Composite analysis of immunological and metabolic markers defines novel subtypes of triple negative breast cancer

CTLA4 expression profiles and their association with clinical outcomes of breast cancer: a systemic review

Purpose

The cytotoxic T-lymphocyte-associated protein 4 (CTLA4) is involved in the progression of various cancers, but its biological roles in breast cancer (BRCA) remain unclear. Therefore, we performed a systematic multiomic analysis to expound on the prognostic value and underlying mechanism of CTLA4 in BRCA.

Methods

We assessed the effect of CTLA4 expression on BRCA using a variety of bioinformatics platforms, including Oncomine, GEPIA, UALCAN, PrognoScan database, Kaplan-Meier plotter, and R2: Kaplan-Meier scanner.

Results

CTLA4 was highly expressed in BRCA tumor tissue compared to normal tissue (P < 0.01). The CTLA4 messenger RNA levels in BRCA based on BRCA subtypes of Luminal, human epidermal growth factor receptor 2, and triple-negative BRCA were considerably higher than in normal tissues (P < 0.001). However, the overexpression of CTLA4 was associated with a better prognosis in BRCA (P < 0.001) and was correlated with clinicopathological characteristics including age, T stage, estrogen receptors, progesterone receptors, and prediction analysis of microarray 50 (P < 0.01). The infiltration of multiple immune cells was associated with increased CTLA4 expression in BRCA (P < 0.001). CTLA4 was highly enriched in antigen binding, immunoglobulin complexes, lymphocyte-mediated immunity, and cytokine-cytokine receptor interaction.

Conclusion

This study provides suggestive evidence of the prognostic role of CTLA4 in BRCA, which may be a therapeutic target for BRCA. Furthermore, CTLA4 may influence BRCA prognosis through antigen binding, immunoglobulin complexes, lymphocyte-mediated immunity, and cytokine-cytokine receptor interaction. These findings help us understand how CTLA4 plays a role in BRCA and set the stage for more research.

CD25high Effector Regulatory T Cells Hamper Responses to PD-1 Blockade in Triple-Negative Breast Cancer

Regulatory T cells (Treg) impede effective antitumor immunity. However, the role of Tregs in the clinical outcomes of patients with triple-negative breast cancer (TNBC) remains controversial. Here, we found that an immunosuppressive TNBC microenvironment is marked by an imbalance between effector αβCD8+ T cells and Tregs harboring hallmarks of highly suppressive effector Tregs (eTreg). Intratumoral eTregs strongly expressed PD-1 and persisted in patients with TNBC resistant to PD-1 blockade. Importantly, CD25 was the most selective surface marker of eTregs in primary TNBC and metastases compared with other candidate targets for eTreg depletion currently being evaluated in trials for patients with advanced TNBC. In a syngeneic TNBC model, the use of Fc-optimized, IL2 sparing, anti-CD25 antibodies synergized with PD-1 blockade to promote systemic antitumor immunity and durable tumor growth control by increasing effector αβCD8+ T-cell/Treg ratios in tumors and in the periphery. Together, this study provides the rationale for the clinical translation of anti-CD25 therapy to improve PD-1 blockade responses in patients with TNBC.

SIGNIFICANCE

An imbalance between effector CD8+ T cells and CD25high effector Tregs marks immunosuppressive microenvironments in αPD-1-resistant TNBC and can be reversed through effector Treg depletion to increase αPD-1 efficacy.

GPR81-mediated reprogramming of glucose metabolism contributes to the immune landscape in breast cancer

BACKGROUND

Local tumor microenvironment (TME) plays a crucial role in immunotherapy for breast cancer (BC). Whereas, the molecular mechanism responsible for the crosstalk between BC cells and surrounding immune cells remains unclear. The present study aimed to determine the interplay between GPR81-mediated glucometabolic reprogramming of BC and the immune landscape in TME.

MATERIALS AND METHODS

Immunohistochemistry (IHC) assay was first performed to evaluate the association between GPR81 and the immune landscape. Then, several stable BC cell lines with down-regulated GPR81 expression were established to directly identify the role of GPR81 in glucometabolic reprogramming, and western blotting assay was used to detect the underlying molecular mechanism. Finally, a transwell co-culture system confirmed the crosstalk between glucometabolic regulation mediated by GPR81 in BC and induced immune attenuation.

RESULTS

IHC analysis demonstrated that the representation of infiltrating CD8⁺ T cells and FOXP3⁺ T cells were dramatically higher in BC with a triple negative (TN) subtype in comparison with that with a non-TN subtype (P < 0.001). Additionally, the ratio of infiltrating CD8⁺ to FOXP3⁺ T cells was significantly negatively associated with GPR81 expression in BC with a TN subtype (P < 0.001). Furthermore, GPR81 was found to be substantially correlated with the glycolytic capability (P < 0.001) of BC cells depending on a Hippo-YAP signaling pathway (P < 0.001). In the transwell co-culture system, GPR81-mediated reprogramming of glucose metabolism in BC significantly contributed to a decreased proportion of CD8⁺ T (P < 0.001) and an increased percentage of FOXP3⁺ T (P < 0.001) in the co-cultured lymphocytes.

CONCLUSION

Glucometabolic reprogramming through a GPR81-mediated Hippo-YAP signaling pathway was responsible for the distinct immune landscape in BC. GPR81 was a potential biomarker to stratify patients before immunotherapy to improve BC's clinical prospect.

Therapeutic Potential of Tumor Metabolic Reprogramming in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, with clinical features of high metastatic potential, susceptibility to relapse, and poor prognosis. TNBC lacks the expression of the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). It is characterized by genomic and transcriptional heterogeneity and a tumor microenvironment (TME) with the presence of high levels of stromal tumor-infiltrating lymphocytes (TILs), immunogenicity, and an important immunosuppressive landscape. Recent evidence suggests that metabolic changes in the TME play a key role in molding tumor development by impacting the stromal and immune cell fractions, TME composition, and activation. Hence, a complex inter-talk between metabolic and TME signaling in TNBC exists, highlighting the possibility of uncovering and investigating novel therapeutic targets. A better understanding of the interaction between the TME and tumor cells, and the underlying molecular mechanisms of cell-cell communication signaling, may uncover additional targets for better therapeutic strategies in TNBC treatment. In this review, we aim to discuss the mechanisms in tumor metabolic reprogramming, linking these changes to potential targetable molecular mechanisms to generate new, physical science-inspired clinical translational insights for the cure of TNBC.

