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The NanoString GeoMx digital spatial profiling is a new multiplexed platform that quantifies the abundance of tumor‐ and immune‐related proteins in a spatially resolved manner. We performed DSP for the simultaneous assessment of 52 analytes within spatially resolved tissue compartments defined by pan‐cytokeratin expression. We compared protein targets between 94 African American/Black and 65 European American/White cases, tumor and stromal tissue compartments, estrogen receptor alpha (ER)‐positive and ER‐negative cases, and explored potential biomarkers of survival. Of 33 analytes with robust signal for analysis, results were highly replicable. For a subset of markers, correlative analyses between DSP analytes and traditional immunohistochemistry scores revealed moderate to very strong associations between the two platforms. Similarly, DSP analytes and gene expression scores were concordant for 21 of 25 markers with overlap between the two datasets. Several analytes varied by ER status, and across the 25 immune markers surveyed, 14 had a significant inverse association with ER expression. B7 homolog 3 (B7‐H3; encoded by CD276) was the only analyte to show a significant difference by race, being lower in both the tumor and stromal compartments in Black women. DSP markers that were associated with survival included CD8, CD25, CD56, CD127, EpCAM, ER, Ki‐67, and STING. We conclude that DSP is an efficient tool for screening tumor‐ and immune‐related markers in a simultaneous fashion and yields results that are concordant with established immune profiling assays. DSP immune analytes were inversely associated with ER expression, in agreement with a substantial body of previous work that documents higher immune infiltration in ER‐negative breast cancers. This technology revealed that scores of the B7‐H3 protein were significantly lower in breast cancers from Black women compared with White women, an intriguing finding that requires replication in independent and racially diverse female populations., We evaluated the NanoString GeoMx digital spatial profiling platform for highly multiplexed immune profiling in a population of Black and White women with invasive breast cancer. Using DSP for discovery and conventional immunohistochemistry and gene expression data for validation, we found the DSP technology to be efficient, reproducible, and to yield results that are concordant with established immune profiling assays.

Background The mechanistic target of rapamycin (mTOR) pathway promoted by positive energy imbalance and insulin-like growth factors can be a mechanism by which obesity influences breast cancer risk. We evaluated the associations of body fatness with the risk of breast cancer varied with phosphorylated (p)-mTOR protein expression, an indication of the pathway activation. Methods Women with newly diagnosed breast cancer (n = 715; 574 [80%] Black and 141 [20%] White) and non-cancer controls (n = 1983; 1280 [64%] Black and 713 [36%] White) were selected from the Women’s Circle of Health Study. Surgical tumor samples among the cases were immunostained for p-mTOR (Ser2448) and classified as p-mTOR-overexpressed, if the expression level ≥ 75th percentile, or p-mTOR-negative/low otherwise. Anthropometrics were measured by trained staff, and body composition was determined by bioelectrical impedance analysis. Odds ratios (ORs) of p-mTOR-overexpressed tumors and p-mTOR-negative/low tumors compared to controls were estimated using polytomous logistic regression. The differences in the associations by the p-mTOR expression status were assessed by tests for heterogeneity. Results Cases with p-mTOR-overexpressed tumors, but not cases with p-mTOR-negative/low tumors, compared to controls were more likely to have higher body mass index (BMI), percent body fat, and fat mass index (P-heterogeneity P-heterogeneity = 0.27 and 0.48, respectively). Conclusions Our findings suggest that in this population composed of predominately Black women, body fatness is associated with breast cancer differently for p-mTOR overexpression and p-mTOR negative/low expression. Whether mTOR plays a role in the obesity and breast cancer association warrants confirmation by prospective studies.

