + immune cells that were more prevalent in patients with a worse prognosis should be explored in further studies to confirm or exclude their role as a potential biological marker of DCIS invasive recurrence.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-021-01494-9.

Research Progress on the Role of Regulatory T Cell in Tumor Microenvironment in the Treatment of Breast Cancer

The tumor microenvironment (TME) is a complex ecosystem comprised of cancer cells, stromal cells, and immune cells. Analysis of the composition of TME is essential to assess the prognosis of patients with breast cancer (BC) and the efficacy of different regimes. Treg plays a crucial role in the microenvironment of breast cancer subtypes, and its function contributes to the development and progression of BC by suppressing anti-tumor immunity directly or indirectly through multiple mechanisms. In addition, conventional treatments, such as anthracycline-based neoadjuvant chemotherapy, and neo-therapies, such as immune-checkpoint blockades, have a significant impact on the absence of Tregs in BC TME, thus gaining additional anti-tumor effect to some extent. Strikingly, Treg in BC TME revealed the predicted efficacy of some therapeutic strategies. All these results suggest that we can manipulate the abundance of Treg to achieve the ultimate effect of both conventional and novel treatments. In this review, we discuss new insights into the characteristics of Treg in BC TME, the impact of different regiments on Treg, and the possibilities of Treg as a predictive marker of efficacy for certain treatments.

In Situ Overexpression of Matricellular Mechanical Proteins Demands Functional Immune Signature and Mitigates Non-Small Cell Lung Cancer Progression

Non-small cell lung carcinoma (NSCLC) is a complex cancer biome composed of malignant cells embedded in a sophisticated tumor microenvironment (TME) combined with different initiating cell types, including immune cells and cancer-associated fibroblasts (CAFs), and extracellular matrix (ECM) proteins. However, little is known about these tumors’ immune-matricellular relationship as functional and mechanical barriers. This study investigated 120 patients with NSCLC to describe the immune-matricellular phenotypes of their TME and their relationship with malignant cells. Immunohistochemistry (IHC) was performed to characterize immune checkpoints (PD-L1, LAG-3, CTLA-4+, VISTA 1), T cells (CD3+), cytotoxic T cells (CD8⁺, Granzyme B), macrophages (CD68+), regulatory T cells (FOXP3+, CD4+), natural killer cells (CD57+), and B lymphocytes (CD20+), whereas CAFs and collagen types I, III, and V were characterized by immunofluorescence (IF). We observed two distinct functional immune-cellular barriers—the first of which showed proximity between malignant cells and cytotoxic T cells, and the second of which showed distant proximity between non-cohesive nests of malignant cells and regulatory T cells. We also identified three tumor-associated matricellular barriers: the first, with a localized increase in CAFs and a low deposition of Col V, the second with increased CAFs, Col III and Col I fibers, and the third with a high amount of Col fibers and CAFs bundled and aligned perpendicularly to the tumor border. The Cox regression analysis was designed in two steps. First, we investigated the relationship between the immune-matricellular components and tumor pathological stage (I, II, and IIIA), and better survival rates were seen in patients whose tumors expressed collagen type III > 24.89 fibers/mm². Then, we included patients who had progressed to pathological stage IV and found an association between poor survival and tumor VISTA 1 expression > 52.86 cells/mm² and CD3+ ≤ 278.5 cells/mm². We thus concluded that differential patterns in the distribution of immune-matricellular phenotypes in the TME of NSCLC patients could be used in translational studies to predict new treatment strategies and improve patient outcome. These data raise the possibility that proteins with mechanical barrier function in NSCLC may be used by cancer cells to protect them from immune cell infiltration and immune-mediated destruction, which can otherwise be targeted effectively with immunotherapy or collagen therapy.

Tumour-infiltrating lymphocytes in non-invasive breast cancer: A systematic review and meta-analysis

Background

The role of tumour infiltrating lymphocytes (TILs) as a biomarker in non-invasive breast cancer is unclear. This meta-analysis assessed the prognostic impact of TIL levels in patients with non-invasive breast cancer.

Methods

Systematic literature search was performed to identify studies assessing local recurrence in patients with non-invasive breast cancer according to TIL levels (high vs. low). Subgroup analyses per local recurrence (invasive and non-invasive) were performed. Secondary objectives were the association between TIL levels and non-invasive breast cancer subtypes, age, grade and necrosis. Odds ratios (ORs) and 95% confidence intervals (CI) were extracted from each study and a pooled analysis was conducted with random-effect model.

Results

Seven studies (N = 3437) were included in the present meta-analysis. High-TILs were associated with a higher likelihood of local recurrence (invasive or non-invasive, N = 2941; OR 2.05; 95%CI, 1.03–4.08; p = 0.042), although with a lower likelihood of invasive local recurrence (N = 1722; OR 0.69; 95%CI, 0.49–0.99; p = 0.042). High-TIL levels were associated with triple-negative (OR 3.84; 95%CI, 2.23–6.61; p < 0.001) and HER2-positive (OR 6.27; 95%CI, 4.93–7.97; p < 0.001) subtypes, high grade (OR 5.15; 95%CI, 3.69–7.19; p < 0.001) and necrosis (OR 3.09; 95%CI, 2.33–4.10; p < 0.001).

Conclusions

High-TIL levels were associated with more aggressive tumours, a higher likelihood of local recurrence (invasive or non-invasive) but a lower likelihood of invasive local recurrence in patients with non-invasive breast cancer.

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The prognostic role of TILs in non-invasive breast cancer is unknown.

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We observed an association between high-TILs and local recurrence.

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High-TILs were associated with triple-negative and HER2+ subtypes, high grade and necrosis.

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Non-invasive lesions with aggressive characteristics may also be more immunogenic.

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Patients with low-TILs showed a higher likelihood of presenting an invasive recurrence.