Expression of Cav-1, MCT1, and MCT4 in Ductal Carcinoma In Situ of the Breast and Their Associations With Clinicopathologic Features

Loss of caveolin-1 (Cav-1) and upregulation of monocarboxylate transporters (MCTs, especially MCT1 and MCT4) in respectively tumor-associated stromal cells and malignant epithelial cells of invasive carcinoma have been found to play an important role in the metabolic coupling. However, this phenomenon has only been scarcely described in pure ductal carcinoma in situ (DCIS) of the breast. mRNA and protein expression levels of Cav-1, MCT1, and MCT4 in nine pairs of DCIS tissues and matched normal tissues were examined by quantitative real-time polymerase chain reaction, RNAscope in situ hybridization, and immunohistochemistry. Immunohistochemical staining of Cav-1, MCT1, and MCT4 in 79 DCIS samples was also done using tissue microarray. Cav-1 mRNA expression was significantly lower in DCIS tissues than in their corresponding normal tissues. In contrast, MCT1 and MCT4 mRNA expression levels were higher in DCIS tissues than in corresponding normal tissues. Low stromal Cav-1 expression was significantly associated with high nuclear grade. High epithelial MCT4 expression was associated with larger tumor size and human epidermal growth factor 2 positivity. At a mean follow-up of 10 years, patients with high epithelial MCT1/high epithelial MCT4 expression showed shorter disease-free survival than those with other expressions. No significant association was observed between stromal Cav-1 expression and epithelial MCT 1 or MCT4 expression. Changes in Cav-1, MCT1, and MCT4 are associated with carcinogenesis of DCIS. A high epithelial MCT1/high epithelial MCT4 expression might be associated with a more aggressive phenotype.

Breast Cancer Survival Outcomes and Tumor-Associated Macrophage Markers: A Systematic Review and Meta-Analysis

INTRODUCTION

Tumor-associated macrophages (TAMs) in breast cancer are associated with a poor prognosis. Early studies of TAMs were largely limited to the pan-macrophage marker CD68, however, more recently, an increasing number of studies have used CD163, a marker expressed by alternatively activated M2 macrophages and TAM subsets. We hypothesized that CD163-positive (CD163+) TAMs would be a better predictor of survival outcomes in breast cancer compared to CD68+  TAMs.

METHODS

We performed a systematic literature search of trials (from 1900 to August 2020) reporting overall survival (OS) or progression-free survival (PFS), breast cancer-specific survival (BCSS), TAM phenotype, and density. Thirty-two studies with 8446 patients were included. Meta-analyses were carried out on hazard ratios (HRs) for survival outcomes of breast cancer patients with a high density of TAMs (CD68+ and/or CD163+) compared to a low density of TAMs.

RESULTS

A high density of TAMs (CD68+ and/or CD163+) was associated with decreased OS (HR 1.69, 95% CI 1.37-2.07) and reduced PFS (HR 1.64; 95% CI 1.35-1.99). Subgrouping by CD marker type showed a lower OS for high density of CD163+ TAMs (HR 2.24; 95% CI 1.71-2.92) compared to a high density of CD68+  TAMs (HR 1.5; 95% CI 1.12-2). A high density of TAMs (CD68+  and/or CD163+) in triple-negative breast cancer (TNBC) cases was associated with lower OS (HR 2.81, 95% CI 1.35-5.84).

CONCLUSION

Compared to CD68+  TAMs, a high density of CD163+ TAMs that express a similar phenotype to M2 macrophages are a better predictor of poor survival outcomes in breast cancer.

MCT4/Lactate Promotes PD-L1 Glycosylation in Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) has the highest percentage of lymphocytic infiltration among breast cancer subtypes, and TNBC patients may benefit from anti-PD-1/PD-L1 immunotherapy. However, some cases whether the immune checkpoint blockade (ICB) shows low targeting efficiency have occurred and effective synergistic targets need to be found, which inspired our exploration of the co-expression analysis of MCT4 (SLC16A3) and PD-L1 (CD274) and their potential regulatory mechanisms. After bioinformatic analysis of the relationship between MCT4 and PD-L1, we validated their positive co-expression relationship in triple-negative breast cancer through multiple immunohistochemical staining (mIHC), CRISPR/Cas9, and lentiviral transduction for MCT4 knockout (sgMCT4/231 KO) or overexpression (pEGFP-N1-MCT4/231). We examined the effect of lactate treatment on PD-L1 expression in triple-negative breast cancer cells by qRT-PCR and Western blot. Combined with our results, we found that MCT4 positively regulated PD-L1 expression through discharging lactate and stabilized PD-L1 through promoting its glycosylation by the classic WNT pathway in MDA-MB-231 cells. More importantly, the high co-expression of MCT4 and PD-L1 appears to predict more effective targets for treating TNBC, which would improve immune checkpoint therapy for TNBC.

Immune Lymphocyte Infiltrate and its Prognostic Value in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) occurs more frequently in young (<50 years) non-Hispanic black and Hispanic/Latina women. It is considered the most aggressive subtype of breast cancer, although, recently, immune infiltrate has been associated with long-term survival, lower risk of death and recurrence, and response to neoadjuvant chemotherapy. The aim of this review was to evaluate the clinical impact of the immune infiltrate in TNBC by discussing whether its prognostic value varies across different populations. A comprehensive systematic search in databases such as PubMed and Web of Science was conducted to include papers focused on tumor-infiltrating lymphocytes (TILs) in TNBC in different population groups and that were published before January 2021. TNBC patients with higher levels of TILs had longer overall survival and disease-free survival times compared with TNBC patients with low TIL levels. Similar results were observed for CD4+, CD8+ TIL populations. On the other hand, patients with high TIL levels showed a higher rate of pathological complete response regardless of the population group (Asian, European, and American). These results altogether suggest that TIL subpopulations might have a prognostic role in TNBC, but the underlying mechanism needs to be elucidated. Although the prognosis value of TILs was not found different between the population groups analyzed in the revised literature, further studies including underrepresented populations with different genetic ancestries are still necessary to conclude in this regard.