Background:Evidence suggests etiologic heterogeneity among breast cancer subtypes. Previous studies with six-marker IHC classification of intrinsic subtypes included small numbers of black women.Methods:Using centralized laboratory results for estrogen receptor (ER), progesterone receptor, HER2, proliferation marker, Ki-67, EGFR, and cytokeratin (CK)5/6, we estimated case-only and case–control ORs for established breast cancer risk factors among cases (n = 2,354) and controls (n = 2,932) in the African American Breast Cancer Epidemiology and Risk (AMBER) consortium. ORs were estimated by ER status and intrinsic subtype using adjusted logistic regression.Results:Case-only analyses by ER status showed etiologic heterogeneity by age at menarche, parity (vs. nulliparity), and age at first birth. In case–control analyses for intrinsic subtype, increased body mass index and waist-to-hip ratio (WHR) were associated with increased risk of luminal A subtype, whereas older age at menarche and parity, regardless of breastfeeding, were associated with reduced risk. For basal-like cancers, parity without breastfeeding and increasing WHR were associated with increased risk, whereas breastfeeding and age ≥25 years at first birth were associated with reduced risk among parous women. Basal-like and ER−/HER2+ subtypes had earlier age-at-incidence distribution relative to luminal subtypes.Conclusions:Breast cancer subtypes showed distinct etiologic profiles in the AMBER consortium, a study of more than 5,000 black women with centrally assessed tumor biospecimens.Impact:Among black women, high WHR and parity without breastfeeding are emerging as important intervention points to reduce the incidence of basal-like breast cancer.

PURPOSE: Limited epidemiologic data are available on the expression of adipokines leptin (LEP) and adiponectin (ADIPOQ) and adipokine receptors (LEPR, ADIPOR1, ADIPOR2) in the breast tumor microenvironment (TME). The associations of gene expression of these biomarkers with tumor clinicopathology is not well understood. METHODS: NanoString multiplexed assays were used to assess the gene expression levels of LEP, LEPR, ADIPOQ, ADIPOR1, and ADIPOR2 within tumor tissues among 162 Black and 55 White women with newly diagnosed breast cancer. Multivariate mixed effects models were used to estimate associations of gene expression with breast tumor clinicopathology (overall and separately among Blacks). RESULTS: Black race was associated with lower gene expression of LEPR (P=0.002) and ADIPOR1 (P=0.01). Lower LEP, LEPR, and ADIPOQ gene expression were associated with higher tumor grade (P=0.0007, P

PURPOSE: Understanding the contribution of tumor genome biology to racial disparities of triple-negative breast cancer (TNBC) is important for narrowing the cancer mortality gap between Black and White women. METHODS: We evaluated tumor somatic mutations using targeted sequencing of a customized panel of 151 genes and 15 copy number variations (CNVs) within a population of 133 TNBC patients, including 71 Black and 62 White women. RESULTS: The overall mutational burden between Black and White women with TNBC was not significantly different, with a median of 5 somatic changes per patient (point mutations and CNVs combined) for the customized panel (range 1–31 for Blacks vs. 1–26 for Whites; p=0.76). Of the 151 genes examined, none were mutated at a significantly higher frequency in Black than in White cases, whereas two genes were mutated at a higher frequency in White cases - PIK3CA and NCOR1. No significant difference in the frequency of CNVs was observed between Black and White women with TNBC in our study population. CONCLUSIONS: Of gene mutations and CNVs in TNBC tumors from Black and White women, only PIK3CA and NCOR1 had significantly different, although slight, frequencies by race. These results indicate that overall differences observed in the mutation spectra between Black and White women with breast cancer are likely due to the differential distributions of breast cancer subtypes by race.

