Triple-negative Breast Cancer Microenvironment Research Articles

Membrane Fusion Liposomes Deliver Antifibrotic and Chemotherapeutic Drugs Sequentially to Enhance Tumor Treatment Efficacy by Reshaping Tumor Microenvironment.

The intricate tumor microenvironment in triple-negative breast cancer (TNBC) hampers chemotherapy and immunotherapy efficacy due to dense extracellular matrix (ECM) by tumor-associated fibroblasts (TAFs). Nanoparticle-based therapies, especially "all-in-one" nanoparticles, have shown great potential in combined drug delivery strategies to reshape the tumor microenvironment and enhance therapeutic efficiency. However, these "all-in-one" nanoparticles suffer from limitations in targeting different target cells, uncontrollable dosing ratio, and disregarding the impact of delivery schedules. This study prepared cell membrane fusion liposomes (TAFsomes and CCMsomes) to load FDA-approved antifibrotic drug pirfenidone (PFD/TAFsomes) and antitumor drug doxorubicin (DOX/CCMsomes). These liposomes can specifically target TAFs cells and tumor cells, and combined administration can effectively inhibit TAFs activity, reshape the tumor microenvironment (TME), and significantly enhance the tumor chemotherapy efficacy. Combined drug delivery defeats "all-in-one" liposomes (DOX/PFD/Liposomes, DOX/PFD/TAFsomes, and DOX/PFD/CCMsomes) by flexibly adjusting the drug delivery ratio. Moreover, an asynchronous delivery strategy that optimizes the administration schedule not only further improves the therapeutic effect, but also amplifies the effectiveness of α-PD-L1 immunotherapy by modulating the tumor immune microenvironment. This delivery strategy provides a personalized treatment approach with clinical translation potential, providing new ideas for enhancing the therapeutic effect against solid tumors such as TNBC.

Abstract PO4-28-07: SLC26A9 promotes triple-negative breast cancer progression by regulating lipid metabolism

Abstract Background: The disturbance of lipid metabolism in the microenvironment plays an important role in the occurrence and development of triple-negative breast cancer(TNBC). SLC26A9, a member of the SLC26A family of anion transporters, is involved in breast oncogenesis. However, the effect of SLC26A9 in triple-negative breast cancer on lipid metabolism in the tumor microenvironment remains unclear. Methods: Bioinformatics, tissue microarrays and TNBC cell lines were used to detect the expression of SLC26A9 and its clinical significance. By altering the expression of SLC26A9 gene in TNBC cells, the effects of SLC26A9 on the regulation of lipid metabolism, cell biological behavior and its related molecular mechanisms in the TNBC microenvironment were explored using adoptive staining techniques, flow cytometric analysis and animal models. Results: We found by tissue microarray (TNBC=105 cases, Nor=67 cases) that the expression of SLC26A9 was significantly up-regulated in BC compared to paracancerous tissues, where SLC26A9 expression was higher in TNBC, and the same results were obtained in BC cell lines. Secondly, we found that SCL26A9 was positively correlated with lipid metabolism status in TNBC microenvironment and possessed a close association with P53 mutation by analyzing GEO and TCGA databases. Therefore, we used two cell lines (MDA-MB-231, MDA-MB-468) in which SCL26A9 was highly expressed in TNBC cell lines. It was demonstrated by oil red O staining and lipid fluorescence staining that knockdown/silencing of SLC26A9 diminished the ability of MDA-MB-231 and MDA-MB-468 cells to uptake and utilize lipids, especially for metabolites such as neutral lipids: triglycerides, lipid droplets, and steroidal substances. Then we demonstrated by using fatty acid flow cytometric analysis that knockdown/silencing of SLC26A9 significantly reduced the utilization and production of fatty acids in MDA-MB-231 and MDA-MB-468 cells, which are the key metabolic indicators of cancer cells as well as important energy-providing substances for cancer progression. Therefore, we further verified functionally that cell proliferation, migration, invasion and anti-apoptosis were significantly inhibited in in vitro after knockdown/silencing of SLC26A9, and in vivo tumorigenesis was significantly inhibited in BALB/c nude mice in in vivo. In addition, the expression of markers of lipid metabolic activity (FASN, ACLY) was reduced after knockdown/silencing of SLC26A9 in MDA-MB-231 cells by Western Blot, and the reduced expression of FASN and ACLY mainly inhibited the ab initio synthesis, uptake and utilization of fatty acids in TNBC cells, which in turn regulated the proliferation and invasion of TNBC. Mechanistically, SLC26A9 silencing/knockdown inhibited the synthesis, uptake, and utilization of multiple metabolites of lipids in TNBC, which combined with the TCGA database results revealed the activation of the key signaling pathway, the JAK-STAT3 signaling pathway, to promote the progression of TNBC. Conclusion(s): SLC26A9 is involved in the disturbance of lipid metabolism in the TNBC microenvironment and regulates the progression of TNBC. The search for new SLC26A9 inhibitors is expected to provide a new direction for the treatment of TNBC, but the exact molecular mechanisms need to be further explored. SLC26A9 upregulation in TNBC leads to a poor prognosis by referencing lipid metabolism in the TNBC microenvironment Wench. SLC26A9 is involved in lipid metabolism disorders and cell biological functions in the TNBC microenvironment in vivo. SLC26A9 is involved in disordered lipid metabolism in the TNBC microenvironment. Citation Format: Yingming Zhou, Hu Wang, Zhengxing Zhou, Xuemei Liu, Biguang Tuo, Taolang Li. SLC26A9 promotes triple-negative breast cancer progression by regulating lipid metabolism [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-28-07.

