Specific Breast Cancer Subtypes Research Articles

Simeprevir induces ferroptosis through β-TrCP/Nrf2/GPX4 axis in triple-negative breast cancer cells

The effective treatment regimens of triple-negative breast cancer (TNBC), a specific subtype of breast cancer (BC) with proneness to relapse and poor prognosis, are still lacking. Simeprevir (SIM), approved for hepatitis C infection treatment, has been proved to be a competitive drug for the treatment of various solid tumors recently. However, the anti-tumor mechanisms of SIM and therapeutic effects on TNBC are uncertain. In this study, we suggested that SIM effectively restrained the growth of MDA-MB-231 and BT-549 cells, two cell lines from TNBC. The RNA sequencing revealed that ferroptosis signaling was activated in SIM-treated TNBC cells. SIM induced ferroptosis in TNBC cells through reduced glutathione (GSH) levels, increased iron levels, ROS and lipid peroxidation. Mechanistically, SIM promoted the expression of β-TrCP to inhibit the Nrf2/GPX4 axis in TNBC cells, leading to ferroptosis. Moreover, SIM administration into the xenografts formed by MDA-MB-231 dramatically suppressed the tumor progression by inducing ferroptosis in vivo. Collectively, this finding reveals that SIM may serve as a competitive therapeutic strategy to inhibit TNBC.

Peptidomics and Machine Learning–based Evaluation of Noncoding RNA–Derived Micropeptides in Breast Cancer: Expression Patterns and Functional/Therapeutic Insights

Breast cancer is a highly heterogeneous disease characterized by different subtypes arising from molecular alterations that give the disease different phenotypes, clinical behaviors, and prognostic. The noncoding RNA (ncRNA)–derived micropeptides (MPs) represent a novel layer of complexity in cancer study once they can be biologically active and can present potential as biomarkers and also in therapeutics. However, few large-scale studies address the expression of these peptides at the peptidomics level or evaluate their functions and potential in peptide-based therapeutics for breast cancer. In this study, we propose deepening the landscape of ncRNA-derived MPs in breast cancer subtypes and advance the comprehension of the relevance of these molecules to the disease. First, we constructed a 16,349 unique putative MP sequence data set by integrating 2 previously published lists of predicted ncRNA-derived MPs. We evaluated its expression on high-throughput mass spectrometry data of breast tumor samples from different subtypes. Next, we applied several machine and deep learning tools, such as AntiCP 2.0, MULocDeep, PEPstrMOD, Peptipedia, and PreAIP, to predict its functions, cellular localization, tertiary structure, physicochemical features, and other properties related to therapeutics. We identified 58 peptides expressed on breast tissue, including 27 differentially expressed MPs in tumor compared with nontumor samples and MPs exhibiting tumor or subtype specificity. These peptides presented physicochemical features compatible with the canonical proteome and were predicted to influence the tumor immune environment and participate in cell communication, metabolism, and signaling processes. In addition, some MPs presented potential as anticancer, antiinflammatory, and antiangiogenic molecules. Our data demonstrate that MPs derived from ncRNAs have expression patterns associated with specific breast cancer subtypes and tumor specificity, thus highlighting their potential as biomarkers for molecular classification. We also reinforce the relevance of MPs as biologically active molecules that play a role in breast tumorigenesis, besides their potential in peptide-based therapeutics.

Mast cell heparanase promotes breast cancer stem-like features via MUC1/estrogen receptor axis

Breast cancer is the most frequent type of tumor in women and is characterized by variable outcomes due to its heterogeneity and the presence of many cancer cell-autonomous and –non-autonomous factors. A major determinant of breast cancer aggressiveness is represented by immune infiltration, which can support tumor development. In our work, we studied the role of mast cells in breast cancer and identified a novel activity in promoting the tumor-initiating properties of cancer cells. Mast cells are known to affect breast cancer prognosis, but show different effects according to the diverse subtypes. Starting from the observation that co-injection of mast cells with limiting concentrations of cancer cells increased their in vivo engraftment rate, we characterized the molecular mechanisms by which mast cells promote the tumor stem-like features. We provide evidence that mast cell heparanase plays a pivotal role since both its activity and the stimulation of mast cells with heparan sulfate, the product of heparanase activity, are crucial for this process. Moreover, the pharmacological inhibition of heparanase prevents the function of mast cells. Our data show that soluble factors released by mast cells favor the expression of estrogen receptor in a MUC1-dependent manner. The MUC1/estrogen receptor axis is eventually essential for cancer stem-like features, specifically in HER2-negative cells, and promotes the capability of cancer cells to form mammospheres and express stem-related genes, also reducing their sensitivity to tamoxifen administration. Altogether our findings describe a novel mechanism by which mast cells could increase the aggressiveness of breast cancer uncovering a molecular mechanism displaying differences based on the specific breast cancer subtype.

Abstract C153: Transcriptome-wide study identifies unique pathway functional clusters associated with breast cancer subtypes in population with high indigenous american ancestry

