Biological subtypes of breast cancer: Prognostic and therapeutic implications

Research trends of neoadjuvant therapy for breast cancer: A bibliometric analysis

The approach of neoadjuvant therapy for breast cancer, which involves administering systemic treatment prior to primary surgery, has undergone substantial advancements in recent decades. This strategy is intended to reduce tumor size, thereby enabling less invasive surgical procedures and enhancing patient outcomes. This study presents a comprehensive bibliometric analysis of research trends in neoadjuvant therapy for breast cancer from 2009 to 2024. Using data extracted from the Web of Science Core Collection, a total of 3,674 articles were analyzed to map the research landscape in this field. The analysis reveals a steady increase in publication output, peaking in 2022, with the United States and China identified as the leading contributors. Key institutions, such as the University of Texas System and MD Anderson Cancer Center, have been instrumental in advancing the research on neoadjuvant therapy. The study also highlights the contributions of influential authors like Sibylle Loibl and Gunter von Minckwitz, as well as major journals such as the Journal of Clinical Oncology. Emerging research topics, including immunotherapy, liquid biopsy, and artificial intelligence, are gaining prominence and represent potential future directions for clinical applications. This bibliometric analysis provides critical insights into global research trends, key contributors, and future developments in the field of neoadjuvant therapy for breast cancer, offering a foundation for future research and clinical practice advancements.

A novel method for subgroup discovery in precision medicine based on topological data analysis

BACKGROUND

The Mapper algorithm is a data mining topological tool that can help us to obtain higher level understanding of disease by visualising the structure of patient data as a similarity graph. It has been successfully applied for exploratory analysis of cancer data in the past, delivering several significant subgroup discoveries. Using the Mapper algorithm in practice requires setting up multiple parameters. The graph then needs to be manually analysed according to a research question at hand. It has been highlighted in the literature that Mapper's parameters have significant impact on the output graph shape and there is no established way to select their optimal values. Hence while using the Mapper algorithm, different parameter values and consequently different output graphs need to be studied. This prevents routine application of the Mapper algorithm in real world settings.

METHODS

We propose a new algorithm for subgroup discovery within the Mapper graph. We refer to the task as hotspot detection as it is designed to identify homogenous and geometrically compact subsets of patients, which are distinct with respect to their clinical or molecular profiles (e.g. survival). Furthermore, we propose to include the existence of a hotspot as a criterion while searching the parameter space, addressing one of the key limitations of the Mapper algorithm (i.e. parameter selection).

RESULTS

Two experiments were performed to demonstrate the efficacy of the algorithm, including an artificial hotspot in the Two Circles dataset and a real world case study of subgroup discovery in oestrogen receptor-positive breast cancer. Our hotspot detection algorithm successfully identified graphs containing homogenous communities of nodes within the Two Circles dataset. When applied to gene expression data of ER+ breast cancer patients, appropriate parameters were identified to generate a Mapper graph revealing a hotspot of ER+ patients with poor prognosis and characteristic patterns of gene expression. This was subsequently confirmed in an independent breast cancer dataset.

CONCLUSIONS

Our proposed method can be effectively applied for subgroup discovery with pathology data. It allows us to find optimal parameters of the Mapper algorithm, bridging the gap between its potential and the translational research.

Hypoxia-Responsive Polymersomes for Stemness Reduction in Patient-Derived Solid Tumor Spheroids

Aggressive solid tumors are associated with rapid growth, early hypoxia, a lack of targeted therapies, and a poor prognosis. The hypoxic niches within the rapidly growing solid tumors give rise to a stem-cell-like phenotype with higher metastasis and drug resistance. To overcome the drug resistance of these regions, we used hypoxia-responsive polymersomes with an encapsulated anticancer drug (doxorubicin, Dox) and a stemness modulator (all-trans retinoic acid, ATRA). Reductase enzymes overexpressed in hypoxia reduce the azobenzene linker of the polymers, disrupt the bilayer structure of the polymersomes, and release the encapsulated drugs. We used triple-negative breast cancer (TNBC) as a representative of aggressive and hypoxic solid tumors. We observed that ATRA synergistically enhanced the efficacy of Dox in killing cancer cells. A synergistic combination of the two drug-encapsulated polymersomes reduced the volumes of patient-derived TNBC spheroids by 90%. In contrast, Dox alone decreased the spheroid volumes by 70% and encapsulated ATRA by 19%. Mechanistic studies revealed that ATRA inhibited efflux pumps, leading to a higher concentration of doxorubicin within TNBC cells. In addition, the combination of encapsulated Dox and ATRA significantly decreased stemness expression of the TNBC cells in hypoxia compared to that of Dox alone.

Metabolomic Profiling of Disease Progression Following Radiotherapy for Breast Cancer

BACKGROUND

This study aims to explore metabolic biomarkers and pathways in breast cancer prognosis.

METHODS

We performed a global post-radiotherapy (RT) urinary metabolomic analysis of 120 breast cancer patients: 60 progression-free (PF) patients as the reference and 60 with progressive disease (PD: recurrence, second primary, metastasis, or death). UPLC-MS/MS (Metabolon Inc.) identified 1742 biochemicals (1258 known and 484 unknown structures). Following normalization to osmolality, log transformation, and imputation of missing values, a Welch's two-sample t-test was used to identify biochemicals and metabolic pathways that differed between PF and PD groups. Data analysis and visualization were performed with MetaboAnalyst.

RESULTS

Metabolic biomarkers and pathways that significantly differed between the PD and PF groups were the following: amino acid metabolism, including phenylalanine, tyrosine, and tryptophan biosynthesis (impact value (IV) = 1.00; p = 0.0007); histidine metabolism (IV = 0.60; p < 0.0001); and arginine and proline metabolism (IV = 0.70; p = 0.0035). Metabolites of carbohydrate metabolism, including glucose (p = 0.0197), sedoheptulose (p = 0.0115), and carboxymethyl lysine (p = 0.0098), were elevated in patients with PD. Gamma-glutamyl amino acids, myo-inositol, and oxidative stress biomarkers, including 7-Hydroxyindole Sulfate and sulfate, were elevated in patients who died (p ≤ 0.05).

CONCLUSIONS

Amino acid metabolism emerged as a key pathway in breast cancer progression, while carbohydrate and oxidative stress metabolites also showed potential utility as biomarkers for breast cancer progression. These findings demonstrate applications of metabolomics in identifying metabolic biomarkers and pathways as potential targets for predicting breast cancer progression.

Baseline 18F-FDG PET/CT for predicting pathological response to neoadjuvant chemotherapy and prognosis in locally advanced breast cancer patients: analysis of tumor and lymphoid organs metabolic parameters

PURPOSE

To investigate metabolic parameters from baseline 18F-FDG PET/CT as predictors of pathological complete response (pCR) to neoadjuvant chemotherapy (NAC) and disease recurrence in locally advanced breast cancer (LABC) patients.

MATERIALS AND METHODS

From 142 LABC in 137 patients (bilateral-synchronous BC: 5/137), the following parameters from baseline (pre-treatment) 18F-FDG PET/CT were retrospectively analyzed, along with clinic-histological data: primary tumor activity (SUVmax, SUVmean, SUVpeak, tumor-to-liver ratio-TLR-, MTV, TLG); lymphoid organs activity (spleen and bone marrow SUVmax and SUVmean, spleen-to-liver ratio-SLR-, bone marrow-to-liver ratio-BLR); and PET-positive lymph-nodes' number. Predictors of pCR and recurrence-free survival (RFS) were assessed by univariable logistic regression and Cox regression (significant or suggestive association: p < 0.05; p < 0.10).

RESULTS

74/142 tumors were "Luminal A/B HER2-", 44/142 "Luminal B HER2+/HER2+", 24/142 TNBC; pCR after NAC occurred in 26/142 tumors (18.3%) and disease recurrence at follow-up (45 ± 18.1 months) in 25/127 assessable patients (19.7%). Significant or suggestive predictors of NAC response, in Luminal A/B HER2-: lower spleen SUVmax and patients' age (OR 0.06; 0.93) for pCR; lower TLRmax, TLRmean and BLRmax (OR 1.33; 1.22; and 26.42) for residual disease. Significant negative RFS predictors: higher SUVmax, SUVmean, SUVpeak (HR 1.10; 1.15; 1.11), TLRmax and TLRmean (HR 1.02; 1.00), MTV and TLG (HR 1.32; 1.26) in Luminal A/B HER2-; higher spleen SUVmax, PET-positive nodes' number and patients' age (HR 6.24; 1.20; 1.08) in Luminal B HER2+/HER2+.

CONCLUSION

Primary tumor and lymphoid organs parameters at baseline 18F-FDG PET/CT resulted as predictors of NAC response and prognosis in LABC patients, respectively, reflecting the BC cells' proliferative activity and metabolic burden, and the role of tumor-induced immune-system activation on tumors' behavior and treatment responsiveness. In LABC candidates to NAC, baseline PET information could improve treatment planning and prognostic stratification.

Tanshinone IIA destabilizes SLC7A11 by regulating PIAS4-mediated SUMOylation of SLC7A11 through KDM1A, and promotes ferroptosis in breast cancer

INTRODUCTION

Breast cancer (BC) is the most common malignancy in women with unfavorite prognosis.

OBJECTIVES

Tanshinone IIA (Tan IIA) inhibits BC progression, however, the underlying mechanism remains largely undefined.