Background: Racial disparities in breast cancer outcome continues to be a major health care challenge. The reasons underlying this disparity are multifactorial with a recent focus on the tumor microenvironment. The characterization of infiltrating immune cell populations in the tumor microenvironment are lacking in Black breast cancer patients. To address this research gap, we employed immunohistochemical (IHC) staining and quantitative digital imaging to assess CD8+ T-cells in breast tumor samples from the Women’s Circle of Health Study (WCHS), a population-based case-control study of breast cancer in Black and White women. Our aim was to characterize and compare the density, localization and distribution of CD8+ T cells, and explore their prognostic value in each racial group. Methods: Tumor-infiltrating CD8+ lymphocytes were assessed by IHC staining of tissue microarray (TMA) cores from 736 breast cancer patients, including 597 Blacks and 139 Whites. The Aperio platform was used for quantitative image analysis of TMA cores. Racial differences in demographic and clinical characteristics were evaluated using the Mann-Whitney U and Fisher’s exact tests. Overall (OS) and breast cancer-specific (DSS) survival were summarized by race using the Kaplan-Meier method and compared using the log-rank test. The associations between demographic/clinical factors and CD8 expression were evaluated using a general linear model (GLM). Multivariable Cox regression models were used to evaluate associations between survival outcomes and both race and CD8 expression, while adjusting for age. Results: Black women had a higher percentage of high-grade tumors in addition to higher prevalence of ER-negative and triple negative tumors than white women. There was a statistically significant difference in OS (p=0.043), showing worse outcomes among Black patients. Black patients had significantly higher CD8+ expression compared to White patients, with mean values of 756.2/mm2 and 292.4/mm2 respectively (p Conclusions: We observed a stronger presence of CD8+ T cells in tumor microenvironment from Black breast patients, suggesting the existence of distinct tumor immune responses in this population. Our current data do not support that CD8+ T cells contribute to breast cancer survival disparities given the lack of prognostic significance of CD8 expression in this sample. CD8+ T cells may become less cytotoxic towards tumor cells as a result of immunosuppression or exhaustion; therefore, in-depth immuno-profiling of the versatile immune cell subsets and their qualities of breast tumor microenvironment in Black patients is warranted to understand their roles in breast cancer racial disparities. Citation Format: Yara Abdou, Song Yao, Kristopher Attwood, Gary Zirpoli, Wiam Bshara, Christine Ambrosone, Angela Omilian. Racial differences in infiltration of CD8+ T-cells in breast tumors of Black and White women [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-10-02.

PURPOSE: The Women’s Circle of Health Follow-Up Study is an ongoing longitudinal study of African American/Black breast cancer survivors in New Jersey, specifically designed to evaluate the impact of obesity and related comorbidities on breast cancer survival and health-related quality-of-life in this understudied population. Here, we describe our recruitment and data collection methods, and compare characteristics of the overall cohort and the subcohort with follow-up data. METHODS: Newly diagnosed breast cancer cases have been recruited into the study since 2006. Pre-diagnosis data on relevant factors and a saliva sample are collected during an in-person interview within 12 months from diagnosis. In 2013, we began active follow up by recontacting participants annually, including two home visits at approximately 2 and 3 years post-diagnosis, during which blood samples are collected. Mortality outcomes (all-cause and breast cancer-specific mortality) are ascertained through linkage with New Jersey State Cancer Registry files. We expect to assemble a cohort of over 2,000 Black breast cancer survivors with at least 800 of them having detailed post-diagnosis data. RESULTS: Distribution of sociodemographic characteristics, body mass index, comorbidities, clinicopathologic characteristics, and treatment modalities were very similar between those in the full cohort and the subset with follow-up data and blood samples. Obesity (>50%), hypertension (>58%) and diabetes (22%) were common in this population. CONCLUSIONS AND IMPLICATIONS FOR CANCER SURVIVORS: This ongoing longitudinal study represents a unique resource to better understand breast cancer outcomes, patient-reported symptoms, and health-related quality of life among Black breast cancer survivors.

COX and ALOX genes are involved in inflammatory processes and that may be related to breast cancer risk differentially between White and Black women. We evaluated distributions of genetic variants involved in COX2 and ALOX-related pathways and examined their associations with breast cancer risk among 1,275 White and 1,299 Black cases and controls who participated in the Women’s Circle of Health Study. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable-adjusted logistic regression models. Our results showed differential associations of certain genetic variants with breast cancer according to menopausal and ER status in either White or Black women. In White women, an increased risk of breast cancer was observed for COX2-rs689470 (OR: 2.02, P = 0.01) in the dominant model, and was strongest among postmenopausal women (OR: 2.72, P = 0.02) and for estrogen receptor positive (ER+) breast cancers (OR: 2.60, P = 0.001). A reduced risk was observed for ALOX5-rs7099874 (OR: 0.75, P = 0.01) in the dominant model, and was stronger among postmenopausal women (OR: 0.68, P = 0.03) and for ER+ cancer (OR: 0.66, P = 0.001). Four SNPs (rs3840880, rs1126667, rs434473, rs1042357) in the ALOX12 gene were found in high LD (r2 >0.98) in White women and were similarly associated with reduced risk of breast cancer, with a stronger association among postmenopausal women and for ER− cancer. Among Black women, increased risk was observed for ALOX5-rs1369214 (OR: 1.44, P = 0.003) in the recessive model and was stronger among premenopausal women (OR: 1.57, P = 0.03) and for ER+ cancer (OR: 1.53, P = 0.003). Our study suggests that genetic variants of COX2 and ALOX genes are associated with breast cancer, and that these associations and genotype distributions differ in subgroups defined by menopausal and ER status between White and Black women. Findings may provide insights into the etiology of breast cancer and areas for further research into reasons for breast cancer differences between races.