Nodal status in luminal A invasive breast cancer: relationships with cytotoxic CD8 + and regulatory FOXP3 + cells tumor-associated infiltrate and other prognostic factors

Luminal A breast cancers are generally associated with low metastatic potential and good prognosis. However, there is a proportion of patients, who present with metastases in lymph nodes. The aim of our study was to determine the association between the number of positive lymph nodes and infiltrates of tumor-associated cytotoxic CD8 + (CTLs), regulatory FOXP3 + T cells (Tregs), as well as other prognostic factors. Immunohistochemistry (IHC) for CD8 + and FOXP3 + was performed in 87 formalin-fixed paraffin-embedded primary breast cancer tissues, and cell infiltrate was assessed under light microscope. We observed that node-positive cases were associated with higher numbers of Treg cells and lower CTL/Treg ratio. There was also an inverse correlation between the CTL/Treg ratio and the number of metastatic lymph nodes. Similar relationships were found between the number of metastatic lymph nodes and Treg density or CTL/Treg ratio in pT1 BC. An elevated intratumoral CTL/Treg ratio was associated with pN0 stage. The relationship between lymphovascular invasion (LVI) and Treg density was also noted in node-negative tumors. In addition, more advanced nodal stage was related to LVI, higher pT, and lower PR expression. The numbers of CD8 + and FOXP3 + were also associated with tumor size, histologic grade, PR expression, and mitotic index. The results of our study suggested that the levels of tumor-infiltrating regulatory and cytotoxic cells as well as the balance between them play a role in lymphovascular spread of luminal A breast cancers.

Prognostic and therapeutic role of tumor-infiltrating lymphocyte subtypes in breast cancer

Increased levels of total tumor-infiltrating lymphocytes (TILs) are generally associated with good prognosis in several breast cancer subtypes. Subtypes of TILs impact both tumor cells and immune cells in a variety of different ways, leading to either a pro-tumor or antitumor effect. Tumor-infiltrating CD8+ T cells and natural killer (NK) cells perform as effector cells against tumor cells and are associated with better clinical outcome. Immunotherapy approaches that improve the antitumor activity and proliferation of CD8+ T and NK cells include PD-1/PD-L1 blockade, CAR T cell therapy, or ex vivo-stimulated NK cells. A subset of CD8+ T cells, tissue-resident memory T cells, has also recently been associated with good prognosis in breast cancer patients, and has potential to serve as a predictive biomarker and therapeutic target. Tumor-infiltrating B cells also secrete apoptosis-inducing IgG antibodies and can act as antigen-presenting cells to prime CD4+ and CD8+ T cells. On the other hand, regulatory T and regulatory B cells modulate the immune response from CD8+ T cells and NK cells by secreting immunosuppressive cytokines and inhibiting maturation of antigen-presenting cells (APCs). These regulatory cells are typically associated with poor prognosis, therefore rendering suppression of their regulatory function a key immunotherapeutic strategy.

Delineating the breast cancer immune microenvironment in the era of multiplex immunohistochemistry/immunofluorescence

Breast cancer is the most common malignancy and the leading cause of cancer death in females worldwide. Treatment is challenging, especially for those who are triple-negative. Increasing evidence suggests that diverse immune populations are present in the breast tumour microenvironment, which opens up avenues for personalised drug targets. Historically, our investigations into the immune constitution of breast tumours have been restricted to analyses of one or two markers at a given time. Recent technological advances have allowed simultaneous labelling of more than 35 markers and detailed profiling of tumour-immune infiltrates at the single-cell level, as well as determining the cellular composition and spatial analysis of the entire tumour architecture. In this review, we describe emerging technologies that have contributed to the field of breast cancer diagnosis, and discuss how to interpret the vast data sets obtained in order to effectively translate them for clinically relevant use.

Higher densities of tumour-infiltrating lymphocytes and CD4+ T cells predict recurrence and progression of ductal carcinoma in situ of the breast

AIMS

Host immunity influences cancer progression and therapeutic response. We investigated the potential of tumour-infiltrating lymphocytes (TILs) around ductal carcinoma in situ (DCIS) in predicting recurrence and progression.

METHODS AND RESULTS

CD4, CD8, programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) expression in DCIS from 198 patients was determined by immunohistochemistry. We correlated disease-free survival (DFS), clinicopathological parameters and biomarker expression with TIL density and CD4/CD8 ratio. High TIL density was associated with high nuclear grade (P < 0.001), DCIS PD-L1 expression (P = 0.008), TIL PD-L1 expression (P < 0.001), oestrogen (ER) negativity (P < 0.001), progesterone (PR) negativity (P < 0.001), human epidermal growth factor receptor 2 (HER2) positivity (P = 0.002) and triple negativity (P = 0.001). TIL PD-L1 expression was associated with triple-negative DCIS (P = 0.028). TIL density was associated with molecular subtypes (P < 0.001). High CD4⁺ T cell density was associated with high nuclear grade (P = 0.001), microinvasion (P = 0.037), ER negativity (P < 0.001), PR negativity (P = 0.001), HER2 positivity (P = 0.004), triple negativity (P = 0.023) and PD-L1 expression in TILs (P < 0.011). High CD4/CD8 ratio was associated with PD-L1 expression in DCIS (P = 0.035) and TILs (P < 0.001). DCIS with higher TIL density disclosed worse DFS (P = 0.012) and was affirmed with multivariate analysis [95% confidence interval (CI) = 1.109-2.554, hazard ratio (HR) = 1.683, P = 0.014]. Poorer DFS for ipsilateral invasive recurrence was found for DCIS with higher CD4⁺ T cell density (P = 0.006) or CD4/CD8 ratio (P = 0.02), confirmed by multivariate analysis for the former (95% CI = 1.369-10.196, HR = 3.736, P = 0.01) and latter (95% CI = 1.311-7.935, HR = 3.225, P = 0.011).

CONCLUSION

DCIS with higher TIL density was associated with poorer prognostic parameters and predicted recurrence, while both CD4⁺ T cell density and CD4/CD8 ratio were associated with both recurrence and ipsilateral invasive recurrence.