METHODS

The cytotoxicity of Tan IIA was assessed by CCK-8 and LDH assays. Ferroptosis was monitored by the level of MDA, Fe2+, lipid ROS and GSH. IHC and western blot were employed to detect the localization and expression of SLC7A11, PIAS4, KDM1A and other key molecules. The SUMOylation of SLC7A11 was detected by Ni-beads pull-down assay and Co-IP. Luciferase and ChIP assays were employed to detect the direct association between KDM1A and PIAS4 promoter. The proliferative and metastatic properties of BC cells were assessed by colony formation, CCK-8 and Transwell assays, respectively. The in vitro findings were verified in xenograft and lung metastasis models.

RESULTS

Tan IIA promoted ferroptosis by suppressing SLC7A11 in BC cells. Silencing of PIAS4 or KDM1A inhibited cell growth and metastasis in BC. Mechanistically, PIAS4 facilitated the SUMOylation of SLC7A11 via direct binding to SLC7A11, and KDM1A acted as a transcriptional activator of PIAS4. Functional studies further revealed that Tan IIA decreased KDM1A expression, thus suppressing PIAS4 expression transcriptionally. The inhibition of PIAS4-dependent SUMOylation of SLC7A11 further induced ferroptosis, thereby inhibiting proliferation and metastasis in BC.

CONCLUSION

Tan IIA promoted ferroptosis and inhibited tumor growth and metastasis via suppressing KDM1A/PIAS4/SLC7A11 axis.

Navigating heme pathways: the breach of heme oxygenase and hemin in breast cancer

Breast cancer remains a significant global health challenge, with diverse subtypes and complex molecular mechanisms underlying its development and progression. This review comprehensively examines recent advances in breast cancer research, with a focus on classification, molecular pathways, and the role of heme oxygenases (HO), heme metabolism implications, and therapeutic innovations. The classification of breast cancer subtypes based on molecular profiling has significantly improved diagnosis and treatment strategies, allowing for tailored approaches to patient care. Molecular studies have elucidated key signaling pathways and biomarkers implicated in breast cancer pathogenesis, shedding light on potential targets for therapeutic intervention. Notably, emerging evidence suggests a critical role for heme oxygenases, particularly HO-1, in breast cancer progression and therapeutic resistance, highlighting the importance of understanding heme metabolism in cancer biology. Furthermore, this review highlights recent advances in breast cancer therapy, including targeted therapies, immunotherapy, and novel drug delivery systems. Understanding the complex interplay between breast cancer subtypes, molecular pathways, and innovative therapeutic approaches is essential for improving patient outcomes and developing more effective treatment strategies in the fight against breast cancer.

Nuclear α-actinin-4 regulates breast cancer invasiveness and EMT

Epithelial-to-mesenchymal transition (EMT) is a key process where cells lose their adhesion properties and augment their invasive properties. α-Actinin4 (ACTN4) is an actin crosslinking protein that responds to mechanical stimuli and is found to be elevated in breast cancer patients. While ACTN4 has been implicated in regulating cancer invasiveness by modulating cytoskeletal organization, its nuclear functions remain much less explored. Here we address this question by first establishing a correlation between nuclear localization and invasiveness in breast cancer cells. Using cancer databases, we then establish a correlation between ACTN4 expression and EMT in breast cancer. Interestingly, TGFβ-induced EMT induction in MCF10A normal mammary epithelial cells leads to increased ACTN4 expression and nuclear enrichment. We then show that ACTN4 knockdown in MDA-MB-231 breast cancer cells, which harbor sizeable fraction of nuclear ACTN4, leads to reduced invasiveness and loss of mesenchymal traits. Similar behavior was observed in knockdown cells expressing K255E ACTN4, which is primarily localized to the cytosol. Together, our findings establish a role for nuclear ACTN4 in regulating invasiveness via modulation of EMT.

PRODE recovers essential and context-essential genes through neighborhood-informed scores

Gene context-essentiality assessment supports precision oncology opportunities. The variability of gene effects inference from loss-of-function screenings across models and technologies limits identifying robust hits. We propose a computational framework named PRODE that integrates gene effects with protein-protein interactions to generate neighborhood-informed essential (NIE) and neighborhood-informed context essential (NICE) scores. It outperforms the canonical gene effect approach in recovering missed essential genes in shRNA screens and prioritizing context-essential hits from CRISPR-KO screens, as supported by in vitro validations. Applied to Her2 + breast cancer tumor samples, PRODE identifies oxidative phosphorylation genes as vulnerabilities with prognostic value, highlighting new therapeutic opportunities.

Leukemia inhibitory factor in peripheral blood as a prognostic marker in breast cancer

PURPOSE

Analysis of gene expression profiles in peripheral blood cells has been explored as an approach for early detection of breast cancer. Thus, we aimed to evaluate the diagnostic and prognostic potential of LIF expression in the peripheral blood of women with breast cancer.

METHODS

A total of 121 women over 18 years of age with breast cancer and 80 healthy women were included. Peripheral blood samples were collected from patients at diagnosis and during chemotherapy treatment, as well as samples from healthy women for comparison. LIF expression was evaluated by qPCR.

RESULTS

LIF expression does not differ between patients and healthy women, ruling out its use as a liquid biopsy diagnostic tool for this disease. However, LIF expression increases during treatment in patients with positive progression and luminal tumor subtype, suggesting its potential as a prognostic marker. To reinforce this result, there was a negative correlation between LIF and HIF-1α and LIF and heparanase expression in blood, and LIF blood expression and a prognostic tumor score, all known markers associated with an unfavorable prognosis.

CONCLUSION

An increase in LIF expression in patients with negative disease progression suggests its potential as a therapeutic response indicator, particularly for those with the luminal tumor subtype. The negative correlation between LIF, HIF-1α, and heparanase provides new insights into LIF's role in breast cancer progression, with potential clinical implications for treatment monitoring. Elevated LIF expression in blood samples may reflect its interaction in tumorigenesis, immune regulation, and the tumor microenvironment.

Canine, Feline, and Murine Mammary Tumors as a Model for Translational Research in Breast Cancer

In veterinary medicine, mammary tumors are the most common neoplasms in female dogs and the third most frequent in cats, representing a significant challenge. Efforts have been directed toward adopting standardized diagnostic criteria to better understand tumor behavior and progression in these species. Meanwhile, the use of animal models has substantially advanced the understanding of comparative mammary carcinogenesis. These models provide critical insights into factors responsible for the disease in humans, with the expectation that such factors can be identified and controlled. In this context, this review presents a work based mainly on articles published by a research group specializing in mammary pathology (Laboratory of Comparative Pathology-Department of General Pathology-ICB/UFMG) and its collaborators, complementing their results with literature findings. The publications were categorized into animal research, experimental research, and human research. These studies addressed topics such as diagnosis, prognostic and predictive factors, tumor microenvironment, inflammation associated with tumors, treatment approaches, and factors influencing tumor growth. The conceptual network analysis underscores the importance of in vivo breast cancer models, both experimental and spontaneous, for understanding tumor progression mechanisms and therapeutic responses, offering valuable contributions to veterinary and human oncology.

A preclinical design approach for translation of biohybrid photosensitive nanoplatform for photodynamic therapy of breast cancer

Translating photodynamic therapy research into practice with high efficacy should follow characterization and optimization steps in an integrated process. In this way, integration of molecular-based simulations with in vitro and in vivo studies to produce more accurate models with higher prediction precision is inevitable. This study reports on the development a two-phase approach to design and synthesize, and characterize novel hybrid nano-photosensitizers to target breast cancer using molecular docking, microfluidic-based testing and animal studies. In the first phase, using pkCSM artificial intelligence tool and molecular docking, pharmacokinetic weaknesses of photoprotoporphyrin and its retention potential within albumin protein were identified. Biohybrid photosensitive nanoplatform were then synthesized using opto-microfluidics and characterized. In addition, an in-vivo method was used to qualitatively evaluate the opto-biological stability of the final optimized biohybrid nanoplatform. At the second phase, variables of photodynamic treatment were firstly optimized using design of experiment method for the optimized biohybrid photosensitive nanoplatform. Then, on-chip photodynamic studies were carried out in static and dynamic conditions. Results revealed that optimized biohybrid photosensitive nanoplatform as a nano-photosensitizer induced significant death of triple negative human cancer cells in static and dynamic cell cultures under optimized irradiation conditions. Consequently, the presented multiphase study that combined in-silico simulations with microfluidic-based synthesis and characterizations of nano-photosensitizers provided a more convergent model for development of efficacious cancer treatment for photodynamic therapy applications.

A review of six bioactive compounds from preclinical studies as potential breast cancer inhibitors

Breast cancer is one of the predominant causes of mortality in women worldwide. Although therapeutics such as surgery, chemotherapy, hormonal therapy, and radiotherapy have been used, they are associated with adverse effects or multidrug resistance. The use of natural compounds is a promising strategy, owing to their abundance and medicinal value. This review focuses on six natural compounds, namely cinnamaldehyde, diosmin, taxifolin, phloretin, arctigenin, and eugenol, and details their mechanisms of breast cancer inhibition based on in vitro and in vivo studies. These compounds generally promote apoptosis and cell cycle arrest, hinder metastasis and invasion, and decrease tumor growth. This review reinforces the use of natural compounds as therapeutics for breast cancer from their preclinical studies. These compounds might be promising for drug development due to their abundance, high reliability, and safety.