Immune Cells in Hyperprogressive Disease under Immune Checkpoint-Based Immunotherapy

Immunotherapy, an antitumor therapy designed to activate antitumor immune responses to eliminate tumor cells, has been deeply studied and widely applied in recent years. Immune checkpoint inhibitors (ICIs) are capable of preventing the immune responses from being turned off before tumor cells are eliminated. ICIs have been demonstrated to be one of the most effective and promising tumor treatments and significantly improve the survival of patients with multiple tumor types. However, low effective rates and frequent atypical responses observed in clinical practice limit their clinical applications. Hyperprogressive disease (HPD) is an unexpected phenomenon observed in immune checkpoint-based immunotherapy and is a challenge facing clinicians and patients alike. Patients who experience HPD not only cannot benefit from immunotherapy, but also experience rapid tumor progression. However, the mechanisms of HPD remain unclear and controversial. This review summarized current findings from cell experiments, animal studies, retrospective studies, and case reports, focusing on the relationships between various immune cells and HPD and providing important insights for understanding the pathogenesis of HPD.

CDK/cyclin dependencies define extreme cancer cell-cycle heterogeneity and collateral vulnerabilities

Progression through G1/S phase of the cell cycle is coordinated by cyclin-dependent kinase (CDK) activities. Here, we find that the requirement for different CDK activities and cyclins in driving cancer cell cycles is highly heterogeneous. The differential gene requirements associate with tumor origin and genetic alterations. We define multiple mechanisms for G1/S progression in RB-proficient models, which are CDK4/6 independent and elicit resistance to FDA-approved inhibitors. Conversely, RB-deficient models are intrinsically CDK4/6 independent, but exhibit differential requirements for cyclin E. These dependencies for CDK and cyclins associate with gene expression programs that denote intrinsically different cell-cycle states. Mining therapeutic sensitivities shows that there are reciprocal vulnerabilities associated with RB1 or CCND1 expression versus CCNE1 or CDKN2A. Together, these findings illustrate the complex nature of cancer cell cycles and the relevance for precision therapeutic intervention.

Knudsen et al. find that there is extensive heterogeneity in the requirement for CDK and cyclins across cancer models. Multiple biochemically distinct mechanisms drive cell division. Divergent cell-cycle states harbor distinct genetic and pharmacological vulnerabilities, suggesting that cell-cycle diversity could be exploited for a precision approach to cancer therapy.

Cutting edge: Metabolic immune reprogramming, reactive oxygen species, and cancer

A recently proposed term "immunometabolism" points to the functional intracellular metabolic changes that occur within different immune cells. Recent findings suggest that immune responses can be determined by the metabolic status of immune cells and metabolic reprogramming is an important feature of immune cell activation. Metabolic reprogramming is also well known for cancer cells and has been suggested as a major sign of cancer progression. Metabolic reprogramming of immune cells is also seen in the tumor microenvironment. In the past decade, immunometabolism has progressively become an extraordinarily vibrant and productive area of study in immunology because of its importance for immunotherapy. Understanding the immunometabolic situation of T cells and other immune cells along with the metabolic behavior of cancer cells can help us design new therapeutic approaches against cancers. Here, we have the aim to review the cutting-edge findings on the immunometabolic situation in immune and tumor cells. We discuss new findings on signaling pathways during metabolic reprogramming, its regulation, and the participation of reactive oxygen species in these processes.

Emerging role of circulating tumor cells in immunotherapy

Over the last few years, immunotherapy, in particular, immune checkpoint inhibitor therapy, has revolutionized the treatment of several types of cancer. At the same time, the uptake in clinical oncology has been slow owing to the high cost of treatment, associated toxicity profiles and variability of the response to treatment between patients. In response, personalized approaches based on predictive biomarkers have emerged as new tools for patient stratification to achieve effective immunotherapy. Recently, the enumeration and molecular analysis of circulating tumor cells (CTCs) have been highlighted as prognostic biomarkers for the management of cancer patients during chemotherapy and for targeted therapy in a personalized manner. The expression of immune checkpoints on CTCs has been reported in a number of solid tumor types and has provided new insight into cancer immunotherapy management. In this review, we discuss recent advances in the identification of immune checkpoints using CTCs and shed light on the potential applications of CTCs towards the identification of predictive biomarkers for immunotherapy.

Clinicopathological and prognostic significance of programmed cell death ligand 1 expression in patients diagnosed with breast cancer: meta-analysis

BACKGROUND

Uncertainty exists regarding the clinical relevance of programmed cell death ligand 1 (PD-L1) expression in breast cancer.

METHODS

A systematic review was performed in accordance with PRISMA guidelines. Observational studies that compared high versus low expression of PD-L1 on breast cancer cells were identified. Log hazard ratios (HRs) for disease-free and overall survival and their standard errors were calculated from Kaplan-Meier curves or Cox regression analyses, and pooled using the inverse-variance method. Dichotomous variables were pooled as odds ratios (ORs) using the Mantel-Haenszel method.

RESULTS

Sixty-five studies with 19 870 patients were included; 14 404 patients were classified as having low and 4975 high PD-L1 expression. High PD-L1 was associated with achieving a pathological complete response following neoadjuvant chemotherapy (OR 3.30, 95 per cent confidence interval 1.19 to 9.16; P < 0.01; I2 = 85 per cent). Low PD-L1 expression was associated with human epidermal growth factor receptor 2 (OR 3.98, 1.81 to 8.75; P < 0.001; I2 = 96 per cent) and luminal (OR 14.93, 6.46 to 34.51; P < 0.001; I2 = 99 per cent) breast cancer subtypes. Those with low PD-L1 had favourable overall survival rates (HR 1.30, 1.05 to 1.61; P = 0.02; I2 = 85 per cent).

CONCLUSION

Breast cancers with high PD-L1 expression are associated with aggressive clinicopathological and immunohistochemical characteristics and are more likely to achieve a pathological complete response following neoadjuvant chemotherapy. These breast cancers are, however, associated with worse overall survival outcomes.