Identification of an immune overdrive high-risk subpopulation with aberrant expression of FOXP3 and CTLA4 in colorectal cancer

Colorectal cancer (CRC) is characterized by a heterogeneous tumor microenvironment (TME) that regulates cancer progression and therapeutic response. Overexpression of FOXP3 and CTLA4 is associated with immunosuppressive TME and poor prognosis in many cancer types. However, opposite results were reported in CRC. Thus, we performed comprehensive analyses to evaluate the exact prognostic value of FOXP3 and CTLA4 in CRC. Here, the expression levels of FOXP3 and CTLA4 were used to construct a subtyping system based on >1200 CRC patients from multiple independent public datasets. We revealed that, in CRC patients with relatively high expression of FOXP3, there exist two different subpopulations with opposite survival patterns according to CLTA4 expression. We further established a method for evaluating all cohorts and identified a novel FOXP3^HighCTLA4^High* CRC risk subpopulation that accounts for 5-10% of CRC patients. Moreover, different methods of functional enrichment and immune evaluation were used to analyze the TME characteristics of different FOXP3/CTLA4 subtypes. The FOXP3^HighCTLA4^High* CRC risk subpopulation was characterized by an immune overdrive TME phenotype, including high immune cell infiltration, low tumor purity, high immune checkpoint levels, and TGF-β activation. Finally, the constructed FOXP3/CTLA4 subtyping system was further validated by quantitative RT-PCR, immunochemistry staining, and multicolor immunofluorescence in an independent CRC cohort we collected. This high-risk subpopulation was also observed in kidney cancers and low-grade glioma patients by a Pan-cancer analysis. Together, our study revealed that the established FOXP3/CTLA4 molecular subtyping system could be used to select treatment and management strategies for CRC and other cancers.

Immune Escape during Breast Tumor Progression

Immunotherapy using checkpoint inhibitors is one of the most promising current cancer treatment strategies. However, in breast cancer, its success has been limited to a subset of patients with triple-negative disease, whose durability of observed responses remain unclear. The lack of detailed understanding of breast tumor immune evasion mechanisms and the treatment of patients with highly heterogeneous metastatic disease contribute to these disappointing results. Here we discuss the current knowledge about immune-related changes during breast tumor progression, with special emphasis on the in situ-to-invasive breast carcinoma transition that may represent a key step of immunoediting in breast cancer. Comprehensive characterization of early-stage disease and better understanding of immunologic drivers of disease progression will likely expand the tools available for immunotherapy and improve patient stratification.

Immune microenvironment in different molecular subtypes of ductal breast carcinoma

PURPOSE

Ductal breast carcinoma as a heterogeneous disease has different molecular subtypes associated with clinical prognosis and patients' survival. The role of immune system as a consistent part of the tumor microenvironment (TME) has been documented in progression of ductal breast carcinoma. Here, we aimed to describe the important immune cells and the immune system-associated molecules in Ductal Carcinoma In situ (DCIS) and Invasive Ductal Carcinoma (IDC) with special emphasis on their associations with different molecular subtypes and patients' prognosis.

RESULTS

The immune cells have a dual role in breast cancer (BC) microenvironment depending on the molecular subtype or tumor grade. These cells with different frequencies are present in the TME of DCIS and IDC. The presence of regulatory cells including Tregs, MDSC, Th2, Th17, M2 macrophages, HLADR^- T cells, and Tγδ cells is related to more immunosuppressive microenvironment, especially in ER^- and TN subtypes. In contrast, NK cells, CTL, Th, and Tfh cells are associated to the anti-tumor activity. These cells are higher in ER⁺ BC, although in other subtypes such as TN or HER2⁺ are associated with a favorable prognosis.

CONCLUSION

Determining the specific immune response in each subtype could be helpful in estimating the possible behavior of the tumor cells in TME. It is important to realize that different frequencies of immune cells in BC environment likely determine the patients' prognosis and their survival in each subtype. Therefore, elucidation of the distinct immune players in TME would be helpful toward developing targeted therapies in each subtype.

The prognostic significance of immune microenvironment in breast ductal carcinoma in situ

BACKGROUND

The role of different subtypes of tumour infiltrating lymphocytes (TILs) in breast ductal carcinoma in situ (DCIS) is still poorly defined. This study aimed to assess the prognostic significance of B and T lymphocytes and immune checkpoint proteins expression in DCIS.

METHODS

A well characterised DCIS cohort (n = 700) with long-term follow-up comprising pure DCIS (n = 508) and DCIS mixed with invasive carcinoma (IBC; n = 192) were stained immunohistochemically for CD20, CD3, CD4, CD8, FOXP3, PD1 and PDL1. Copy number variation and TP53 mutation status were assessed in a subset of cases (n = 58).

RESULTS

CD3+ lymphocytes were the predominant cell subtype in the pure DCIS cohort, while FOXP3 showed the lowest levels. PDL1 expression was mainly seen in the stromal TILs. Higher abundance of TILs subtypes was associated with higher tumour grade, hormone receptor negativity and HER2 positivity. Mutant TP53 variants were associated with higher levels of stromal CD3+, CD4+ and FOXP3+ cells. DCIS coexisting with invasive carcinoma harboured denser stromal infiltrates of all immune cells and checkpoint proteins apart from CD4+ cells. Stromal PD1 was the most differentially expressed protein between DCIS and invasive carcinoma (Z = 5.8, p < 0.0001). Dense TILs, stromal FOXP3 and PDL1 were poor prognostic factors for DCIS recurrence, while dense TILs were independently associated with poor outcome for all recurrences (HR = 7.0; p = 0.024), and invasive recurrence (HR = 2.1; p = 0.029).

CONCLUSIONS

Immunosuppressive proteins are potential markers for high risk DCIS and disease progression. Different stromal and intratumoural lymphocyte composition between pure DCIS, DCIS associated with IBC and invasive carcinoma play a potential role in their prognostic significance and related to the underlying genomic instability. Assessment of overall TILs provides a promising tool for evaluation of the DCIS immune microenvironment.

Immune microenvironment in ductal carcinoma in situ: a comparison with invasive carcinoma of the breast

Background

The immune microenvironment in ductal carcinoma in situ (DCIS) and its significance are not well established. This study was conducted to evaluate the immune microenvironment of DCIS including the composition of tumor-infiltrating lymphocyte (TIL) subsets and PD-L1+ immune cells and to compare it with that of invasive breast cancer.

