Breast Cancer Tumor 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 PO3-03-01: Impact of Environmental Temperature on Clinical Outcomes and Tumor Microenvironment of Early-Stage Breast Cancer

Abstract Background Preclinical evidence using mouse model suggests that thermal/cold stress increases tumor growth by modulating the tumor microenvironment (TME); however, the clinical relevance of temperature on breast cancer (BC) outcomes is unknown. Studies show that residing in cold regions is associated with higher incidence of BC. We aim to study the impact of environmental temperature on the pathological complete response (pCR) and survival of early-stage BC patients (pts). Methodology A multi-institutional study was conducted within the Oncology Research Information Exchange Network (ORIEN). We analyzed the clinical and genomic data for early-stage BC pts from 12 centers in different environment zones (5 warm and 7 cold) (based on average annual regional temperature obtained from National Centers for Environmental Information). Cox regression was used to measure the association of climate and overall/relapse-free survival (OS/RFS) after adjusting for age, race, body mass index, grade, stage, treatments, comorbidities, and subtype. Raw feature counts were normalized, and differential expression analysis was carried out using DESeq2, while adjusting for all of the covariates. Differential expression rank order was used for subsequent gene set enrichment analysis (GSEA), performed using the cluster profile package in R. Gene sets queried included the Hallmark, Canonical pathways, and GO Biological Processes Ontology collections available through the Molecular Signatures Database (MSigDB). Results Out of the 1,304 early-stage BC pts, 271 pts received neoadjuvant chemotherapy (NAC) (186 warm, 85 cold). Higher clinical T- and N-stages were observed in pts from warm compared to cold regions (p< 0.001). Pts residing in cold regions had more comorbidities (57.6% vs 4.8%, p< 0.001). Pts in warm regions had higher pCR, though not statistically significant (8% vs 2.5%, p= 0.1). In the overall population, the OS (univariate (UV) HR= 0.48, 95% CI 0.27-0.64, p < 0.001; adjusted HR (aHR)= 0.56, 95% CI 0.32 - 0.96, p= 0.03) and RFS (UV HR= 0.51, 95% CI 0.38 - 0.68, p< 0.001; aHR= 0.52, 95% CI 0.36 - 0.75, p= 0.0005) were higher in pts from warm compared to cold regions (Table 1). Among the patient subgroup treated with NAC, the OS (aHR= 0.35, p= 0.02) and RFS (aHR= 0.49, p= 0.02) of pts from warmer regions was also higher than cold regions. RNA sequencing was performed on 826 tumors (443 warm, 383 cold) using pre-treatment samples. Naïve B-cells (mean: 0.09 vs 0.08, p=0.004), CD4 naïve T cells (0.03 vs 0.02, p= 0.0008), CD4+ memory T cells (0.03 vs 0.02, p= 0.04), gamma-delta T-cells (0.007 vs 0.004, p= 0.006) were higher in pts residing in cold compared to warm regions while CD8 T cells, T regulatory cells, macrophages, dendritic cells, natural killer cells were similar in both regions. Macrophage signaling, cholesterol metabolism and the pathway for negative regulation of cell migration in angiogenesis were upregulated in pts living in warm compared to cold regions. Conclusion Early-stage BC pts living in cold have worse OS and RFS compared to warm regions. Our study is the first to report significant differences in the TME among these pts. However, it is important to acknowledge that the limited availability of comprehensive data regarding patients' relocation to different environmental temperature zones during treatments, and individual temperature preferences may be considered a potential limitation of our study. To ensure the validity and robustness of these intriguing findings, larger multi-center studies should be conducted, encompassing detailed information on the duration of exposure to both warm and cold weather conditions. Table 1: OS and RFS of patients living in warm vs cold environments Citation Format: Arya Mariam Roy, Spencer Rosario, Anthony George, Qiang Hu, Brian Czerniecki, John Carpten, Virginia Borges, Bryan Schneider, Jill Kolesar, Christopher Moskaluk, Craig Shriver, Cindy Matsen, Shridar Ganesan, Sneha Phadke, Wajeeha Razaq, Kristopher Attwood, Shipra Gandhi. Impact of Environmental Temperature on Clinical Outcomes and Tumor Microenvironment of Early-Stage Breast Cancer [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 PO3-03-01.

Abstract PO4-26-03: Collagen deposition in the breast cancer microenvironment correlates with ER-positive, Histological Grade I and low proliferation tumors