Current Triple-Negative Breast Cancer Subtypes: Dissecting the Most Aggressive Form of Breast Cancer

Triple-negative breast cancer (TNBC) is a highly heterogeneous disease defined by the absence of estrogen receptor (ER) and progesterone receptor (PR) expression, and human epidermal growth factor receptor 2 (HER2) overexpression that lacks targeted treatments, leading to dismal clinical outcomes. Thus, better stratification systems that reflect intrinsic and clinically useful differences between TNBC tumors will sharpen the treatment approaches and improve clinical outcomes. The lack of a rational classification system for TNBC also impacts current and emerging therapeutic alternatives. In the past years, several new methodologies to stratify TNBC have arisen thanks to the implementation of microarray technology, high-throughput sequencing, and bioinformatic methods, exponentially increasing the amount of genomic, epigenomic, transcriptomic, and proteomic information available. Thus, new TNBC subtypes are being characterized with the promise to advance the treatment of this challenging disease. However, the diverse nature of the molecular data, the poor integration between the various methods, and the lack of cost-effective methods for systematic classification have hampered the widespread implementation of these promising developments. However, the advent of artificial intelligence applied to translational oncology promises to bring light into definitive TNBC subtypes. This review provides a comprehensive summary of the available classification strategies. It includes evaluating the overlap between the molecular, immunohistochemical, and clinical characteristics between these approaches and a perspective about the increasing applications of artificial intelligence to identify definitive and clinically relevant TNBC subtypes.

CIBERSORT analysis of TCGA and METABRIC identifies subgroups with better outcomes in triple negative breast cancer

Studies have shown that the presence of tumor infiltrating lymphocytes (TILs) in Triple Negative Breast Cancer (TNBC) is associated with better prognosis. However, the molecular mechanisms underlying these immune cell differences are not well delineated. In this study, analysis of hematoxylin and eosin images from The Cancer Genome Atlas (TCGA) breast cancer cohort failed to show a prognostic benefit of TILs in TNBC, whereas CIBERSORT analysis, which quantifies the proportion of each immune cell type, demonstrated improved overall survival in TCGA TNBC samples with increased CD8 T cells or CD8 plus CD4 memory activated T cells and in Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) TNBC samples with increased gamma delta T cells. Twenty-five genes showed mutational frequency differences between the TCGA high and low T cell groups, and many play important roles in inflammation or immune evasion (ATG2B, HIST1H2BC, PKD1, PIKFYVE, TLR3, NOTCH3, GOLGB1, CREBBP). Identification of these mutations suggests novel mechanisms by which the cancer cells attract immune cells and by which they evade or dampen the immune system during the cancer immunoediting process. This study suggests that integration of mutations with CIBERSORT analysis could provide better prediction of outcomes and novel therapeutic targets in TNBC cases.

Prune-1 drives polarization of tumor-associated macrophages (TAMs) within the lung metastatic niche in triple-negative breast cancer

M2-tumor-associated macrophages (M2-TAMs) in the tumor microenvironment represent a prognostic indicator for poor outcome in triple-negative breast cancer (TNBC).

Here we show that Prune-1 overexpression in human TNBC patients has positive correlation to lung metastasis and infiltrating M2-TAMs. Thus, we demonstrate that Prune-1 promotes lung metastasis in a genetically engineered mouse model of metastatic TNBC augmenting M2-polarization of TAMs within the tumor microenvironment. Thus, this occurs through TGF-β enhancement, IL-17F secretion, and extracellular vesicle protein content modulation.

We also find murine inactivating gene variants in human TNBC patient cohorts that are involved in activation of the innate immune response, cell adhesion, apoptotic pathways, and DNA repair. Altogether, we indicate that the overexpression of Prune-1, IL-10, COL4A1, ILR1, and PDGFB, together with inactivating mutations of PDE9A, CD244, Sirpb1b, SV140, Iqca1, and PIP5K1B genes, might represent a route of metastatic lung dissemination that need future prognostic validations.

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Prune-1 correlates to M2-TAMs confirming lung metastatic dissemination in GEMM

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Cytokines and EV proteins are responsible of M2-TAMs polarization processes

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A small molecule with immunomodulatory properties ameliorates metastatic dissemination

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Identification of gene variants within immune response and cell adhesion in TNBC

Novel PD-L1 mAb HC16 reveals upregulation of PD-L1 in BAC subtype

Programmed death-ligand 1 (PD-L1) is an inhibitory transmembrane protein that can prevent autoimmune response. Upregulated PD-L1 serves as a predictive biomarker for patients who may respond well to immune checkpoint therapies. However, variable associations of PD-L1 level with prognoses have been reported. In this study, a short peptide sequence corresponding to PD-L1 amino acids 172-187 (from the extracellular Ig-like C-type domain, and with high predicted antigenicity and hydrophilicity) was used to generate a monoclonal antibody (mAb). The resultant PD-L1 mAb, clone HC16, was examined for binding specificity and reactivity in cancer cell-lines, as assessed by immunocytochemical, immunoblotting, and co-immunoprecipitation. The potential diagnostic and clinical applicability of clone HC16 was further tested using malignant tissue arrays derived from various cancer types analyzed with an automated immunohistochemical (IHC) staining platform. Additionally, tumor samples from patients diagnosed with non-small cell lung cancer (NSCLC) were analyzed by western blotting. Clone HC16 showed obvious staining activity in lung and breast cancer tissues. Interestingly, we observed that PD-L1 level was negatively associated with clinical stage in NSCLC. Strong PD-L1 expression tended to be found in patients diagnosed with bronchioloalveolar carcinoma (BAC). These results demonstrate that clone HC16 harbors good target specificity and is suitable for further development in diagnostic tools to assess PD-L1 expression in human tissues. In addition, our findings also suggest a role for PD-L1 in a non-invasive subtype of lung cancer.

Hyperprogression: A novel response pattern under immunotherapy

Checkpoint blockade therapy has shown significant therapeutic benefits and resulted in durable responses in patients with various tumors. However, accumulating evidence has demonstrated that 4-29% of all patients with cancers with various histologies may suffer from tumor flare following such therapy. This novel tumor response pattern, termed hyperprogression, is a potentially deleterious side effect of checkpoint blockade therapy that accelerates disease progression in a subset of patients. In this review, we describe possible immune checkpoint blockade biomarkers and the epidemiology, different definitions, and predictors of hyperprogression based on the research findings and further present the available evidence supporting pathophysiological hypotheses that might explain hyperprogression during checkpoint blockade therapy. We also compare hyperprogression and pseudoprogression. Finally, we discuss areas requiring further study.

