Breast Tumor Biology Research Articles

Abstract PS01-07: Impact of Race and Ethnicity on Recurrence Risk in Patients with Ductal Carcinoma in Situ Treated with Breast-Conserving Surgery

Abstract Background: Among women with invasive breast cancer, clinical presentation, tumor biology and survival vary by race and ethnicity. However, the impact of race and ethnicity on clinical presentation and recurrence risk in women with ductal carcinoma in situ (DCIS) treated with breast-conserving surgery (BCS) has not been well studied. We sought to compare rates of recurrence in women with DCIS across racial and ethnic groups and identify factors associated with recurrence. Methods: Patients with DCIS treated with BCS from 1978 to 2016 at a single institution were identified. Patients were grouped and analyzed based on self-reported race and ethnicity as: Asian, Hispanic, non-Hispanic Black (Black), non-Hispanic White (White). Individuals with undefined ethnicity were classified by race, while those lacking both race and ethnicity data were excluded. Clinicopathologic characteristics were compared across racial and ethnic groups. The association of race and ethnicity on recurrence risk was analyzed using Kaplan–Meier methods, competing risk analysis and multivariable analysis. Results: Overall, 4207 cases were included, of which 6% (n= 261) were Asian, 9% (n = 358) Black, 5% (n = 226) Hispanic and 80% (n = 3362) White. Median age was 57 years (IQR 49, 67), 56% received radiotherapy (RT) and 26% received endocrine therapy. Black women with DCIS were older; Asian women were younger (median age: 60 vs 53 respectively, p < 0.001). Black women were more likely to have a clinical presentation (p = 0.006), and Black and Hispanic women were more likely to require ≥3 excisions (p = 0.006). The use of RT was most common among Hispanic women (p = 0.02). At a median follow-up of 8.8 years, 602 (14%) had local recurrence (LR) (315 [52%] DCIS; 284 [47%] invasive and 3 [ < 1%] unknown). The 10-year rate of LR was 15% and was lower in those treated with RT than without (11% vs 20%, respectively; p< 0.0001), despite those receiving RT having more high-risk characteristics. Rates of LR varied significantly by race and ethnicity, with the highest 10-year rate in Black women (25%) compared with Asian (11%), Hispanic (15%) and White (14%) women (p = 0.03). This statistically significant difference persisted among the no RT cohort (10-year rate: 31% [Black], 13% [Asian], 25% [Hispanic], 19% [White], p = 0.043), but did not reach significance in the RT cohort (21% [Black], 9% [Asian], 9% [Hispanic] and 11% [White], p = 0.3). Using competing risk analysis, the risk of invasive recurrence was similar or lower than DCIS recurrence in each racial group with or without RT. After adjusting for other factors on multivariable analysis, there remained a higher risk of LR among Black women (hazard ratio [HR] 1.48, 95% CI 1.12-1.95, p = 0.01). Older age (p < 0.001), radiologic presentation (p = 0.02), margins ≥ 2 mm (p < 0.001), the use of endocrine therapy (p < 0.001) and the use of RT (p < 0.001) were associated with lower rates of LR (Table). Sixteen women (0.4%) developed distant disease, with similar rates among Asian (0%), Black (0.8%), Hispanic (0.9%) and White (0.3%) women (p = 0.2). Conclusion: Compared with Asian, Hispanic and White women, Black women with DCIS had a significantly higher rate of LR after BCS, even after adjusting for known clinicopathologic risk factors. Rates of distant recurrence were low, and similar across racial groups. These higher rates of LR should be considered when making decisions about adjuvant therapy. Table. Factors associated with local recurrence in women with ductal carcinoma in situ treated with breast-conserving surgery. HR, hazard ratio; CI confidence interval; Ref, referent. Citation Format: Natália Polidorio, V. Morgan Jones, Varadan Sevilimedu, Monica Morrow, Kimberly Van Zee, Andrea Barrio. Impact of Race and Ethnicity on Recurrence Risk in Patients with Ductal Carcinoma in Situ Treated with Breast-Conserving Surgery [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 PS01-07.

Biological Basis of Breast Cancer-Related Disparities in Precision Oncology Era.

Precision oncology is based on deep knowledge of the molecular profile of tumors, allowing for more accurate and personalized therapy for specific groups of patients who are different in disease susceptibility as well as treatment response. Thus, onco-breastomics is able to discover novel biomarkers that have been found to have racial and ethnic differences, among other types of disparities such as chronological or biological age-, sex/gender- or environmental-related ones. Usually, evidence suggests that breast cancer (BC) disparities are due to ethnicity, aging rate, socioeconomic position, environmental or chemical exposures, psycho-social stressors, comorbidities, Western lifestyle, poverty and rurality, or organizational and health care system factors or access. The aim of this review was to deepen the understanding of BC-related disparities, mainly from a biomedical perspective, which includes genomic-based differences, disparities in breast tumor biology and developmental biology, differences in breast tumors' immune and metabolic landscapes, ecological factors involved in these disparities as well as microbiomics- and metagenomics-based disparities in BC. We can conclude that onco-breastomics, in principle, based on genomics, proteomics, epigenomics, hormonomics, metabolomics and exposomics data, is able to characterize the multiple biological processes and molecular pathways involved in BC disparities, clarifying the differences in incidence, mortality and treatment response for different groups of BC patients.