Abstract Breast cancer is a highly heterogeneous neoplasm both at the molecular and histological levels. Breast cancer cells present extremely high levels of genetic heterogeneity concerning mutational burden, copy number variations (CNVs) and epigenetic signatures. While this level of heterogeneity is well established, other layers of heterogeneity, such as tumor microenvironment (TME) heterogeneity, remains to be elucidated. TME in breast cancer is an intricate network encompassing tumor cells, “normal” stroma cells such as fibroblasts, lymphocytes, and a plethora of extracellular matrix (ECM) proteins produced either by cancer cells or stromal cells. These three interacting modules (cancer cells, stromal cells and the ECM) can affect each other in a reciprocal way with profound effects on patient prognosis and treatment outcome. Major protein components of the TME are ECM-related collagens, that are produced by breast cancer cells or/and cancer associated fibroblasts. The ECM collagen in breast cancer, that is mainly composed of collagen types I, III and V, has multiple roles modulating tumor growth, cancer cell invasiveness and metastasis. Here by Masson Trichrome and Immunohistochemistry/Aniline Blue co-stains for collagen fibers and proliferation index (Ki-67) in breast cancer FFPE tissue samples, we identified a statistically significant correlation between collagen deposition and Estrogen Receptor (ER)) status (p< 0.05, proliferation index (p< 0.01) and histological Grade (p=0.01). Further, in order to expand and support our findings, we analyzed the METABRIC study through the cBioPortal hub in relevance to collagen genes and multiple clinicopathological parameters. We were able to identify a coregulated subset of collagen genes that presented a positive correlation with ER-positive (p< 10−10, q< 10−10), low proliferating (p< 10−10, q< 10−10), Grade I (p=2.35e−9, q< 1.07e−8) group of breast cancer cases, supporting our findings. In addition, analyses of collagen-high patients from the METABRIC study indicated that most cases presented with PIK3CA, CBFB and MAP3K1 mutations, while through the g.Profiler software we identified collagen-high relevant gene signatures that encompassed gene ontology terms related to tissue development, extracellular matrix organization and cell migration. Collectively, our preliminary results indicate that ECM collagen deposition in breast cancer is characteristic of low-grade tumors with a better differentiation and possibly with a favorable prognosis. Citation Format: Angelos Koutras, Chaido Sirinian, Olga Bogri, Martha Nifora, Maria Theakou, Soren Degn, Ioannis Mouratidis, Dimitrios Chaniotis, Stavros Peroukidis, Ilias Georgakopoulos-Soares, Anastasios Papanastasiou. Collagen deposition in the breast cancer microenvironment correlates with ER-positive, Histological Grade I and low proliferation tumors [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 PO4-26-03.

Abstract PO5-04-06: Enhancing Antitumor Activity of Her2 CAR T cells through TR2BB Co-Expression and Cytokine Signal 3 Incorporation

Abstract Chimeric antigen receptor T cells (CARTs) targeting Her2 represent a promising approach for the treatment of patients with Her2 expressing breast cancers (BC). Her2 CARTs confront major challenges within the immune-suppressive tumor microenvironment (TME) of breast cancer, which inhibits sustained T cell proliferation and persistent antitumor activity. To bolster Her2 CARTs' expansion and persistence, we engineered a TNF-related apoptosis-inducing ligand receptor 2 (TR2) specific scFv connected to the endodomain of 4-1BB (TR2BB). TR2BB co-expressing Her2 CARTs exhibited enhanced antitumor potential against BC tumors by triggering myelod derived suppressor cell (MDSC) apoptosis, thereby remodeling the TME and promoting T cell proliferation. Despite better tumor control in mice receiving CAR.TR2BB T cells, recent trials have demonstrated the importance of incorporating a cytokine signal for optimal tumor control in patients with solid tumors. Thus, we hypothesized that we could further augment anti-tumor activity of Her2 CAR.TR2BB T cells against BC by incorporating a cytokine signal 3 through IL-15 or C7R. We engineered the CARTs to (1) ectopically produce IL-15, a crucial T-cell homeostasis and survival cytokine, and (2) express a constitutively active IL-7 receptor (C7R) that triggers IL-7 receptor signaling independently of ligand or the common receptor gamma chain (γc). Our repeat weekly tumor challenge assay revealed that CAR.TR2BB.IL15 T cells outperformed CAR.TR2BB.C7R and CAR.TR2BB in T cell proliferation. Both CAR.TR2BB.IL15 and CAR.TR2BB.C7R exhibited improved cytotoxic potential after three weeks of antigen stimulation compared to CAR.TR2BB alone in comparison with CAR.TR2BB alone. Furthermore, in our in vivo xenograft NSG mouse models implanted with Her2 expressing breast cancer cell line and MDSCs, CAR.TR2BB.IL15 T cells showed superior tumor control and improved survival rates. In summary, the addition of IL15 transgene to our TME targeting Her2 CARTs provides an advantage in terms of T cell persistence, proliferation, and tumor control in in vitro and in vivo models. These promising preclinical results propel us to apply this optimized Her2 targeting CART therapy in a phase I clinical trial for patients with metastatic Her2-expressing breast cancers. Citation Format: Diego Chamorro, Lauren Somes, Emily Madaras, Saisha Nalawade, Paul Shafer, Andres Mosquera, Mary Kathryn McKenna, Valentina Hoyos. Enhancing Antitumor Activity of Her2 CAR T cells through TR2BB Co-Expression and Cytokine Signal 3 Incorporation [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 PO5-04-06.