Abstract Purpose: Breast cancer incidence and outcomes differ by US census racial/ethnic category. Since large-scale genetic studies of human disease are predominately focused on populations of European ancestry, little is known about breast cancer molecular biology in Hispanic/Latinos which can widen cancer health disparities due to suboptimal translation of discoveries into clinical practice or public health policy. We aim to identify most relevant pathways in breast cancer subtype differentiation in breast cancer patients from Peru and compared them with those obtained analyzing the Cancer Genome Atlas (TCGA) Breast Cancer (BRCA) dataset and with the published results of the Molecular Profile of Breast Cancer Study (MPBCS), a multi-country Latin American cohort. Patients and Methods: Formalin fixed paraffin embedded tumor tissues samples were whole exome sequenced for a total of 271 patients recruited by the Peruvian Breast Cancer Genomics Study (PEGEN-BC). Quality control was conducted to remove genes with low counts for PEGEN and TCGA-BRCA cohorts, and only female stage II-III breast cancer patients were kept for downstream analysis. Intrinsic tumor subtypes were classified using the estrogen receptor (ER) status-adjusted PAM50 method with genefu package in R. Differential gene expression and pathway analyses between subtypes were performed by the GSEA 4.3.2 software. [LF1] [CX2] Statistical and biological significance was determined using p-values < 0.1 and absolute value of enrichment score > 1.5. Top 20 pathways for each cohort were selected and ranked for comparison. Results: PAM50 classification of the PEGEN-BC cohort defined 20.2% of tumors as Luminal A (LumA), 27.9% as Luminal B (LumB), 27.1% as HER2E, 22.5% as Basal and 2.3% as Normal. Transcriptomic pathway analysis showed that most of the significantly changed pathways were similar to previous findings in the literature, for example, proliferation pathways being upregulated in LumB, HER2E and Basal tumors, compared to the LumA subtype, and a strong dependency on the estrogen pathways for LumA and LumB. Within cohorts, we identified novel clusters of pathways that share related functions. For example, 6 out of the 20 top significant pathways in LumB vs. HER2E comparison for the PEGEN-BC cohort were glycan/glycosylation-related, suggesting the possibility of tumor immune response differences between LumB and HER2E due to glycan related pathway differences among Peruvian patients. Conclusions: We identified novel pathway clusters associated with specific breast cancer subtypes in a population with high Indigenous American ancestry from Peru. Further analyses will be conducted next to explore if the observed patterns were specific to genetic ancestry background or observed independently of genetic ancestry. Citation Format: Chenghuiyun Xu, Valentina A. Zavala, David Rocke, Xiaosong Huang, Sandro Casavilca-Zambrano, Jeannie Navarro-Vásquez, Ruddy Liendo-Picoaga, Monica Calderón, Guillermo Valencia, Patricia Rioja, Carlos A Castañeda, Zaida Morante, Silvia P. Neciosup, Hugo A Fuentes, Julio E. Abugattas, Jose M. Cotrina, Luis A. Salinas, Marco Gálvez-Nino, Jovanny Zabaleta, Andrea S. Llera, Tatiana Vidaurre, Laura Fejerman. Transcriptome-wide study identifies unique pathway functional clusters associated with breast cancer subtypes in population with high indigenous american ancestry [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr C153.

Unveiling the mysteries of HER2-low expression in breast cancer: pathological response, prognosis, and expression level alterations

BackgroundThe novel anti-HER2 antibody drug conjugates (ADCs) can effectively improve the long-term survival of patients with HER2-low expression breast cancer. However, pathological responses to neoadjuvant therapy (NAT) within HER2-low expression breast cancer, the relationship between pathological response and prognosis and the transformation of HER2 status are all now poorly understood.MethodsThe patients with HER2-0 and HER2-low expression breast cancer receiving NAT at Harbin Medical University Cancer Hospital between Jan. 2014 and Nov. 2018 were retrospectively explored. HER2 low expression refers to the IHC 1 + or 2 + and FISH negative. The Kappa test was utilized for analyzing the consistency rate of HER2 expression. To evaluate disease-free survival (DFS) and overall survival (OS), this research employed both the Kaplan-Meier analysis and the Cox regression.ResultsIn this study, 178 patients with HER2-0 and 344 patients with HER2-low expression breast cancer were included. In comparison with the HER2-0 group, it is shown that patients in the HER2-low group have more possibility to be younger compared to those 50 years old (P < 0.014), have more premenopausal patients (P < 0.001), a higher proportion of hormone receptor (HR) positive patients (P < 0.001), and less proportion of stage III V patients (P < 0.034). When NAT was finished, the pCR rate became 23.6% in the HER2-0 group while 22.1% in the HER2-low group, and there was also a higher pCR rate in HR- patients in comparison with that in HR + patients (P < 0.01). Considering HER2 expression inconsistency, the overall HER2 inconsistency rate was 30.4% (Kappa = 0.431, P < 0.01). Among patients initially diagnosed as HER2-0, 34% (N = 61) were re-diagnosed as HER2-low after NAT. After stratification by HR expression status, HR+/HER2-0 patients transformed to HER2-low after NAT in 37%, and 32% of HR- patients changed from HER2-0 to HER2-low. In this survival analysis, there were both better DFS rates (P = 0.009) and OS rates (P = 0.026) in the HR-/HER2-low patients in comparison with the HR-/HER2-0 patients, while the HER2-0 and HER2-low patients in the HR + group had no significant survival difference. Additionally, for non-pCR patients, there was better DFS (P = 0.029) and OS (P = 0.038) in the HER2-low group in comparison with that of the HER2-0 group, while no significant survival difference exists between pCR patients.ConclusionAfter HR stratification, there are unique clinical characteristics and prognostic outcomes in HER2-low expression breast cancer, which indicates the potential to become a specific molecular subtype of breast cancer. The significant instability of HER2-low expression status between primary tumor and residual invasive disease suggests that multiple detections of HER2 status should be emphasized in NAT strategies.