Socioecologic Factors and Racial Differences in Breast Cancer Multigene Prognostic Scores in US Women

Disproportionately aggressive tumor biology among non-Hispanic Black women with early-stage, estrogen receptor (ER)-positive breast cancer contributes to racial disparities in breast cancer mortality. It is unclear whether socioecologic factors underlie racial differences in breast tumor biology. To examine individual-level (insurance status) and contextual (area-level socioeconomic position and rural or urban residence) factors as possible mediators of racial and ethnic differences in the prevalence of ER-positive breast tumors with aggressive biology, as indicated by a high-risk gene expression profile. This retrospective cohort study included women 18 years or older diagnosed with stage I to II, ER-positive breast cancer between January 1, 2007, and December 31, 2015. All data analyses were conducted between December 2022 and April 2023. The primary outcome was the likelihood of a high-risk recurrence score (RS) (≥26) on the Oncotype DX 21-gene breast tumor prognostic genomic biomarker. Among 69 139 women (mean [SD] age, 57.7 [10.5] years; 6310 Hispanic [9.1%], 274 non-Hispanic American Indian and Alaskan Native [0.4%], 6017 non-Hispanic Asian and Pacific Islander [8.7%], 5380 non-Hispanic Black [7.8%], and 51 158 non-Hispanic White [74.0%]) included in our analysis, non-Hispanic Black (odds ratio [OR], 1.33; 95% CI, 1.23-1.43) and non-Hispanic American Indian and Alaska Native women (OR, 1.38; 95% CI, 1.01-1.86) had greater likelihood of a high-risk RS compared with non-Hispanic White women. There were no significant differences among other racial and ethnic groups. Compared with non-Hispanic White patients, there were greater odds of a high-risk RS for non-Hispanic Black women residing in urban areas (OR, 1.35; 95% CI, 1.24-1.46), but not among rural residents (OR, 1.05; 95% CI, 0.77-1.41). Mediation analysis demonstrated that lack of insurance, county-level disadvantage, and urban vs rural residence partially explained the greater odds of a high-risk RS among non-Hispanic Black women (proportion mediated, 17%; P < .001). The findings of this cohort study suggest that the consequences of structural racism extend beyond inequities in health care to drive disparities in breast cancer outcome. Additional research is needed with more comprehensive social and environmental measures to better understand the influence of social determinants on aggressive ER-positive tumor biology among racial and ethnic minoritized women from disadvantaged and historically marginalized communities.

Abstract 6108: Investigation of breast tumor biology and microenvironment in women of African descent using a single cell multiomic approach

Abstract Women of African descent are at an increased risk of developing and dying from aggressive subtypes of breast cancer. A connection between aggressive disease and Western Sub-Saharan African ancestry has been postulated, but it remains largely unknown to what extent breast cancer in Africa is reminiscent of breast cancer in U.S. African American (AA) women who experience disproportionately high mortality rates. We performed ATAC- and RNA-sequencing on 9 human triple-negative breast cancer cell lines of U.S. origin and discovered that African ancestry influences the chromatin landscape, leading to disparate transcription factor (TF) activity and downstream gene expression patterns indicative of an aggressive tumor biology. Here, we describe an ambitious study that employs single-nucleus (sn) ATAC- and RNA-sequencing (snMultiome) of frozen breast tumors to characterize chromatin accessibility and gene expression patterns with single-cell resolution in AA (n=33), Kenyan (n=25), and European American (EA, n=24) women in relation to genetic ancestry, risk factor exposures, clinical characteristics, and 5-year survival. To achieve this, we successfully isolated intact, high-quality single nuclei from archival frozen breast tumor tissue through an optimized combination of enzymatic digestion and automated tissue homogenization. We performed snMultiome sequencing of 82 tumors using the 10x Genomics platform. Following filtering, normalization (SCT for snRNA; LSI for snATAC), peak calling (MACS2), and integration (Harmony), our dataset includes a total of 296,557 nuclei. Cancerous (163,419 nuclei) and non-cancerous (133,138 nuclei) cells were distinguished based on DNA copy number (CopyKat). Within the microenvironment, 11 major immune, epithelial, and stromal cell types were successfully annotated, exhibiting distinct patterns by population group (e.g. AA tumors showed markedly increased abundance of myeloid and T-cells, while Kenyan tumors showed increased abundance of pericytes and fibroblasts). A large number of enriched TFs within each cell type varied significantly by population group, suggesting distinct chromatin accessibility patterns related to genetic ancestry. Within cancerous cells, striking intra- and inter-tumoral heterogeneity was observed by genetic ancestry even within molecular subtype groups. Current efforts focus on in-depth molecular characterization of ancestry- and risk factor-related differences in the tumor epithelium and microenvironment and distinct signatures present in lethal disease. This project holds the potential to yield crucial insights into how ancestry or other factors may influence the etiology of different breast cancer subtypes, as well as produce clinically actionable biomarkers and therapeutic targets to enhance precision medicine within patient populations at high risk for aggressive disease. Citation Format: Alexandra R. Harris, Huaitian Liu, Brittany Jenkins-Lord, Tiffany H. Dorsey, Francis Makokha, Shahin Sayed, Gretchen Gierach, Stefan Ambs. Investigation of breast tumor biology and microenvironment in women of African descent using a single cell multiomic approach [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6108.

Current status of optoacoustic breast imaging and future trends in clinical application: is it ready for prime time?