Abstract PO2-25-04: Anti-TIGIT upregulate CD226 on CD8+T cell as a potential therapeutic manner in HER2 positive breast cancer

Abstract Purpose: HER2 positive breast cancer subtype shows high malignancy, aggressive invasion, frequent recurrence, and low efficacy to PD-1 inhibitor though enriches in immune microenvironment. TIGIT is an immune checkpoint which expresses on T/NK cells and participates in immune evasion of cancer cells. Here, we investigated the effect of anti-HER2 and anti-TIGIT combination regarding to HER2 breast cancer treatment and tumor microenvironment, further exploring mechanisms behind the combination utilization. Methods: We re-analyzed the untreated human and mouse HER2 breast cancer scRNA-seq dataset to explore proportions of unique cell clusters in tumor immune microenvironment and communicated signals between immune cells and tumor cells. Mouse HER2 non-sensitive model and 27 non-pCR patients were utilized to investigate the variation of TIGIT and its ligand CD112/CD155 in HER2 non-sensitive population. Relevance between CD112/CD155 and prognosis was verified by 200 patients tissue microarray IHC. We validated the efficacy of combination of anti-TIGIT and anti-Neu and delineated scRNA-seq landscape via mouse model. Multilayer analysis including CellChat and AuCell were used to investigate difference of immune network between ctrl group, monotherapy and combination. In vitro and in vivo studies were used to verify the efficacy of anti-TIGIT and pivotal clusters. Results: We found that CD8+T cells occupied major proportion in TILs in both human and mouse HER2 breast cancer tumor immune microenvironment. CD8+T cells showed TIGIT signal to malignant epithelial cells instead of PD-1 signal. Increased CD8+TIGIT+T cells were related to poor prognosis in 200-patients cohort. In HER2 non-sensitive mouse model, significantly increased CD8+TIGIT+T cells were found in HER2 non-sensitive group. Multiplex IHF of 27 non-pCR patients also confirmed that CD8+TIGIT+T cells increased after treatment. CD112, ligand of TIGIT on malignant cells, demonstrated higher expression after anti-HER2 treatment in HER2 non-sensitive population and negatively correlated with prognosis. In scRNA-seq about control group, monotherapy and combination group, we defined malignant cells as sensitive subclone, Neu resistant subclone and others according to cell ratio variation in ctrl, monotherapy and combination group. CD112 upregulated in all subclones in monotherapy group. GSVA analysis indicated Neu resistant subclone had highest IFN-γ response among subclones. In Neu resistant subclone, combination group showed highest expression of MHC-I genes and upregulated IFN-γresponse, suggested the restored antigen presenting ability of Neu resistant subclone. Higher CD226, MHC-I and IFN-γ signals between malignant epithelial cells and CD8+T cells was found in combination group via CellChat. AuCell manifested upregulated T cell activation and IFN-γ production pathways in combination group. Public dataset showed favorable results. Increased CD226 expression and promoted cytotoxicity on CD8+T cells can only be induced by anti-TIGIT therapy in vitro and in vivo. 200-patients cohort indicated the predictive values of CD8+CD226+T cells in HER2 breast cancer. Conclusion: In conclusion, engaged immune checkpoint TIGIT shades malignant cells from CD8+T mediated immune surveillance in HER2 breast cancer. Disruption of TIGIT inhibit tumor growth in vivo by immune elimination of malignant cells. Besides, CD8+CD226+T cells induced by combined therapy can predict patient prognosis. Citation Format: Liyi Zhang, Qi Zhang, Zehao Wang, Zhibo Shao, Jingyan Xue, Yayun Chi, Bingqiu Xiu, Jiong Wu. Anti-TIGIT upregulate CD226 on CD8+T cell as a potential therapeutic manner in HER2 positive breast cancer [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 PO2-25-04.

Abstract PS18-09: The DARC side of Breast Cancer - DARC, Duffy-null and African ancestry influence in the Triple Negative Breast Cancer tumor microenvironment