The analysis of transcriptomic signature of TNBC-searching for the potential RNA-based predictive biomarkers to determine the chemotherapy sensitivity

Neoadjuvant chemotherapy is the foundation treatment for triple-negative breast cancer (TNBC) and frequently results in pathological complete response (pCR). However, there are large differences in clinical response and survival after neoadjuvant chemotherapy of TNBC patients. The aim was to identify genes whose expression significantly associates with the efficacy of neoadjuvant chemotherapy in patients with TNBC. Transcriptomes of 46 formalin-fixed paraffin-embedded (FFPE) tumor samples from TNBC patients were analyzed by RNA-seq by comparing 26 TNBCs with pCR versus 20 TNBCs with pathological partial remission (pPR). Subsequently, we narrowed down the list of genes to those that strongly correlated with drug sensitivity of 63 breast cancer cell lines based on Dependency Map Consortium data re-analysis. Furthermore, the list of genes was limited to those presenting specific expression in breast tumor cells as revealed in three large published single-cell RNA-seq breast cancer datasets. Finally, we analyzed which of the selected genes were significantly associated with overall survival (OS) in TNBC TCGA dataset. A total of 105 genes were significantly differentially expressed in comparison between pPR versus pCR. As revealed by PLSR analysis in breast cancer cell lines, out of 105 deregulated genes, 42 were associated with sensitivity to docetaxel, doxorubicin, paclitaxel, and/or cyclophosphamide. We found that 24 out of 42 sensitivity-associated genes displayed intermediate or strong expression in breast malignant cells using single-cell RNAseq re-analysis. Finally, 10 out of 24 genes were significantly associated with overall survival in TNBC TCGA dataset. Our RNA-seq-based findings suggest that there might be transcriptomic signature consisted of 24 genes specifically expressed in tumor malignant cells for predicting neoadjuvant response in FFPE samples from TNBC patients prior to treatment initiation. Additionally, nine out of 24 genes were potential survival predictors in TNBC. This group of 24 genes should be further investigated for its potential to be translated into a predictive test(s).

Triple-Negative, HER2/Neu, and Ki67 Markers in Breast Cancer Patients Undergoing Standard of Care Treatment in India: Real-World Evidence on Tumor Aggressiveness and Survival Outcomes

INTRODUCTION

Breast cancer is among the most prevalent cancers in women globally, with patients' survival adversely impacted by Ki67 expression and triple-negative phenotypes. In this study, we examined the relationship between HER2/neu, triple-negative, and Ki67 phenotypes and tumor aggressiveness along with the survival of breast cancer patients from India.

MATERIALS AND METHODS

A retrospective cohort study was performed using hospital-based data from a tertiary care center spanning January 2013 to August 2023. The study included breast cancer patients who received neoadjuvant chemotherapy based on preoperative assessment and/or adjuvant chemotherapy following postoperative evaluation. Patients with other primary cancers or those treated with investigational drugs were excluded. Data on variables such as age, parity, menopause, cancer stage and grade, estrogen receptor (ER), progesterone receptor (PR), HER2/neu, Ki67 score, and the use of biologicals, hormones, and chemoradiotherapy were analyzed using correlation and regression tests to identify factors associated with aggressive tumor behavior. Kaplan-Meier survival model and Cox-proportional hazard test were applied.

RESULTS

A total of 389 breast cancer patients with a mean age of 54.3 years met the eligibility criteria and were included in the analysis. A higher prevalence of hormone receptor positivity was observed among Indian patients than in Western countries. Younger, premenopausal women were more likely to present with high-grade tumors and high Ki67 scores, poorer overall survival, and the need for chemoradiotherapy. On the other hand, nulliparous patients mostly had triple-negative tumors with high Ki67 scores. Aggressive tumor behavior was linked to HER2/neu positivity, ER and PR negativity, and the requirement for both neoadjuvant and adjuvant chemotherapy. At the same time, premenopausal patients more frequently were candidates for radiation therapy. HER2/neu expression demonstrated a moderate negative correlation with co-expression of hormone receptors (ER and PR). Cancer grade was associated with Ki67 levels, nulliparity, triple-negative status, and hormone receptor expressions (ER and PR). Median survival was not reached for the study cohort.

CONCLUSION

Tumor aggressiveness was associated with a high Ki67 score, HER2/neu positivity, and the absence of hormone receptor expression in patients.

Metabolic Profiling of Breast Cancer Cell Lines: Unique and Shared Metabolites

Breast Cancer (BrCa) exhibits a high phenotypic heterogeneity, leading to the emergence of aggressive clones and the development of drug resistance. Considering the BrCa heterogeneity and that metabolic reprogramming is a cancer hallmark, we selected seven BrCa cell lines with diverse subtypes to provide their comprehensive metabolome characterization: five lines commonly used (SK-Br-3, T-47D, MCF-7, MDA-MB-436, and MDA-MB-231), and two patient-derived xenografts (Hbcx39 and Hbcx9). We characterized their endometabolomes using 1H-NMR spectroscopy. We found distinct metabolite profiles, with certain metabolites being common but differentially accumulated across the selected BrCa cell lines. High levels of glycine, lactate, glutamate, and formate, metabolites known to promote invasion and metastasis, were detected in all BrCa cells. In our experiment setting were identified unique metabolites to specific cell lines: xanthine and 2-oxoglutarate in SK-Br-3, 2-oxobutyrate in T-47D, cystathionine and glucose-1-phosphate in MCF-7, NAD+ in MDA-MB-436, isocitrate in MDA-MB-231, and NADP+ in Hbcx9. The unique and enriched metabolites enabled us to identify the metabolic pathways modulated in a cell-line-specific manner, which may represent potential candidate targets for therapeutic intervention. We believe this study may contribute to the functional characterization of BrCa cells and assist in selecting appropriate cell lines for drug-response studies.

Interaction of GPER-1 with the endocrine signaling axis in breast cancer

G Protein-Coupled Estrogen Receptor 1 (GPER-1) is a membrane estrogen receptor that has emerged as a key player in breast cancer development and progression. In addition to its direct influence on estrogen signaling, a crucial interaction between GPER-1 and the hypothalamic-pituitary-gonadal (HPG) axis has been evidenced. The novel and complex relationship between GPER-1 and HPG implies a hormonal regulation with important homeostatic effects on general organ development and reproductive tissues, but also on the pathophysiology of cancer, especially breast cancer. Recent research points to a great versatility of GPER-1, interacting with classical estrogen receptors and with signaling pathways related to inflammation. Importantly, through its activation by environmental and synthetic estrogens, GPER-1 is associated with hormone therapy resistance in breast cancer. These findings open new perspectives in the understanding of breast tumor development and raise the possibility of future applications in the design of more personalized and effective therapeutic approaches.

Unveiling the role of SYNGR4 in breast cancer development: a novel target for immunotherapy

Introduction

SYNGR4 is considered to be one of the causative genes for amyotrophic lateral sclerosis, but its role in breast cancer development has not been revealed.

Methods

The expression of SYNGR4 in a variety of malignancies including breast cancer was analyzed using Genotype Tissue Expression (GTEx) and the Cancer Genome Atlas (TCGA) databases and verified by specimens collected from our center. The effect of SYNGR4 on breast cancer prognosis was analyzed using bioinformatics and possible pathways by which this molecule affects breast cancer prognosis were explored. The effect of SYNGR4 on immune infiltration of breast cancer was analyzed using GSVA, and the effects of SYNGR4 on breast cancer proliferation, migration, and tumor-associated macrophage polarization in cancer foci were verified by cellular and animal experiments, respectively.

Results

SYNGR4 is highly expressed in a variety of malignant tumors, including breast cancer, and affects the prognosis of breast cancer patients. This may be a volatile effect through Organelle fission, chromosome segregation, nuclear division, etc. SYNGR4 overexpression affects breast cancer proliferation, migration, and tumor immune infiltration, and promotes breast cancer tumor-associated macrophage polarization toward M2.

Discussion

SYNGR4 overexpression can affect the prognosis of breast cancer patients by promoting M2 polarization of tumor-associated macrophages in breast cancer, and this molecule may be a novel target for breast cancer immunotherapy.

Targeting ROR2 homooligomerization disrupts ROR2-dependent signaling and suppresses stem-like cell properties of human breast adenocarcinoma

Breast cancer stem-like cells (CSCs) are enriched following treatment with chemotherapy, and posited as having a high level of plasticity and enhanced tumor-initiation capacity, which can enable cancer relapse. Here, we show that such features are shared by breast cancer (BCA) cells that express receptor tyrosine kinase-like orphan receptor (ROR2), which is expressed primarily during embryogenesis and by various cancers. We find that Wnt5a can induce ROR2 homooligomerization to activate noncanonical Wnt signaling and enhance tumor-initiation capacity of BCA cells. Molecular analysis reveals that the cysteine-rich domain and transmembrane domain are required for ROR2 homooligomerization to activate ROR2. Treatment with a newly generated monoclonal antibody (mAb) specific for ROR2 can block Wnt5a-induced ROR2 homooligomerization, ROR2-dependent noncanonical Wnt signaling, and impair the capacity of BCA patient-derived xenografts to initiate tumor in immune-deficient mice. Collectively, these results indicate that targeting ROR2 (e.g., using mAb) suppresses BCA stemness and, thereby, may prevent BCA relapse.

Hormone Receptor-Positive HER2-Negative/MammaPrint High-2 Breast Cancers Closely Resemble Triple-Negative Breast Cancers

PURPOSE

The MammaPrint (MP) prognostic assay categorizes breast cancers into high- and low-risk subgroups, and the high-risk group can be further subdivided into high-1 (MP-H1), and very high-risk high-2 (MP-H2). The aim of this analysis was to assess clinical and molecular differences between the hormone receptor-positive (HR+)/HER2-negative MP-H1, -H2, and triple-negative (TN) MP-H1 and -H2 cancers.