Immune parameters associated with survival in metaplastic breast cancer

Background

Metaplastic breast carcinoma (MBC) is a rare histological type of breast cancer, which commonly shows resistance to standard therapies and is associated with poor prognosis. The immune microenvironment in MBC and its significance has not been well established due to its low incurrence rate and complex components. We aimed to investigate the diversity of immune parameters including subsets of TILs and PDL1/PD1 expression in MBC, as well as its correlation with prognosis.

Methods

A total of 60 patients diagnosed with MBC from January 2006 to December 2017 were included in our study. The percentage (%) and quantification (per mm²) of TILs and presence of tertiary lymphoid structures (TLS) were evaluated by hematoxylin and eosin staining (HE). The quantification of CD4+, CD8+ TILs (per mm²), and PD-1/PDL1 expression were evaluated through immunohistochemistry and analyzed in relation to clinicopathological characteristics. A ≥ 1% membranous or cytoplasmatic expression of PD1 and PDL1 was considered a positive expression.

Results

We found squamous cell carcinoma MBC (33/60, 55%) exhibiting most TILs of all the MBC subtypes (p = 0.043). Thirty-three of 60 (50%) of the patients had coexisting invasive ductal carcinoma of no special type (IDC-NST), and the average percentage of TILs in MBC components was lower compared with NST components (p < 0.001). Thirty (50%) patients exhibited positive (≥ 1%) PDL1 expression in their tumor cells, while 36 (60%) had positive (≥ 1%) PDL1 expression in their TILs. Twenty-seven (45%) of all the patients had positive (≥ 1%) PD1 expression in their tumor cells and 33 (55%) had PD1-positive (≥ 1%) stromal TILs. More CD8+ TILs were associated with positive PDL1 expression of tumor cells as well as positive PD1 expression in stromal cells. Greater number of stromal TILS (> 300/mm², 20%), CD4+ TILs (> 250/mm²), and CD8+ TILs (> 70/mm²) in MBC were found associated with longer disease-free survival. Positive expression of PDL1 in tumor cells (≥ 1%) and PD1 in stromal cells (≥ 1%) were also associated with longer survival.

Conclusions

The immune characteristics differ in various subtypes as well as components of MBC. Immune parameters are key predictive factors of MBC and provide the clinical significance of applying immune checkpoint therapies in patients with MBC.

Prognostic Role of Immune Markers in Triple Negative Breast Carcinoma

Tumor immune microenvironment (TIME) is a significant prognostic parameter for triple negative breast carcinomas (TNBC) due to being a target for immunotherapeutic agents and its essential role during the cancer immunoediting process. In this study, CD8, FOXP3, CD163, PD-L1/SP142 and PD-L1/SP263 antibodies were examined in a sample of 51 TNBC cases. Patients who received neoadjuvant therapy were excluded. CD8, FOXP3 and CD163 antibodies were evaluated separately in intratumoral area (ITA) and tumor stroma (TS). PD-L1 status was also examined in tumor cells (TC) and immune cells (IC) using both SP142 and SP263 antibodies. In multivariate Cox regressions, the only antibody that was found to be significantly associated with survival was SP142. SP142-positivity in TC and IC was related to increased overall survival. Higher CD163 expression in ITA and SP263-positivity in IC were associated with younger age. Lymphatic/angioinvasion was more frequent in cases with negative/low CD8 and FOXP3 expressions. Moreover, metastatic axillary lymph node(s) was associated with negative/low FOXP3 expression in TS. CD8, FOXP3, CD163, SP142 and SP263 expressions were positively correlated with each other, except a mild discordance caused by CD163 in ITA. Although PD-L1 status with both SP142 and SP263 antibodies were concordant in the majority of cases, 33.3% and 13.7% of the cases showed SP142-negative/SP263-positive pattern in TC and IC respectively. In conclusion, we suggest that composition, density and localization of the immune cells and the check point molecules are important prognostic parameters in TNBC. Immunohistochemistry can be used as an accessible and less expensive tool to demonstrate TIME.

Expression of the immune checkpoint VISTA in breast cancer

V-domain Ig suppressor of T cell activation (VISTA) is a novel immune checkpoint that is an emerging target for cancer immunotherapy. This study aimed to investigate the expression of VISTA and its association with clinicopathologic parameters as well as with the key immune markers including programmed cell death-1 (PD-1) and PD-1 ligand-1 (PD-L1) in invasive ductal carcinoma (IDC) of the breast [corrected]. Immunohistochemistry was used to detect VISTA, PD-1, PD-L1, and CD8 in tissue microarrays from 919 patients with IDC (N = 341 in the exploratory cohort and  = 578 in the validation cohort). VISTA was expressed on the immune cells of 29.1% (267/919) of the samples and on the tumor cells of 8.2% (75/919). VISTA was more frequently expressed in samples that were estrogen receptor-negative, progesterone receptor-negative, human epidermal growth factor receptor 2-positive, poorly differentiated, human epidermal growth factor receptor 2-enriched, and consisting of basal-like tumors. VISTA on immune cells correlated with PD-1, PD-L1, stromal CD8, and tumor-infiltrating lymphocyte expression and was an independent prognostic factor for improved relapse-free and disease-specific survival in patients with estrogen receptor-negative, progesterone receptor-negative, and basal-like IDC. These findings support therapeutic strategies that modulate VISTA expression, perhaps in combination with PD-1/PD-L1 blockade, in human breast cancer immunotherapy.

Assessment of outcomes and novel immune biomarkers in metaplastic breast cancer: a single institution retrospective study

BACKGROUND

Metaplastic breast cancer remains poorly characterized given its rarity and heterogeneity. The majority of metaplastic breast cancers demonstrate a phenotype of triple-negative breast cancer; however, differences in clinical outcomes between metaplastic breast cancer and triple-negative breast cancer in the era of third-generation chemotherapy remain unclear.

METHODS

We compared the clinical outcomes between women with metaplastic breast cancer and women with triple-negative breast cancer diagnosed between 1994 and 2014. Metaplastic breast cancer patients were matched 1:3 to triple-negative breast cancer patients by stage and age at diagnosis. Distant disease-free survival (DDFS) and overall survival (OS) were estimated using Kaplan Meier methods and Cox proportional hazard regression models. Immune checkpoint markers were characterized by immunohistochemistry in a subset of samples.