Abstract Background. Despite a recent convergence of breast cancer (BC) incidence rates between African American (AA) and European American (EA) women, AA women continue to have ~40% higher mortality rates. BC is a heterogeneous collection of diseases, where African ancestry women are disproportionately burdened with the most aggressive subtype of BC, triple negative BC (TNBC). We have previously reported that the African ancestry-specific Duffy-null allele (FY-) is a risk factor for TNBC diagnoses. FY- is a promoter variant that removes expression of the Duffy Antigen Receptor for Chemokines (DARC/ACKR1), from red blood cells (RBCs). DARC serves as a portal of entry for Plasmodium vivax malaria parasite, and FY- confers immunity, leading to fixation of FY- among Sub-Saharan African populations. DARC is an atypical chemokine receptor that functions to modulate chemokine levels in circulation and tissues to aid immune cell recruitment. DARC is also expressed on breast tumor epithelial cells, however the significance of DARC in the TNBC tumor microenvironment (TME) has not fully been explored. Leveraging our African ancestry enriched International Study for the Center of Breast Cancer Subtypes cohort and in vivo murine models, we employed multi-omics approaches to explore the function of FY- and DARC expression across cell types in the TNBC TME. Genomics. Using transcriptomic data from the TCGA BC cohort, we have previously reported that DARC expression is highly correlated with deconvoluted immune cell abundance using CIBERSORT. To build upon this finding among TNBC patients, we have analyzed RNAseq data from two cohorts of African ancestry women to explore correlation of DARC expression status and immune cell abundance. Among TNBC cases, we report that higher DARC expression was significantly associated with increased immune cell abundance, with increases in B cell, T cell and monocyte populations. Using whole genome sequencing data across 86 African ancestry cases, we are currently investigating germline FY- status with mutational signatures. Circulating biomarkers. Patient plasma was collected prior to surgery, where Luminex multiplex assays were performed to quantify levels of >40 circulating chemokines and cytokines. FY- status has been determined for ~550 patients using single-plex or multiplex PCR genotyping methods from germline saliva DNA. Our univariate analyses show several circulating chemokines, including CCL2, CXCL2, CXCL6 and CXCL11, have significant differences between FY- and non-FY- BC patients. Curation of clinicopathological variables for multivariate analysis is ongoing. Murine models. We crossed C3(1)Tag BC transgenic mice with a DARC knock-out (KO) line to generate mice lacking DARC expression that spontaneously develop tumors in the mammary fat pads. The C3(1)Tag model is reported to have similar gene expression profiles to basal-like TNBC tumors. Tumors were collected at pre-determined time points of 25 and 30 weeks, where DARC KO mice had increased tumor size and tumor burden at 30 weeks. Initial fluorescent staining revealed an increase in immune cell infiltration in the TME of DARC expressing mice compared to DARC KO mice. To further explore this, we employed multiplex staining across a representative cohort of DARC expressing and KO mice at 25 and 30 weeks to capture the specific immune cell populations infiltrating the TME. Conclusions. TNBC tumors have worse prognosis due to lack of targeted therapeutic options. Increased immunogenicity of TNBC tumors, especially among African ancestry women may be driven in part by DARC expression. Characterization of FY- status, in coordination with DARC among other cell types in the TNBC TME could present new opportunities for biomarker and/or therapeutic development to improve prognosis for these underserved populations. Citation Format: Rachel Martini, Stevens Patino, Emma Guyonnet, Brian Stonaker, Isra Elhussein, Julie Sahler, Avery August, Nancy Manley, Rick Kittles, Clayton Yates, Lisa Newman, Melissa Davis. The DARC side of Breast Cancer - DARC, Duffy-null and African ancestry influence in the Triple Negative Breast Cancer tumor microenvironment [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 PS18-09.

Development of 42 marker panel for in-depth study of cancer associated fibroblast niches in breast cancer using imaging mass cytometry.

Imaging Mass Cytometry (IMC) is a novel, and formidable high multiplexing imaging method emerging as a promising tool for in-depth studying of tissue architecture and intercellular communications. Several studies have reported various IMC antibody panels mainly focused on studying the immunological landscape of the tumor microenvironment (TME). With this paper, we wanted to address cancer associated fibroblasts (CAFs), a component of the TME very often underrepresented and not emphasized enough in present IMC studies. Therefore, we focused on the development of a comprehensive IMC panel that can be used for a thorough description of the CAF composition of breast cancer TME and for an in-depth study of different CAF niches in relation to both immune and breast cancer cell communication. We established and validated a 42 marker panel using a variety of control tissues and rigorous quantification methods. The final panel contained 6 CAF-associated markers (aSMA, FAP, PDGFRa, PDGFRb, YAP1, pSMAD2). Breast cancer tissues (4 cases of luminal, 5 cases of triple negative breast cancer) and a modified CELESTA pipeline were used to demonstrate the utility of our IMC panel for detailed profiling of different CAF, immune and cancer cell phenotypes.

Spatial and single-cell explorations uncover prognostic significance and immunological functions of mitochondrial calcium uniporter in breast cancer

The mitochondrial calcium uniporter (MCU) is a transmembrane protein facilitating the entry of calcium ions into mitochondria from the cell cytosol. Maintaining calcium balance is crucial for enhancing cellular energy supply and regulating cell death. The interplay of calcium balance through MCU and the sodium-calcium exchanger is known, but its regulation in the breast cancer tumor microenvironment remains elusive. Further investigations are warranted to explore MCU’s potential in BRCA clinical pathology, tumor immune microenvironment, and precision oncology. Our study, employing a multi-omics approach, identifies MCU as an independent diagnostic biomarker for breast cancer (BRCA), correlated with advanced clinical status and poor overall survival. Utilizing public datasets from GEO and TCGA, we discern differentially expressed genes in BRCA and examine their associations with immune gene expression, overall survival, tumor stage, gene mutation status, and infiltrating immune cells. Spatial transcriptomics is employed to investigate MCU gene expression in various regions of BRCA, while spatial transcriptomics and single-cell RNA-sequencing methods explore the correlation between MCUs and immune cells. Our findings are validated through the analysis of 59 BRCA patient samples, utilizing immunohistochemistry and bioinformatics to examine the relationship between MCU expression, clinicopathological features, and prognosis. The study uncovers the expression of key gene regulators in BRCA associated with genetic variations, deletions, and the tumor microenvironment. Mutations in these regulators positively correlate with different immune cells in six immune datasets, playing a pivotal role in immune cell infiltration in BRCA. Notably, high MCU performance is linked to CD8 + T cells infiltration in BRCA. Furthermore, pharmacogenomic analysis of BRCA cell lines indicates that MCU inactivation is associated with increased sensitivity to specific small molecule drugs. Our findings suggest that MCU alterations may be linked to BRCA progression, unveiling new diagnostic and prognostic implications for MCU in BRCA. The study underscores MCU's role in the tumor immune microenvironment and cell cycle progression, positioning it as a potential tool for BRCA precision medicine and drug screening.