MiRNA-105–5p regulates the histone deacetylase HDAC2 through FOXG1 to affect the malignant biological behavior of triple-negative breast cancer cells

BackgroundTriple-negative breast cancer (TNBC) is a specific subtype of breast cancer (BC). Some potential molecular targets have been identified, and miR-105–5p was found to be abnormally expressed in TNBC tissues. ObjectiveThe objective of this study was to probe the effect of miR-105–5p on TNBC via FOXG1/HDAC2-mediated acetylation. MethodsAn animal model of TNBC was established by injecting BC cells into the axillary area of nude mice. The levels of miR-105–5p, FOXG1, HDAC2, Bcl-2, Bax, and Ki67 were detected via RT‒qPCR, Western blotting and immunohistochemistry. Flow cytometry, CCK-8, Transwell and colony formation assays were used to measure apoptosis, proliferation and migration, respectively. Total histone acetylation levels were measured by ELISA. The binding of FOXG1 to HDAC2 was detected by co-immunoprecipitation. The binding relationship between miR-105–5p and FOXG1 was verified using a dual-luciferase reporter gene assay. ResultsIn this study, miR-105–5p and HDAC2 were highly expressed in the MDA-MB-231 and BT-549 BC cell lines, whereas FOXG1 was expressed at low levels. The inhibition of miR-105–5p inhibited the proliferation and migration of MDA-MB-231 and BT-549 cells and promoted their apoptosis. Bioinformatics analysis revealed that miR-105–5p and FOXG1 had a negative targeting regulatory relationship. FOXG1 overexpression had a similar effect on cancer cells as the inhibition of miR-105–5p. Moreover, experiments revealed that FOXG1 and HDAC2 could bind to each other and that HDAC2 overexpression or treatment with the histone acetyltransferase inhibitor Garcinol weakened the effect of FOXG1 overexpression. In addition, FOXG1 knockdown inhibited the effect of the miR-105–5p inhibitor, while Garcinol treatment further enhanced the effect of FOXG1 knockdown, inhibited histone acetylation, promoted the proliferation and migration of cancer cells, and inhibited apoptosis. Moreover, the in vivo results confirmed the in vitro results. ConclusionmiR-105–5p promotes HDAC2 expression by reducing FOXG1, inhibits histone acetylation, and aggravates the malignant biological behavior of TNBC cells.

Enhancing precision in bone metastasis diagnosis for lobular breast cancer: reassessing the role of 18F-FDG PET/CT.

Detection of osseous metastases by imaging can be challenging in patients with invasive lobular breast cancer (ILC). ILC may demonstrate low metabolic rate due to lower tumor cell density, decreased proliferation rate, diffuse infiltration of surrounding tissue, and low level of GLUT-1 expression. The aim of this study is to assess the diagnostic accuracy of 18F-FDG PET/CT in identifying bone metastases in ILC patients. Out of 52 individuals diagnosed with lobular breast cancer and underwent 18F-FDG PET/CT for evaluation of metastases, 21 patients were included in our study population after applying inclusion and exclusion criteria. The radiological and clinical follow-up of at least 6 months served as the reference standard comparator. Bone metastases were confirmed in six patients. 18F-FDG PET/CT was true positive in two and false negative in four patients. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 18F-FDG PET/CT were 33.33, 93.33, 66.67, 77.78, and 76.19%, respectively (95% confidence interval). The tendency of ILC osseous metastases to be more sclerotic explains the low diagnostic accuracy of 18F-FDG PET/CT in detection of bone metastases, making it a less suited method of evaluation. The results of the present study indicate that 18F-FDG PET/CT has a low diagnostic accuracy in detecting bone metastases in lobular breast cancer and, by inference, new functional modalities can be explored in these patients. The findings contribute valuable insights to optimize the integration of molecular imaging into the diagnostic algorithm for this specific breast cancer subtype.

Ultrasound Controllable Release of Proteolysis Targeting Chimeras for Triple-Negative Breast Cancer Treatment.

Triple-negative breast cancer (TNBC) is a special subtype of breast cancer, which is highly aggressive and incurable. Here, we proposed an ultrasound activatable bromodomain-containing protein 4 (BRD4) proteolysis targeting chimera (PROTAC) release strategy for the first time for precisely controlled protein degradation in preclinical TNBC model. Through combination of PROTAC and ultrasound-targeted microbubble destruction (UTMD) technology, the present strategy also aims to concurrently solve the major limitations of poor loading capacity of microbubbles and undesirable targeting and membrane permeability of PROTAC. PROTAC (ARV-825)-encapsulated microbubbles, ARV-MBs, were developed for the efficacious treatment of TNBC invitro and invivo. The microbubbles we synthesized showed ultrasound-responsive drug release ability, which could effectively promote the penetration of PROTAC into tumor site and tumor cell. Under ultrasound, ARV-MBs could play an effective antitumor effect by potentiating the ubiquitination and degradation of BRD4 in tumor. The current study may provide a new idea for promoting clinical translation of drug-loaded microbubbles and PROTAC, and offer a new efficacious therapeutic modality for TNBC.

NNBGWO-BRCA marker: Neural Network and binary grey wolf optimization based Breast cancer biomarker discovery framework using multi-omics dataset

Background and ObjectiveBreast cancer is a multifaceted condition characterized by diverse features and a substantial mortality rate, underscoring the imperative for timely detection and intervention. The utilization of multi-omics data has gained significant traction in recent years to identify biomarkers and classify subtypes in breast cancer. This kind of research idea from part to whole will also be an inevitable trend in future life science research. Deep learning can integrate and analyze multi-omics data to predict cancer subtypes, which can further drive targeted therapies. However, there are few articles leveraging the nature of deep learning for feature selection. Therefore, this paper proposes a Neural Network and Binary grey Wolf Optimization based BReast CAncer bioMarker (NNBGWO-BRCAMarker) discovery framework using multi-omics data to obtain a series of biomarkers for precise classification of breast cancer subtypes. MethodsNNBGWO-BRCAMarker consists of two phases: in the first phase, relevant genes are selected using the weights obtained from a trained feedforward neural network; in the second phase, the binary grey wolf optimization algorithm is leveraged to further screen the selected genes, resulting in a set of potential breast cancer biomarkers. ResultsThe SVM classifier with RBF kernel achieved a classification accuracy of 0.9242 ± 0.03 when trained using the 80 biomarkers identified by NNBGWO-BRCAMarker, as evidenced by the experimental results. We conducted a comprehensive gene set analysis, prognostic analysis, and druggability analysis, unveiling 25 druggable genes, 16 enriched pathways strongly linked to specific subtypes of breast cancer, and 8 genes linked to prognostic outcomes. ConclusionsThe proposed framework successfully identified 80 biomarkers from the multi-omics data, enabling accurate classification of breast cancer subtypes. This discovery may offer novel insights for clinicians to pursue in further studies.