RESULTS

Forty-four metaplastic breast cancer patients (stage I 14%; stage II 73%; stage III 11%; stage IV 2%) with an average age of 55.4 (± 13.9) years at diagnosis. Median follow-up for the included metaplastic breast cancer and triple-negative breast cancer patients (n = 174) was 2.8 (0.1-19.0) years. The DDFS and OS between matched metaplastic breast cancer and triple-negative breast cancer patients were similar, even when adjusting for clinical covariates (DDFS: HR = 1.64, p = 0.22; OS: HR = 1.64, p = 0.26). Metaplastic breast cancer samples (n = 27) demonstrated greater amount of CD163 in the stroma (p = 0.05) and PD-L1 in the tumor (p = 0.01) than triple-negative breast cancer samples (n = 119), although more triple-negative breast cancer samples were positive for CD8 in the tumor than metaplastic breast cancer samples (p = 0.02).

CONCLUSIONS

Patients with metaplastic breast cancer had similar outcomes to those with triple-negative breast cancer based on DDFS and OS. The immune checkpoint marker profile of metaplastic breast cancers in this study may prove useful in future studies attempting to demonstrate an association between immune profile and survival.

Tumor antigens heterogeneity and immune response-targeting neoantigens in breast cancer

Breast cancer is both the most common type of cancer and the most frequent cause of cancer mortality in women, mainly because of its heterogeneity and limited immunogenicity. The aim of specific active cancer immunotherapy is to stimulate the host's immune response against cancer cells directly using a vaccine platform carrying one or more tumor antigens. In particular, the ideal tumor antigen should be able to elicit T cell and B cell responses, be specific for the tumor and be expressed at high levels on cancer cells. Neoantigens are ideal targets for immunotherapy because they are exclusive to individual patient's tumors, are absent in healthy tissues and are not subject to immune tolerance mechanisms. Thus, neoantigens should generate a specific reaction towards tumors since they constitute the largest fraction of targets of tumor-infiltrating T cells. In this review, we describe the technologies used for neoantigen discovery, the heterogeneity of neoantigens in breast cancer and recent studies of breast cancer immunotherapy targeting neoantigens.

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.

Prognostic and clinicopathological value of PD-L1 expression in primary breast cancer: a meta-analysis

PURPOSE

To evaluate the association between PD-L1 expression (PD-L1+) and clinicopathological characteristics and effect on prognosis in primary breast cancer (PBC).

METHODS

A systematic search of the PubMed, Web of Science, and Embase databases was conducted in November 2018. Studies detecting PD-L1 using immunohistochemistry, and concerning its prognostic or clinicopathological significance in PBC were included. The HR with 95% CI for survival, and the events for clinicopathological features were pooled.

RESULTS

Forty-seven studies were included, with a total of 14,367 PBC patients. PD-L1+ tumor cells (TCs) were associated with ductal carcinomas, large tumor size, histological Grade 3 tumors, high Ki-67, ER and PR negative, and triple-negative breast cancer; and also, related to high tumor-infiltrating lymphocytes (TILs) and PD-1 expression. PD-L1+ TCs were significantly associated with shorter disease-free survival (DFS, HR = 1.43, 95% CI 1.21-1.70, P < 0.0001) and overall survival (OS, HR = 1.58, 95% CI 1.14-2.20, P = 0.006). And the HRs of PD-L1+ TCs on DFS and OS were higher (1.48 and 1.70, respectively) and homogeneous when using whole tissue section, compared with tumor microarrays. However, PD-L1+ TILs related to better DFS (HR = 0.45, 95% CI 0.28-0.73, P = 0.001) and OS (HR = 0.41, 95% CI 0.27-0.63, P < 0.0001).

CONCLUSION

PD-L1 expression on TCs associates with high-risk clinicopathological parameters and poor prognosis in PBC patients, while PD-L1+ TILs may relate to a better survival. Comprehensive assessment of TCs and TILs is required when evaluating the clinical relevance of PD-L1 expression in future studies.

Prognostic Implications of PD-L1 Expression in Breast Cancer: Systematic Review and Meta-analysis of Immunohistochemistry and Pooled Analysis of Transcriptomic Data

PURPOSE

Conflicting data have been reported on the prognostic value of PD-L1 protein and gene expression in breast cancer.Experimental Design: Medline, Embase, Cochrane Library, and Web of Science Core Collection were searched, and data were extracted independently by two researchers. Outcomes included pooled PD-L1 protein positivity in tumor cells, immune cells, or both, per subtype and per antibody used, and its prognostic value for disease-free and overall survival. A pooled gene expression analysis of 39 publicly available transcriptomic datasets was also performed.

RESULTS

Of the initial 4,184 entries, 38 retrospective studies fulfilled the predefined inclusion criteria. The overall pooled PD-L1 protein positivity rate was 24% (95% CI, 15%-33%) in tumor cells and 33% (95% CI, 14%- 56%) in immune cells. PD-L1 protein expression in tumor cells was prognostic for shorter overall survival (HR, 1.63; 95% CI, 1.07-2.46; P = 0.02); there was significant heterogeneity (I² = 80%, P _{heterogeneity} < 0.001). In addition, higher PD-L1 gene expression predicted better survival in multivariate analysis in the entire population (HR, 0.82; 95% CI, 0.74-0.90; P < 0.001 for OS) and in basal-like tumors (HR, 0.64; 95% CI, 0.52-0.80; P < 0.001 for OS; P _interaction 0.005).

CONCLUSIONS

The largest to our knowledge meta-analysis on the subject informs on PD-L1 protein positivity rates and its prognostic value in breast cancer. Standardization is needed prior to routine implementation. PD-L1 gene expression is a promising prognostic factor, especially in basal-like breast cancer. Discrepant prognostic information might be related to PD-L1 gene expression in the stroma.