BackgroundAnti-tumorigenic vs pro-tumorigenic roles of estrogen receptor-beta (ESR2) in breast cancer remain unsettled. We investigated the potential of TP53 status to be a determinant of the bi-faceted role of ESR2 and associated therapeutic implications for triple negative breast cancer (TNBC).MethodsESR2-TP53 interaction was analyzed with multiple assays including the in situ proximity ligation assay. Transcriptional effects on TP53-target genes and cell proliferation in response to knocking down or overexpressing ESR2 were determined. Patient survival according to ESR2 expression levels and TP53 mutation status was analyzed in the basal-like TNBC subgroup in the Molecular Taxonomy of Breast Cancer International Consortium (n = 308) and Roswell Park Comprehensive Cancer Center (n = 46) patient cohorts by univariate Cox regression and log-rank test. All statistical tests are two-sided.ResultsESR2 interaction with wild-type and mutant TP53 caused pro-proliferative and anti-proliferative effects, respectively. Depleting ESR2 in cells expressing wild-type TP53 resulted in increased expression of TP53-target genes CDKN1A (control group mean [SD] = 1 [0.13] vs ESR2 depletion group mean [SD] = 2.08 [0.24], P = .003) and BBC3 (control group mean [SD] = 1 [0.06] vs ESR2 depleted group mean [SD] = 1.92 [0.25], P = .003); however, expression of CDKN1A (control group mean [SD] = 1 [0.21] vs ESR2 depleted group mean [SD] = 0.56 [0.12], P = .02) and BBC3 (control group mean [SD] = 1 [0.03] vs ESR2 depleted group mean [SD] = 0.55 [0.09], P = .008) was decreased in cells expressing mutant TP53. Overexpressing ESR2 had opposite effects. Tamoxifen increased ESR2-mutant TP53 interaction, leading to reactivation of TP73 and apoptosis. High levels of ESR2 expression in mutant TP53-expressing basal-like tumors is associated with better prognosis (Molecular Taxonomy of Breast Cancer International Consortium cohort: log-rank P = .001; hazard ratio = 0.26, 95% confidence interval = 0.08 to 0.84, univariate Cox P = .02).ConclusionsTP53 status is a determinant of the functional duality of ESR2. Our study suggests that ESR2-mutant TP53 combination prognosticates survival in TNBC revealing a novel strategy to stratify TNBC for therapeutic intervention potentially by repurposing tamoxifen.

COX and ALOX genes are involved in inflammatory processes and that may be related to breast cancer risk differentially between White and Black women. We evaluated distributions of genetic variants involved in COX2 and ALOX-related pathways and examined their associations with breast cancer risk among 1,275 White and 1,299 Black cases and controls who participated in the Women’s Circle of Health Study. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable-adjusted logistic regression models. Our results showed differential associations of certain genetic variants with breast cancer according to menopausal and ER status in either White or Black women. In White women, an increased risk of breast cancer was observed for COX2-rs689470 (OR: 2.02, P = 0.01) in the dominant model, and was strongest among postmenopausal women (OR: 2.72, P = 0.02) and for estrogen receptor positive (ER+) breast cancers (OR: 2.60, P = 0.001). A reduced risk was observed for ALOX5-rs7099874 (OR: 0.75, P = 0.01) in the dominant model, and was stronger among postmenopausal women (OR: 0.68, P = 0.03) and for ER+ cancer (OR: 0.66, P = 0.001). Four SNPs (rs3840880, rs1126667, rs434473, rs1042357) in the ALOX12 gene were found in high LD (r2 >0.98) in White women and were similarly associated with reduced risk of breast cancer, with a stronger association among postmenopausal women and for ER− cancer. Among Black women, increased risk was observed for ALOX5-rs1369214 (OR: 1.44, P = 0.003) in the recessive model and was stronger among premenopausal women (OR: 1.57, P = 0.03) and for ER+ cancer (OR: 1.53, P = 0.003). Our study suggests that genetic variants of COX2 and ALOX genes are associated with breast cancer, and that these associations and genotype distributions differ in subgroups defined by menopausal and ER status between White and Black women. Findings may provide insights into the etiology of breast cancer and areas for further research into reasons for breast cancer differences between races.