Superparamagnetic iron oxide nanoparticles functionalized by biocompatible ligands with enhanced high specific absorption rate for magnetic hyperthermia

This study introduces a novel green nanocomposite system of iron oxide coated with secondary metabolites (Fe3O4@SM) and compares it with commonly used materials for hyperthermia cancer treatment. Fe3O4@SM magnetic nanoparticles were synthesized through a simple co-precipitation process using metal precursors, followed by heating in pressure reactor to obtain superparamagnetic nanoparticles (Hc = 36.5–54.1 Oe at 300 K). These nanoparticles were subsequently coated with plant-based phytochemicals. XRD analysis confirmed the presence of magnetite iron oxide nanoparticles. SEM images further confirmed the spherical shape of the synthesized nanoparticles, exhibiting a face-centered cubic (FCC) iron oxide structure with sizes ranging from 12±7–85±15 nm. Characterization through dynamic light scattering (DLS) and zeta potential (ζ) analysis demonstrated colloidal stability, with a polydispersity index (PDI) ranging from 0.226 to 0.436 and zeta potential values ranging from −29.761–1.85 mV. The surface of the nanoparticles was analyzed using GC-MS, which identified bioactive functional groups including ester (42.79 %), terpene (20.69 %), hydrocarbons (17.4 %), and carboxylic (12.37 %) compounds. Compared to Fe3O4 and Fe3O4@GO, Fe3O4@SM exhibited a higher rate of temperature increase within the therapeutic range, reaching Tmax = 45°C with a heating rate (dT/dt) of 0.273 °C/s and specific absorption rate (SAR) of 230.6 W/g at 304 kHz and 400 Oe. In vitro assays utilizing a triple negative breast cancer microenvironment confirmed the non-toxicity of these materials through a DNS assay. The developed nanoparticles offer dual mechanisms of action, combining thermal and chemo effects, making them promising candidates for hyperthermia cancer treatment.

Dissection of triple-negative breast cancer microenvironment and identification of potential therapeutic drugs using single-cell RNA sequencing analysis

Breast cancer remains a leading cause of mortality in women worldwide. Triple-negative breast cancer (TNBC) is a particularly aggressive subtype characterized by rapid progression, poor prognosis, and lack of clear therapeutic targets. In the clinic, delineation of tumor heterogeneity and development of effective drugs continue to pose considerable challenges. Within the scope of our study, high heterogeneity inherent to breast cancer was uncovered based on the landscape constructed from both tumor and healthy breast tissue samples. Notably, TNBC exhibited significant specificity regarding cell proliferation, differentiation, and disease progression. Significant associations between tumor grade, prognosis, and TNBC oncogenes were established via pseudotime trajectory analysis. Consequently, we further performed comprehensive characterization of the TNBC microenvironment. A crucial epithelial subcluster, E8, was identified as highly malignant and strongly associated with tumor cell proliferation in TNBC. Additionally, epithelial-mesenchymal transition-associated fibroblast and M2 macrophage subclusters exerted an influence on E8 through cellular interactions, contributing to tumor growth. Characteristic genes in these three cluster cells could therefore serve as potential therapeutic targets for TNBC. The collective findings provided valuable insights that assisted in the screening of a series of therapeutic drugs, such as pelitinib. We further confirmed the anti-cancer effect of pelitinib in an orthotopic 4T1 tumor-bearing mouse model. Overall, our study sheds light on the unique characteristics of TNBC at single-cell resolution and the crucial cell types associated with tumor cell proliferation that may serve as potent tools in the development of effective anti-cancer drugs.

The Effect of Salvianolic Acid A on Tumor-Associated Macrophage Polarization and Its Mechanisms in the Tumor Microenvironment of Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, with a high degree of malignancy and poor prognosis. Tumor-associated macrophages (TAMs) have been identified as significant contributors to the growth and metastasis of TNBC through the secretion of various growth factors and chemokines. Salvianolic acid A (SAA) has been shown to have anti-cancer activities. However, the potential activity of SAA on re-polarized TAMs remains unclear. As there is a correlation between the TAMs and TNBC, this study investigates the effect of SAA on TAMs in the TNBC microenvironment. For that purpose, M2 TAM polarization was induced by two kinds of TNBC-conditioned medium (TNBC-TCM) in the absence or presence of SAA. The gene and protein expression of TAM markers were analyzed by qPCR, FCM, IF, ELISA, and Western blot. The protein expression levels of ERK and p-ERK in M2-like TAMs were analyzed by Western blot. The migration and invasion properties of M2-like TAMs were analyzed by Transwell assays. Here, we demonstrated that SAA increased the expression levels of CD86, IL-1β, and iNOS in M2-like TAMs and, conversely, decreased the expression levels of Arg-1 and CD206. Moreover, SAA inhibited the migration and invasion properties of M2-like TAMs effectively and decreased the protein expression of TGF-β1 and p-ERK in a concentration-dependent manner, as well as TGF-β1 gene expression and secretion. Our current findings for the first time demonstrated that SAA inhibits macrophage polarization to M2-like TAMs by inhibiting the ERK pathway and promotes M2-like TAM re-polarization to the M1 TAMs, which may exert its anti-tumor effect by regulating M1/M2 TAM polarization. These findings highlight SAA as a potential regulator of M2 TAMs and the possibility of utilizing SAA to reprogram M2 TAMs offers promising insights for the clinical management of TNBC.