Role of ICAM-1 in triple-negative breast cancer.

Intercellular adhesion molecule-1 (ICAM-1) is related to the occurrence and development of a variety of tumors. However, the role of ICAM-1 in the regulation of growth, metastasis, and clinical prognosis of the specific molecular subtypes of breast cancer, triple-negative breast cancer (TNBC), remains to be elucidated. This study explored the role of ICAM-1 in breast cancer and its triple-negative subtypes by systematic bioinformatics methods. The results showed that the expression of ICAM-1 in breast cancer tissues was significantly higher than that in normal tissues, especially in TNBC subtypes. In breast cancer, ICAM-1 mainly activates pathways related to apoptosis and epithelial-mesenchymal transition, while its overexpression in TNBC is associated with inflammatory response, apoptosis, and other processes. TNBC patients displaying higher ICAM-1 expression demonstrate enhanced responses to immunotherapy. High ICAM-1 expression is sensitive to drugs targeting tumor cell proliferation, apoptosis, and angiogenesis. In conclusion, breast cancer is characterized by significantly high expression of ICAM-1, with TNBC subtypes expressing ICAM-1 at much higher levels than other subtypes. The diagnosis, prognosis, development, distant metastases, and immunotherapy of TNBC are correlated with high expression of ICAM-1. This research provides available data for the further study of the diagnosis and treatment of TNBC.

Predictive value of pretreatment circulating inflammatory response markers in the neoadjuvant treatment of breast cancer: meta-analysis.

Systemic inflammatory response markers have been found to have a prognostic role in several cancers, but their value in predicting the response to neoadjuvant chemotherapy in breast cancer is uncertain. A systematic review and meta-analysis of the literature was carried out to investigate this. A systematic search of electronic databases was conducted to identify studies that explored the predictive value of circulating systemic inflammatory response markers in patients with breast cancer before commencing neoadjuvant therapy. A meta-analysis was undertaken for each inflammatory marker where three or more studies reported pCR rates in relation to the inflammatory marker. Outcome data are reported as ORs and 95% confidence intervals. A total of 49 studies were included, of which 42 were suitable for meta-analysis. A lower pretreatment neutrophil-to-lymphocyte ratio was associated with an increased pCR rate (pooled OR 1.66 (95% c.i. 1.32 to 2.09); P < 0.001). A lower white cell count (OR 1.96 (95% c.i. 1.29 to 2.97); P = 0.002) and a lower monocyte count (OR 3.20 (95% c.i. 1.71 to 5.97); P < 0.001) were also associated with a pCR. A higher lymphocyte count was associated with an increased pCR rate (OR 0.44 (95% c.i. 0.30 to 0.64); P < 0.001). The present study found the pretreatment neutrophil-to-lymphocyte ratio, white cell count, lymphocyte count, and monocyte count of value in the prediction of a pCR in the neoadjuvant treatment of breast cancer. Further research is required to determine their value in specific breast cancer subtypes and to establish optimal cut-off values, before their adoption in clinical practice.

Exploring the epigenetic profile of ID4 in breast cancer: bioinformatic insights into methylation patterns and chromatin accessibility dynamics.

Inhibitor of differentiation 4 (ID4) is a dominant-negative regulator of basic helix-loop-helix (bHLH) transcription factors. The expression of ID4 is dysregulated in various breast cancer subtypes, indicating a potential role for ID4 in subtype-specific breast cancer development. This study aims to elucidate the epigenetic regulation of ID4 within breast cancer subtypes, with a particular focus on DNA methylation and chromatin accessibility. Bioinformatic analyses were conducted to assess DNA methylation and chromatin accessibility in ID4 regulatory regions across breast cancer subtypes. Gene Set Enrichment Analysis (GSEA) was conducted to identify related gene sets. Transcription factor binding within ID4 enhancer and promoter regions was explored. In vitro experiments involved ER+ breast cancer cell lines treated with estradiol (E2) and Tamoxifen. Distinct epigenetic profiles of ID4 were observed, revealing increased methylation and reduced chromatin accessibility in luminal subtypes compared to the basal subtype. Gene Set Enrichment Analysis (GSEA) implicated estrogen-related pathways, suggesting a potential link between estrogen signaling and the regulation of ID4 expression. Transcription factor analysis identified ER and FOXA1 as regulators of ID4 enhancer regions. In vitro experiments confirmed the role of ER, demonstrating reduced ID4 expression and increased methylation with estradiol treatment. Conversely, Tamoxifen treatment increased ID4 expression, indicating the potential involvement of ER signaling through ERα in the epigenetic regulation of ID4 in breast cancer cells. This study shows the intricate epigenetic regulation of ID4 in breast cancer, highlighting subtype-specific differences in DNA methylation and chromatin accessibility.