Optoacoustic imaging (OAI) is an emerging field with increasing applications in patients and exploratory clinical trials for breast cancer. Optoacoustic imaging (or photoacoustic imaging) employs non-ionizing, laser light to create thermoelastic expansion in tissues and detect the resulting ultrasonic emission. By combining high optical contrast capabilities with the high spatial resolution and anatomic detail of grayscale ultrasound, OAI offers unique opportunities for visualizing biological function of tissues in vivo. Over the past decade, human breast applications of OAI, including benign/malignant mass differentiation, distinguishing cancer molecular subtype, and predicting metastatic potential, have significantly increased. We discuss the current state of optoacoustic breast imaging, as well as future opportunities and clinical application trends. CLINICAL RELEVANCE STATEMENT: Optoacoustic imaging is a novel breast imaging technique that enables the assessment of breast cancer lesions and tumor biology without the risk of ionizing radiation exposure, intravenous contrast, or radionuclide injection. KEY POINTS: • Optoacoustic imaging (OAI) is a safe, non-invasive imaging technique with thriving research and high potential clinical impact. • OAI has been considered a complementary tool to current standard breast imaging techniques. • OAI combines parametric maps of molecules that absorb light and scatter acoustic waves (like hemoglobin, melanin, lipids, and water) with anatomical images, facilitating scalable and real-time molecular evaluation of tissues.

Psychosocial stressors and breast cancer gene expression in the Black Women's Health Study.

Prior studies indicate that the physiologic response to stress can affect gene expression. We evaluated differential gene expression in breast cancers collected from Black women with high versus low exposure to psychosocial stressors. We analyzed tumor RNA sequencing data from 417 Black Women's Health Study breast cancer cases with data on early life trauma and neighborhood disadvantage. We conducted age-adjusted differential gene expression analyses and pathway analyses. We also evaluated Conserved Transcriptional Response to Adversity (CTRA) contrast scores, relative fractions of immune cell types, T cell exhaustion, and adrenergic signaling. Analyses were run separately for estrogen receptor positive (ER+; n = 299) and ER- (n = 118) cases. Among ER+ cases, the top differentially expressed pathways by stress exposure were related to RNA and protein metabolism. Among ER- cases, they were related to developmental biology, signal transduction, metabolism, and the immune system. Targeted analyses indicated greater immune pathway enrichment with stress exposure for ER- cases, and possible relevance of adrenergic signaling for ER+ cases. CTRA contrast scores did not differ by stress exposure, but in analyses of the CTRA components, ER- breast cancer cases with high neighborhood disadvantage had higher pro-inflammatory gene expression (p = 0.039) and higher antibody gene expression (p = 0.006) compared to those with low neighborhood disadvantage. There are multiple pathways through which psychosocial stress exposure may influence breast tumor biology. Given the present findings on inflammation and immune response in ER- tumors, further research to identify stress-induced changes in the etiology and progression of ER- breast cancer is warranted.

Abstract C044: Investigation of breast tumor biology and microenvironment in women of African descent using a single cell multiomic approach

Abstract Women of African descent are at an increased risk of developing and dying from aggressive subtypes of breast cancer. A connection between aggressive disease and Western Sub-Saharan African ancestry has been postulated, but it remains largely unknown to what extent breast cancer in Africa is reminiscent of breast cancer in U.S. African American (AA) women who experience disproportionately high mortality rates. We performed ATAC- and RNA-sequencing on 9 human triple-negative breast cancer cell lines of U.S. origin and discovered that African ancestry influences the chromatin landscape, leading to disparate transcription factor activity and downstream gene expression patterns indicative of an aggressive tumor biology. Here, we describe an ambitious study that employs single-nucleus ATAC- and RNA-sequencing (snMultiome) of frozen breast tumors to characterize chromatin accessibility and gene expression patterns with single-cell resolution in AA (n=32), Kenyan (n=18), and European American (EA, n=20) women in relation to ancestry and risk factor exposure. In an initial pilot in 10 Kenyan women, we successfully isolated intact, high-quality single nuclei from frozen breast tumor tissue through an optimized combination of enzymatic digestion and an automated tissue homogenizer. We performed multiome sequencing on a total of 36525 nuclei across these 10 pilot tumors using the 10x Genomics platform. Following filtering, normalization (SCT for snRNA; LSI for snATAC), peak calling (MACS2), and integration (Seurat-v4 for snRNA; Harmony for snATAC), we characterized tumor, stromal, and immune cell populations (totaling 10 distinct cell types). We observed striking intra- and inter-tumoral heterogeneity across Kenyan women, with increased abundance of immune subpopulations (myeloid, T-cells, B-cells) in triple-negative subtypes. After demonstrating technical feasibility and success in this sample subset, we are now performing integration, cell type annotation, and downstream analyses in our larger cohort to characterize differences in both tumor biology and the tumor microenvironment in European American, African American, and Kenyan women at the single cell level. To date, 70 tumors spanning breast cancer subtypes have been sequenced. We are currently performing downstream analyses in this cohort to characterize ancestry- and risk factor-related differences in the tumor epithelium and microenvironment at the single-cell level. This project holds the potential to yield crucial insights into how ancestry or other factors may influence the etiology of different breast cancer subtypes, as well as produce clinically actionable biomarkers and therapeutic targets to enhance precision medicine within patient populations at high risk for aggressive disease. Citation Format: Alexandra R. Harris, Huaitian Liu, Brittany Jenkins-Lord, Francis Makokha, Shahin Sayed, Gretchen Gierach, Stefan Ambs. Investigation of breast tumor biology and microenvironment in women of African descent using a single cell multiomic approach [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr C044.