Abstract 6800: The tumor progression mechanism of increasing CXCL16-CXCR6 pathway within the tumor microenvironment in TNBC

Abstract Background: Triple negative breast cancer (TNBC) is characterized rapid progression, higher relapse, and poor prognosis, so the establishment of an effective therapeutic target is required. CXCL16, a chemokine abundantly present in the TNBC tumor microenvironment (TME), is secreted by tumor-associated macrophages (TAM) and is known to promote tumor growth and metastasis. However, the exact mechanism through which CXCL16 facilitates tumor growth and metastasis remains unclear. This study aims to study the role of CXCL16 in the tumor progression and confirm the anti-tumor effects of CXCL16 neutralization in TNBC model. Method: MDA-MB-231 human TNBC cell lines were utilized for in vitro validation, and a syngeneic model involving 4T1 mouse TNBC cell lines and Balb/c mice was used for in vivo studies. Results: Stimulation of TNBC cells with recombinant human CXCL16 protein (rhCXCL16) activates the tumor growth signaling pathways, including pAKT and STAT3, as well as EMT markers. These results shows that CXCL16 can promote tumor growth and metastasis. Treatment with CXCL16 neutralizing antibodies inhibited the promotion of cancer growth and metastasis by rhCXCL16. Additionally, combination treatment of CXCL16 antibodies with PD-1 antibodies in the 4T1 syngeneic model increased the proportion of CD8+ T cells and CD80+ M1 like macrophages. These results shows that neutralization of CXCL16 can regulate polarization of macrophage and proportion of T cells. These regulation and changes of immune cells allow neutralization of CXCL16 control the TME to resist tumor cells, suggesting that optimal condition can be constructed to maximize the effectiveness of anti-cancer drugs. Conclusion: This study confirms that the CXCL16-CXCR6 pathway within the TME triggers tumor growth and metastasis, while neutralization of CXCL16 can inhibit tumor progression. This effect is attributed to the increase in CD8+ T cell and M1 macrophage proportions within the TME. In conclusion, these research findings propose the potential of CXCL16 as a novel biomarker and therapeutic target for TNBC. Citation Format: Yun sun Lee, Cham Han Lee, Seong Yun Ha, Sang Hyeob Lee, Jin Yi Yang, Young Sang Kim, Sung Moo Kim, Seong Keun Kim. The tumor progression mechanism of increasing CXCL16-CXCR6 pathway within the tumor microenvironment in TNBC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6800.

Abstract 2912: SFRP2 and CD38 colocalize in triple negative breast cancer microenvironment

Abstract Introduction: A promising target for breast cancer is secreted frizzled-related protein 2 (SFRP2), and a humanized monoclonal antibody to SFRP2 (hSFRP2 mAb) inhibits primary triple negative breast cancer (TNBC) in vivo. CD38 is a known cause of PD-1 inhibitor resistance in some tumors, and in metastatic osteosarcoma hSFRP2 mAb overcomes PD-1 mAb resistance by reducing CD38 in tumor infiltrating lymphocytes (TILs). Could this phenomenon be replicated in TNBC? This is unknown as the expression of CD38 in TNBC has not been studied. This study will establish the presence of SFRP2 and CD38 in the TNBC microenvironment. Methods: Immunohistochemistry (IHC) was performed on an 88 core human TNBC tissue microarray (TMA) with antibodies to SFRP2 and CD38. Spatial analysis software was used to determine percent positivity. Each core was categorized using the scoring system for the estrogen receptor in breast cancer (<1% negative, 1-10% low positive, and >10% positive). Multiplex IHC was performed on 4 human triple TNBCs sections. Tissues were stained with antibodies to CD38, CD68 (macrophage), CD3 (T-cell), CD19 (B-cell), CytoKeratin (tumor), and SFRP2. Percent positivity of each marker was analyzed with a software package. For flow cytometry of tumor associated macrophages (TAMs), 1 million EO771 cells were injected into the mammary fat pad of female C57/BL6 mice. After 4 weeks tumors were extracted and a cell suspension was incubated in a mastermix with antibodies to SFRP2, CD38, PD1, CD11B and F480. Cells were fixed and conjugated to a fluorochrome secondary antibody. TAM gated cells were analyzed for the presence of SFRP2 and CD38. Results: For the TNBC TMA, 83 cores were positive and 4 cores were low positive for SFRP2, 1 not evaluable; 87 cores were positive and 1 low positive for CD38. For multiplex IHC there was a total of 1,753,544 individual cells in all 4 human TNBC tumors that were stained. 94% of cells stained positive for SFRP2, and 65% stained positive for CD38. Of the cells that were positive for SFRP2, 70% were also positive for CD38, 15% were positive for CD68, 1% were positive for CD19, 77% were positive for CytoKeratin, and 10% were positive for CD3. Of the cells that were CD38 positive, 99% were also positive for SFRP2, 15% were positive for CD68, 1% were positive for CD19, 81% were positive for CytoKeratin, and 9% were positive for CD3. Flow cytometry analysis of TAMs confirmed the presence of SFRP2, CD38 on TAMs. TAMs that were negative for PD1 and CD38 (pro-inflammatory) had a 56% reduction in SFRP2 compared to TAMs that were double positive for PD1 and CD38 (anti-inflammatory). Conclusion: SFRP2 and CD38 are prevalent in human TNBC and colocalize in the TNBC microenvironment in tumor cells, TAMs and TILs, but not B-cells. The presence and co-localization of SFRP2 and CD38 in TAMs was confirmed with flow cytometry. This confirms that SFRP2 is a therapeutic target in TNBC and provides a mechanistic rational for combination therapy with PD-1 inhibitor. Citation Format: Lillian Hsu, Patrick Nasarre, Rupak Mukherjee, Eleanor Hilliard, Martin Romeo, Elizabeth O'Quinn, Whitney Christians, Nancy Klauber DeMore. SFRP2 and CD38 colocalize in triple negative breast cancer microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2912.