Background Blacks tend to have a stronger inflammatory immune response than Whites. We hypothesized that racial differences in host immunity also manifest in the tumor microenvironment, constituting part of a distinct aggressive tumor biology underlying higher mortality in Black women. Methods Pathological and gene expression profiling approaches were used for characterizing infiltrating immune cells in breast tumor microenvironment from 1315 patients from the Women’s Circle of Health Study. Racial differences in tumor immune phenotypes were compared, with results validated in a publicly accessible dataset. Prognostic associations of immune phenotypes were assessed in 3 independent cohorts. Results We found marked and consistent differences in tumor immune responses between Black and White patients. Not only did tumors from Blacks display a stronger overall immune presence but also the composition and quality of immune infiltrates differed, regardless of tumor subtypes. Black patients had a stronger CD4+ and B-cell response, and further, a more exhausted CD8+ T-cell profile. A signature indicating a higher ratio of exhausted CD8+ T cells to total CD8+ T cells (ExCD8-r) was consistently associated with poorer survival, particularly among hormone receptor–positive patients. Among hormone receptor–negative patients, combinations of the absolute fraction of CD8+ T cells and ExCD8-r signature identified the CD8lowExCD8-rhigh subgroup, the most prevalent among Blacks, with the worst survival. Conclusions Our findings of a distinct exhausted CD8+ T-cell signature in Black breast cancer patients indicate an immunobiological basis for their more aggressive disease and a rationale for the use of immune checkpoint inhibitors targeting the exhaustion phenotype.

Background African American/Black women with breast cancer have poorer survival than White women, and this disparity persists even after adjusting for non-biological factors. Differences in tumor immune biology have been reported between Black and White women, and the tumor immune milieu could potentially drive racial differences in breast cancer etiology and outcome. Methods We examined the association of CD8+ cytotoxic T cells with clinical-pathological variables in the Women’s Circle of Health Study (WCHS) population of predominantly Black breast cancer patients. We evaluated 688 invasive breast tumor samples (550 Black, 138 White) using immunohistochemical staining of tissue microarray slides. CD8+ T cells were scored for each patient tumor sample with digital image analysis. Results Black women had a significantly higher percentage of high-grade, estrogen receptor (ER)-negative, and triple-negative tumors than White women and significantly higher CD8+ T cell density (median 87.6/mm2 vs. 53.1/mm2; p + T cell density was significantly higher in younger patients and patients with high-grade and ER/PR-negative tumors. No significant associations were observed between CD8+ T cell density and overall survival or breast cancer-specific survival in the overall population, or when Black patients were analyzed as a separate group. However, when stratified by subtype, Black women with triple-negative breast cancer and high CD8+ T cell density showed a trend towards better overall survival in comparison with patients with low CD8+ T cell density (HR = 0.51; 95% CI 0.25–1.04). Conclusions Our data raise the possibility that distinct mechanisms of immune cell action may occur in different racial groups.

Loss of immunoreactivity in tissue sections has been shown to occur when slide sections are stored at room temperature for prolonged periods of time. We conducted a systematic investigation to determine the extent of staining loss in various storage conditions to determine an optimal storage method. We investigated 6 antibodies that are commonly used for breast cancer subtyping in research studies with immunohistochemistry (ER, PR, HER2, CK5/6, EGFR, and Ki67) in formalin-fixed paraffin-embedded breast tissue microarrays consisting of 148 patients. Tissue microarrays were sectioned at various time points: fresh, 1 week, 1 month, 6 months, and 12 months before staining. Slides sectioned at each time point were stored in 5 storage conditions: desiccator, paraffin dipped, 4°C, -20°C, and -80°C. Immunohistochemistry scores were assessed over time with McNemar Test and Bowker Test of Symmetry. Desiccator storage was the only storage condition that did not show any loss in immunoreactivity for any antibody or time point in our study. Paraffin coated slides were the most difficult storage method operationally and also showed the most loss in immunoreactivity. Storing sections in a desiccator was the most effective method for minimizing immunoreactivity loss. Cold storage at 4°C is an intermediate option that is not as protective as a desiccator, but offers the advantage of being accessible to virtually all research labs.