Abstract 474: Integrating imaging and multi-omics data to elucidate racial differences in breast tumor biology to optimize precision oncology approaches and patient outcome

Abstract Background: Racial disparities in breast cancer incidence and clinical outcome have been well characterized. In particular, African American (AA) patients have higher mortality rates than other racial groups. Research into these racial disparities has primarily focused on socioeconomic determinants, with some studies exploring potential molecular determinants and limited biological differences found between AA and Caucasian patient tumors. Tumor intrinsic and extrinsic factors that promote racial differences in breast cancer development and patient outcome are not fully understood and strategies to address this are scarce. As a result, we have developed a platform that combines patient-specific imaging and multi-omics data to elucidate how biological differences integrate to promote racial disparities in tumor behavior and patient outcome. Methods: Imaging and transcriptomic data from over 500 patients were integrated within the SimBioSys TumoScope biophysical modeling software to understand racial differences in tumor biology and coordinated tumor behavior. Results: AA patients have tumors that display higher growth rates, characteristically have higher adipose tissue around the tumor, higher spatial variation in drug secretion, lower spatial variation in blood flow/and increased tumor stiffness. Conclusion: Using a transdisciplinary approach, our results show that metabolic and structural tumor features are associated with the disproportionately poor survival rates observed in AA breast cancer patients. By characterizing racial-specific tumor intrinsic and extrinsic biological factors and their potential interactions, strategies may emerge to personalize clinical management based on racial differences. In this way, precision oncology approaches can be applied to increase life-expectancy for racial minorities with breast cancer. Citation Format: Nicole Liadis, Tyler Earnest, Eduardo Braun, Anu Antony, Lance Munn, Michael Hallock, Daniel Cook, The SimBioSys Team. Integrating imaging and multi-omics data to elucidate racial differences in breast tumor biology to optimize precision oncology approaches and patient outcome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 474.

Implementing subtype-specific pre-clinical models of breast cancer to study pre-treatment aspirin effects.

BackgorundPrior data suggest pre‐diagnostic aspirin use impacts breast tumour biology and patient outcome. Here, we employed faithful surgical resection models of HER2+ and triple‐negative breast cancer (TNBC), to study outcome and response mechanisms across breast cancer subtypes.MethodNOD/SCID mice were implanted with HER2+ MDA‐MB‐231/LN/2‐4/H2N, trastuzumab‐resistant HER2+ HCC1954 or a TNBC patient‐derived xenograft (PDX). A daily low‐dose aspirin regimen commenced until primary tumours reached ~250 mm3 and subsequently resected. MDA‐MB‐231/LN/2‐4/H2N mice were monitored for metastasis utilising imaging. To interrogate the survival benefit of pre‐treatment aspirin, 3 weeks post‐resection, HCC1954/TNBC animals received standard‐of‐care (SOC) chemotherapy for 6 weeks. Primary tumour response to aspirin was interrogated using immunohistochemistry.ResultsAspirin delayed time to metastasis in MDA‐MB‐231/LN/2‐4/H2N xenografts and decreased growth of HER2+/TNBC primary tumours. Lymphangiogenic factors and lymph vessels number were decreased in HER2+ tumours. However, no survival benefit was seen in aspirin pre‐treated animals (HCC1954/TNBC) that further received adjuvant SOC, compared with animals treated with SOC alone. In an effort to study mechanisms responsible for the observed reduction in lymphangiogenesis in HER2+ BC we utilised an in vitro co‐culture system of HCC1954 tumour cells and mesenchymal stromal cells (MSC). Aspirin abrogated the secretion of VEGF‐C in MSCs and also decreased the lymph/angiogenic potential of the MSCs and HCC1954 by tubule formation assay. Furthermore, aspirin decreased the secretion of uPA in HCC1954 cells potentially diminishing its metastatic capability.ConclusionOur data employing clinically relevant models demonstrate that aspirin alters breast tumour biology. However, aspirin may not represent a robust chemo‐preventative agent in the HER2+ or TNBC setting.

Relationship between Cigarette Smoking and Cancer Characteristics and Survival among Breast Cancer Patients.

Carcinogenic effects of tobacco smoke may affect breast tumorigenesis. To assess whether cigarette smoking is associated with breast cancer characteristics, we investigated the relationships between smoking, pathological characteristics, and outcomes in 2153 women diagnosed with breast cancer 2001–2016. Patients were classified as never, former, or current smokers at the time of diagnosis. Logistic regression and multivariable Cox proportional hazards analysis were performed to determine whether smoking was associated with tumor characteristics. Multivariable Cox proportional hazards analysis was conducted to compare former or current smokers to never smokers in survival with adjustment for the potential confounders. The majority of women (61.8%) never smoked, followed by former smokers (26.2%) and current smokers (12.0%). After adjustment for demographic variables, body mass index, and comorbidities, tumor characteristics were not significantly associated with smoking status or pack-years smoked. Ten-year overall survival was significantly lower for former and current smokers compared to never smokers (p = 0.0105). However, breast cancer specific survival did not differ significantly between groups (p = 0.1606). Although cigarette smoking did not alter the underlying biology of breast tumors or breast cancer-specific survival, overall survival was significantly worse in smokers, highlighting the importance of smoking cessation in the recently diagnosed breast cancer patient.

Abstract P4-07-32: Mammaprint and Blueprint are prognostic of outcome following neoadjuvant chemotherapy