Abstract 2893: Inhibition of ADAMTS4 and 5 to regulate the tumor microenvironment

Abstract Background: Triple-negative breast cancer accounts for approximately 10~15% of all breast cancers and is characterized by the absence of ER, PR, and HER2 receptors, making targeted therapies challenging due to the lack of biomarkers. ADAMTSs (ADAM metallopeptidase with thrombospondin) are complex extracellular proteases known for their roles in facilitating cancer cell proliferation and safeguarding tumor functions. This enzyme is secreted by cancer cells and various immune cells, influencing the tumor microenvironment. ADAMTSs modulate cellular adhesion, migration, proliferation, and vascular development by cleaving components of the extracellular matrix and regulatory factors such as chemokines and cytokines. Our aim is to positively manipulate the tumor microenvironment of triple-negative breast cancer by inhibiting ADAMTSs, presenting a new strategy for treating this challenging type of breast cancer that lacks targeted therapeutic options. Results: To confirm the anticancer effects of a protease inhibitor concurrently targeting ADAMTS4 and 5, a co-culture of triple-negative breast cancer cells (MDA-MB-157) and THP-1 was established to artificially create a tumor microenvironment. Subsequently, a wound healing assay was conducted, revealing that treatment with the ADAMTS4 and 5 dual inhibitor effectively inhibited cancer cell migration. This observed anticancer effect is attributed to the inhibition of CXCL16 secretion by the ADAMTS4 and 5 dual inhibitor. To verify the anti-tumor mechanisms of ADAMTS4 and 5, MDA-MB-157 cells, a triple-negative breast cancer cell line, were treated with IFNγ and TNFα to promote CXCL16 secretion artificially. Upon treatment with varying concentrations of the ADAMTS4,5 dual inhibitor, it was confirmed that the secretion of CXCL16 was inhibited in a dose-dependent manner. In a mouse model with transplanted 4T1 breast cancer cells, treatment with the ADAMTS4,5 dual inhibitor resulted in the suppression of CXCL16 secretion, leading to an increase in M1 macrophages. Additionally, it was observed that the inhibitor induced CD8+ T cell activation. These regulation and changes of immune cells through inhibition of ADAMTS4 and 5 control the TME to resist tumor cells. Conclusion: ADAMTSs are known as protein-degrading enzymes responsible for the degradation, modification, and regulation of proteins. Recent research has revealed that ADAMTSs play a crucial role in the proliferation and survival of cancer. Activation of ADAMTS4 and 5 has been shown to promote the secretion of CXCL16, leading to the differentiation of macrophages into tumor-associated macrophages. Specifically, ADAMTS4 and 5 convert membrane-bound CXCL16 into a soluble form, exacerbating the tumor microenvironment of triple-negative breast cancer. Therefore, inhibiting ADAM4,5 is intended to change or maintain TME in a suitable state for anti-cancer therapy, which could lead to a new strategy for anti-cancer therapy. Citation Format: Cham han Lee, Seong Keun Kim, Sung Moo Kim, Young Sang Kim, Sang Hyeob Lee, Seong Yun Ha, Yun Sun Lee, Jin Yi Yang. Inhibition of ADAMTS4 and 5 to regulate the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2893.

Abstract 6791: Investigation of sex hormone effects in an organ chip model of endothelial barrier dysfunction in the triple negative breast cancer microenvironment