Pan-inhibition of the three H2S synthesizing enzymes restrains tumor progression and immunosuppression in breast cancer

BackgroundHydrogen sulfide (H2S) is a significant endogenous mediator that has been implicated in the progression of various forms of cancer including breast cancer (BC). Cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3MST) are the three principal mammalian enzymes responsible for H2S production. Overexpression of CBS, CSE and 3MST was found to be associated with poor prognosis of BC patients. Moreover, H2S was linked to an immune-suppressive tumor microenvironment in BC. Recently it was observed that BC cells, in response to single or dual inhibition of H2S synthesizing enzymes, develop an escape mechanism by overexpressing alternative sources of H2S generation. Thus, the aim of this work is to escape the H2S compensatory mechanism by pan repressing the three enzymes using microRNAs (miRNAs) and to investigate their impact on the oncogenic and immunogenic profile of BC cells.MethodsBC female patients (n = 25) were recruited. In-silico analysis was used to identify miRNAs targeting CBS, CSE, and 3MST. MDA-MB-231 cells were cultured and transfected using oligonucleotides. Total RNA was extracted using Biazol, reverse transcribed and quantified using qRT-PCR. H2S levels were measured using AzMc assay. BC hallmarks were assessed using trans-well migration, wound healing, MTT, and colony forming assays.ResultsmiR-193a and miR-548c were validated by eight different bioinformatics software to simultaneously target CBS, CSE and 3MST. MiR-193a and miR-548c were significantly downregulated in BC tissues compared to their non-cancerous counterparts. Ectopic expression of miR-193a and miR-548c in MDA-MB-231 TNBC cells resulted in a marked repression of CBS, CSE, and 3MST transcript and protein levels, a significant decrease in H2S levels, reduction in cellular viability, inhibition of migration and colony forming ability, repression of immune-suppressor proteins GAL3 GAL9, and CD155 and upregulation of the immunostimulatory MICA and MICB proteins.ConclusionThis study sheds the light onto miR-193a and miR-548c as potential pan-repressors of the H2S synthesizing enzymes. and identifies them as novel tumor suppressor and immunomodulatory miRNAs in TNBC.

Integration of multiomics analyses reveals unique insights into CD24-mediated immunosuppressive tumor microenvironment of breast cancer.

Tumor immunotherapy brings new light and vitality to breast cancer patients, but low response rate and limitations of therapeutic targets become major obstacles to its clinical application. Recent studies have shown that CD24 is involved in an important process of tumor immune regulation in breast cancer and is a promising target for immunotherapy. In this study, singleR was used to annotate each cell subpopulation after t-distributed stochastic neighbor embedding (t-SNE) methods. Pseudo-time trace analysis and cell communication were analyzed by Monocle2 package and CellChat, respectively. A prognostic model based on CD24-related genes was constructed using several machine learning methods. Multiple quantitative immunofluorescence (MQIF) was used to evaluate the spatial relationship between CD24+PANCK+cells and exhausted CD8+T cells. Based on the scRNA-seq analysis, 1488 CD24-related differential genes were identified, and a risk model consisting of 15 prognostic characteristic genes was constructed by combining the bulk RNA-seq data. Patients weredivided into high- and low-risk groups based on the median risk score. Immune landscape analysis showed that the low-risk group showed higher infiltration of immune-promoting cells and stronger immune reactivity. The results of cell communication demonstrated a strong interaction between CD24+epithelial cells and CD8+T cells. Subsequent MQIF demonstrated a strong interaction between CD24+PANCK+ and exhausted CD8+T cells with FOXP3+ in breast cancer. Additionally, CD24+PANCK+ and CD8+FOXP3+T cells were positively associated with lower survival rates. This study highlights the importance of CD24+breast cancer cells in clinical prognosis and immunosuppressive microenvironment, which may provide a new direction for improving patient outcomes.

ScRNA-seq characterizing the heterogeneity of fibroblasts in breast cancer reveals a novel subtype SFRP4+ CAF that inhibits migration and predicts prognosis.