Abstract Introduction: Neoadjuvant chemotherapy (NAC) is used increasingly in patients with early-stage breast cancer (EBC). Genomic approaches are necessary to identify better biomarkers that can more accurately predict response to NAC and outcome. The impact of NAC on the molecular biology of breast tumors, especially in patients that fail to respond to treatment, is not well studied. We evaluated the risk of distant recurrence signature, MammaPrint (MP), and the molecular subtyping signature, BluePrint (BP), in the neoadjuvant setting and how the prognostic capability of MP and BP, which was validated on untreated biopsies, is affected by NAC in patients with residual disease. Methods: This analysis included 128 women (median age 50) with stage I-III EBC, of any clinical subtype, diagnosed from 2007-2016 who received NAC at Cedars-Sinai Medical Center. Of 128 patients, 73 had core needle biopsies available before treatment, 17 had surgically resected biopsies with residual disease available after treatment, and 38 with residual disease had paired pre- and post-treatment biopsies. MP classified tumors as High Risk (MP-HR) or Low Risk (MP-LR). MP and BP classified tumors as Luminal A (MP-LR), Luminal B (MP-HR), HER2, or Basal. The primary outcomes were pathological complete response (pCR), recurrence free survival (RFS), distant-metastasis free survival (DMFS), and overall survival (OS). The median follow-up time was 5.2 years. Differences between unmatched independent variables were examined by chi-square test or Fisher’s exact test. Differences in pCR rate were assessed by two-sided proportional z-test. For matched samples, McNemar’s test or Bowker’s test was used. Univariate survival analyses were evaluated using a Cox proportional hazards model. Results: Among 111 pre-treated tumors, MP-HR tumors had a significantly higher pCR rate (40.6%; n=39/96) compared to MP-LR tumors (13.3%; n=2/15; p=0.042). BP HER2 and Basal tumors had significantly higher pCR rates (56.8%; n=25/44 and 45.8%; n=11/24, respectively), compared to Luminal B tumors (16.1%; n=5/31; p&amp;lt;0.001 and p = 0.016 respectively). No Luminal A tumors (n=12) achieved pCR. MP-HR and BP Basal tumors were associated with a higher risk of recurrence or death than MP-LR and Luminal tumors. Among all 128 tumors, post-treated samples were more likely to be classified as MP-LR than pre-treated samples (45.5%; n=25/55 vs. 13.5%; n=15/111), whereas BP subtype distribution was similar. Among 38 paired samples with residual disease, BP subtype did not significantly differ after NAC (p=0.392) and had 92% concordance between pre- and post-treated samples. Basal tumors, whether classified before or after NAC was significantly associated with a RFS (HR=4.79, 95% CI 1.09-20.97; p=0.038), DMFS (HR=4.86, 95% CI 1.28-18.64; p=0.018), or OS event (HR=22.03, 95% CI 2.41-201.26; p=0.006) compared to luminal tumors. A significant number (26%; n=10; p=0.002) of tumors had discordant MP risk between pre- and post-treatment samples, all of which reclassified from MP-HR (Luminal B) to MP-LR (Luminal A). MP-HR tumors that reclassified as MP-LR after NAC had better 5-year OS (100%) compared to tumors that remained MP-HR (73.3%, 95% CI 47.2 - 87.9). Conclusions: MP and BP accurately predicted chemosensitivity and outcomes in NAC treated patients. Activated molecular pathways captured by BP classification remained stable after NAC treatment, with a high concordance rate. Approximately 1 out of 4 Luminal B (MP-HR) tumors reclassified as Luminal A (MP-LR) after NAC and have improved 5-year outcome compared to tumors that remained MP-HR. Together, this preliminary evidence supports the prognostic accuracy of MP and BP on tumors following NAC treatment. Future studies will study the effect of NAC on the BC transcriptome and their association with clinical outcomes. Citation Format: Alice P. Chung, Marissa Srour, Farnaz Dadmanesh, Sungjin Kim, Armando Giuliano, Jennifer Wei, Yen Huynh, Shiyu Wang, Andrea Menicucci, William Audeh. Mammaprint and Blueprint are prognostic of outcome following neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-07-32.

Abstract PR-08: Diabetes affects metabolism, redox signaling, DNA repair capacity and mutational burden in breast cancer

Abstract Comorbidities disproportionately affect underserved populations. Diabetes can increase cancer risk and decreases breast cancer survival. Diabetes-associated breast cancer risk impacts African American women more than European Americans. The goal of this study was to understand how diabetes may shape breast tumor biology. We performed an RNA and whole-exome sequencing (WES) analysis, together with global metabolomics, of matched breast tumors from patients with or without diabetes, with the majority being of African American descent. Additionally, as an experimental model, we generated mammary xenografts following orthotopic injection of breast cancer cells (MDA-MB-231, MDA-MB-468, and HS578T) into the mammary fat pad of diabetic mice (NOD.Cg-Rag1 tm1Mom Ins2 Akita Il2rg tm1Wjl/SzJ). After 4-6 weeks we collected the tumors and performed RNAseq and metabolome analysis. Analyzing the metabolome profile of both human breast tumors and xenografts, we observed a distinct metabolite pattern in diabetic breast tumors and diabetic mice. The key observation was the enrichment of food and microbial-derived metabolites under diabetes, indicating that diabetes may promote the accumulation of these metabolites in breast tumors. Next, we analyzed the RNAseq data from the same tumors and xenografts. Here, we applied Gene Set Enrichment Analysis (GSEA) with the transcriptomic data to find specific pathways activated under diabetic conditions. GSEA indicated the enrichment of gene signatures related to mesenchymal and stem cell-like phenotypes both in the patient tumor and xenografts under diabetes. Additionally, we discovered an enrichment of the reactive oxygen species (ROS) pathway in diabetic tumors and xenografts. Consistent with this observation, treating breast cancer cells (MDA-MB-231 and HS578T) with high glucose (25mM) increased superoxide radical production in these cells. Since higher ROS levels could cause DNA damage, we examined DNA damage in breast cancer cells cultured under high glucose. Here we observed an increase in DNA damage under high glucose as indicated by robust nuclear γH2AX and 53BP1 immunostaining. An additional KEGG analysis indicated the inhibition of various DNA repair pathways (e.g. base-excision, nucleotide excision, and mismatch repair) in breast tumors and xenografts. Corroborating this finding with our WES data, we observed a significant enrichment of several mutational signatures (SBS5, SBS15, and SBS30 DNA repair deficiency signatures) in breast tumors of diabetic patients, suggesting that diabetes may interfere with DNA repair pathways in breast tumors. Taken together, this study suggests that diabetes promotes a mesenchymal and stem cell-like phenotype in human breast tumors with higher oxidative stress &amp; DNA damage and a decreased DNA repair capacity. Our data further indicate that breast tumors from diabetic patients may have an increased susceptibility to DNA damage response inhibitors like PARP inhibitors. Citation Format: Gatikrushna Panigrahi, Tiffany Dorsey, Wei Tang, Julian Candia, Amy Zhang, Stefan Ambs. Diabetes affects metabolism, redox signaling, DNA repair capacity and mutational burden in breast cancer [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PR-08.