Abstract Inflammation and pathological vasculature are common features of the tumor microenvironment (TME). Sex hormones potently modulate vascular physiology and immune cell functions, and there are established correlations with the outcomes of triple negative (TNBC) despite the defining feature of receptor negativity. Circulating estrogens and androgens have been hypothesized as drivers of TNBC through the actions exerted by receptor-positive cells in the TME. Here, we present an organ chip model of the TNBC microenvironment for quantifying the impact of configurable TME variables such as the ECM composition and the relative densities and phenotypes of tumor cells, cancer associated fibroblasts, and myeloid cells on endothelial barrier function. After establishing baselines of vascular permeability in the presence and absence of TNBC cells, we tested the effect of estradiol, estrone, and dihydrotestosterone on barrier permeability. Multilayer polydimethylsiloxane (PDMS) organ chips were fabricated using standard soft lithography. The layers of the device were separated with semi-permeable membranes that allow exchange of soluble factors. Once assembled, the upper channel was loaded with female (XX) human umbilical vein endothelial cells. Collagen hydrogels were injected into the tissue layer and the devices were cultured on a rocker to induce endothelial barrier alignment via application of an average shear stress of 5 dynes/cm2. We optimized rocking conditions by assessing endothelial layer alignment, junctional organization, and permeability. TNBC cells and XX mammary carcinoma fibroblasts were added to the hydrogel to model the effects of TME-derived signals on endothelial barrier permeability. 40 kDa FITC- Dextran was chosen to assay permeability as it can show leakage due to active disruption of the barrier. Staining for F-actin and ZO-1 allowed for quantification of junctional organization. Sex hormone modulation of proinflammatory gene expression was assessed by RT-qPCR. The presence of TNBC cells significantly increased transport of 40kDa FITC-Dextran across the endothelial barrier, disrupted intercellular junction quality, and induced the expression of inflammatory adhesion molecules including ICAM-1. Our results demonstrate that sex hormones modulate TNBC-associated changes in endothelial cell bioenergetics, junctional organization, and macromolecular barrier permeability. Ongoing work will investigate the effects of age-matched XX monocyte derived macrophages on barrier function in the model. This organ chip platform provides an assay for measuring altered vascular inflammation and permeability in the TNBC microenvironment and may provide a venue for investigating vascular-normalizing effects of various candidate therapeutics. Citation Format: Delia Carlino, Ashley Martier, Yasmin Maurice, G. Wills Kpeli, Matthew Burow, Mark Mondrinos. Investigation of sex hormone effects in an organ chip model of endothelial barrier dysfunction in the triple negative breast cancer microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6791.

Abstract 1149: Spatial transcriptomic analysis of tumor microenvironment in patients with triple negative breast cancer with residual disease after neoadjuvant chemotherapy with immune checkpoint inhibitor

Abstract Recent advance of treatment strategy for triple negative breast cancer (TNBC) including immune checkpoint inhibitor improved survival outcome. Especially, adding pembrolizumab on neoadjuvant chemotherapy (NAC) increased pathologic complete response (pCR) rate at the time of curative surgery. Previous studies suggested that PD-L1 expression in both tumor and immune cells was associated with the response of pembrolizumab in TNBC, but PD-L1 expression state were not associated with pembrolizumab response in NAC setting. In addition, neoadjuvant pembrolizumab increased event-free survival (DFS) rate after NAC even though they had not achieved pCR. However, there were no biomarker for EFS increasement of using pembrolizumab. We designed prospective translational research for evaluating tumor microenvironment (TME) of residual TNBC which had treated with NAC followed by curative surgery. We collected formalin fixed paraffin embedded (FFPE) surgical specimens after NAC with or without pembrolizumab. TNBC samples were used for spatial transcriptomics (ST) analysis, with H&E staining and inspection by an experienced pathologist. Libraries were prepared using Visium Spatial Gene Expression Reagent Kit protocol for FFPE (10x Genomics). Sequencing was conducted on the NovaSeq 6000 System (Illumina). From February 2023 to October 2023, 23 TNBC specimens from 22 patients were collected. Twenty specimens were breast tissues and three were lymph nodes, 18 TNBCs had been treated with NAC with pembrolizumab and four with only NAC, and five had residual cancer burden(RCB) class I, 11 of RCB class II and one of RCB class III. We collected BC and LN samples from BC with class III. Of 23 samples, we performed spatial transcriptomic analysis in 12 samples. In intrinsic subtyping, eight specimens were categorized into normal like, two of basal like and two of luminal A BC subtypes. In TNBC subtyping, mesenchymal stem cell like (MSL) were in six specimens, three of stem cell like (SL), two of luminal androgen receptor (LAR) and one of immunomodulatory (IM). We also performed cell type annotation with unsupervised method and categorized into 11 cell types; three cancer cell types, two macrophages, B and T cells, adipocytes, normal epithelium and perivascular-like and cancer associated fibroblasts. Among these 11 cell types, increasement of immune cells including B cells, T cells and macrophage proportions was associated with pembrolizumab treatment in NAC setting. In our study, we evaluated TME state of TNBC after NAC with or without pembrolizumab. We suggested that MSL or SL TNBC subtypes were associated with residual disease after NAC regardless of pembrolizumab use and pembrolizumab may recruit more immune cells in TME of TNBC. For concreating our suggestion, further analyses would be warranted. Citation Format: Ji-Yeon Kim, Kyunghee Park, Yoon La Choi, Jeong Eon Lee, Byung Joo Chae, Jonghan Yu, Seok Won Kim, Seok Jin Nam, Jin Seok Ahn, Woong-Yang Park, Yeon Hee Park. Spatial transcriptomic analysis of tumor microenvironment in patients with triple negative breast cancer with residual disease after neoadjuvant chemotherapy with immune checkpoint inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1149.

A Retrospective View of the Triple-Negative Breast Cancer Microenvironment: Novel Markers, Interactions, and Mechanisms of Tumor-Associated Components Using Public Single-Cell RNA-Seq Datasets.