Materials and methods

A total of 671 cases including three different disease groups of pure DCIS, DCIS with microinvasion (DCIS-M), and invasive carcinoma were included in this study. CD4+, CD8+, and FOXP3+ TIL subsets and PD-L1+ immune cells were detected with immunohistochemistry using tissue microarrays and were analyzed in relation to clinicopathologic characteristics and different disease groups.

Results

In pure DCIS, high infiltrations of CD4+, CD8+, and FOXP3+ T cells and the presence of PD-L1+ immune cells were associated with high nuclear grade, comedo-type necrosis, hormone receptor (HR) negativity, and high Ki-67 proliferation index. All immune cell infiltrations were higher in invasive carcinoma than in pure DCIS regardless of the HR status. While CD4+ T cells were more abundant than CD8+ T cells in pure DCIS, CD8+ T cells were dominant in invasive carcinoma, especially in HR-negative tumors. Within individual cases of invasive carcinoma with DCIS component, all immune cell subset infiltration was higher in the invasive component than in the DCIS component; however, CD4+ TIL infiltration did not differ between the two components in HR-negative tumors. Comparing pure DCIS, DCIS-M, and DCIS associated with invasive carcinoma (DCIS-INV), CD4+ TIL infiltration revealed a gradual increase from pure DCIS to DCIS-M and DCIS-INV in the HR-negative group, whereas FOXP3+ TIL infiltration was significantly increased in DCIS-INV than in pure DCIS in the HR-positive group. The high infiltration of FOXP3+ TIL and the presence of PD-L1+ immune cells were associated with tumor recurrence in patients with pure DCIS.

Conclusions

Our study showed that the immune microenvironment differs significantly not only between DCIS and invasive carcinoma but also between pure DCIS, DCIS-M, and DCIS-INV depending on the HR status.

Higher density of stromal M2 macrophages in breast ductal carcinoma in situ predicts recurrence

Immune response can affect tumour progression and treatment outcome. This study investigated the potential of stromal macrophages around ductal carcinoma in situ (DCIS) in predicting recurrence and progression. CD68 and CD163 expression of macrophages in DCIS from 198 patients was determined by immunohistochemistry. Disease free survival (DFS), clinicopathological parameters and biomarker expression were correlated with the densities of both CD68⁺ and CD163⁺ macrophages. High CD68⁺ macrophage density was associated with high nuclear grade (p < 0.001), oestrogen receptor (ER) negativity (p = 0.029), progesterone receptor (PR) negativity (p = 0.008) and human epidermal growth factor receptor 2 (HER2) positivity (p < 0.001). High CD163⁺ macrophage density was associated with high nuclear grade (p = 0.003), microinvasion (p = 0.01), ER negativity (p < 0.001), PR negativity (p = 0.001), HER2 positivity (p = 0.001) and triple negativity (p = 0.022). DCIS with higher CD68⁺ macrophage density disclosed significantly worse DFS for ipsilateral invasive recurrence (p = 0.004) and is affirmed by multivariate Cox regression analysis (95% CI 1.126-5.102, HR = 2.397, p = 0.023). DCIS with higher CD163⁺ macrophage density showed significantly worse DFS for both recurrence (p = 0.001) and ipsilateral invasive recurrence (p = 0.001). These findings, for CD163⁺ macrophage density, were affirmed by multivariate Cox regression analysis respectively for both recurrence (95% CI 1.210-2.293, HR = 1.880, p = 0.005) and ipsilateral invasive recurrence (95% CI 1.122-5.176, HR = 2.410, p = 0.024). This study demonstrated that DCIS with higher macrophage density was associated with poorer prognostic parameters, while DCIS with higher CD163⁺ macrophage density predicted both  recurrence and ipsilateral invasive recurrence.

Prognostic role of immune infiltrates in breast ductal carcinoma in situ

PURPOSE

Ductal carcinoma in situ (DCIS) of the breast is often regarded as a non-obligate precursor to invasive breast carcinoma but current diagnostic tools are unable to accurately predict the invasive potential of DCIS. Infiltration of immune cells into the tumour and its microenvironment is often an early event at the site of tumourigenesis. These immune infiltrates may be potential predictive and/or prognostic biomarkers for DCIS. This review aims to discuss recent findings pertaining to the potential prognostic significance of immune infiltrates as well as their evaluation in DCIS.

METHODS

A literature search on PubMed was conducted up to 28th January 2019. Search terms used were "DCIS", "ductal carcinoma in situ", "immune", "immunology", "TIL", "TIL assessment", and "tumour-infiltrating lymphocyte". Search filters for "Most Recent" and "English" were applied. Information from published papers related to the research topic were synthesised and summarised for this review.

RESULTS

Studies have revealed that immune infiltrates play a role in the biology and microenvironment of DCIS, as well as treatment response. There is currently no consensus on the evaluation of TILs in DCIS for clinical application.

CONCLUSIONS

This review highlights the recent findings on the potential influence and prognostic value of immunological processes on DCIS progression, as well as the evaluation of TILs in DCIS. Further characterisation of the immune milieu of DCIS is recommended to better understand the immune response in DCIS progression and recurrence.

Treg programming and therapeutic reprogramming in cancer

Overcoming the immunosuppressive tumour microenvironment is the major challenge impeding cancer immunotherapy today. Regulatory T-cells (Tregs) are prevalent in nearly all cancers and, as immunosuppressive regulators of immune responses, they are the principal opponents of cancer immunotherapy. However, disabling Tregs systemically causes severe autoimmune toxicity, hastening the need for more selective methods to target intratumoural Tregs. In this review, we discuss a burgeoning new modality to specifically target tumour-infiltrating Tregs (TI-Tregs) by reprogramming their functionality from immunosuppressive to immune stimulatory within tumours. As the basis for therapeutic selectivity of TI-Tregs, we will focus on the defining features of Tregs within cancer: their highly activated state controlled by the engagement of key surface receptors, their distinct metabolic programme, and their unique transcriptional programme. By identifying proteins and pathways that distinguish TI-Tregs from other Tregs in the body, as well as from the beneficial antitumour effector T-cells within tumours, we highlight mechanisms to selectively reprogramme TI-Tregs for the treatment of cancer.