Study of Mast Cell Distribution and its Role in Breast Carcinoma

Aims: This study is an attempt to find the Mast cell distribution in Tumors of Breast and thereby substantiating its role in Biology and Natural History of Breast Tumors ,principally Breast Cancer. Study Design: Cross Sectional Histopathological study Place of Study: Department of Pathology Faculty of Medicine Northern Border University Arar, K.S.A Materials &amp; Methods: Sample study includes 40 diagnosed cases of Breast Carcinoma. Histopathology slides were collected and subjected to Toluidine Blue Stain for demonstration and distribution of Mast cells, there by comparing the findings with other studies Results: Invasive ductal carcinoma, Lobular Carcinoma [2-4/hpf] and [1-2/hpf] within tumor area Invasive Ductal Carcinoma, Lobular Carcinoma [1-2/hpf] and [2-4/hpf] within Stroma Conclusion: The distribution of Mast cells in breast carcinoma in present study is comparable to other studies Keywords: Mast cell, Breast Carcinoma, Prognosis, Study, Distribution

Adipocyte‐derived Exosomes: Novel Insight in the Link between Obesity and Breast Cancer

Introduction Obesity has an intricate connection to both risk and clinical behaviour of breast cancer. Adipose tissue dysfunction in obesity results in a release of many adipokines that it is well known to promote breast tumor biology. In addition to soluble factors, exosomes (exo), small membrane-derived vesicles secreted by both normal and malignant cells, have been recently suggested to act as additional mediators of cell-to-cell communication. However, a clear understanding in the role of adipocyte-derived exo in mediating the adverse effects of obesity on BC is still lacking. Herein, we evaluated the involvement of adipocyte-derived exo in sustaining BC development and progression. Methods Exo were isolated and fully characterized from conditioned media (CM) of differentiated 3T3-L1 adipocytes (3T3-L1 A), a well-recognized ‘in vitro’ model of white adipocytes. We tested the effects of 3T3-L1 A exo in modulating the proliferation (MTT/soft agar assays), motility/invasion (wound healing/Boyden Chamber migration/invasion assays), and stemness (mammosphere forming efficiency/Limiting Dilution assays) of estrogen receptor α (ERα)-positive MCF-7 and triple-negative MDA-MB-231 BC cells. We also assessed co-culture experiments between BC cells and CM derived from adipocytes isolated from human mammary adipose tissues (MAT) of adult normal weight and obese women. Results The treatment with 3T3-L1 A exo significantly increased the number of colonies of MCF-7 and MDA-MB-231 cells in anchorage-independent soft agar growth assay. Also, we found that 3T3-L1 A exo induced a more aggressive phenotype in both BC cells in terms of migration, invasion and stemness. In accordance with these data, we found that 3T3-L1 A exo significantly induced the expression of the mRNA levels of genes encoding several proteins involved in Epithelial to Mesenchymal Transition (EMT) and associated with stem cell phenotype. To gain insight into the molecular mechanism we focused our attention on the expression and activity of HIF-1α, a well-known regulator of hypoxic response, involved in invasion, migration, EMT and metastasis in BC. Interestingly, 3T3-L1 A exo increased the expression of HIF-1α and its target genes, and the use of a HIF-1α translation inhibitor reduced migration and invasion capabilities induced by exo. Finally, we found that CM derived from MAT increased the migratory abilities of both employed cells in a significantly higher extent with MAT obese-CM and these effects were completely reversed in the presence of a specific exo uptake inhibitor. Conclusions Our data suggest that adipocyte exo contribute to a more aggressive BC phenotype. This may open new avenues for identifying novel specific biomarkers and innovative therapeutic strategies (i.e. HIF-1α inhibitors) in BC treatment, especially in obese patients.