Triple-negative breast cancer (TNBC) is a significant clinical challenge due to its aggressive nature and limited treatment options. In search of new treatment targets, not only single genes but also gene pairs involved in protein interactions, we explored the tumor microenvironment (TME) of TNBC from a retrospective point of view, using public single-cell RNA sequencing datasets. A High-resolution Cell type Annotation Tool, HiCAT, was used first to identify the cell type in 3-level taxonomies. Tumor cells were then identified based on the estimates of copy number variation. With the annotation results, differentially expressed genes were analyzed to find subtype-specific markers for each cell type, including tumor cells, fibroblast, and macrophage. Cell-cell interactions were also inferred for each cell type pair. Through integrative analysis, we could find unique TNBC markers not only for tumor cells but also for various TME components, including fibroblasts and macrophages. Specifically, twelve marker genes, including DSC2 and CDKN2A, were identified for TNBC tumor cells. Another key finding of our study was the interaction between the DSC2 and DSG2 genes among TNBC tumor cells, suggesting that they are more tightly aggregated with each other than those of other subtypes, including normal epithelial cells. The overexpression of DSC2 in TNBC and its prognostic power were verified by using METABRIC, a large bulk RNA-seq dataset with clinical information. These findings not only corroborate previous hypotheses but also lay the foundation for a new structural understanding of TNBC, as revealed through our single-cell analysis workflow.

PGAM1 suppression remodels the tumor microenvironment in triple-negative breast cancer and synergizes with anti-PD-1 immunotherapy.

Triple-negative breast cancer (TNBC) is a high-risk form of breast cancer with a high metastatic potential and lack of effective therapies. Immunotherapy has shown encouraging clinical benefits, and its efficacy in TNBC is affected by immunocyte infiltration in the tumor microenvironment (TME). Phosphoglycerate mutase 1 (PGAM1) is a key enzyme involved in cancer metabolism; however, its role in the TME remains unclear. In this study, we aimed to investigate the role of PGAM1 in TNBC and determine the potential of PGAM1 inhibition in combination with anti-PD-1 immunotherapy. Our results showed that PGAM1 is highly expressed in TNBC and is associated with poor prognosis. In vivo experiments demonstrated that PGAM1 inhibition synergizes with anti-PD-1 immunotherapy, significantly remodeling the TME and leading to an increase in anti-tumor immunocytes, such as CD8+ T cells and M1-macrophages, and a reduction in immunosuppressive cell infiltration, including myeloid-derived suppressor cells, M2-macrophage, and Tregs. Functional and animal experiments showed that this synergistic mechanism inhibited tumor growth in vitro and in vivo. We identified PGAM1 as a novel target that exhibits an antitumor effect via the regulation of immunocyte infiltration. Our results show that PGAM1 can synergize with anti-PD-1 immunotherapy, providing a novel treatment strategy for TNBC.

Identification of hypoxia-immune-related signatures for predicting immune efficacy in triple-negative breast cancer

Abstract Objectives The therapeutic effect against triple-negative breast cancer (TNBC) varies among individuals. Finding signatures to predict immune efficacy is particularly urgent. Considering the connection between the microenvironment and hypoxia, hypoxia-related signatures could be more effective. Therefore, in this study, we aimed sought to construct a hypoxia-immune-related prediction model for breast cancer and identify therapeutic targets. Methods Immune and hypoxia status in the TNBC microenvironment were investigated using single-sample Gene Set Enrichment Analysis (ssGSEA) and Uniform Manifold Approximation and Projection (UMAP). The least absolute shrinkage and selection operator (LASSO) and multivariate Cox regression analysis were employed to build a prognostic model based on hypoxia-immune-related differentially expressed genes. The Cancer Genome Atlas (TCGA) cohort, real-time quantitative polymerase chain reaction (qRT-PCR), and immunofluorescence staining were utilized to analyze the expression differences. Tumor immune dysfunction and exclusion indexes were used to indicate the effect of immunotherapy. Results We identified 11 signatures related to hypoxia and immunity. Among these genes, C-X-C motif chemokine ligand (CXCL) 9, 10, and 11 were up-regulated in TNBC tissues compared to normal tissues. Furthermore, CXCL9, 10, 11, and 13 were found to enhance the effect of immunotherapy. Conclusions These findings suggest the value of the hypoxia-immune-related prognostic model for estimating the risk in patients with TNBC, and CXCL9, 10, 11, and 13 are potential targets to overcome immune resistance in TNBC.

Spindle apparatus coiled-coil protein 1 (SPDL1) serves as a novel prognostic biomarker in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) has a poor prognosis, an ineffective diagnosis, and a high degree of aggressiveness. Therefore, novel therapeutic targets for TNBC urgently need to be identified. Through a series of bioinformatics analyses, including analysis of differential gene expression, protein-protein interaction (PPI) network, univariate cox regression, immune infiltration, pathway enrichment, etc, as well as auxiliary immunohistochemistry (IHC) and protein quantitativae analysis, to explore prognostic marker for TNBC. In TNBC tissues, we found that SPDL1 (CCDC99) was considerably overexpressed at both the mRNA and protein levels compared to that in normal and non-TNBC tissues. Additionally, we found that SPDL1-high expression was strongly linked to poor prognosis in TNBC patients. Excessive SPDL1 expression was positively correlated with tumor growth and strongly linked to the cell cycle, DNA replication, and the p53 signaling pathway. In addition, CIBERSORT analysis revealed that SPDL1 can affect the tumor immune microenvironment (TME) in TNBC, encourage the development of TNBC and act as a potential prognostic biomarker for TNBC. Patients with SPDL1-high expression were more sensitive to AZD8055. Notably, we discovered that SPDL1 is highly expressed in the majority of malignancies and may have an impact on the pancancer prognosis. SPDL1 can serve as a novel prognostic marker for TNBC and pancancer patients.