Sox2 Communicates with Tregs Through CCL1 to Promote the Stemness Property of Breast Cancer Cells

As an important component of the tumor microenvironment, CD4⁺ CD25⁺ Tregs reduce antitumor immunity, promote angiogenesis and metastasis in breast cancer. However, their function in regulating the "stemness" of tumor cells and the communication between Tregs and cancer stem cells (CSCs) remain elusive. Here, we disclose that the primarily cultured Tregs isolated from breast-tumor-bearing Foxp3-EGFP mouse upregulate the stemness property of breast cancer cells. Tregs increased the side-population and the Aldehyde dehydrogenase-bright population of mouse breast cancer cells, promoted their sphere formation in a paracrine manner, and enhanced the expression of stemness genes, such as Sox2 and so forth. In addition, Tregs increased tumorigenesis, metastasis, and chemoresistance of breast cancer cells. Furthermore, Sox2-overexpression tumor cells activated NF-κB-CCL1 signaling to recruit Tregs through reducing the binding of H3K27Me3 on promoter regions of p65 and Ccl1. These findings reveal the functional interaction between Tregs and CSCs and indicate that targeting on the communication between them is a promising strategy in breast cancer therapy. Stem Cells 2017;35:2351-2365.

Tumor-infiltrating lymphocytes and ductal carcinoma in situ of the breast: friends or foes?

In the past three decades, the detection rate of ductal carcinoma in situ of the breast has dramatically increased due to breast screening programs. As a consequence, about 20% of all breast cancer cases are detected in this early in situ stage. Some ductal carcinoma in situ cases will progress to invasive breast cancer, while other cases are likely to have an indolent biological behavior. The presence of tumor-infiltrating lymphocytes is seen as a promising prognostic and predictive marker in invasive breast cancer, mainly in HER2-positive and triple-negative subtypes. Here, we summarize the current understanding regarding immune infiltrates in invasive breast cancer and highlight recent observations regarding the presence and potential clinical significance of such immune infiltrates in patients with ductal carcinoma in situ. The presence of tumor-infiltrating lymphocytes, their numbers, composition, and potential relationship with genomic status will be discussed. Finally, we propose that a combination of genetic and immune markers may better stratify ductal carcinoma in situ subtypes with respect to tumor evolution.

Analysis of tumour-infiltrating lymphocytes reveals two new biologically different subgroups of breast ductal carcinoma in situ

Background

Tumour-infiltrating lymphocytes (TILs) have been demonstrated to significantly influence prognosis and response to therapy of invasive breast cancer (IBC). Thus, it has been suggested that TIL density or/and immunophenotype could serve as biomarkers for selection of IBC patients for immunotherapy. However, much less is known about significance of TILs in breast ductal carcinoma in situ (DCIS).

Methods

We retrospectively investigated TIL density and immunophenotype in 96 pure DCIS and 35 microinvasive carcinomas (miCa). TIL density was assessed on H&E-stained breast biopsy sections as the percentage of tumour stromal area occupied by TILs, and classified into 4 grades: 0 (0%–9%), 1 (10–29%), 2 (30–49%) and 3 (50%–100%). TIL immunophenotype was assessed by immunohistochemistry for CD8, CD4, FoxP3, CD38 or CD20.

Results

Compared to pure DCIS, miCa contained significantly more cases with TIL density grade 3 (p = 0.028). Concordantly, CD8+, CD4+ and CD38+ cells were more numerous in miCa than in pure DCIS. In the pure DCIS subgroup with TIL density grades 2 and 3, all TIL subpopulations were more numerous than in the pure DCIS with TIL density grades 0 and 1, however the ratio between T-lymphocytes (CD8+ and CD4+) and B-lymphocytes (CD20+) was significantly lower (p = 0.029). On the other side, this ratio was significantly higher in miCa, in comparison with pure DCIS having TIL density grades 2 and 3 (p = 0.017). By cluster analysis of tumour cell pathobiological features we demonstrated similarity between miCa and the pure DCIS with TIL density grades 2 and 3. The only significant difference between those two categories was in the ratio of T- to B-TILs, higher in miCa.

Conclusion

Results indicate that TIL density level can distinguish 2 biologically different DCIS subgroups, one of which (DCIS with ≥30% TILs, the TIL-rich DCIS) is like miCa. Similarity of TIL-rich pure DCIS and miCa as well as the role of B-lymphocytes in DCIS invasiveness are worth further investigating with regards to the potential development of immunotherapy-based prevention of DCIS progression.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4013-6) contains supplementary material, which is available to authorized users.

The prevalence and clinical relevance of tumor-infiltrating lymphocytes (TILs) in ductal carcinoma in situ of the breast

Background

Tumor-infiltrating lymphocytes (TILs) are a robust prognostic adjunct in invasive breast cancer, but their clinical role in ductal carcinoma in situ (DCIS) has not been ascertained.

Patients and methods

We evaluated the prevalence and clinical relevance of TILs in a well annotated series of 1488 consecutive DCIS women with a median follow-up of 8.2 years. Detailed criteria for TILs evaluation were pre-defined involving the International Immuno-Oncology Biomarker Working Group. TILs percentage was considered both as a continuous and categorical variable. Levels of TILs were examined for their associations with ipsilateral breast event (IBE), whether in situ or invasive.

Results

Of the 1488 patients with DCIS under study, 35.1% had <1%, 58.3% 1-49% and 6.5% ≥50% peri-ductal stromal lymphocytes. The interobserver agreement in TILs evaluation, measured by the intraclass correlation coefficient (ICC) was 0.96 (95% CI 0.95-0.97). At univariable analysis, clinical factors significantly associated with TILs (P ≤0.001) were intrinsic subtype, grade, necrosis, type of surgery. Her-2 positive DCIS were more frequently associated with TILs (24% of patients with TILs ≥50%), followed by the triple negative (11%), Luminal B/Her-2 positive (9%) and Luminal A/B subtypes (1%) (P < 0.0001). We did not find any association between TILs as a continuous variable and the risk of IBEs. Likewise, when patients were stratified by TILs percentage (<1%, between 1% and 49.9%, and ≥50%), no statistically significant association was observed (10-year cumulative incidence of IBEs: 19%, 17.3%, and 18.7% respectively, P = 0.767).