Cancer-associated fibroblasts (CAFs) are a diverse group of cells that significantly impact the tumor microenvironment and therapeutic responses in breast cancer (BC). Despite their importance, the comprehensive profile of CAFs in BC remains to be fully elucidated. To address this gap, we utilized single-cell RNA sequencing (scRNA-seq) to delineate the CAF landscape within 14 BC normal-tumor paired samples. We further corroborated our findings by analyzing several public datasets, thereby validating the newly identified CAF subtype. Additionally, we conducted coculture experiments with BC cells to assess the functional implications of this CAF subtype. Our scRNA-seq analysis unveiled eight distinct CAF subtypes across five tumor and six adjacent normal tissue samples. Notably, we discovered a novel subtype, designated as SFRP4+ CAFs, which was predominantly observed in normal tissues. The presence of SFRP4+ CAFs was substantiated by two independent scRNA-seq datasets and a spatial transcriptomics dataset. Functionally, SFRP4+ CAFs were found to impede BC cell migration and the epithelial-mesenchymal transition (EMT) process by secreting SFRP4, thereby modulating the WNT signaling pathway. Furthermore, we established that elevated expression levels of SFRP4+ CAF markers correlate with improved survival outcomes in BC patients, yet paradoxically, they predict a diminished response to neoadjuvant chemotherapy in cases of triple-negative breast cancer. This investigation sheds light on the heterogeneity of CAFs in BC and introduces a novel SFRP4+ CAF subtype that hinders BC cell migration. This discovery holds promise as a potential biomarker for refined prognostic assessment and therapeutic intervention in BC.

Expression and function of cytokine interleukin-22 gene in the tumor microenvironment of triple negative breast cancer

BackgroundThe tumor microenvironment (TME) and interleukin-22 (IL-22) in cytokines have recently attracted much attention due to their potential impact on tumor biology. However, the role of IL-22 in triple negative breast cancer (TNBC) TME is still poorly understood. This article investigated the gene expression and function of IL-22 in TNBC TME. MethodsTumor samples from TNBC patients were collected, and adjacent noncancerous tissues were used as controls. A functional test was performed to evaluate the impact of IL-22 for TNBC cells, including proliferation, migration, and apoptosis. ResultsIL-22 gene expression in TNBC tumor samples was markedly higher relative to adjacent non-cancerous tissues (P < 0.05). In addition, it was also observed that IL-22facilitated proliferation and migration of TNBC cells, and inhibit apoptosis. This article reveals the role of IL-22 in the TME of TNBC. The up-regulation of IL-22 gene expression in TNBC tumors and its promoting effect on cancer cell invasiveness highlight its potential as a therapeutic target in TNBC treatment strategies. ConclusionThe findings suggested that targeting IL-22 and its related pathways can offer new insights for developing effective therapies for TNBC.

A Pioglitazone Nanoformulation Designed for Cancer-Associated Fibroblast Reprogramming and Cancer Treatment.

The recent focus of cancer therapeutics research revolves around modulating the immunosuppressive tumor microenvironment (TME) to enhance efficacy. The tumor stroma, primarily composed of cancer-associated fibroblasts (CAFs), poses significant obstacles to therapeutic penetration, influencing resistance and tumor progression. Reprogramming CAFs into an inactivated state has emerged as a promising strategy, necessitating innovative approaches. This study pioneers the design of a nanoformulation using pioglitazone, a Food and Drug Administration-approved anti-diabetic drug, to reprogram CAFs in the breast cancer TME. Glutathione (GSH)-responsive dendritic mesoporous organosilica nanoparticles loaded with pioglitazone (DMON-P) are designed for the delivery of cargo to the GSH-rich cytosol of CAFs. DMON-P facilitates pioglitazone-mediated CAF reprogramming, enhancing the penetration of doxorubicin (Dox), a therapeutic drug. Treatment with DMON-P results in the downregulation of CAF biomarkers and inhibits tumor growth through the effective delivery of Dox. This innovative approach holds promise as an alternative strategy for enhancing therapeutic outcomes in CAF-abundant tumors, particularly in breast cancer.

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.

Anti-IL-8 monoclonal antibodies inhibits the autophagic activity and cancer stem cells maintenance within breast cancer tumor microenvironment.

Breast cancer tumor microenvironment (TME) is a promising target for immunotherapy. Autophagy, and cancer stem cells (CSCs) maintenance are essential processes involved in tumorigenesis, tumor survival, invasion, and treatment resistance. Overexpression of angiogenic chemokine interleukin-8 (IL-8) in breast cancer TME is associated with oncogenic signaling pathways, increased tumor growth, metastasis, and poor prognosis. Thus, we aimed to investigate the possible anti-tumor effect of neutralizing antibodies against IL-8 by evaluating its efficacy on autophagic activity and breast CSC maintenance. IL-8 monoclonal antibody supplemented tumor tissue culture systems from 15 females undergoing mastectomy were used to evaluate the expression of LC3B as a specific biomarker of autophagy and CD44, CD24 as cell surface markers of breast CSCs using immunofluorescence technique. Our results revealed that anti-IL-8 mAb significantly decreased the level of LC3B in the cultured tumor tissues compared to its non-significant decrease in the normal breast tissues.Anti-IL-8 mAb also significantly decreased the CD44 expression in either breast tumors or normal cultured tissues. While it caused a non-significant decrease in CD24 expression in cultured breast tumor tissue and a significant decrease in its expression in the corresponding normal ones. Anti-IL-8 monoclonal antibody exhibits promising immunotherapeutic properties through targeting both autophagy and CSCs maintenance within breast cancer TME.