Abstract PS7-67: Breast cancer subtype differences according to race/ethnicity

Abstract Background:Breast cancer incidence and mortality rate differ across racial/ethnic population in the US, little is known about Asian and Pacific Island subpopulations. For the Asian subgroups (Japanese, Chinese, Korean, Filipino, Vietnamese, etc.) in the U.S., overall incidence has increased over recent decades. From 2012-2016 Hawai’i incidence rates were significantly higher than the US overall for breast cancer, although cancer mortality rates in Hawai’i were significantly lower than the US overall for breast cancer. Significant disparities in breast cancer incidence and mortality exist, with Native Hawaiian and Filipino women particularly affected. Native Hawaiian women have the highest incidence and also have a 50% higher risk of breast cancer mortality compared to White women. In addition, there are dramatic racial/ethnic differences in mortality rates in the state, with Native Hawaiians having the highest mortality rates compared to all other major racial/ethnic groups. Methods:We examined unique breast cancer cases in a major health system in Hawai’i from 2013-2019 according to race/ethnicity. We found statically significant differences in breast cancer subtype according to race/ethnicity and menopausal status. Results:In 561 premenopausal breast cancer cases, we found that Native Hawaiians were less likely to have triple negative breast cancer (OR 0.2, p=0.02) and Japanese were less likely to have triple positive breast cancer (OR 0.17, p=0.002) compared to other race/ethnicities. In 1,954 postmenopausal breast cancer cases, we found that Filipino women were more likely to have hormone negative/HER2 positive breast cancer (OR 2.38, p=0.006) compared to other race/ethnicities. Table 1-Breast cancer subtype according to race/ethnicity in premenopausal women Table 2-Breast cancer subtype according to race/ethnicity in postmenopausal women Summary:Although behavioral, environmental, social, economic, and biological factors have been shown to influence risk and survival for breast cancer, they do not entirely explain the differences observed across populations. These findings show the need to characterize the underlying differences in breast tumor biology of breast cancer patients from different racial/ethnic groups to better understand known health disparities. Our hypothesis is that molecular characteristics are key contributors to the disparities in disease outcome across the different racial/ethnic groups. We have previously shown the importance of the tumor microenvironment differences in racial/ethnic groups in our population. Citation Format: Jami Fukui, Surbhi Bansil, Anthony Silva, Jeffrey Killeen, Ian Pagano. Breast cancer subtype differences according to race/ethnicity [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS7-67.

Neighborhood Social Environmental Factors and Breast Cancer Subtypes among Black Women.

The disproportionate burden of more aggressive breast cancer subtypes among African American/Black women may stem from multilevel determinants. However, data are limited regarding the impacts of neighborhood social environmental characteristics among Black women. We evaluated the association between neighborhood-level socioeconomic status (nSES) and breast cancer subtypes in the Women's Circle of Health and Women's Circle of Health Follow-up Study, which included 1,220 Black women diagnosed from 2005 to 2017 with invasive breast cancer. nSES at diagnosis was measured using NCI's census tract-level SES index. We used multilevel multinomial logistic regression models to estimate the association of nSES with breast cancer subtypes [triple-negative breast cancer (TNBC), HER2-positive vs. luminal A], adjusting for individual-level SES, body mass index, and reproductive factors. We tested for interactions by neighborhood racial composition. Compared with census tracts characterized as high nSES, the relative risk ratios (RRR) for TNBC were 1.81 [95% confidence interval (CI): 1.20-2.71] and 1.95 (95% CI: 1.27-2.99) for women residing in areas with intermediate and low nSES, respectively (P trend = 0.002). Neighborhood racial composition modified the association between nSES and TNBC; the highest relative risk of TNBC was among women residing in low nSES areas with low proportions of Black residents. Black women residing in socioeconomically disadvantaged neighborhoods may have an increased risk of TNBC, particularly in areas with lower proportions of Black residents. Places people live may influence breast tumor biology. A deeper understanding of multilevel pathways contributing to tumor biology is needed.

P.258 Depression and suicidal ideation in treatment resistant depression patients in Latin America: final results from the multicentre, prospective, observational TRAL study

Somatostatin (SST) mediates cytostatic and pro-apoptotic effects through five somatostatin receptors (SSTR1-5). The modest clinical benefits of SST analogs in cancers of different origin such as breast cancer are attributed to diminished SSTRs expression at tumor sites. In the present study, SSTR3 was overexpressed in MCF-7 and MDA-MB-231, and analyzed for downstream signaling molecules associated with cytostatic and cytotoxic effect. Cells overexpressing SSTR3 displayed inhibition of EGF induced proliferation and enhanced antiproliferative effect of SSTR3-specific agonist in comparison to non-transfected cells. SSTR3 overexpression in MCF-7 cells (R3-MCF-7) constitutively enhanced TUNEL staining, PARP-1 and p27Kip1 expression suggesting apoptosis and cell-cycle arrest. Conversely, R3-MB-231 cells with SSTR3 overexpression exerted cytostatic and were devoid of any cytotoxic effects. The expression of PTP-1C and the status of ERK1/2, p38 and PI3K phosphorylation was modulated in a cell-specific manner. These findings provide new insights in understanding the antiproliferative role of SSTR3 in breast tumor biology.

Eradicating the Roots: Advanced Therapeutic Approaches Targeting Breast Cancer Stem Cells

Accumulating evidences have demonstrated that the existence of breast cancer-initiating cells, which drives the original tumorigenicity, local invasion and migration propensity of breast cancer. These cells, termed as breast cancer stem cells (BCSCs), possess properties including self-renewal, multidirectional differentiation and proliferative potential, and are believed to play important roles in the intrinsic drug resistance of breast cancer. One of the reasons why BCBCs cause difficulties in breast cancer treating is that BCBCs can control both genetic and non-genetic elements to keep their niches safe and sound, which allows BCSCs for constant self-renewal and differentiation. Therapeutic strategies designed to target BCSCs may ultimately result in effective interventions for the treatment of breast cancer. Novel strategies including nanomedicine, oncolytic virus therapy, immunotherapy and induced differentiation therapy are emerging and proved to be efficient in anti-BCSCs therapy. In this review, we summarized breast tumor biology and the current challenges of breast cancer therapies, focused on breast cancer stem cells, and introduced promising therapeutic strategies targeting BCSCs.