EXPERIMENTAL DESIGN

Pretreatment gene expression data from 742 HER2-negative breast cancers enrolled in the I-SPY2 neoadjuvant trial were used. Prognostic risk categories were assigned using the MP assay. Transcriptional similarities across the four receptor and prognostic groups were assessed using principal component analyses and by identifying differentially expressed genes. We also examined pathologic complete response rates and event-free survivals by risk group.

RESULTS

Principal component analysis showed that HR+/MP-H2 tumors clustered with TN/MP-H2 cancers. Only 125 genes showed differential expression between the HR+/MP-H2 and TN/MP-H2 cancers, whereas 1,465 genes were differentially expressed between HR+/MP-H2 and -H1. Gene set analysis revealed similarly high expression of cell cycle, DNA repair, and immune infiltration-related pathways in HR+/MP-H2 and TN/MP-H2 cancers. HR+/MP-H2 cancers also showed low estrogen receptor-related gene expression. Pathologic complete response rates were similarly high in TN/MP-H2 and HR+/MP-H2 cancers (42% vs. 30.5%; P = 0.11), and MP-H2 cancers with residual cancer had similarly poor event-free survival regardless of estrogen receptor status.

CONCLUSIONS

In conclusion, HR+/MP-H2 cancers closely resemble TN breast cancers in transcriptional and clinical features and benefit from similar treatment strategies.

Nanoparticulate drug combination inhibits DNA damage repair and PD-L1 expression in BRCA-mutant and wild type triple-negative breast cancer

The high mortality rate associated with metastatic breast cancer presents a significant global challenge. Inherent and chemotherapy-induced DNA damage repair, alongside immunosuppression, drastically contribute to triple-negative breast cancer (TNBC) relapse and metastasis. While poly (ADP-ribose) polymerase (PARP) inhibitors such as olaparib show effectiveness against BRCA1-mutant TNBC, they may lead to drug resistance and reduced efficacy due to increased programmed death-ligand 1 (PD-L1) expression. Our study explored the use of polymer-lipid nanoparticles (PLN) loaded with doxorubicin (DOX) and oligomeric hyaluronic acid (oHA), functionalized iRGD-peptide for integrins targeting (iRGD-DOX-oHA-PLN), to prevent TNBC immunosuppression, DNA repair, and metastasis. The results demonstrate that the iRGD-DOX-oHA-PLNs efficiently downregulated single and double-strand DNA repair proteins and enhanced DNA damage while decreasing PD-L1 expression compared to olaparib. Accordingly, iRGD-DOX-oHA-PLN treatment showed significantly higher efficiency in reducing levels of primary tumor growth and numbers of metastases to the lung and liver compared to olaparib in vitro and in vivo in both BRCA1-mutant and wild type TNBC orthotopic xenograft models.

A Comprehensive Analysis of Neoadjuvant Chemotherapy in Breast Cancer: Adverse Events, Clinical Response Rates, and Surgical and Pathological Outcomes-Bozyaka Experience

Objectives: To evaluate the neoadjuvant chemotherapy (NACTx) process in breast cancer (BC), its significant treatment-related adverse events (trAEs), tumor clinical response rates, and surgical and pathological outcomes, and to analyze factors influencing cavity shaving and axillary lymph node dissection (ALND) following sentinel lymph node biopsy (SLNB). Methods: A comprehensive retrospective study was conducted at a single center on patients who received NACTx for BC between 2015 and 2021. Results: Medical records of 242 patients were reviewed. Approximately one-fifth encountered grade ≥ 3 trAEs (21.5%), leading 3.3% to discontinue chemotherapy. Anthracycline cardiotoxicity (2.2%) caused one death (mortality rate = 0.4%). For clinical response and surgical and pathological outcomes, 229 patients were eligible. Clinical progression occurred in 3.9% of the patients (14% in triple-negative BC, p = 0.004). Breast-conserving surgery (BCS) was performed in 55% of the patients. There was no significant difference between the type of breast surgery (BCS vs. mastectomy) and molecular subtype, histology, tumor size, or tumor's pathological response degree. Cavity shaving was required in one-fifth of the patients who underwent BCS (n = 134) due to an invasive tumor at the surgical margin (SM). Tumor histology (invasive ductal vs. invasive lobular carcinoma; OR: 4.962, 95% CI 1.007-24.441, p = 0.049) and tumor SUVMax value (OR: 0.866, 95% CI 0.755-0.993, p = 0.039) had significant independent efficacy on SM positivity. Initially, 75% underwent SLNB, but nearly half of them needed ALND. ALND rates were significantly higher in the luminal A and LB-HER2(-) groups (87% vs. 69%) than in the HER2(+) and TN groups (43% to 50%) (p = 0.001). All luminal A patients and those with lobular histology required ALND after SLNB, but no patients in the HER2-enriched group required ALND. ER positivity and higher PR expression levels were associated with an increased need for ALND after SLNB, whereas HER2 positivity and higher SUVMax values of LN(s) were associated with a significantly reduced need for ALND. About 27% of the patients achieved overall pCR. No pCR was achieved in the LA group. Conclusions: The BC NACTx process requires close monitoring due to severe AEs and disease progression. NACTx decisions must be made on experienced multidisciplinary tumor boards, considering tumor characteristics and expected targets.

The spatially informed mFISHseq assay resolves biomarker discordance and predicts treatment response in breast cancer

Current assays fail to address breast cancer's complex biology and accurately predict treatment response. On a retrospective cohort of 1082 female breast tissues, we develop and validate mFISHseq, which integrates multiplexed RNA fluorescent in situ hybridization with RNA-sequencing, guided by laser capture microdissection. This technique ensures tumor purity, unbiased whole transcriptome profiling, and explicitly quantifies intratumoral heterogeneity. Here we show mFISHseq has 93% accuracy compared to immunohistochemistry. Our consensus subtyping and risk groups mitigate single sample discordance, provide early and late prognostic information, and identify high risk patients with enriched immune signatures, which predict response to neoadjuvant immunotherapy in the multicenter, phase II, prospective I-SPY2 trial. We identify putative antibody-drug conjugate (ADC)-responsive patients, as evidenced by a 19-feature T-DM1 classifier, validated on I-SPY2. Deploying mFISHseq as a research-use only test on 48 patients demonstrates clinical feasibility, revealing insights into the efficacy of targeted therapies, like CDK4/6 inhibitors, immunotherapies, and ADCs.

Untangling Breast Cancer: Trailing Towards Nanoformulations-based Drug Development

All over the world, cancer death and prevalence are increasing. Breast cancer (BC) is the major cause of cancer mortality (15%) which makes it the most common cancer in women. BC is defined as the furious progression and quick division of breast cells. Novel nanotechnology-based approaches helped in improving survival rate, metastatic BC is still facing obstacles to treat with an expected overall 23% survival rate. This paper represents epidemiology, classification (non-invasive, invasive and metastatic), risk factors (genetic and non-genetic) and treatment challenges of breast cancer in brief. This review paper focus on the importance of nanotechnology-based nanoformulations for treatment of BC. This review aims to deliver elementary insight and understanding of the novel nanoformulations in BC treatment and to explain to the readers for enduring designing novel nanomedicine. Later, we elaborate on several types of nanoformulations used in tumor therapeutics such as liposomes, dendrimers, polymeric nanomaterials and many others. Potential research opportunities for clinical application and current challenges related to nanoformulations utility for the treatment of BC are also highlighted in this review. The role of artificial intelligence is elaborated in detail. We also confer the existing challenges and perspectives of nanoformulations in effective tumor management, with emphasis on the various patented nanoformulations approved or progression of clinical trials retrieved from various search engines.

Molecular Classification of Breast Cancer Using Weakly Supervised Learning

PURPOSE

The molecular classification of breast cancer is crucial for effective treatment. The emergence of digital pathology has ushered in a new era in which weakly supervised learning leveraging whole-slide images has gained prominence in developing deep learning models because this approach alleviates the need for extensive manual annotation. Weakly supervised learning was employed to classify the molecular subtypes of breast cancer.

MATERIALS AND METHODS

Our approach capitalizes on two whole-slide image datasets: one consisting of breast cancer cases from the Korea University Guro Hospital (KG) and the other originating from The Cancer Genomic Atlas dataset (TCGA). Furthermore, we visualized the inferred results using an attention-based heat map and reviewed the histomorphological features of the most attentive patches.

RESULTS

The KG+TCGA-trained model achieved an area under the receiver operating characteristics value of 0.749. An inherent challenge lies in the imbalance among subtypes. Additionally, discrepancies between the two datasets resulted in different molecular subtype proportions. To mitigate this imbalance, we merged the two datasets, and the resulting model exhibited improved performance. The attentive patches correlated well with widely recognized histomorphologic features. The triple-negative subtype has a high incidence of high-grade nuclei, tumor necrosis, and intratumoral tumor-infiltrating lymphocytes. The luminal A subtype showed a high incidence of collagen fibers.

CONCLUSION

The artificial intelligence (AI) model based on weakly supervised learning showed promising performance. A review of the most attentive patches provided insights into the predictions of the AI model. AI models can become invaluable screening tools that reduce costs and workloads in practice.