Abstract PO3-20-07: Five years and counting: A case of a 47-year-old female with De Novo Metastatic HER2 positive disease on multiple lines of treatment

Abstract HER2-positive breast cancer refers to a specific subtype of breast cancer characterized by the overexpression or amplification of the human epidermal growth factor receptor 2 (HER2) protein on the surface of cancer cells. The overexpression of HER2 leads to increased signaling pathways that promote cell growth and division, making HER2-positive breast cancer inherently more aggressive compared to other subtypes. The aggressive behaviour of HER2-positive disease may be attributed to its rapid cell growth, high metastatic potential, and increased risk of recurrence. Fortunately, there are targeted therapies that specifically inhibit the HER2 protein. These targeted treatments help to block HER2 signaling, slow down tumor growth, and reduce the risk of recurrence. We report a case 47 year old premenoapausal Filipino female diagnosed with de-novo metastatic HER2-positive breast cancer with liver and lung metastasis in 2018. Advised Pertuzumab Trastuzumab and Taxane therapy but due to financial constraints was amenable only to Trastuzumab and Paclitaxel. During treatment noted symptomatic cardiac decline, hence shifted to Lapatinib &amp; Capecitabine, tolerated well with stable disease for 1 year. Disease then progressed to the contralateral breast, given 6 cycles of Ado Trastuzumab Emtansine with partial response followed by modified radical mastectomy of the right and toilet total mastectomy of the left breast. She was lost to follow up. Her cancer recurred 1 year later as skin lesions on chest wall. She was given 6 cycles of Ado Trastuzumab Emtansine, however still with progression as skin lesions on the chest. Patient was then given 5 cycles of Trastuzumab with Eribulin. Despite treatment, there was progression with symptomatic brain metastasis and further increase in size and number of skin metastasis of the chest wall. Lesions were noted to be ulcerating and bleeding. Hence patient underwent 5 of 5 sessions of Fractionated stereotactic radiation therapy and 10 of 10 sessions of palliative radiotherapy to the chest wall. Patient was then given Pertuzumab &amp; Trastuzumab with note of improvement of chest wall lesions. However, after 7 cycles of treatment, noted progression again as skin metastasis on the chest wall. Hence patient was shifted to Trastuzumab Deruxtecan. At the time of writing, the patient has had a good response with Fam-Trastuzumab Deruxtecan-nxki with partial resolution of her skin metastases on the chest with stable disease of lung and brain target lesions. No bleeding or ulcerations of the lesions and no recurrence of dizziness or imbalance reported. The patient will continue to receive Fam-Trastuzumab Deruxtecan-nxki until disease progression and/or unacceptable toxicity. Here we have a case of patient with extended survival after being fortunate to have received multiple lines of treatment for the disease. In this case we were able to apply the advances of research in HER2-positive breast cancer and see it in the clinical setting. Thus, ultimately translating to extended overall survival for the patient. We see the importance of continuous research on HER2-positive breast cancer disease and how these studies have helped us in overcoming treatment resistance, understanding disease progression, tailoring of therapies to individual patients, optimizing treatment outcomes, developing new therapies, and enhancing the quality of life for patient. Ongoing research continues to explore new therapeutic approaches and strategies to further improve outcomes for individuals with metastatic HER2-positive breast cancer. This is truly an exciting time for cancer research because what used to be a very deadly disease is now becoming something that we are able manage. Citation Format: Sofia Dominique Unson, Rubi Li. Five years and counting: A case of a 47-year-old female with De Novo Metastatic HER2 positive disease on multiple lines of treatment [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 PO3-20-07.

Abstract PO2-08-04: Unraveling alterations in the pre-neoplastic breast microenvironment of BRCA1/2 mutation carriers using spatial transcriptomics

Abstract Breast cancer is the most common cancer in females, affecting one in every eight women and accounting for the majority of cancer-related deaths in women worldwide. Germline mutations in the BRCA1 and BRCA2 genes are significant risk factors for specific subtypes of breast cancer. BRCA1 mutations are associated with basal-like breast cancers, whereas BRCA2 mutations are associated with luminal-like disease. There are currently few chemoprevention strategies available for BRCA1/2 mutation carriers, and irreversible prophylactic mastectomy is the primary option. Designing chemo-preventive strategies requires an in-depth understanding of the physiological processes underlying tumor initiation. Here, we employ spatial transcriptomics to investigate defects in mammary epithelial cell differentiation accompanied by distinct microenvironmental alterations in preneoplastic breast tissues from BRCA1/2 mutation carriers and normal breast tissues from non-carrier controls. We uncovered spatially defined receptor-ligand interactions in these tissues for the investigation of autocrine and paracrine signaling. We discovered that β1-integrin-mediated autocrine signaling in BRCA2-deficient mammary epithelial cells differs from BRCA1-deficient mammary epithelial cells. In addition, we found that the epithelial-to-stromal paracrine signaling in the breast tissues of BRCA1/2 mutation carriers is greater than in control tissues. More integrin-ligand pairs were differentially correlated in BRCA1/2-mutant breast tissues than non-carrier breast tissues with more integrin receptor-expressing stromal cells. These results reveal alterations in the communication between mammary epithelial cells and the microenvironment in BRCA1 and BRCA2 mutation carriers, laying the foundation for designing innovative breast cancer chemo-prevention strategies for high-risk patients. Citation Format: Mihriban Karaayvaz, Anthony Caputo, Kavya Vipparthi, Peter Bazeley, Erinn Downs-Kelly, Patrick McIntire, Ying Ni, Bo Hu, Ruth Keri. Unraveling alterations in the pre-neoplastic breast microenvironment of BRCA1/2 mutation carriers using spatial transcriptomics [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 PO2-08-04.