Conclusion

TILs occur more frequently in the Her-2 positive DCIS. Although we did not find a significant association between TILs and the 10-year risk of IBE, our data suggest that immunotherapies might be considered in subsets of DCIS patients.

Immune Escape in Breast Cancer During In Situ to Invasive Carcinoma Transition

To investigate immune escape during breast tumor progression, we analyzed the composition of leukocytes in normal breast tissues, ductal carcinoma in situ (DCIS), and invasive ductal carcinomas (IDC). We found significant tissue and tumor subtype-specific differences in multiple cell types including T cells and neutrophils. Gene expression profiling of CD45+CD3+ T cells demonstrated a decrease in CD8+ signatures in IDCs. Immunofluorescence analysis showed fewer activated GZMB+CD8+ T cells in IDC than in DCIS, including in matched DCIS and recurrent IDC. T-cell receptor clonotype diversity was significantly higher in DCIS than in IDCs. Immune checkpoint protein TIGIT-expressing T cells were more frequent in DCIS, whereas high PD-L1 expression and amplification of CD274 (encoding PD-L1) was only detected in triple-negative IDCs. Coamplification of a 17q12 chemokine cluster with ERBB2 subdivided HER2+ breast tumors into immunologically and clinically distinct subtypes. Our results show coevolution of cancer cells and the immune microenvironment during tumor progression.Significance: The design of effective cancer immunotherapies requires the understanding of mechanisms underlying immune escape during tumor progression. Here we demonstrate a switch to a less active tumor immune environment during the in situ to invasive breast carcinoma transition, and identify immune regulators and genomic alterations that shape tumor evolution. Cancer Discov; 7(10); 1098-115. ©2017 AACR.See related commentary by Speiser and Verdeil, p. 1062This article is highlighted in the In This Issue feature, p. 1047.

Assessing Tumor-infiltrating Lymphocytes in Solid Tumors: A Practical Review for Pathologists and Proposal for a Standardized Method From the International Immunooncology Biomarkers Working Group: Part 1: Assessing the Host Immune Response, TILs in Invasive Breast Carcinoma and Ductal Carcinoma In Situ, Metastatic Tumor Deposits and Areas for Further Research

Assessment of tumor-infiltrating lymphocytes (TILs) in histopathologic specimens can provide important prognostic information in diverse solid tumor types, and may also be of value in predicting response to treatments. However, implementation as a routine clinical biomarker has not yet been achieved. As successful use of immune checkpoint inhibitors and other forms of immunotherapy become a clinical reality, the need for widely applicable, accessible, and reliable immunooncology biomarkers is clear. In part 1 of this review we briefly discuss the host immune response to tumors and different approaches to TIL assessment. We propose a standardized methodology to assess TILs in solid tumors on hematoxylin and eosin sections, in both primary and metastatic settings, based on the International Immuno-Oncology Biomarker Working Group guidelines for TIL assessment in invasive breast carcinoma. A review of the literature regarding the value of TIL assessment in different solid tumor types follows in part 2. The method we propose is reproducible, affordable, easily applied, and has demonstrated prognostic and predictive significance in invasive breast carcinoma. This standardized methodology may be used as a reference against which other methods are compared, and should be evaluated for clinical validity and utility. Standardization of TIL assessment will help to improve consistency and reproducibility in this field, enrich both the quality and quantity of comparable evidence, and help to thoroughly evaluate the utility of TILs assessment in this era of immunotherapy.

Expression of GARP Is Increased in Tumor-Infiltrating Regulatory T Cells and Is Correlated to Clinicopathology of Lung Cancer Patients

Regulatory T cells (Tregs) are immunosuppressive T cells that play an important role in immune homeostasis. Multiple markers have been associated with the characterization, as well as function of Tregs. Recently, glycoprotein A repetitions predominant (GARP), a transmembrane protein containing leucine-rich repeats, has been found to be highly expressed on the surface of activated Tregs. GARP maintains Tregs’ regulatory function and homeostasis through the activation and secretion of transforming growth factor β. In this study, we investigated the expression of GARP in Tregs from the peripheral blood (PB) and tumor tissues of lung cancer patients. The association between the proportion and expression level of GARP on Tregs and the clinicopathological factors of lung cancer patients was also analyzed. Results showed that in the tumor tissues of patients with lung cancer, GARP expression was increased in Tregs and was associated with lymph node metastasis, distant metastasis, and clinical stage. Furthermore, the infiltrating Tregs from early stage patients exhibited higher GARP expression than that from advanced cancer patients, which indicated that GARP might be an early prognostic biomarker. In vitro coculture studies demonstrated that human lung cancer cell lines might induce the expression of GARP in Tregs by certain mechanisms. Overall, this research demonstrated the potential value of GARP in Tregs definition and cancer immunotherapy.

Adjuvant therapy in patients with ductal carcinoma in situ of the breast: The Pandora's box

Most patients with ductal carcinoma in situ of the breast (DCIS) are eligible for breast conservation treatment. The key management decision is whether to add radiotherapy and/or endocrine therapy to minimize the risk of a subsequent recurrence. Recent analyses indicating a lack of benefit in terms of breast cancer-associated mortality have suggested that more conservative approaches, omitting adjuvant therapy or even surgery, may be advisable in selected patients. These mortality observations are directly influenced by widespread use of mammographic screening which has opened a Pandora's box of subclinical DCIS and early invasive lesions. Confusion as to how aggressively such possibly indolent lesions should be treated has led to misunderstandings among patients and medical professionals. While awaiting further prospective evidence from clinical trials, we endorse an active treatment of DCIS as the standard of care. Our rationale is twofold: invasive recurrences are associated with an increase in breast cancer mortality, which is not the only relevant endpoint for DCIS. The benefit of complete surgical excision, adjuvant radiotherapy and endocrine treatment in preventing recurrence and invasive progression has been demonstrated in DCIS. The challenge now is how to identify DCIS patients who will not progress to invasive carcinoma even without complete excision and, at the other extreme, those patients at the highest risk who require mastectomy for local control. The current controversies over whether and which adjuvant therapy should be implemented can at least in part be addressed by developing effective doctor-patient communications that enable mutual understanding about the management of this biologically heterogeneous disease.