RNA-Seq transcriptome analysis shows anti-tumor actions of melatonin in a breast cancer xenograft model

Melatonin is a pleiotropic anti-cancer molecule that controls cancer growth by multiple mechanisms. RNA-Seq can potentially evaluate therapeutic response and its use in xenograft tumor models can differentiate the changes that occur specifically in tumor cells or in the tumor microenvironment (TME). Melatonin actions were evaluated in a xenograft model of triple-negative breast cancer. Balb/c nude mice bearing MDA-MB-231 tumors were treated with melatonin or vehicle. RNA-Seq was performed on the Illumina HiSeq. 2500 and data were mapped against human and mouse genomes separately to differentiate species-specific expression. Differentially expressed (DE) genes were identified and Weighted Gene Co-expression Network Analysis (WGCNA) was used to detect clusters of highly co-expressed genes. Melatonin treatment reduced tumor growth (p < 0.01). 57 DE genes were identified in murine cells, which represented the TME, and were mainly involved in immune response. The WGCNA detected co-expressed genes in tumor cells and TME, which were related to the immune system among other biological processes. The upregulation of two genes (Tnfaip8l2 and Il1f6) by melatonin was validated in the TME, these genes play important roles in the immune system. Taken together, the transcriptomic data suggests that melatonin anti-tumor actions occur through modulation of TME in this xenograft tumor model.

PD-L1 expression and the prognostic significance in gastric cancer: a retrospective comparison of three PD-L1 antibody clones (SP142, 28-8 and E1L3N)

Background

Immunohistochemistry (IHC) for programmed cell death ligand 1 (PD-L1) displays staining diversity. We compared IHC staining of PD-L1 in gastric cancer (GC) by using three commercially available antibody clones, and analyzed the correlation with the prognosis.

Methods

IHC using PD-L1 antibodies (clones SP142, 28–8 and E1L3N) in 315 formalin-fixed paraffin-embedded samples was qualitatively compared at the 1, 5 and 10% cut-off by two pathologists on total, tumor and immune/stromal cells. We used computer – assisted scoring to quantitatively analyze and compare the “H-score” of PD-L1 expression in 66 samples on total cells. The antibody clone SP142 was selected to investigate the infiltration of PD-L1⁺CD8⁺ T cells using automated quantitative immunofluorescence analyses (n = 50) and the prognostic significance. The prognoses were assessed by log-rank test.

Results

PD-L1 clones SP142 and 28–8 displayed great concordance by qualitative (κ = 0.816, 0.810 for total cells and tumor cells at the 5% cut-off) and quantitative analyses (R² = 0.7991, 0.8187 for positive percentage and “H-score”). PD-L1 clone SP142 showed the highest positivity in immune/stromal cells staining (18.41%) compared to 28–8 (7.62%), while clone E1L3N showed poor staining in both tumor and immune/stromal cells. Clone SP142, but not 28–8 and E1L3N, predicted a worse prognosis at the 5% cut-off (p = 0.0243). Both the clone SP142 and 28–8 had high inter-pathologist correlation for tumor staining (R² = 0.9805 and R² = 0.9853), but a moderate correlation for stromal/immune cell staining (R² = 0.5653 and R² = 0.5745). Furthermore, a higher density of PD-L1⁺CD8⁺ T cells was correlated with a shorter survival time (R² = 0.0909, p = 0.0352).

Conclusions

PD-L1 antibody clone SP142 was superior in cell staining, particularly in immune/stromal cell and prognosis. These findings are important for selection of PD-L1 antibody clones in the future diagnostic test.

Electronic supplementary material

The online version of this article (10.1186/s13000-018-0766-0) contains supplementary material, which is available to authorized users.

Immunological therapy: A novel thriving area for triple-negative breast cancer treatment

Triple-negative breast cancer (TNBC) refers to cancers that are low in expression of the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). TNBC tends to behave more aggressively than other types of breast cancer. Unlike other breast cancer subtypes (ie, ER-positive, HER2-positive subtypes), there are no approved targeted treatments available, other than the administration of chemotherapy. Immunotherapy is a new kind of treatment approach for TNBC when compared with the surgical treatment, chemotherapy, endocrine therapy, and molecular targeting therapy. The present article reviews the research progresses of immunotherapy for TNBC in recent years. The full text structure covers molecular classification of TNBC, active immunotherapy of TNBC, passive immunotherapy of TNBC, oncolytic immunotherapy and the prospect of immunotherapy for TNBC.

Anti-Inflammatory Drug Use and Ovarian Cancer Risk by COX1/COX2 Expression and Infiltration of Tumor-Associated Macrophages

BACKGROUND

Nonsteroidal anti-inflammatory drug (NSAID) use may affect ovarian cancer risk via prostaglandin synthesis and tumor-associated macrophage (TAM) infiltration. We evaluated if associations between aspirin or non-aspirin NSAID use and ovarian cancer risk differed by tumor expression of prostaglandin-related (COX1, COX2) and TAM-related (CD68, CD163) markers.

METHODS

We evaluated cases and matched controls from the Nurses' Health Study (NHS), NHSII, and New England Case-Control Study (NECC). Cases with IHC data on COX1 and COX2 (n = 532) or CD68 and CD163 (n = 530) were included. We used polytomous logistic regression, adjusted for ovarian cancer risk factors, to estimate OR for NSAID use and ovarian cancer risk by marker level.

RESULTS

Recent aspirin use had a nonsignificant inverse association and recent non-aspirin NSAID use had no association with ovarian cancer risk. NSAID use was not differentially associated with ovarian cancer by COX1 or COX2 expression. However, recent aspirin use was associated with lower ovarian cancer risk for high [OR 0.54; 95% confidence interval (CI), 0.37-0.78], but not low (OR 1.50; 95% CI, 0.97-2.31), CD163 density (P _{heterogeneity} < 0.001). Similar results were observed for aspirin duration and tablets and for recent non-aspirin NSAID use. Results were not clearly different by macrophage density defined by the less specific macrophage marker, CD68.

CONCLUSIONS

NSAID use was inversely associated with risk of ovarian cancer with high density CD163, a marker for M2-type, immunosuppressive macrophages. However, the relationship did not differ by prostaglandin synthesis markers.

IMPACT

Future research should explore prostaglandin-independent mechanisms for the association between NSAID use and ovarian cancer risk, including immune mechanisms.

Characterization of the Neuroendocrine Tumor Immune Microenvironment

OBJECTIVES

The immune environment and the potential for neuroendocrine tumors (NETs) to respond to immune checkpoint inhibitors remain largely unexplored. We assessed immune checkpoint marker expression, lymphocytic infiltrate, and associated mutational profiles in a cohort of small intestine and pancreatic NETs.