Nanoparticle-integrated dissolving microneedles for the co-delivery of R848/aPD-1 to synergistically reverse the immunosuppressive microenvironment of triple-negative breast cancer

Nowadays, effective immunotherapy against triple-negative breast cancer (TNBC) remains challenging due to the immunosuppressive tumor microenvironment. Immune checkpoint inhibitor is mostly employed to restore the activity of tumor-specific immune cells, which however brings little therapeutic outcome owing to the limited number of tumor-infiltrating CD8+ T cells and the inefficient delivery of immune drugs to the tumor tissue. Aiming to solve these problems, we herein constructed a tailor-made dissolving microneedle co-encapsulating the TLR7/8 agonist R848 and the immune checkpoint inhibitor aPD-1, termed αNP-RNP@DMN, and fabricated it as a transdermal drug delivery system. This well-designed microneedle patch, endowed with efficient tumor drug delivery ability, was able to mature tumor-infiltrating dendritic cells (TIDCs) and further promote the infiltration of CD8+ T cells into the tumor tissue with the aid of R848. Moreover, the introduction of aPD-1 blocked the programmed cell death protein 1/programmed cell death ligand 1(PD-1/PD-L1) immune checkpoints, synergistically reversing the immunosuppressive microenvironment of TNBC. In vivo therapeutic results demonstrated that αNP-RNP@DMN not only significantly prolonged the survival time of 4T1 tumor-bearing mice, but also inhibited tumor recurrence and lung metastasis after surgery, implying the great potential of this effective drug delivery system for enhanced immunotherapy of superficial tumors. Statement of significanceThe limited number of tumor-infiltrating CD8+ T cells and the inefficient delivery of immune drugs to the tumor tissue hinder the effective immunotherapy of triple-negative breast cancer (TNBC). Herein, a dissolving microneedle co-encapsulating TLR7/8 agonist R848 and immune checkpoint inhibitor aPD-1 was developed and fabricated as a transdermal drug delivery system. This tailor-made microneedle patch not only promoted drug accumulation in tumor sites in a safe and painless manner, but also lifted the immune-suppressive state of tumor-infiltrating dendritic cells (TIDCs). The activated TIDCs further enhanced T-cell infiltration into the tumor tissue, thus successfully boosting the therapeutic efficacy of aPD-1. This study demonstrated that this well-designed microneedle patch could be served as an effective drug delivery system for enhanced immunotherapy of TNBC.

TTK inhibition activates STING signal and promotes anti-PD1 immunotherapy in breast cancer

Despite progress in the application of checkpoint immunotherapy against various tumors, attempts to utilize immune checkpoint blockade (ICB) agents in triple negative breast cancer (TNBC) have yielded limited clinical benefits. The low overall response rate of checkpoint immunotherapy in TNBC may be attributed to the immunosuppressive tumor microenvironment (TME). In this study, we investigated the role of mitogen-associated kinase TTK in reprogramming immune microenvironment in TNBC. Notably, TTK inhibition by BAY-1217389 induced DNA damage and the formation of micronuclei containing dsDNA in the cytosol, resulting in elicition of STING signal pathway and promoted antitumor immunity via the infiltration and activation of CD8+ T cells. Moreover, TTK inhibition also upregulated the expression of PD-L1, demonstrating a synergistic effect with anti-PD1 therapy in 4T1 tumor-bearing mice. Taken together, TTK inhibition facilitated anti-tumor immunity mediated by T cells and enhanced sensitivity to PD-1 blockade, providing a rationale for the combining TTK inhibitors with immune checkpoint blockade in clinical trials.

An exosome-based specific transcriptomic signature for profiling regulation patterns and modifying tumor immune microenvironment infiltration in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is a highly heterogeneous tumor that lacks effective treatment and has a poor prognosis. Exosomes carry abundant genomic information and have a significant role in tumorigenesis, metastasis, and drug resistance. However, further exploration is needed to investigate the relationship between exosome-related genes and the heterogeneity and tumor immune microenvironment of TNBC. Based on the exosome-related gene sets, multiple machine learning algorithms, such as Cox boost, were used to screen the risk score model with the highest C-index. A 9-gene risk score model was constructed, and the TNBC population was divided into high- and low-risk groups. The effectiveness of this model was verified in multiple datasets. Compared with the low-risk group, the high-risk group exhibited a poorer prognosis, which may be related to lower levels of immune infiltration and immune response rates. The gene mutation profiles and drug sensitivity of the two groups were also compared. By screening for genes with the most prognostic value, the hub gene, CLDN7, was identified, and thus, its potential role in predicting prognosis, as well as providing ideas for the clinical diagnosis, treatment, and risk assessment of TNBC, was also discussed. This study demonstrates that exosome-related genes can be used for risk stratification in TNBC, identifying patients with a worse prognosis. The high-risk group exhibited a poorer prognosis and required more aggressive treatment strategies. Analysis of the genomic information in patient exosomes may help to develop personalized treatment decisions and improve their prognosis. CLDN7 has potential value in prognostic prediction in the TNBC population.