Characterizing the immune microenvironment in high-risk ductal carcinoma in situ of the breast

PURPOSE

The recent increase in the incidence of ductal carcinoma in situ (DCIS) has sparked debate over the classification and treatment of this disease. Although DCIS is considered a precursor lesion to invasive breast cancer, some DCIS may have more or less risk than is realized. In this study, we characterized the immune microenvironment in DCIS to determine if immune infiltrates are predictive of recurrence.

METHODS

Fifty-two cases of high-grade DCIS (HG-DCIS), enriched for large lesions and a history of recurrence, were age matched with 65 cases of non-high-grade DCIS (nHG-DCIS). Immune infiltrates were characterized by single- or dual-color staining of FFPE sections for the following antigens: CD4, CD8, CD20, FoxP3, CD68, CD115, Mac387, MRC1, HLA-DR, and PCNA. Nuance multispectral imaging software was used for image acquisition. Protocols for automated image analysis were developed using CellProfiler. Immune cell populations associated with risk of recurrence were identified using classification and regression tree analysis.

RESULTS

HG-DCIS had significantly higher percentages of FoxP3⁺ cells, CD68⁺ and CD68⁺PCNA⁺ macrophages, HLA-DR⁺ cells, CD4⁺ T cells, CD20⁺ B cells, and total tumor infiltrating lymphocytes compared to nHG-DCIS. A classification tree, generated from 16 immune cell populations and 8 clinical parameters, identified three immune cell populations associated with risk of recurrence: CD8⁺HLADR⁺ T cells, CD8⁺HLADR^- T cells, and CD115⁺ cells.

CONCLUSION

These findings suggest that the tumor immune microenvironment is an important factor in identifying DCIS cases with the highest risk for recurrence and that manipulating the immune microenvironment may be an efficacious strategy to alter or prevent disease progression.

Immune infiltrates in the breast cancer microenvironment: detection, characterization and clinical implication

Although unlike melanoma, breast cancer is not generally viewed as a highly immunogenic cancer, recent studies have described a rich tumor immune microenvironment in a subset of breast cancers. These immune infiltrates, comprised cells from the innate and adaptive immune response, can be detected and characterized in biopsy specimens and have prognostic value. Tumor-infiltrating lymphocytes (TILs) represent the majority of mononuclear immune infiltrates in the breast tumor microenvironment and can be easily identified in formalin-fixed paraffin-embedded tissues after standard hematoxylin and eosin staining. High levels of TILs are most common in HER2+ and basal-like subtypes where they are associated with good prognosis and with response to certain therapies such as the anti-HER2 antibody trastuzumab. International collaborative efforts are underway to standardize the assessment of TILs so as to facilitate their implementation as a breast cancer biomarker. Using immunohistochemistry to further characterize TILs, recent reports describe the presence of important lymphocyte populations including CD8+ cytotoxic, FOXP3+ regulatory, and CD4+ helper and follicular T cells which have overlapping associations with prognosis and response to therapies. Moreover, recently identified immune checkpoint markers (PD-1, PD-L1) are present in some breast cancers, implying some cases might be especially amenable to immune checkpoint inhibitor treatment strategies which are being evaluated in a number of active clinical trials.

Maraviroc decreases CCL8-mediated migration of CCR5(+) regulatory T cells and reduces metastatic tumor growth in the lungs

Regulatory T cells (Tregs) play a crucial physiological role in the regulation of immune homeostasis, although recent data suggest Tregs can contribute to primary tumor growth by suppressing antitumor immune responses. Tregs may also influence the development of tumor metastases, although there is a paucity of information regarding the phenotype and function of Tregs in metastatic target organs. Herein, we demonstrate that orthotopically implanted metastatic mammary tumors induce significant Treg accumulation in the lungs, which is a site of mammary tumor metastasis. Tregs in the primary tumor and metastatic lungs express high levels of C-C chemokine receptor type 5 (CCR5) relative to Tregs in the mammary fat pad and lungs of tumor-free mice, and Tregs in the metastatic lungs are enriched for CCR5 expression in comparison to other immune cell populations. We also identify that C-C chemokine ligand 8 (CCL8), an endogenous ligand of CCR5, is produced by F4/80(+) macrophages in the lungs of mice with metastatic primary tumors. Migration of Tregs toward CCL8 ex vivo is reduced in the presence of the CCR5 inhibitor Maraviroc. Importantly, treatment of mice with Maraviroc (MVC) reduces the level of CCR5(+) Tregs and metastatic tumor burden in the lungs. This work provides evidence of a CCL8/CCR5 signaling axis driving Treg recruitment to the lungs of mice bearing metastatic primary tumors, representing a potential therapeutic target to decrease Treg accumulation and metastatic tumor growth.