Loss of ERα involved-HER2 induction mediated by the FOXO3a signaling pathway in fulvestrant-resistant breast cancer

Patients with estrogen receptor alpha (ERα)-positive breast cancer are commonly treated with anti-estrogen drugs as an initial treatment strategy. Fulvestrant, an estrogen receptor antagonist, effectively blocks ERα signaling; however, long-term fulvestrant treatment induces drug resistance in the absence of ERα. In this study, we investigated the molecular mechanism underlying the loss of ERα, FOXO3a, and induction of HER2 in fulvestrant-resistant breast cancer. Short-term fulvestrant treatment degraded ERα proteins via the ubiquitin-proteasome degradation pathway in MCF7 cells. MCF7 cells turn into highly proliferative cells (fulvestrant-resistant cells: Ful-R) after long-term fulvestrant treatment. These cells exhibit markedly suppressed estrogen and progesterone receptor levels. The phosphorylation of EGFR, HER2, and ERK was induced in Ful-R, and these phosphorylation inhibitors suppressed cell proliferation in Ful-R. FOXO3a, a transcriptional regulator of ERα was decreased in Ful-R, and a ubiquitin-proteasome inhibitor restored the expression of FOXO3a. These results suggest that the suppression of FOXO3a and ERα led to the increased expression of TGF-α, EGFR, and HER2 and subsequent cell proliferation in Ful-R. This study highlights the potential development of therapeutic drugs targeting FOXO3a for the treatment of HER2-positive, estrogen, and progesterone receptor-negative her2-type proliferative breast cancers.

Clinical Implications of Breast Cancer Intrinsic Subtypes

Estrogen receptor-positive (ER+) and estrogen receptor-negative (ER-) breast cancers have different genomic architecture and show large-scale gene expression differences consistent with different cellular origins, which is reflected in the luminal (i.e., ER+) versus basal-like (i.e., ER-) molecular class nomenclature. These two major molecular subtypes have distinct epidemiological risk factors and different clinical behaviors. Luminal cancers can be subdivided further based on proliferative activity and ER signaling. Those with a high expression of proliferation-related genes and a low expression of ER-associated genes, called luminal B, have a high risk of early recurrence (i.e., within 5 years), derive significant benefit from adjuvant chemotherapy, and may benefit from adding immunotherapy to chemotherapy. This subset of luminal cancers is identified as the genomic high-risk ER+ cancers by the MammaPrint, Oncotype DX Recurrence Score, EndoPredict, Prosigna, and several other molecular prognostic assays. Luminal A cancers are characterized by low proliferation and high ER-related gene expression. They tend to have excellent prognosis with adjuvant endocrine therapy. Adjuvant chemotherapy may not improve their outcome further. These cancers correspond to the genomic low-risk categories. However, these cancers remain at risk for distant recurrence for extended periods of time, and over 50% of distant recurrences occur after 5 years. Basal-like cancers are uniformly highly proliferative and tend to recur within 3-5 years of diagnosis. In the absence of therapy, basal-like breast cancers have the worst survival, but these also include many highly chemotherapy-sensitive cancers. Basal-like cancers are often treated with preoperative chemotherapy combined with an immune checkpoint inhibitor which results in 60-65% pathologic complete response rates that herald excellent long-term survival. Patients with residual cancer after neoadjuvant therapy can receive additional postoperative chemotherapy that improves their survival. Currently, there is no clinically actionable molecular subclassification for basal-like cancers, although cancers with high androgen receptor (AR)-related gene expression and those with high levels of immune infiltration have better prognosis, but currently their treatment is not different from basal-like cancers in general. A clinically important, minor subset of breast cancers are characterized by frequent HER2 gene amplification and high expression of a few dozen genes, many residing on the HER2 amplicon. This is an important subset because of the highly effective HER2 targeted therapies which are synergistic with endocrine therapy and chemotherapy. The clinical behavior of HER2-enriched cancers is dominated by the underlying ER subtype. ER+/HER2-enriched cancers tend to have more indolent course and lesser chemotherapy sensitivity than their ER counterparts.

The splicing machinery is dysregulated and represents a therapeutic vulnerability in breast cancer

Breast cancer (BCa) is a highly prevalent pathological condition (̴30% in women) with limited and subtype-dependent prognosis and therapeutic options. Therefore, BCa management might benefit from the identification of novel molecular elements with clinical potential. Since splicing process is gaining a great relevance in cancer, this work analysed the expression of multiple Spliceosome Components (SCs = 17) and Splicing Factors (SFs = 26) and found a drastic dysregulation in BCa (n = 69) vs. control (negative biopsies; n = 50) samples. Among all the components analysed, we highlight the upregulation of ESRP1 and down-regulation of PRPF8 and NOVA1 in BCa vs. control samples. Indeed, ESRP1 was specially overexpressed in triple-negative BCa (TNBCa) and associated with worse prognosis (i.e., higher BCa grade and lower overall survival), suggesting an association of ESRP1 with BCa aggressiveness. On the other hand, PRPF8 expression was generally downregulated in BCa with no associations to clinical characteristics, while NOVA1 expression was lower in TNBCa patients and highly aggressive tumours. Consistently, NOVA1 overexpression in vitro reduced functional parameters of aggressiveness in ER-/PR- cell lines (MDA-MB-231 and BT-549) but not in ER+/PR+ cells (MCF7), suggesting a critical role of NOVA1 in subtype-specific BCa. Finally, the in vitro pharmacological inhibition of splicing machinery using pladienolide B decreased aggressiveness features in all the BCa cell lines, showing a subtype-independent inhibitory potential, but being relatively innocuous in normal-like breast cells. These results demonstrate the profound dysregulation of the splicing machinery in BCa and their potential as source of promising diagnosis/prognosis markers, as well as valuable therapeutic targets for BCa.

A Real-World Comparison Between Adjuvant Docetaxel with Cyclophosphamide (TC) and Anthracycline-Taxane Chemotherapy in Early HER-2 Negative Breast Cancer

BACKGROUND

Anthracycline-taxane chemotherapy is the gold standard in high-risk breast cancer (BC), despite the potential risk of congestive heart failure (CHF). A suitable alternative for anthracycline-sparing chemotherapy is through the combination of docetaxel and cyclophosphamide (TC).

METHODS

Through a retrospective study of stage I-III HER2-negative BC, using administrative databases, we analyzed a total of 10,634 women treated with adjuvant chemotherapy in Ontario, Canada, between 2009 and 2017. We compared TC versus standardized anthracycline-taxane chemotherapies (ACT and FEC-D). We investigated the overall survival (OS), and explored the incidence of CHF, emergency department (ED) visits and febrile neutropenia.

RESULTS

With a median follow-up of 5.5 years, the 5-year analysis showed an increased OS in patients treated with TC, versus those treated with ACT, HR 0.77 (0.63-0.95, p = 0.015). Among ER+ BC, there was an increased OS in patients treated with ACT and FEC-D, versus those treated with TC, HR 0.70 (0.52-0.95, p = 0.021) and HR 0.71 (0.56-0.91, p = 0.007), respectively. There were no substantial differences in CHF, between TC and anthracycline-based treatments. Patients treated with TC and FEC-D had more ED visits, compared to those treated with ACT.

CONCLUSION

Our study shows that anthracycline-taxane regimens were the most commonly prescribed adjuvant chemotherapy options in HER2-negative BC. Women who received ACT had the lowest OS, likely due to their unfavorable pathology.

Dysregulated miRNA Expression and Androgen Receptor Loss in Racially Distinct Triple-Negative Breast Cancer

Androgen receptor (AR)-negative triple-negative breast cancer (TNBC), often termed quadruple-negative breast cancer (QNBC), disproportionately impacts women of African descent, leading to poorer overall survival (OS). MiRNAs regulate the expression of gene drivers involved in critical signaling pathways in TNBC, such as the AR gene, and their expression varies across races and breast cancer subtypes. This study investigates whether differentially expressed miRNAs influence AR transcription, potentially contributing to the observed disparities between African American (AA) and European American (EA) QNBC patients. Race-annotated TNBC samples (n = 129) were analyzed for AR expression status and revealed the prevalence of QNBC in AA patients compared to EA (76.6% vs. 57.7%) and a significant association of AR loss with poor survival among AAs. The Cancer Genome Atlas (TCGA) RNA-seq data showed that AAs with TNBC (n = 32) had lower AR mRNA levels than EAs (n = 67). Among TCGA patients in the AR-low group, AAs had significantly poorer OS than EAs. In our cohort, 46 miRNAs exhibited differential expression between AAs and EAs with QNBC. Ten of these miRNAs (miR-1185-5p, miR-1305, miR-3161, miR-3690, miR-494-3p, miR-509-3-5p, miR-619-3p, miR-628-3p, miR-873-5p, and miR-877-5p) were predicted to target the AR gene/signaling. The loss of AR expression is linked to poorer prognoses in AA women. The understanding of the specific miRNAs involved and their regulatory mechanisms on AR expression could provide valuable insights into why AA women are more prone to QNBC.

Modeling intratumor heterogeneity in breast cancer

Reduced therapy response in breast cancer has been correlated with heterogeneity in biomarker composition, expression level, and spatial distribution of cancer cells within a patient tumor. Thus, there is a need for models to replicate cell-cell, cell-stromal, and cell-microenvironment interactions during cancer progression. Traditional two-dimensional (2D) cell culture models are convenient but cannot adequately represent tumor microenvironment histological organization,in vivo3D spatial/cellular context, and physiological relevance. Recently, three-dimensional (3D)in vitrotumor models have been shown to provide an improved platform for incorporating compositional and spatial heterogeneity and to better mimic the biological characteristics of patient tumors to assess drug response. Advances in 3D bioprinting have allowed the creation of more complex models with improved physiologic representation while controlling for reproducibility and accuracy. This review aims to summarize the advantages and challenges of current 3Din vitromodels for evaluating therapy response in breast cancer, with a particular emphasis on 3D bioprinting, and addresses several key issues for future model development as well as their application to other cancers.