Advancements and Clinical Significance of Breast Cancer Exosome Detection

Exosomes, which are lipid bilayer vesicles actively secreted by cells with a diameter of 30-100 nm, play a crucial role in the occurrence, development, and formation of the tumor microenvironment in breast cancer. They have become an important component of liquid biopsies for breast cancer and ideal targets for early diagnosis, treatment assessment, and clinical therapy. Breast cancer is the most common malignancy among women. However, traditional exosome detection methods have several limitations, and there are still many difficulties and challenges in achieving widespread clinical application of exosomes. Nowadays, significant progress has been made in exosome detection and analysis techniques, including optical methods such as colorimetry, fluorescence, surface-enhanced Raman scattering, as well as various electrochemical and thermal signal methods. This review summarizes the current biomarkers and novel developments in detection techniques applied to liquid biopsy of exosomes in breast cancer.

Abstract 1488: Spatial characterization of the tumor microenvironment of metastatic triple-negative breast cancer

Abstract Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer associated with high rates of recurrence and metastasis, which contribute to poor overall survival. The challenges in treating TNBC stem from its high intratumor heterogeneity and lack of expression of the estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 druggable targets. The tumor microenvironment (TME) plays a crucial role in disease progression. Within the TME, complex spatial interactions among tumor cells, immune cells, stroma, angiogenesis- and hypoxia-inducing factors collectively contribute to the advancement and spread of TNBC. In-depth understanding of the TME and interactions of the various components within can elucidate newer therapeutic targets, enhancing the prognosis of TNBC patients. Imaging mass cytometry (IMC) enables detailed analysis of cell-cell and cell-matrix interactions within the TME at the single-cell level. In this study, we aim to characterize the spatial relationships among various cell types within the TNBC TME using IMC, while also investigating differences in the TME of TNBC patients who developed distant metastasis (DM) compared to those who remained non-metastatic (NM). IMC was performed on formalin-fixed paraffin-embedded TNBC primary resection tissues (n= 16; DM= 7, NM= 9) from Stavanger University Hospital, Norway, using a panel of 25 metal-conjugated antibodies. Regions of interest were marked by the pathologist and the slides were laser ablated using Hyperion Imaging System. DeepCell was used to segment single cells based on surface markers. Mean intensity values of all markers for each cell were extracted and consolidated in R scripts for unsupervised clustering. Cell clusters were annotated based on phenotypic markers. Normalized expression of markers was compared for each cell type across DM and NM patients, including markers for cell proliferation, angiogenesis, hypoxia, and cell migration. Neighborhood analysis examined spatial associations between different cell types, highlighting differences in DM and NM patients. The IMC panel successfully provided spatial insights into the TME, including the characterization of tumor cells, immune cells (B cells, T cells, macrophages), endothelial cells, and proliferating cells. We identified 18 unique phenotypic cell clusters that were present at different frequencies in DM and NM patients. These clusters demonstrated different expression profiles of functional markers. t-SNE plots revealed distinct patterns of cell type distribution and unique protein expression profiles, highlighting significant differences between the two groups. Our data suggest a distinct spatial organization of the TME in TNBC patients who develop metastasis. This warrants further investigations to determine the role and interplay of TME features in predicting the risk of distant metastasis in TNBC. Citation Format: Mahak Bhargava, Jaspreet Kaur, Geetanjali Saini, Junjun Zheng, Yitian Xu, Shu-Hsia Chen, Ping-Ying Pan, Emma Rewcastle, Umay Kiraz, Emiel Adrianus Janssen, Ritu Aneja. Spatial characterization of the tumor microenvironment of metastatic triple-negative breast cancer [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 1488.

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 5485: Spatial characterization of the immunosuppressive tumor microenvironment in estrogen receptor positive breast cancer at single cell level