METHODS

We assessed expression of PDCD1 (PD-1), CD274 (PD-L1), and PDCD1LG2 (PD-L2) in archival tissue from 64 small intestine (SINETs) and 31 pancreatic NETs (pNET). We additionally assessed T-cell infiltrates, categorizing T-cell subsets based on expression of the T-cell markers CD3, CD8, CD45RO (PTPRC), or FOXP3. Finally, we explored associations between immune checkpoint marker expression, lymphocytic infiltrate, and tumor mutational profiles.

RESULTS

Expression of PD-1 or PD-L1 in small intestine or pancreatic NET was rare, whereas expression of PD-L2 was common in both NET subtypes. T-cell infiltrates were more abundant in pNET than in SINET. We found no clear associations between immune checkpoint marker expression, immune infiltrates, and specific mutational profile within each tumor type.

CONCLUSIONS

Our findings provide an initial assessment of the immune environment of well-differentiated NETs. Further studies to define the immunologic differences between pNET and SINET, as well as the role of PD-L2 in these tumors, are warranted.

Antibody-Fc/FcR Interaction on Macrophages as a Mechanism for Hyperprogressive Disease in Non-small Cell Lung Cancer Subsequent to PD-1/PD-L1 Blockade

PURPOSE

Hyperprogression (HP), a paradoxical boost in tumor growth, was described in a subset of patients treated with immune checkpoint inhibitors (ICI). Neither clinicopathologic features nor biological mechanisms associated with HP have been identified.

EXPERIMENTAL DESIGN

Among 187 patients with non-small cell lung cancer (NSCLC) treated with ICI at our institute, cases with HP were identified according to clinical and radiologic criteria. Baseline histologic samples from patients treated with ICI were evaluated by IHC for myeloid and lymphoid markers. T-cell-deficient mice, injected with human lung cancer cells and patient-derived xenografts (PDX) belonging to specific mutational subsets, were assessed for tumor growth after treatment with antibodies against mouse and human programmed death receptor-1 (PD-1). The immune microenvironment was evaluated by flow cytometry and IHC.

RESULTS

Among 187 patients, 152 were evaluable for clinical response. We identified four categories: 32 cases were defined as responders (21%), 42 patients with stable disease (27.7%), 39 cases were defined as progressors (25.7%), and 39 patients with HP (25.7%). Pretreatment tissue samples from all patients with HP showed tumor infiltration by M2-like CD163⁺CD33⁺PD-L1⁺ clustered epithelioid macrophages. Enrichment by tumor-associated macrophages (TAM) was observed, even in tumor nodules from immunodeficient mice injected with human lung cancer cells and with PDXs. In these models, tumor growth was enhanced by treatment with anti-PD-1 but not anti-PD-1 F(ab)₂ fragments.

CONCLUSIONS

These results suggest a crucial role of TAM reprogramming, upon Fc receptor engagement by ICI, eventually inducing HP and provide clues on a distinctive immunophenotype potentially able to predict HP.See related commentary by Knorr and Ravetch, p. 904.

Downregulation of MCT4 for lactate exchange promotes the cytotoxicity of NK cells in breast carcinoma

Monocarboxylate transporter‐4 (MCT4), a monocarboxylic acid transporter, demonstrates significantly increased expression in the majority of malignancies. We performed an experiment using BALB/C mice, and our results showed that ShMCT4 transfection or the pharmaceutic inhibition of MCT4 with 7acc1 strengthens the activity of NK cells. The results of a calcein assay revealed that the cytotoxicity of NK cells was strengthened via inhibition of MCT4. In addition, ELISA testing showed that the content of perforin and CD107a was increased, and PCR amplification and immunoblotting revealed that the expression of NKG2D and H60 was upregulated after the inhibition of MCT4. Further, we observed an elevated pH value, decreased extracellular lactate flow, and attenuated tumor growth. Therefore, we concluded that the inhibition of MCT4 enhanced the cytotoxicity of NK cells by blocking lactate flux and reversing the acidified tumor microenvironment. In addition to these findings, we also discovered that MCT4 depletion may have a pronounced impact on autophagy, which was surmised by observing that the inhibition of autophagy (3MA) pulled the enhanced cytotoxicity of NK cells downwards. Together, these data suggest that the key effect of MCT4 depletion on NK cells probably utilizes inductive autophagy as a compensatory metabolic mechanism to minimize the acidic extracellular microenvironment associated with lactate export in tumors.

How shall we treat early triple-negative breast cancer (TNBC): from the current standard to upcoming immuno-molecular strategies

Triple-negative breast cancer (TNBC) is a long-lasting orphan disease in terms of little therapeutic progress during the past several decades and still the standard of care remains chemotherapy. Experimental discovery of molecular signatures including the ‘BRCAness’ highlighted the innate heterogeneity of TNBC, generating the diversity of TNBC phenotypes. As it contributes to enhancing genomic instability, it has widened the therapeutic spectrum of TNBC. In particular, unusual sensitivity to DNA damaging agents was denoted in patients with BRCA deficiency, suggesting therapeutic benefit from platinum and poly(ADP-ribose) polymerase inhibitors. However, regardless of enriched chemosensitivity and immunogenicity, majority of patients with TNBC still suffer from dismal clinical outcomes including early relapse and metastatic spread. Therefore, efforts into more precise and personalised treatment are critical at this point. Accordingly, the advance of multiomics has revealed novel actionable targets including PI3K-Akt-mTOR and epidermal growth factor receptor signalling pathways, which might actively participate in modulating the chemosensitivity and immune system. Also, TNBC has long been considered a potential protagonist of immunotherapy in breast cancer, supported by abundant tumour-infiltrating lymphocytes and heterogeneous tumour microenvironment. Despite that, earlier studies showed somewhat unsatisfactory results of monotherapy with immune-checkpoint inhibitors, consistently durable responses in responders were noteworthy. Based on these results, further combinatorial trials either with other chemotherapy or targeted agents are underway. Incorporating immune-molecular targets into combination as well as refining the standard chemotherapy might be the key to unlock the future of TNBC. In this review, we share the current and upcoming treatment options of TNBC in the framework of scientific and clinical data, especially focusing on early stage of TNBC.