Abstract B081: Common copy number aberrations in breast cancer in Latinas

Abstract Background: Latinos represent the largest and fastest-growing minority population in the US; breast cancer is the most common cancer and causes the most cancer deaths in this population. Copy number amplifications and deletions are an important determinant of the biology of breast tumors and, in some cases, may help to guide treatment. However, little is known about the copy number profile of breast tumors from Latinas. For example, in The Cancer Genome Atlas (TCGA), one of the largest publicly available tumor mutation datasets, there are data on only 31 Latina (out of a total of &amp;gt;1000) breast cancer cases. Therefore, we used whole exome sequencing on matched tumor/normal pairs in 146 tumors from 142 women, to investigate copy number aberrations in breast tumors from Latinas. Methods: We enrolled 142 Latinas with invasive breast cancer and obtained blood and tumor tissue (formalin-fixed paraffin embedded). We performed whole exome sequencing of 146 pairs of tumor (somatic) and normal (germline) samples resulting in 142 tumor-normal pairs for analysis. Target coverage for normal was ~30X and for tumor was ~100X. Sequence data were aligned using Burrows-Wheeler Aligner, and copy number aberrations were called using CNVkit. We estimated genetic ancestry from the germline genotype data using ADMIXTURE. Results: Age at diagnosis ranged from 31 to 75 years with a median age of 48 years. Histologically, 83% were estrogen-receptor positive, 71 % were progesterone-receptor positive, and 17% were human epidermal growth factor receptor positive; 87% were Stage 1 or 2 at diagnosis. The mean genetic ancestry in our sample was ~52.3% European, ~41.6% Indigenous American, and ~6.2% African. Large copy number amplifications were detected mostly commonly at 1q and 8q, and large deletions were detected at 11q, 16q and 17p. Genes commonly gained/amplified included MYC (43%), FGFR1 (19.2%), CCND1 (18.0%), and ERRB2 (14.4%). Genes commonly deleted in at least one chromosome include TP53, MAP2K4, BRCA1, PP2R2A, CHEK2, and PALB2. Summary: Breast tumors from Latinas display similar rates of large chromosomal copy number gains and losses at common positions and similar rates of gene-specific copy number amplifications and deletions compared non-Latina European ancestry women. Citation Format: Elad Ziv, Daniel Schmolze, Donglei Hu, Aaron Adamson, Shu Tao, Charleen Adams, Linda Steele, Scott Huntsman, Jeffrey Weitzel, Jung Byun, Kevin Gardner, Eliseo Perez-Stable, Anna Napoles-Springer, Susan Neuhausen. Common copy number aberrations in breast cancer in Latinas [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr B081.

Abstract B035: Identification of a tumor cell adaptive stress response signaling pathway, which drives aggressive breast cancer phenotype and therapeutic resistance, in African American patients with locally advanced breast cancer subtypes

Abstract Introduction: The higher incidence of biologically aggressive and treatment-resistant breast cancer (BCa) subtypes, which includes triple negative (TN), basal, and inflammatory breast cancer (IBC), contributes to worse survival outcomes in African American/AA patients, 42% higher death rate compared to White BCa. Amongst locally advanced BCa, IBC is a model of aggressive, most lethal, frequently basal/TN, accounting for 10% AA BCa and disparity in outcomes exist after adjusting for socioeconomic and diagnosis factors. IBC exhibits a unique phenotype wherein malignant cells do not form solid masses and instead, present as hyperproliferative tumor cell clusters, termed tumor emboli, in the skin and lymphatics. Our key finding was the identification of a tumor cell adaptive stress response pathway linking the mitogen activated ser/thr kinase/MNK, X-linked inhibitor of anti-apoptotic protein, XIAP, and nuclear transcription factor, NFkB, mediated proliferative, invasive and immunosuppressive signaling. Our goal was to determine the role of the adaptive stress response pathway, which we have identified to contribute to aggressiveness of TNBC and IBC, in AA breast tumor biology. Methods: Expression of MNK, XIAP and NFkB target gene sets, a 40-gene oxidative stress response that correlates with response to cell death stimuli and a 79-gene IBC signature (identified from comparative analysis of IBC and non-IBC biospecimens) were evaluated in The Cancer Genome Atlas (TCGA) breast cancer datasets (1109 tumor; 113 normal) stratified according to race and molecular subtypes (luminal A, B, Her2, basal). The mean expression for each gene in these signatures were also assessed among different subtypes and race using R. Gene Ontology (GO) analysis was performed using GATHER online tool. XIAP immunohistochemistry (IHC) conducted in BCa samples (n=93) from Duke and MDACC biorepositories. Results: TCGA analysis of the IBC-related signatures identified genes differentially expressed (&amp;gt;2-fold change; Wilcoxon rank sum test, FDR&amp;lt;0.05) among BCa subtypes and between AA vs White within a subtype. Additionally, the oxidative stress response metagene was significantly upregulated in AA basal (p=0.037) whereas there were fewer differences in immune-related genes within AA subtypes suggesting attenuated immune response. IHC, to date, shows high XIAP in high grade, ER-negative and in majority of AA BCa and in IBC samples independent of molecular subtypes and grade. Conclusions: We report a heightened adaptive stress response gene signature and identify genes in the MNK:XIAP:NFkB pathway and IBC-related signatures in AA BCa, suggesting potential biomarkers and drug discovery targets. High XIAP expression in high grade BCa, frequent in AA patients, is of therapeutic relevance as XIAP, the most potent caspase inhibitor, is linked to chemo- and immunotherapy resistance and XIAP inhibitors are in clinical trials. Supported by DOD-Breakthrough-W81XWH-17-1-0297; Duke SOM bridge funds; NCI-1P20-CA202925-01A12. Citation Format: Gayathri R Devi, Muthana Al Abo, Larisa Gearhart-Serna, Joseph Geradts, Shannon J McCall, Savitri Krishnamurthy. Identification of a tumor cell adaptive stress response signaling pathway, which drives aggressive breast cancer phenotype and therapeutic resistance, in African American patients with locally advanced breast cancer subtypes [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr B035.