Increased CD4 and CD8-positive T cell infiltrate signifies good prognosis in a subset of triple-negative breast cancer

Tumour-infiltrating lymphocytes (TILs) signify immune response to tumour in a variety of cancers including breast cancer. However, earlier studies examining the clinical significance of TILs in breast cancers have generated mixed results. There are only a few that address the relationship between TILs and clinical outcomes in triple-negative breast cancers (TNBC). The aim of this study is to evaluate the clinical significance of TILs that express CD4 + and CD8 + , in TNBC. Immunohistochemical staining of CD4 and CD8 was performed on tissue microarrays of 164 cases of TNBC. TILs were counted separately as intratumoral when within the cancer cell nests (iTILs) and as stromal when within cancer stroma (sTILs). High CD8 + iTILs and sTILs, and CD4 + iTILs correlated with histologic grade. On Kaplan-Meier analysis, a significantly better survival rate was observed in high CD8 + iTIL (disease-free survival, DFS: P = 0.004, overall survival, OS: P = 0.02) and both high CD4 + iTILs (DFS: P = 0.025, OS: P = 0.023) and sTILs (DFS: P = 0.01, OS: P = 0.002). In multivariate analysis, CD8 + iTILs (DFS: P = 0.0095), CD4 + sTILs (DFS: P = 0.0084; OS: P = 0.0118), and CD4 (high) CD8 (high) CD8 iTILs (DFS: P = 0.0121; OS: P = 0.0329) and sTILs (DFS: P = 0.0295) showed significantly better survival outcomes. These results suggest that high levels of both CD8 + iTILs and CD4 + sTILs as well as CD4 (high) CD8 (high) iTILs and sTILs are independent prognostic factors in TNBC.

Emerging roles of regulatory T cells in tumour progression and metastasis

The metastasis of cancer is a complex and life-threatening process that is only partially understood. Immune suppressive cells are recognized as important contributors to tumour progression and may also promote the development and growth of tumour metastases. Specifically, regulatory T cells (Tregs) have been found to promote primary tumour progression, and emerging pre-clinical data suggests that Tregs may promote metastasis and metastatic tumour growth. While the precise role that Tregs play in metastatic progression is understudied, recent findings have indicated that by suppressing innate and adaptive anti-tumour immunity, Tregs may shield tumour cells from immune detection, and thereby allow tumour cells to survive, proliferate and acquire characteristics that facilitate dissemination. This review will highlight our current understanding of Tregs in metastasis, including an overview of pre-clinical findings and discussion of clinical data regarding Tregs and therapeutic outcome. Evolving strategies to directly ablate Tregs or to inhibit their function will also be discussed. Improving our understanding of how Tregs may influence tumour metastasis may lead to novel treatments for metastatic cancer.

Frequency, suppressive capacity, recruitment and induction mechanisms of regulatory T cells in sinonasal squamous cell carcinoma and nasal inverted papilloma

Background

Sinonasal squamous cell carcinoma (SSCC) and nasal inverted papilloma (NIP) represent the predominant type of malignant and benign tumors in sinonasal tract, respectively. CD4⁺CD25⁺Foxp3⁺ natural regulatory T (Treg) cells might play critical role(s) in the suppression of anti-tumor immune response and thus shed light on tumor progression from benign to malignant.

Objective

This study aimed to evaluate the frequency and suppressive capacity of Treg cells in SSCC compared to NIP and further to explore the underlying mechanisms.

Patients and Methods

Frequencies of Treg, Th1 and Th2 cells were evaluated by flow cytometry in tissue homogenate and peripheral blood from 31 SSCC patients, 32 NIP patients and 35 normal controls. Treg cells were tested for regulatory function by co-culture with effector T cells. CCR4 and its ligands, CCL22 and CCL17, were analyzed by flow cytometry and Luminex, respectively. The chemoattractant properties of CCR4/CCL22 and CCR4/CCL17 for Treg cells were assessed using the Boyden chamber technique, to elucidate the potential mechanisms of Treg recruitment in tumor microenvironment. Treg cells induction via TGF-β was assessed with transwells after local CD4⁺Foxp3⁺ T cells were assessed by immunohistochemistry and TGF-β concentration was measured by Luminex.

Results

Tumor-infiltrating Treg cells increased significantly from normal to NIP to SSCC (P ≤ 0.001 for normal vs. NIP and P = 0.004 for NIP vs. SSCC). Significantly elevated frequency and enhanced suppression capacity of circulating Treg cells in SSCC were detected compared to NIP and healthy controls, concomitant with Th1 decrease and Th2 increase. Apparently increased CCL22 attracted CCR4-expressing Treg cells to tumor microenvironment in SSCC, compared to NIP. SSCC produced significantly more TGF-β than NIP and thus possessed greater potential for Treg cell induction.

Conclusion

Frequency and suppressive capacity of Treg cells enhanced with progression of malignancy from NIP to SSCC. Circulating Treg cells were recruited to tumor tissue via CCR4/CCL22 signalling, whereas tumor-synthesised TGF-β contributed to induction of peripheral Treg cells.

The antigenic repertoire of premalignant and high-risk lesions

Prophylactic vaccines have been a major advance in preventing the development of infections after exposure to pathogens. When contemplating an effective approach to cancer prevention, vaccines offer unique advantages over other more standard approaches: First, once appropriately stimulated, antigen-specific T cells will travel to all sites of disease and eradicate cells bearing the proteins to which the T cells have been primed by vaccination. Second, successful immunization will further result in the development of immunologic memory, providing lifelong immunologic surveillance. There is evidence of an adaptive tumor immune infiltrate even at the earliest stages of breast and colon cancer development. Furthermore, there is measurable immunity to lesion-associated antigens present in patients who will eventually develop malignancy even before cancer is clinically evident. Recent studies are beginning to unmask the preinvasive antigenic repertoire for these two malignancies. Preliminary experiments in transgenic mouse models of mammary and intestinal tumors suggest that immunization against antigens expressed in preinvasive and high-risk lesions may be effective in preventing the development of invasive malignancy.

Foxp3 expression in T regulatory cells and other cell lineages

Forkhead box P3 (Foxp3) is an important transcription factor that belongs to the forkhead/winged-helix family of transcriptional regulators. Foxp3 has been extensively studied over the past 13 years as a master regulator of transcription in a specific T-cell type, CD4(+) regulatory T cells (Treg), both in humans and in mice. Compelling data characterize Foxp3 as critically important and necessary for the development and the differentiation of Treg. It has been considered initially as the only specific marker for Treg. However, recent work has proposed that Foxp3 can be expressed by other types of lymphoid cells or myeloid cells and also by some non-hematopoietic cells such as epithelial cells. It remains controversial about the expression of Foxp3 in cells other than Treg, but understanding the potential expression and function of this master regulator in different cell subsets could have a wide range of implications for immune tolerance and several pathologies including autoimmune disorders and immune responses to cancer.