Background The molecular mechanisms underlying the association between increased adiposity and aggressive breast cancer phenotypes remain unclear, but likely involve the adipokines, leptin (LEP) and adiponectin (ADIPOQ), and their receptors (LEPR, ADIPOR1, ADIPOR2). Methods We used immunohistochemistry (IHC) to assess LEP, LEPR, ADIPOQ, ADIPOR1, and ADIPOR2 expression in breast tumor tissue microarrays among a sample of 720 women recently diagnosed with breast cancer (540 of whom self-identified as Black). We scored IHC expression quantitatively, using digital pathology analysis. We abstracted data on tumor grade, tumor size, tumor stage, lymph node status, Ki67, estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) from pathology records, and used ER, PR, and HER2 expression data to classify breast cancer subtype. We used multivariable mixed effects models to estimate associations of IHC expression with tumor clinicopathology, in the overall sample and separately among Blacks. Results Larger proportions of Black than White women were overweight or obese and had more aggressive tumor features. Older age, Black race, postmenopausal status, and higher body mass index were associated with higher LEPR IHC expression. In multivariable models, lower LEPR IHC expression was associated with ER-negative status and triple-negative subtype (P Conclusions Lower LEPR IHC expression within the breast tumor microenvironment might contribute mechanistically to inter-individual variation in aggressive breast cancer clinicopathology, particularly ER-negative status and triple-negative subtype.

Background: Forkhead box protein A1 (FOXA1) promotes luminal differentiation, and hypermethylation of the gene can be a mechanism of developing estrogen receptor–negative (ER−) breast cancer. We examined FOXA1 in breast tumor and adjacent normal tissue in relation to reproductive factors, particularly higher parity and no breastfeeding, that are associated with ER− tumors. Methods: We performed IHC for FOXA1 in breast tumors (n = 1,329) and adjacent normal tissues (n = 298) in the Women's Circle of Health Study (949 Blacks and 380 Whites). Protein expression levels were summarized by histology (H) scores. Generalized linear models were used to assess FOXA1 protein expression in relation to reproductive factors by ER status. Results: ER-positive (ER+) versus ER− tumors had higher FOXA1 protein expression (P < 0.001). FOXA1 expression was higher in tumor versus paired adjacent normal tissue in women with ER+ or non-triple–negative cancer (both P < 0.001), but not in those with ER− or triple-negative cancer. Higher number of births (1, 2, and 3+) was associated with lower FOXA1 protein expression in ER+ tumors [differences in H score, or β = −8.5; 95% confidence interval (CI), −15.1 to −2.0], particularly among parous women who never breastfed (β = −10.4; 95% CI, −19.7 to −1.0), but not among those who breastfed (β = −7.5; 95% CI, −16.9 to 1.8). The associations for ER− tumors were similar, although they were not statistically significant. Conclusions: In this tumor-based study, higher parity was associated with lower FOXA1 expression in ER+ tumors, and breastfeeding may ameliorate the influence. Impact: These findings contribute to our understanding of FOXA1 methylation and breast cancer etiology.