Abstract PO1-14-03: Discovery of proliferation essential gene signature and ACTL6A as potential biomarker for predicting prognosis and neoadjuvant therapy response in triple-positive breast cancer

Abstract Background: Based on the expression of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), a special subtype of breast cancer which expresses all three receptors can be distinguished, namely triple-positive breast cancer (TPBC). TPBC patients has a higher risk of recurrence and lower survival rate compared to other luminal breast cancers. However, there are few studies on predicting molecules of prognosis and treatment response for TPBC. Methods: Proliferation essential genes (PEGs) were identified using CRISPR-Cas9 dataset of DepMap. The expression profiles and clinical data of TPBC were obtained from the TCGA database, GEO datasets and our center cohort. To develop a TPBC-PEG prognostic signature, cox regression and Lasso (Least absolute shrinkage and selection operator) regression analysis were applied. Functional analysis was performed using Gene Set Enrichment analysis. Finally, the relationship between candidate genes and neoadjuvant therapy (NAT) sensitivity was explored using real-time qPCR (RT-qPCR) and immunohistochemistry (IHC) based on clinical samples. Results: Among 900 TPBC-PEGs, 437 genes showed significant differential expression between TPBC and normal tissues. Subsequently, we identified 3 prognostic PEGs (ACTL6A, CCT2, TARS) and used them to construct a PEG signature. Patients with high PEG signature scores exhibited worse overall survival and lower sensitivity to NAT compared to those with low PEG signature scores. RT-qPCR indicated that in patients who lacked sensitivity to NAT, ACTL6A and CCT2 were significantly upregulated. The IHC results showed that ACTL6A protein was highly expressed in the NAT-insensitive group and non-pathological complete response patients. Conclusion: In this study, we developed an efficient PEG prognostic model that can predict the outcome for TPBC. Furthermore, we found that the expression of ACTL6A is associated with neoadjuvant therapy sensitivity in TPBC patients and can serve as an important factor in predicting patient prognosis and drug sensitivity. Figure 3. Construction and validation of a PEG signature for TPBC patients. Figure 6. The predictive value of ACTL6A on NAT efficacy and its correlation with clinical characteristics. Citation Format: Xiaofen Li, Wenfen Fu, Shiping Luo, Jie Zhang, Qingshui Wang, Chuangui Song. Discovery of proliferation essential gene signature and ACTL6A as potential biomarker for predicting prognosis and neoadjuvant therapy response in triple-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 PO1-14-03.

Abstract PO4-16-03: Ectopic expression of lineage-specific transcription factors in Breast Cancer

Abstract Background: Lineage-specific transcription factors (LTFs) are purported to define cellular lineages and their expression could be used to identify subtypes of cancer. In many cancers, tuft cell differentiation appears to have prognostic impact. However, such differentiation has not been documented in breast cancer. Methods: We sought to study the fidelity of LTFs (MYOG, POU2F3, FOXA1, FOXA2, FOXA3, FOXJ1, HNF4A, HNF4G, SPIB, SOX8, GRHL1, GRHL2, and GRHL3) for their presence and prognostic impact in breast cancer. Single cell RNA data from GSE 161529, which contains 421,761 single cells, was downloaded and analyzed for the expression and co-expression of LTFs. The data was first subdivided based on ER+ and TNBC status. Analysis was performed using cells from 10ER+ samples and 4 TNBC samples. Cell clustering using Louvain’s method was run using all genes. Cell type assignment was then performed using well-known markers for both tumor and lymphocyte marker from existing publications. Further analysis was restricted to keratin expressing cells and to study the presence and co-expression of LTFs in the epithelial cells. KM-Plotter was employed to determine the prognostic value of these LTFs. The analysis was further stratified by expression of estrogen receptor positive and negative status. The endpoint of relapse free survival was used, as it provided data on the largest number of patients. Results: Single-cell analysis pipeline successfully identified distinct populations of tumor epithelial cells accompanied by various lymphocytes, including B cells, CD8+ T cells, CD4+ T cells, dendritic cells, and macrophages, in both ER+ tumors and TNBC tumor samples. We further confirmed the expression of the LTFs in the epithelial (keratin+) compartment. Expression of all LTFs (except MYOG, and FOXA2) was scattered in the different epithelial clusters. Further analysis of single LTFs showed differentiational co-expression based on ER+ status. POU2F3+/ER+ cells also co-expressed FOXA1 and GRHL1 while POU2F3+/ER- cells were GRHL1+ and (weak) SPIB+. The analysis of LTFs using KM-Plotter tool revealed their expression documenting multiple cell lineages in breast cancer; this was noted in ER+, HER2+ cancers and TNBCs. The directionality of the outcome (good or bad prognosis) varied with the specific TFs and subtype of breast cancer. High expression of POU2F3, and FOXA1, and SPIB were associated with better relapse-free survival (RFS) in ER+ breast cancer. POU2F3, FOXA2, FOXA3 were associated with worse RFS, whereas SPIB was with prognosis in ER- breast cancers. Conclusions: We for the first time document the expression of LTFs in breast cancer and their prognostic relevance based on ER+ and ERneg status. Expression of POU2F3, a marker of tuft cells which are known to regulate immune response, was noted to be associated with improved outcomes in ER+ tumors. Further characterization of the relevance of LTFs and their co-expression with respect to therapeutic response is ongoing. Citation Format: Sunil Badve, Jian Hu, Yu Zhang, Yesim Gokmen-Polar. Ectopic expression of lineage-specific transcription factors in 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 PO4-16-03.

Abstract PO1-27-07: Is HER2-low a biologically distinct breast cancer (BC) subtype? Prognosis and pathological complete response rate after neoadjuvant treatment (NAT) in early breast cancer (BC) HER2 negative