Abstract We characterized immune cell exclusion in estrogen receptor positive (ER+) breast cancer through the study of spatial relationships among various subsets of cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), and other immune cells using a novel in-situ spatial transcriptomic technology. ER+ breast cancer is the most common breast cancer subtype. While endocrine therapy and immune checkpoint inhibitors have considerably reduced relapse and mortality for breast cancer patients, tumor resistance to treatment remains a major challenge. The tumor microenvironment (TME) plays an important role in this mechanism of resistance. Our previous spatial proteomic analysis of ER+ breast FFPE samples demonstrated the intricate relationship between tumor and immunosuppressive cells such as CAFs and TAMs via the CXCR4-CXCL12 axis associated with the exclusion of CD8 T cells from the TME. However, the limited number of antibodies in the panel made it challenging to investigate the diversity of those CAF and TAM populations and better understand their contribution to T cell exclusion. For this purpose, we further characterized the TME of 4 human ER+ breast cancer FFPE cores using the Xenium in-situ transcriptomic platform with a breast cancer-focused panel of 280 genes from 10x Genomics plus 100 additional genes selected from literature and publicly available single cell datasets to delineate CAF and TAM sub-populations. Image analysis enabled the quantification and spatial mapping of the target genes within each cell boundary. Cells were manually annotated through unsupervised clustering of over 1 million cells. The cell phenotyping analysis allowed us to annotate major cell types including tumor cells, macrophages, T cells and fibroblasts. With our curated panel, we further characterized CAF and TAM sub-populations by identifying myofibroblastic CAFs (myCAFs), inflammatory CAFs (iCAFs), and antigen-presenting CAFs (apCAFs) in addition to M1 and M2-like macrophages as reported in the literature. We then performed spatial neighborhood analysis based on the similarity of the cell type composition in the vicinity of each cell. The results showed that myCAFs and M2-like macrophages are found in proximity to tumor cells and may play a role in T-cell exclusion. In addition, iCAFs mainly express CXCL12, a chemokine known to attract immunosuppressive cells such as regulatory T cells and M2-like macrophages as well as repel cytotoxic T cells from infiltrating the tumor via the CXCR4-CXCL12 axis. Overall, our work shows the potential of spatial transcriptomics to elucidate the spatial distribution of cells and their contribution to the immunosuppressive TME, which may enable researchers to improve understanding of tumor biology and drug target discovery efforts. Citation Format: Julien Tessier, Sandra Curras-Alonso, Joon Sang Lee, Fabien Delahaye, Hong Ma, Katie Malley, Dinesh Bangari, Donald Jackson, Angela Hadjipanayis. Spatial characterization of the immunosuppressive tumor microenvironment in estrogen receptor positive breast cancer at single cell level [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 5485.

Abstract 4154: PET imaging to characterize the tumor microenvironment in a breast cancer model of obesity

Abstract Introduction: Obesity is known to reduce efficacy for cancer treatment patients and is thought to modulate the tumor microenvironment and glucose metabolism. In this study, we aim to quantify obesity-induced differences in the breast cancer tumor microenvironment with positron emission tomography (PET) imaging of hypoxia, glucose metabolism, and granzyme B. These experiments are testing the hypothesis that tumors in obese mice have increased glucose metabolism and hypoxia, measured by [18F]F-fluorodeoxyglucose (FDG) and [18F]F-fluoromisonidazole (FMISO) uptake. We also hypothesize that immunotherapy (IMT) increases immune activation, as measured by [68Ga]Ga-Granzyme B peptide (GZP), and that obese mice will respond less to immunotherapy than lean mice. Methods: C57/Bl6 mice were placed on a high-fat diet (HFD) with 60% kcal fat (n=18) or low-fat diet (LFD) composed of 10% kcal fat (n=18) to induce obesity. Blood serum was collected for analysis of cholesterol levels prior to tumor implantation. Body weight and food intake were measured weekly. 14 weeks after initiating each diet, 5x105 E0771 cells were implanted into the 3rd mammary fat pad and allowed to grow to 50-150mm3. Tumor-bearing mice were imaged with [18F]F-FDG and [18F]F-FMISO PET to measure glucose metabolism and hypoxia, respectively prior to treatment. Following imaging, mice began treatment with either saline (n=6/diet) or checkpoint blockade IMT with 200 ug anti-PD-1 and 100 ug anti-CTLA-4 (n=12/diet). After 3 doses of IMT, mice were imaged with [68Ga]Ga-GZP PET to measure immune activation. Tumor volume measurements and treatment administration occurred every 3 days. Metrics of standardized uptake value (SUV) including mean, max, and peak were quantified from imaging data. A one-way independent ANOVA or independent t-test was used to compare differences between groups. Results: HFD-fed mice had significantly increased body weight (p&amp;lt;0.0001) and serum cholesterol (p=0.005) compared to LFD-fed mice. SUVmean for tumor hypoxia (p=0.003) and glucose metabolism (p=0.02) were significantly increased at baseline in HFD-fed mice compared to LFD-fed mice. IMT increases immune activation for both LFD-fed (p=0.009) and HFD-fed mice (p=0.05). IMT treatment significantly reduces tumor burden for LFD mice (p&amp;lt;0.0001), but not HFD mice (p=0.096). Conclusions: Obesity plays a role in the reduction of the effectiveness of immunotherapy. At baseline, tumors of obese mice have increased tumor glucose metabolism and hypoxia. Although immunotherapy increases immune activation, this is not sufficient to reduce tumor burden or improve overall survival. Understanding obesity-induced differences in tumor biology may provide imaging-directed treatment decision making. Citation Format: Shannon E. Lynch, Corinne Crawford, Addison Hunt, Luke Sligh, Benjamin M. Larimer, Suzanne E. Lapi, Anna G. Sorace. PET imaging to characterize the tumor microenvironment in a breast cancer model of obesity [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 4154.