An Azomethine Derivative, BCS3, Targets XIAP and cIAP1/2 to Arrest Breast Cancer Progression Through MDM2-p53 and Bcl-2-Caspase Signaling Modulation

Background: Breast cancer influences more than 2 million women worldwide annually. Since apoptotic dysregulation is a cancer hallmark, targeting apoptotic regulators encompasses strategic drug development for cancer therapy. One such class of apoptotic regulators is inhibitors of apoptosis proteins (IAP) which are a class of E3 ubiquitin ligases that actively function to support cancer growth and survival. Methods: The current study reports design, synthesis, docking analysis (based on binding to IAP-BIR3 domains), anti-proliferative and anti-tumor potential of the azomethine derivative, 1-(4-chlorophenyl)-N-(4-ethoxyphenyl)methanimine (BCS3) on breast cancer (in vitro and in vivo) and its possible mechanisms of action. Results: Strong selective cytotoxic activity was observed in MDA-MB-231, MCF-7, and MDA-MB-468 breast cancer cell lines that exhibited IC50 values, 1.554 µM, 5.979 µM, and 6.462 µM, respectively, without affecting normal breast cells, MCF-10A. For the evaluation of the cytotoxic potential of BCS3, immunofluorescence, immunoblotting, and FACS (apoptosis and cell cycle) analyses were conducted. BCS3 antagonized IAPs, thereby causing MDM2-p53 and Bcl-2-Caspase-mediated intrinsic and extrinsic apoptosis. It also modulated p53 expression causing p21-CDK1/cyclin B1-mediated cell cycle arrest at S and G2/M phases. The in vitro findings were consistent with in vivo findings as observed by reduced tumor volume and apoptosis initiation (TUNEL assay) by IAP downregulation. BCS3 also produced potent synergistic effects with doxorubicin on tumor inhibition. Conclusions: Having witnessed the profound anti-proliferative potential of BCS3, the possible adverse effects related to anti-cancer therapy were examined following OECD 407 guidelines which confirmed its systemic safety profile and well tolerability. The results indicate the promising effect of BCS3 as an IAP antagonist for breast cancer therapy with fewer adverse effects.

Drug discovery of N-methyl-pyrazole derivatives as potent selective estrogen receptor degrader (SERD) for the treatment of breast cancer

Nowadays, ERα is considered to be a primary target for the treatment of breast cancer, and selective estrogen receptor degraders (SERDs) are emerging as promising antitumor agents. By analysing ERα-SERDs complexes, the pharmacophore features of SERDs and the crucial protein-ligand interactions were identified. Then, by utilizing the scaffold-hopping and bioisosteres strategy, 23 novel derivatives were designed, synthesized and biologically evaluated. Among these derivatives, A20 exhibited potent ERα binding affinity (IC50 = 24.0 nM), degradation ability (EC50 = 5.3 nM), excellent ER selectivity, and outstanding anti-proliferative effects on MCF-7 cells (IC50 = 0.28 nM). Further biological studies revealed that A20 could degrade ERα through proteasome-mediated pathway, suppress signal transduction of MCF-7 cells, and arrest the cell cycle in G1 phase. Moreover, A20 showed excellent antitumor effect (TGI = 92.98 %, 30 mg kg-1 day-1) in the MCF-7 xenograft model in vivo with good safety and favorable pharmacokinetics (F = 39.6 %), making it a promising candidate for the treatment of breast cancer.

Alterations in the expression of homologous recombination repair (HRR) genes in breast cancer tissues considering germline BRCA1/2 mutation status

INTRODUCTION

Homologous recombination (HR) is a crucial DNA-repair mechanism, and its disruption can lead to the accumulation of mutations that initiate and promote cancer formation. The key HR genes, BRCA1 and BRCA2, are particularly significant as their germline pathogenic variants are associated with a hereditary predisposition to breast and/or ovarian cancer.

MATERIALS AND METHODS

The study was performed on 45 FFPE breast cancer tissues obtained from 24 and 21 patients, with and without the germline BRCA1/2 mutation, respectively. The expression of 11 genes: BRCA1, BRCA2, ATM, BARD1, FANCA, FANCB, FANCI, RAD50, RAD51D, BRIP1, and CHEK2 was assessed using Custom RT2 PCR Array (Qiagen), and results were analysed using R.

RESULTS

Cancer tissues from patients with BRCA1 or BRCA2 germline mutations displayed no significant differences in the expression of the selected HR genes compared to BRCA1 or BRCA2 wild-type cancer tissues. In BRCA1mut cancer tissues, BRCA1 expression was significantly higher than in BRCA2mut and BRCA wild-type cancer tissues.

CONCLUSIONS

In cancer tissues harbouring either BRCA1 or BRCA2 germline mutations, no significant differences in expression were observed at the mRNA level of any tested HR genes, except BRCA1. However, the significant differences observed in BRCA1 expression between germline BRCA1mut, germline BRCA2mut and BRCA1/2wt tissues may indicate a compensatory mechanism at the mRNA level to mitigate the loss of BRCA1 function in the cells.

Integrative analysis of homologous recombination repair patterns unveils prognostic signatures and immunotherapeutic insights in breast cancer

Globally, breast cancer (BC) is the leading cause of female death and morbidity. Homologous recombination repair (HRR) is critical in BC. However, the prognostic role and immunotherapy response of HRR in BC remains to be clarified. Firstly, we identified HRR types in BC samples from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) dataset (GSE42568) based on 65 HRR genes (HRRGs). A differentially expressed gene (DEG) list for different HRR types was generated. Then, the influences of gene sets composed of these DEGs on biological pathways and BC prognosis were explored. Next, we identified gene clusters based on gene sets composed of DEGs. Genes associated with prognosis for DEGs were identified using univariate Cox regression. Finally, the HRR score was constructed based on genes associated with prognosis. We analyzed how HRR score correlates with tumor mutation burden (TMB), immune cell infiltration (ICI), and immunotherapy response. Three HRR clusters were discovered. HRR subtype A demonstrated decreased infiltration and a high number of immunosuppressive cells with a poor prognosis. DEGs among various HRR types were predominantly enriched in cell cycle and genomic stability-related pathways. The prognostic model based on sixteen DEGs accurately predicted BC prognosis. The HRRGs were differentially expressed in three DEG clusters. TMB, ICI, and immunotherapy responses differed significantly between the high and low HRR groups (HSG, LSG). The HSG was distinguished by a high degree of ICI and low TMB. LSG had a better response to anti-PD-1 or anti-PD-1 and anti-CTLA4 combination therapy. This work revealed that HRR patterns would contribute to predicting prognosis and immunotherapy response in BC, which may benefit patients.

Sacituzumab Govitecan for Second and Subsequent Line Palliative Treatment of Patients with Triple-Negative Breast Cancer: A Polish Real-World Multicenter Cohort Study

INTRODUCTION

Sacituzumab govitecan (SG) is approved for patients with previously treated metastatic or locally advanced triple-negative breast cancer (TNBC), as per the ASCENT trial results. Real-world studies (RWSs) cover more diverse patients than clinical trials, offering crucial data for healthcare policies. This study aimed to investigate the safety and efficacy of SG in real-world Polish patients with previously treated metastatic TNBC.

METHODS

In this ambispective multicenter cohort study, we collected demographic and clinical data. Premedication, adjustments in SG dosage, and treatment regimen adhered to the product's characteristics.

RESULTS

We included 79 female patients. The median age at SG initiation was 53 years; 32% of patients were initially diagnosed with a non-TNBC subtype. The median number of previous palliative lines was 2. Seven patients presented with brain metastases. The median overall survival was 10.3 months, and the median progression-free survival (PFS) was 4.4 months. The overall response rate was 35%, with a median time to response of 2 months. SG was discontinued by 70% of patients, primarily due to disease progression (95%). Treatment delays due to adverse events (AEs) occurred in 67% and dose reductions in 25% of patients, with neutropenia being the most common. Grade ≥ 2 AEs included neutropenia (43%), anemia (10.1%), and diarrhea (4%). A longer interval between breast cancer diagnosis and SG initiation or between metastasis diagnosis and SG initiation correlated with improved PFS, likely reflecting the disease's biological aggressiveness rather than treatment efficacy.

CONCLUSION

In this RWS, SG demonstrated effectiveness and safety in patients with previously treated metastatic TNBC, consistent with ASCENT trial outcomes. Further research is needed to explore the efficacy of SG in different patient populations and healthcare systems.

Polyphenols as Immunomodulators and Epigenetic Modulators: An Analysis of Their Role in the Treatment and Prevention of Breast Cancer

Breast cancer poses a substantial health challenge for women globally. Recently, there has been a notable increase in scholarly attention regarding polyphenols, primarily attributed to not only the adverse effects associated with conventional treatments but also their immune-preventive impacts. Polyphenols, nature-derived substances present in vegetation, including fruits and vegetables, have received considerable attention in various fields of science due to their probable wellness merits, particularly in the treatment and hindrance of cancer. This review focuses on the immunomodulatory effects of polyphenols in breast cancer, emphasizing their capacity to influence the reaction of adaptive and innate immune cells within the tumor-associated environment. Polyphenols are implicated in the modulation of inflammation, the enhancement of antioxidant defenses, the promotion of epigenetic modifications, and the support of immune functions. Additionally, these compounds have been shown to influence the activity of critical immune cells, including macrophages and T cells. By targeting pathways involved in immune evasion, polyphenols may augment the capacity of the defensive system to detect and eliminate tumors. The findings suggest that incorporating polyphenol-rich foods into the diet could offer a promising, collaborative (integrative) approach to classical breast cancer remedial procedures by regulating how the defense mechanism interacts with the disease.