Abstract Background: Overexpression of HER2 is a significant prognostic and predictive factor in early breast cancer. HER2 positive tumors are those scored by immunohistochemistry (IHC) 3+ or 2+ with amplification by in situ hybridization (ISH). These tumors may benefit from HER2-targeted treatment and additionally, in early HER2-positive BC, achieving a complete pathological response after neoadjuvant treatment improves patient survival. In recent years, new anti-HER2 antibody-drug conjugates have proven effective for HER2 low BC (defined as IHC score 1+ or 2+ not amplified) in the metastatic disease setting; however, in HER2-low early BC, studies testing novel anti-HER2 antibody-drug conjugates as neoadjuvant therapy (NAT) are ongoing. Currently, we don´t know exactly whether HER2 expression can influence the pathological response rate after NAT or disease-free survival (DFS) in these patients compared to HER2-zero (IHC 0). The aim of our study is to determine the impact on response rate to NAT and survival outcomes in early HER2-negative BC. Methods: We conducted a retrospective study in two hospitals in Andalucia, Spain. Patients with early HER2 negative BC treated with NAT from January 2015 to June 2022 were included. Patients were divided into HER2 low patients (IHC 1+ or 2+ not amplified) and HER2 0 (IHC 0). We collected clinical and pathological characteristics, pathological response rate using the Residual Cancer Burden (RCB) system where a complete pathological response (pCR) was defined as ypT0/ypTis and ypN0, and survival outcomes. The primary objective of the study was to analyze the pCR rate after NAT according to HER2 score, and secondary objectives were to assess disease-free survival and overall survival (DFS and OS rates). Results: 574 patients were included (100% women). 397 patients had hormone receptors (luminal BC) on these tumors, and 177 did not have them, i.e., triple-negative BC (TNBC). 225 patients were HER2-zero, and 312 patients were HER2-low (253/312 patients had luminal BC and 59/312 patients were TNBC). The pCR in HER2-low patients was 17.3% and 23.1% in HER2-zero patients (p=0.047). For luminal BC patients, the pCR was 16.7% in HER2-low tumors and 13.7% in HER2-zero tumors (p=0.29). Similarly, there was no difference in pCR rates in TNBC patients (45.8% in HER2-low and 53.8% in HER2-zero tumors, respectively, (p=0.958). The overall survival (OS) at 96 months was 88.7% (95% CI 85.6%-92%). Regarding survival outcomes, neither HER2 expression level was associated with higher 8-year DFS: 81.1% in HER2-low patients (95% CI 75.7%-86.8%) and 74.9% in HER2-zero patients (95% CI 62.3%-90.1%) p=0.64. There was no difference between histological subtypes at 8-years regarding DFS rate: 80.5% (95% CI 74.3%-87.2%) in luminal HER2-low patients and 76.3% (95% CI 60.8%-95.7%) in luminal HER2-zero patients, p=0.22; 83.8% in TNBC HER2-low (95% CI 74.5%-94.2%) and 77.5% in TNBC HER2-zero patients (95% CI 69.4%-86.6%) p=0.26. We also didn´t find significant differences in terms of OS. For HER2-low patients, the 8-year OS was 90.9% (95% CI 87%-94.9%) and for HER2-zero patients, it was 86.4% (95% CI 80.8%- 92.5%) p=0.46. There were also no differences in OS for different histological subgroups with an 8-year OS in luminal HER2-low breast cancer patients of 92.5% (95% CI 88%-96.7%) and 87% in HER2-zero (95% CI 78.9%-96.1%) p=0.91. In patients with triple-negative breast cancer phenotype, the OS was 84.2% for HER2-low (95% CI 74.5%-95.2%) and 85.3% for HER2-zero (95% CI 77.9%-93.4%) p=1. Conclusions: We found no difference in survival outcomes and response rate to conventional NAT between HER2-low and HER2-zero expression levels. Therefore, our data do not support the hypothesis of HER2-low as a biologically specific breast cancer subtype. Further research on this approach with HER2 antibody-drug conjugate schemes as an alternative to traditional NAT schemes is warranted. Citation Format: Ana Gil-Torralvo, Yeray Rodriguez, Alejandro Falcon, David Morales, Mónica Cejuela, Isabel Miras, Marta Amérigo, Manuel Ruíz - Borrego, Juan Bayo, Francisco Javier Salvador Bofill. Is HER2-low a biologically distinct breast cancer (BC) subtype? Prognosis and pathological complete response rate after neoadjuvant treatment (NAT) in early breast cancer (BC) HER2 negative [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 PO1-27-07.

Abstract PO2-01-14: Development of Artificial Intelligence-based Machine Learning Models for Predicting Survival In Hormone-Receptor-Positive/HER2-Negative Early Breast Cancer undergoing Neoadjuvant Chemotherapy