Combination of oxymatrine (Om) and astragaloside IV (As) enhances the infiltration and function of TILs in triple-negative breast cancer (TNBC)

Triple-negative breast cancer (TNBC) is the most aggressive subtype and has a poor response to treatment due to an immunosuppressive microenvironment. Chinese Medicine effective constituents such as oxymatrine (Om) and astragaloside IV (As) have shown promise in cancer treatment by providing anti-fibrosis and immune-enhancing effects. However, the potential combined effect of Om and As on TNBC and its mechanism is still uncertain. This study focuses on exploring the impact of Om and As on enhancing the immunosuppressive microenvironment of TNBC and uncovering the potential mechanism behind it. In this study, a trans-Cancer associated fibroblasts (CAFs) infiltration system of T cells was utilized to investigate the potential benefits of Om, while the impact of As on the morphology and quantity of mitochondria in T cells was examined in a co-culture system with tumor cells. Further to investigate the combined effects of Om and As on tumor suppression and immunosuppressive microenvironment improvement, this study established an in situ TNBC mouse model with 4 T1-luc. In vitro, our findings indicate that Om can effectively suppress the activation of CAFs by downregulating the expression of FAP and α-SMA, and also promoting the infiltration of T cells trans CAFs. It was discovered that the mitochondrial activity of T cells could be improved by increasing the number of mitochondria and cristae. In vivo, the optimal ratio of Om and As (2:1) was found to increase the apoptosis rate of tumor cells in a co-culture system and enhance the infiltration of CD4+ and CD8+ T cells, as confirmed by Flow Cytometry results. Our study suggests that Om and As could enhance the immune system's ability to treat TNBC by improving the infiltration and increasing the anti-tumor function of TILs. This intervention may lead to a promising therapeutic direction for the treatment of TNBC.

Histological spatial analysis on the induction of PD-L1+ macrophages by CD8+ T cells at the marginal microenvironment of triple-negative breast cancer

BackgroundProgrammed death-ligand 1 (PD-L1) plays important roles in the evasion of antitumor immunity. Because we observed the localization of PD-L1-positive (PD-L1+) cells in the marginal region of triple-negative breast cancer (TNBC) specimens, we hypothesized that the marginal microenvironment of TNBC would involve the induction of PD-L1+ cells.MethodsOne hundred and one TNBC surgical specimens were examined. We performed immunohistochemical (IHC) studies of PD-L1, CD68, CD8, and pan-cytokeratin in these specimens. We analyzed the localization of IHC-positive cells and the distance between these cells by histological spatial analysis.ResultsIn 30.7% of TNBC specimens, PD-L1+ cells were located in the marginal region. Approximately three PD-L1+ cells accumulated around a single TNBC cell. Most PD-L1+ cells were located within 50 μm of TNBC cells. PD-L1+ cells were indicated to interact with TNBC cells in the marginal region. PD-L1+CD68+ cells were located in the marginal region, while CD68+ macrophages (MΦs) were observed either in the marginal region or the core region. PD-L1 expression in MΦs was induced in the marginal region. The colocalization of CD8+ T cells in the marginal region indicates that PD-L1 expression in MΦs would be induced by interaction with CD8+ T cells. Because CD8+ T cells are positive for CCL2, CCL2 may induce PD-L1 expression in MΦs.ConclusionAt the marginal microenvironment of TNBC, PD-L1 expression would be induced in MΦs by interaction with CD8+ T cells through CCL2. The interaction between PD-L1+ MΦs and TNBC cells would facilitate the growth of TNBC under antitumor immunity. These interactions would be potential targets for restoring antitumor immunity and suppressing TNBC progression.

Prognostic value and immune landscapes of TERT promoter methylation in triple negative breast cancer.

Treatment options for patients with triple-negative breast cancer (TNBC) remain limited to mainstay therapies owing to a lack of efficacious therapeutic targets. Accordingly, there is an urgent need to discover and identify novel molecular targets for the treatment and diagnosis of this disease. In this study, we analyzed the correlation of telomerase reverse transcriptase (TERT) methylation status with TERT expression, prognosis, and immune infiltration in TNBC and identified the role of TERT methylation in the regulation TNBC prognosis and immunotherapy. Data relating to the transcriptome, clinicopathological characteristics and methylation of TNBC patients were obtained from The Cancer Genome Atlas (TCGA) database. TERT expression levels and differential methylation sites (DMSs) were detected. The correlations between TERT expression and DMSs were calculated. Kaplan-Meier curves was plotted to analyze the relationship between the survival of TNBC patients and the DMSs. The correlations of DMSs and TERT expression with several immunological characteristics of immune microenvironment (immune cell infiltration, immunomodulators, immune-related biological pathways, and immune checkpoints) were assessed. The results were validated using 40 TNBC patients from Sun Yat-sen University Cancer Center (SYSUCC). Six DMSs were identified. Among them, four sites (cg11625005, cg07380026, cg17166338, and cg26006951) were within the TERT promoter, in which two sites (cg07380026 and cg26006951) were significantly related to the prognosis of patients with TNBC. Further validation using 40 TNBC samples from SYSUCC showed that the high methylation of the cg26006951 CpG site was associated with poor survival prognosis (P=0.0022). TERT expression was significantly correlated with pathological N stage and clinical stage, and cg07380026 were significantly associated with pathological T and N stages in the TCGA cohort. Moreover, the methylation site cg26006951, cg07380026 and TERT expression were significantly correlated with immune cell infiltration, common immunomodulators, and the level of the immune checkpoint receptor lymphocyte activation gene 3 (LAG-3) in TNBC patients. TERT promotertypermethylation plays an important role in TERT expression regulation and tumor microenvironment in TNBC. It is associated with overall survival and LAG-3 expression. TERT promoter hypermethylation may be a potential molecular biomarker for predicting response to the TERT inhibitors and immune checkpoint inhibitors in TNBC.