Understanding the role of TNFR2 signaling in the tumor microenvironment of breast cancer

Breast cancer (BC) is the most frequently diagnosed malignancy among women. It is characterized by a high level of heterogeneity that emerges from the interaction of several cellular and soluble components in the tumor microenvironment (TME), such as cytokines, tumor cells and tumor-associated immune cells. Tumor necrosis factor (TNF) receptor 2 (TNFR2) appears to play a significant role in microenvironmental regulation, tumor progression, immune evasion, drug resistance, and metastasis of many types of cancer, including BC. However, the significance of TNFR2 in BC biology is not fully understood. This review provides an overview of TNFR2 biology, detailing its activation and its interactions with important signaling pathways in the TME (e.g., NF-κB, MAPK, and PI3K/Akt pathways). We discuss potential therapeutic strategies targeting TNFR2, with the aim of enhancing the antitumor immune response to BC. This review provides insights into role of TNFR2 as a major immune checkpoint for the future treatment of patients with BC.

Is Progesterone Receptor a Neglected Feature in Breast Cancer? A Retrospective Study Analysing the Clinicopathological Characteristics of Breast Cancer Based on Progesterone Receptor Status

PURPOSE

The aim of this study is to analyse PR independently and its relationship with demographic and clinicopathological information.

INTRODUCTION

Steroid hormones, particularly estrogen and progesterone, play a crucial role in breast cancer (BC) etiology. Research attention has focused mainly on estrogen while the progesterone impact on breast cancer has yet to be fully uncover. Hormone receptors, including those for estrogen and progesterone, are crucial in BC molecular classification, shaping prognosis and treatment strategies. Beyond its metabolic effects, progesterone and its receptor (PR) have significant clinical implications, impacting clinical outcomes.

MATERIALS AND METHODS

The study comprised 2223 women who were diagnosed with BC at the Comprehensive Cancer Centre in Portugal (IPO-Porto) between 2012 and 2016. Variables, including age at diagnosis, body mass index (BMI), laterality, topographic localization, histological type, differentiation grade, tumor stage, estrogen receptor (ER) and Human Epidermal growth factor Receptor 2 (HER2) expression, were stratified according to the expression of Progesterone Receptor. Statistical analysis included Pearson's Chi-squared test, binary and multinomial regression, and Cox proportional hazard model. Statistical significance was set for P < .05.

RESULTS

The results reveal a statistical association between PR and BMI, histological type, differentiation grade, tumour stage, ER and HER2. Progesterone receptor negativity is associated with adverse clinical outcomes, including advanced tumor stages, and diminished overall survival.

CONCLUSION

Further research is needed to elucidate the precise contributions of progesterone to breast cancer progression and to optimize therapeutic approaches for improved patient outcomes.

Current Therapeutic Opportunities for Estrogen Receptor Mutant Breast Cancer

Estrogen receptor α (ERα) drives two out of three breast cancers and therefore ERα is a major therapeutic target for ER-positive breast cancer patients. Drugs that inhibit ERα activity or block estrogen synthesis in the body are currently being used in the clinic to treat ER-positive breast cancer and have been quite successful in controlling breast cancer progression for the majority of patients. However, ER-positive breast cancer often becomes resistant to these endocrine therapies, leading to endocrine-resistant metastatic breast cancer, a very aggressive cancer that leads to death. Recent large-scale genomic studies have revealed a series of activating somatic mutations in the ERα gene (ESR1) in endocrine-resistant metastatic breast cancer patients. Of these, Y537S and D538G mutations are found at a much higher rate in patients with metastatic breast cancer. Remarkably, these mutations produce an ERα with much higher transcriptional activity than wild type in the absence of estradiol, and traditional endocrine therapy has poor efficacy against ER mutants. Therefore, the development of new drugs that target ER mutants is an unmet clinical need for endocrine-resistant metastatic breast cancer. This review summarizes the recent preclinical and clinical trials targeting estrogen receptor mutant breast cancer.

Immune landscape of the tumour microenvironment in Ethiopian breast cancer patients

BACKGROUND

The clinical management of breast cancer (BC) is mainly based on the assessment of receptor expression by tumour cells. However, there is still an unmet need for novel biomarkers important for prognosis and therapy. The tumour immune microenvironment (TIME) is thought to play a key role in prognosis and therapy selection, therefore this study aimed to describe the TIME in Ethiopian BC patients.

METHODS

RNA was isolated from formalin-fixed paraffin-embedded (FFPE) tissue from 82 women with BC. Expression of PAM50 and 54 immune genes was analysed using the Nanostring platform and differentially expressed genes (DEGs) were determined using ROSALIND®. The abundance of different cell populations was estimated using Nanostring's cell type profiling module, while tumour infiltrating lymphocytes (TILs) were analysed using haematoxylin and eosin (H&E) staining. In addition, the PIK3CA gene was genotyped for three hotspot mutations using qPCR. Kaplan-Meier survival analysis and log-rank test were performed to compare the prognostic relevance of immune subgroups.

RESULTS

Four discrete immune phenotypes (IP1-4) were identified through hierarchical clustering of immune gene expression data. These IPs were characterized by DEGs associated with both immune activation and inhibition as well as variations in the extent of immune infiltration. However, there were no significant differences regarding PIK3CA mutations between the IPs. A downregulation of immune suppressive and activating genes and the lowest number of infiltrating immune cells were found in IP2, which was associated with luminal tumours. In contrast, IP4 displayed an active TME chracterized by an upregulation of cytotoxic genes and the highest density of immune cell infiltrations, independent of the specific intrinsic subtype. IP1 and IP3 exhibited intermediate characteristics. The IPs had a prognostic relevance and patients with an active TME had improved overall survival compared to IPs with a significant downregulation of the majority of immune genes.

CONCLUSION

Immune gene expression profiling identified four distinct immune contextures of the TME with unique gene expression patterns and immune infiltration. The classification into distinct immune subgroups may provide important information regarding prognosis and the selection of patients undergoing conventional treatments or immunotherapies.

Differential bone morphology and hypoxia activity in skeletal metastases of ER+ and ER- breast cancer

Bone metastases occur in the majority of advanced breast cancer patients, and the most common complications are osteolytic bone metastases. However, due to the limitations of models and methodologies for bone metastasis studies, the intricacies of bone metastasis have not been fully acknowledged and revealed in prior work. Our earlier study indicated that certain breast cancer cells undergo a pre-osteolytic stage before the establishment of overt metastatic lesions. Here, we further identify a differential bone morphology between ER (estrogen receptor)+ and ER- breast cancer. Specifically, we observe a more pronounced osteolytic phenotype in the bone metastatic lesions of ER- cells investigated, linked to elevated hypoxia signaling that stimulates the secretion of osteolytic inducers from cancer cells. In the in vivo mouse model, the application of the hypoxia-inducible factor (HIF) inhibitor 2-methoxyestradiol demonstrates a promising efficacy in suppressing tumor growth and osteoclast differentiation in the bone lesions established by bone-tropic subpopulation of ER- MDA-MB-231 cell. Overall, our findings explore the complexity of phenotype and morphology in bone metastatic lesions of ER+ and ER- breast cancer, which offers a compelling rationale for leveraging HIF inhibitors to the treatment targeting skeletal complications of breast cancer bone metastases, especially for ER- tumors.

A dual-targeted trinity of antibody-peptide-drug delivery consortium to combat HER2+ tumor

We pioneered a dual-targeted trinity of antibody-peptide-drug delivery consortium to combat HER2+ tumors. This innovative approach leverages the self-assembly of peptides with high affinity to antibodies to create nanofibers for antibody encapsulation, offering a novel strategy in antibody drug delivery.

Unveiling the Link Between Breast Cancer Treatment and Osteoporosis: Implications for Anticancer Therapy and Bone Health

Background: The interplay between breast cancer treatment and osteoporosis has important consequences for anticancer therapy and patient bone health. Many breast cancer therapies involve hormonal treatments that lower estrogen levels, which can lead to an increased risk of osteoporosis due to reduced bone mineral density. Aromatase inhibitors, chemotherapy, and surgeries such as oophorectomy can further aggravate bone loss, highlighting the necessity of prioritizing bone health during cancer treatment. Objective: This review is aimed at investigating the complex relationship between breast cancer therapies and bone health by examining the molecular and cellular mechanisms through which anticancer treatments lead to bone loss. It also seeks to assess the effects of various treatment options, such as selective estrogen receptor modulators (SERMs) and bisphosphonates, on reducing bone loss and maintaining bone health during cancer therapy. Method: The review explores the mechanisms underlying bone loss in breast cancer patients undergoing treatment, focusing on factors such as estrogen depletion, inflammatory cytokines, and changes in bone remodelling processes. Additionally, it evaluates the efficacy of different therapeutic interventions, including pharmacological treatments like bisphosphonates and third-generation SERMs, in mitigating bone-related side effects. Results: The findings indicate a critical need to balance the effectiveness of breast cancer treatments with the preservation of bone health. Pharmacological treatments like bisphosphonates and denosumab have been identified as essential for managing bone health in breast cancer patients. Furthermore, third-generation SERMs show potential in reducing bone loss associated with cancer therapy.