Abstract Background. In hormone-receptor positive (HoR)/HER2 negative early breast cancer (BC) multiple efforts have been made to predict disease recurrence and survival. Machine learning techniques have been used but few studies have looked into their applicability in predicting survival on the basis of clinico-pathological characteristics. The aim of this study was to evaluate a random survival forest model to predict the prognosis of this specific BC subtype. Methods. In this multicenter, retrospective study, patients who fulfilled the following inclusion criteria were included: (1) diagnosis of pathologically confirmed HoR-positive/HER2-negative invasive BC; (2) early or locally advanced, stage I-II-III (3) patients receiving neoadjuvant anthracycline and/or taxane-based chemotherapy, concurrently or sequentially; (4) patients undergoing surgery for primary BC. Survival endpoints were disease-free survival (DFS) and overall survival (OS). A random survival forest algorithm was used to develop the predictive model. Ten-fold cross-validation was performed. The C-index and the continuous rank probability score (CRPS) were used to evaluate the discrimination of the predictive model, and a ROC curve was used to evaluate model precision. A cut point analysis based on maximally selected rank statistics was conducted to evaluate the best cut-off in the out-of-bag (OOB) mortality that could maximize DFS and OS prediction. Variable importance was assessed using Breiman-Cutler permutation importance. Results. Overall, 572 patients with HoR-positive/HER2-negative early BC were included. At univariate analysis age, T stage, N stage, grading, ER, PR and Ki67 were found to be significantly associated with DFS and ER, PgR, HER2, pCR ypT and ypN retained statistical significance at multivariate analysis. ER, pCR, pathological T and N stage were found to be significantly associated with OS at univariate and multivariate analysis. The following variables were included in the final model: menopausal status, age, histology, grade, clinical T/N, ER/PgR, Ki67 and HER2, pathological complete response (pCR), ypT and ypN. For DFS, the cross-validated C-index was 0.68 (95% CI 0.63-0.73) and the OOB CRPS was 0.15, with a OOB performance error of 0.31. The AUC calculated at 60 months was 0.91 (95% CI 0.88-0.94). Out-of bag RSF-based risk scores for individual patients were calculated and an optimal cut-off of 22.58 was identified. The HR between high risk and low risk group was 3.08 (95% CI 2.16-4.39, p&amp;lt; 0.001). For OS, the cross-validated C-index was 0.66 (95% CI 0.60-0.71) and the OOB CRPS was 0.17, with a OOB performance error of 0.35. The AUC calculated at 60 months 0.91 (95% CI 0.88-0.95). An optimal cut-off of 21.54 was identified and the HR between low risk and high risk group was 2.50 (95% CI 1.73-3.61, p&amp;lt; 0.001). For DFS, the most important variables were cN (9.00), ypN (7.35), ER (7.21), ypT (5.38), PgR (4.11), pCR (4.01) and age (2.82) while for OS the most important variables were cN (7.88), ER (5.37), PgR (3.61), age (3.37), pCR (2.80), ypT (2.64) and ypN (2.60). Discussion. We analyzed the performance of RSF in the prediction of DFS and OS based on the contribution of clinico-pathological features commonly available at the baseline of the NCT and post-surgery. By selecting patients with HoR-positive HER2-negative disease, we were able to show which clinico-pathological features within a ML model have greater predictive importance. The model could be integrated with image-based tumor and radiology features to improve its predictive accuracy. This retrospective multicenter study suggests that the combination of easily accessible clinico-pathological features within a ML model may reliably predict DFS and OS in the context of HoR-positive/HER2-negative BCs. Citation Format: Luca Mastrantoni, Giovanna Garufi, Noemi Maliziola, Elena Di Monte, Giorgia Arcuri, Valentina Frescura, Angelachiara Rotondi, Giulia Giordano, Luisa Carbognin, Alessandra Fabi, Ida Paris, Gianluca Franceschini, Armando Orlandi, Antonella Palazzo, Giovanni Scambia, Giampaolo Tortora, Emilio Bria. Development of Artificial Intelligence-based Machine Learning Models for Predicting Survival In Hormone-Receptor-Positive/HER2-Negative Early Breast Cancer undergoing Neoadjuvant Chemotherapy [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 PO2-01-14.

Selective impact of ALK and MELK inhibition on ERα stability and cell proliferation in cell lines representing distinct molecular phenotypes of breast cancer

Breast cancer (BC) is a leading cause of global cancer-related mortality in women, necessitating accurate tumor classification for timely intervention. Molecular and histological factors, including PAM50 classification, estrogen receptor α (ERα), breast cancer type 1 susceptibility protein (BRCA1), progesterone receptor (PR), and HER2 expression, contribute to intricate BC subtyping. In this work, through a combination of bioinformatic and wet lab screenings, followed by classical signal transduction and cell proliferation methods, and employing multiple BC cell lines, we identified enhanced sensitivity of ERα-positive BC cell lines to ALK and MELK inhibitors, inducing ERα degradation and diminishing proliferation in specific BC subtypes. MELK inhibition attenuated ERα transcriptional activity, impeding E2-induced gene expression, and hampering proliferation in MCF-7 cells. Synergies between MELK inhibition with 4OH-tamoxifen (Tam) and ALK inhibition with HER2 inhibitors revealed potential therapeutic avenues for ERα-positive/PR-positive/HER2-negative and ERα-positive/PR-negative/HER2-positive tumors, respectively. Our findings propose MELK as a promising target for ERα-positive/PR-positive/HER2-negative BC and highlight ALK as a potential focus for ERα-positive/PR-negative/HER2-positive BC. The synergistic anti-proliferative effects of MELK with Tam and ALK with HER2 inhibitors underscore kinase inhibitors’ potential for selective treatment in diverse BC subtypes, paving the way for personalized and effective therapeutic strategies in BC management.

Triple Negative Breast Cancer (TNBC): Cannabis sativa-Role of Phytocannabinoids

This review paper highlights the role of phytocannabinoids in controlling triple-negative breast cancer (TNBC). Triple-negative breast cancer (TNBC) is a specific subtype of breast cancer that does not express estrogen receptor (ER), progesterone receptor (PR), or human epidermal growth factor receptor 2 (HER-2), which has clinical features that include high invasiveness, high metastatic potential, proneness to relapse, and poor prognosis. TNBC is one of the most aggressive subtypes of breast cancer that is often associated with poor patient outcomes because of the development of metastases in secondary organisms like in the brain, bone, and lungs. Triple-negative breast cancer (TNBC) is a kind of breast cancer that does not have any of the receptors that are commonly found in breast cancer. The highest number of TNBC cases has been recorded in India. Currently, TNBC is highly prevalent among Indian women and develops approximately 20% to 43% of all patients with breast cancer. Triple-negative breast cancer (TNBC) is an aggressive malignancy that requires effective targeted drug therapy. Patients with TNBC develop metastasis and recurrence over time and have reduced survival compared to patients with other subtypes of breast cancer. Pre-clinical studies have demonstrated that phytocannabinoids exert important antitumor properties in the main breast cancer subtypes, particularly in TNBC, where different phytocannabinoids and synthetic cannabinoids have shown interesting therapeutic actions. Neither CBD nor THC are universally efficacious in reducing cancer cell viability. Focusing on in vitro studies, the effect of CBD on cancer cell viability ranges from no effect, to a modest reduction, and to significant cytotoxicity depending on concentrations, cancer cell lines, cell growth conditions, the performed assays, and the time of CBD exposure. However, it should also be noted that research into the efficacy, dosage and drug safety of cannabinoids in tumor therapy still has a long way to go, especially with regard to human clinical trials to be conducted, through which alone the benefits and advantages for cancer patients but also possible risks can be defined.