Cell cycle traverse rate predicts long-term outcomes in a multi-institutional cohort of patients with triple-negative breast cancer

BACKGROUND

Ki67 index (KI) and mitotic index (MI) are proliferation markers with established prognostic value in breast carcinomas. While KI is evaluated immunohistochemically and reported as a percentage, MI is determined visually and reflects total mitotic cells in 10 high-power fields. Our objective was to integrate KI and MI into a novel metric; the cell cycle traverse rate (CCTR). Given the lack of prognostic and predictive biomarkers in TNBC, we sought to assess the potential of CCTR as a risk-stratification tool for chemotherapy-treated TNBC patients from two independent cohorts: the Nottingham group (n = 124) and the Norway group (n = 71).

METHODS

We evaluated the ability of CCTR to predict survival after adjuvant chemotherapy for TNBC patients (n = 195) in two independent cohorts. Using immunohistochemistry and RNA sequencing, we determined the differences in immunohistochemical biomarkers, gene ontologies, molecular pathways and immune cell fractions based on CCTR.

RESULTS

TNBC shows a significantly lower median CCTR compared to luminal A (p < 0.01), luminal B (p < 0.01), and HER2+ samples (p < 0.01). CCTR outperformed both KI and MI in effectively risk-stratifying TNBC patients suggesting that combining KI and MI into a single metric, namely CCTR, could serve as a superior prognostic marker for Breast Cancer Specific Survival (BCSS) (p = 0.041). CCTR-high group exhibited enriched expression of various oncogenic signatures, including angiogenesis, epithelial-to-mesenchymal transition (EMT), Hedgehog signaling, hypoxia, Notch signaling, PI3K-AKT-mTOR signaling, TGFβ signaling, p53 signaling, and TNFα signaling via NFκB. These findings suggest the potential involvement of these pathways in the aggressiveness and clinical outcomes of TNBC patients.

CONCLUSIONS

Collectively, these findings suggest that CCTR offers superior predictive information compared to KI and MI alone with respect to long-term outcomes from adjuvant chemotherapy in patients with TNBC that may guide treatment decision making.

A review on tyrosine kinase inhibitors for targeted breast cancer therapy

Breast cancer is a heterogeneous disease with complex molecular pathogenesis. Overexpression of several tyrosine kinase receptors is associated with poor prognosis, therefore, they can be key targets in breast cancer therapy. Tyrosine kinase inhibitors (TKIs) have emerged as leading agents in targeted cancer therapy due to their effectiveness in disrupting key molecular pathways involved in tumor growth. TKIs target various tyrosine kinases, including the human epidermal growth factor receptor 2 (HER2), epidermal growth factor receptor (EGFR), Vascular endothelial growth factor receptor (VEGFR), anaplastic lymphoma kinase (ALK), vascular endothelial growth factor receptor (VEGFR)-associated multi-targets, rearranged during transfection (RET), fibroblast growth factor receptor (FGFR), receptor tyrosine kinase-like orphan signal 1 (ROS1), Mitogen-activated protein kinase (MAPK), and tropomyosin receptor kinase (TRK). These drugs target the tyrosine kinase domain of receptor tyrosine kinases and play a vital role in proliferation and migration of breast cancer cells. Several TKIs, including lapatinib, neratinib, and tucatinib, have been developed and are currently used in clinical settings, often in combination with chemotherapy, endocrine therapy, or other targeted agents. TKIs have demonstrated remarkable benefits in enhancing progression-free and overall survival in patients with breast cancer and have become a standard of care for this population. This review provides an overview of TKIs currently being examined in preclinical studies and clinical trials, especially in combination with drugs approved for breast cancer treatment. TKIs have emerged as a promising therapeutic option for patients with breast cancer and hold potential for treating other breast cancer subtypes. The development of new TKIs and their integration into personalized treatment strategies will continue to shape the future of breast cancer therapy.

Precision medicine in breast cancer (Review)

Precision medicine in breast cancer is a revolutionary approach that customizes diagnosis and treatment based on individual and tumor characteristics, departing from the traditional one-size-fits-all approach. Breast cancer is diverse, with various subtypes driven by distinct genetic mutations. Understanding this diversity is crucial for tailored treatment strategies that target specific vulnerabilities in each tumor. Genetic testing, particularly for mutations in breast cancer gene (BRCA) DNA repair-associated genes, helps assess hereditary risks and influences treatment decisions. Molecular subtyping guides personalized treatments, such as hormonal therapies for receptor-positive tumors and human epidermal growth factor receptor 2 (HER2)-targeted treatments. Targeted therapies, including those for HER2-positive and hormone receptor-positive breast cancers, offer more effective and precise interventions. Immunotherapy, especially checkpoint inhibitors, shows promise, particularly in certain subtypes such as triple-negative breast cancer, with ongoing research aiming to broaden its effectiveness. Integration of big data and artificial intelligence enhances personalized treatment strategies, while liquid biopsies provide real-time insights into tumor dynamics, aiding in treatment monitoring and modification. Challenges persist, including accessibility and tumor complexity, but emerging technologies and precision prevention offer hope for improved outcomes. Ultimately, precision medicine aims to optimize treatment efficacy, minimize adverse effects and enhance the quality of life for patients with breast cancer.

Site-specific O-GlcNAcylation of progesterone receptor (PR) supports PR attenuation of interferon stimulated genes (ISGs) and tumor growth in breast cancer

Hormone receptor positive (HR+) breast cancer, defined by expression of estrogen receptor (ER) and/or progesterone receptor (PR), is the most commonly diagnosed type of breast cancer. PR alters the transcriptional landscape to support tumor growth in concert with, or independent of, ER. Understanding the mechanisms regulating PR function is critical to developing new strategies to treat HR+ breast cancer. O-linked β-N-acetylglucosamine (O-GlcNAc) is a posttranslational modification responsible for nutrient sensing that modulates protein function. Although PR is heavily posttranslationally modified, through both phosphorylation and O-GlcNAcylation, specific sites of O-GlcNAcylation on PR and how they regulate PR action have not been investigated. Using established PR-expressing breast cancer cell lines, we mapped several sites of O-GlcNAcylation on PR. RNA-sequencing after PR O-GlcNAc site mutagenesis revealed site-specific O-GlcNAcylation of PR is critical for ligand-independent suppression of interferon signaling, a regulatory function of PR in breast cancer. Furthermore, O-GlcNAcylation of PR enhances PR-driven tumor growth in vivo. Herein, we have delineated one contributing mechanism to PR function in breast cancer that impacts tumor growth and provided additional insight into the mechanism through which PR attenuates interferon signaling.

PD-L1 protein expression in breast cancer

AIMS

The immune checkpoint marker, Programmed cell death-ligand 1 (PD-L1), is expressed by both cancer epithelial cells and tumour-infiltrating immune cells (TICs) thus constituting a potential target for immunotherapy. This is of particular interest in triple negative breast cancer. In this study, we assessed the prognostic value of PD-L1 expression in tumour epithelial cells and TICs in a series of patients with breast cancer with long-term follow-up, and associations between PD-L1 expression and histopathological type and grade, proliferation and molecular subtype.

METHODS

Using immunohistochemistry for PD-L1 in tissue microarrays, we assessed PD-L1 expression in 821 tumours. Expression of PD-L1 was assessed separately in the epithelial and stromal compartments and classified as <1%, ≥1% to <10% or ≥10% positive staining cells. We correlated PD-L1 expression in tumour epithelial cells and TICs with tumour characteristics using Pearson's χ2 test, and prognosis by cumulative incidence of death from breast cancer and Cox regression analyses.

RESULTS

We found membranous staining in ≥1% of tumour epithelial cells in 53/821 cases (6.5%). Of these, 21 (2.6%) were ≥10%. Among TICs, staining (≥1%) was seen in 144/821 cases (17.6%). Of these, 62 were ≥10% (7.6%). PD-L1 was associated with high histopathological grade and proliferation, and the medullary and metaplastic patterns. In TICs, PD-L1 ≥1% found in 22/34 (34.4%) human epidermal growth factor receptor 2 type and 29/58 (50%) basal phenotype. An independent association between PD-L1 expression and prognosis was not observed.

CONCLUSIONS

PD-L1 is expressed more frequently in TICs than tumour epithelial cells. Expression in TICs is associated with aggressive tumour characteristics and non-luminal tumours but not with prognosis.

Recent advancements in small interfering RNA based therapeutic approach on breast cancer

Breast cancer (BC) is the most common and malignant tumor diagnosed in women, with 2.9 million cases in 2023 and the fifth highest cancer-causing mortality worldwide. Recent developments in targeted therapy options for BC have demonstrated the promising potential of small interfering RNA (siRNA)-based cancer therapeutic approaches. As BC continues to be a global burden, siRNA therapy emerges as a potential treatment strategy to regulate disease-related genes in other types of cancers, including BC. siRNAs are tiny RNA molecules that, by preventing their expression, can specifically silence genes linked to the development of cancer. In order to increase the stability and effectiveness of siRNA delivery to BC cells, minimize off-target effects, and improve treatment efficacy, advanced delivery technologies such as lipid nanoparticles and nanocarriers have been created. Additionally, combination therapies, such as siRNAs that target multiple pathways are used in conjunction with conventional chemotherapy agents, have shown synergistic effects in various preclinical studies, opening up new treatment options for breast cancer that are personalized and precision medicine-oriented. Targeting important genes linked to BC growth, metastasis, and chemo-resistance has been reported in BC research using siRNA-based therapies. This study reviews recent reports on therapeutic approaches to siRNA for advanced treatment of BC. Furthermore, this review evaluates the role and mechanisms of siRNA in BC and demonstrates the potential of exploiting siRNA as a novel target for BC therapy.