Background: Aberrant activation of the mammalian Target of Rapamycin (mTOR) pathway is implicated in breast carcinogenesis and outcomes. Based on protein expression data, the activation could be heterogeneous by race, body fatness, and tumor clinicopathological characteristics. To understand potential impacts of mTOR pathway signaling in breast cancer, we evaluated the association of race and clinicopathological characteristics with gene expression of select mTOR pathway genes in breast tumors. Methods: Study participants were from the Women's Circle of Health Study (WCHS), complemented with samples from the Roswell Park Pathology Network Shared Resource (PNSR). Tumor tissue blocks were collected from 367 newly-diagnosed breast cancer cases (190 Black and 177 White women). Gene expressions of AKT1, EIF4EBP1, MTOR, RPS6KB2, TSC1 were quantitated using NanoString assays. Generalized linear models were performed to relate gene expression levels with demographic and clinicopathological variables. The regression coefficient (β) was converted to percentage difference. Additionally, we conducted an external validation of mTOR gene expression using data from The Cancer Genome Atlas (TCGA; N=332). Results: Study participants were mostly within the ages of 51 to 65 years old. Black women had lower expression levels of AKT1, MTOR, RPS6KB2 and TSC1 compared to White women. Black race vs White race was significantly associated with lower gene expression of AKT1 (-21.34%, 95% CI = -31.61%, -8.61%) and RPS6KB2 (-12.19%, 95% CI = -19.75%, -3.92%). The racial differences in expression levels of these two genes were consistent across luminal A, luminal B, HER2-enriched, and triple-negative subtypes. Higher tumor grade was associated with higher expression levels of EIF4EBP1 and RPS6KB2, but with lower expression of TSC1. In comparison to luminal A tumors, luminal B tumors had higher expression of RPS6KB2 (17.35%, 95% CI = 4.08%, 32.31%); whereas HER2-enriched (-23.66%, 95% CI= -41.73%, -1.00%) and triple-negative (-22.89%, 95% CI= -40.55%, -1.00%) had lower expression of TSC1. All these associations were unchanged after additionally adjusting for body mass index in a subset. Similarly, results from the TCGA data showed that in comparison to luminal A tumors, luminal B tumors had higher expression of RPS6KB2 (53.73%, 95% CI = 27.12%, 87.76%) whereas HER2-enriched had a lower expression of TSC1 (-26.66%, 95% CI = -43.45%, -4.88%) and triple-negative subtype had a lower expression of TSC1 (-17.30%, 95% CI = -50.68%, -3.05%). Conclusions: Variables such as race and breast cancer subtypes should be considered in studying the mTOR pathway genes in breast cancer tumors. Citation Format: Mmadili N. Ilozumba, Song Yao, Adana A. Llanos, Angela Omilian, Weizhou Zhang, Susmita Datta, Chi-Chen Hong, Warren Davis, Thaer Khoury, Christine B. Ambrosone, Ting-Yuan D. Cheng. Breast tumor gene expression in the mTOR pathway and clinicopathological characteristics in Black women and White women [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 869.

Objectives Ki-67 has been proposed to be used as a surrogate marker to differentiate luminal breast carcinomas (BCs). The purpose of this study was to determine the utility of and best approaches for using tissue microarrays (TMAs) and Ki-67 staining to distinguish luminal subtypes in large epidemiology studies of luminal/human epidermal growth factor receptor 2 (HER2)-negative BC. Methods Full-section and TMA (three 0.6-mm cores and two 1.0-mm cores) slides of 109 cases were stained with Ki-67 antibody. We assessed two ways of collapsing TMA cores: a weighted approach and mitotically active approach. Results For cases with at least a single 0.6-mm TMA core (n = 107), 16% were misclassified using a mitotically active approach and 11% using a weighted approach. For cases with at least a single 1.0-mm TMA core (n = 101), 5% were misclassified using either approach. For the 0.6-mm core group, there were 33.3% discordant cases. The number of discordant cases increased from 18% in the group of two cores to 40% in the group of three cores (P = .039). Conclusions Ki-67 tumor heterogeneity was common in luminal/HER2- BC. Using a weighted approach was better than using a mitotically active approach for core to case collapsing. At least a single 1.0-mm core or three 0.6-mm cores are required when designing a study using TMA.

Energy imbalance has an important role in breast cancer prognosis. Hyperactive mechanistic Target of Rapamycin (mTOR) pathway is associated with breast tumor growth, but the extent to which body fatness is associated with mTOR pathway activities in breast cancer is unclear. We performed immunostaining for mTOR, phosphorylated (p)-mTOR, p-AKT, and p-p70S6K in tumor tissue from 590 women (464 African Americans/Blacks and 126 Whites) with newly diagnosed invasive breast cancer in the Women’s Circle of Health Study. Anthropometric measures were taken by study staff, and body composition was measured by bioelectrical impedance analysis. Linear regressions were used to estimate percent differences in protein expression between categories of body mass index (BMI), waist circumference, waist/hip ratio, fat mass, fat mass index, and percent body fat. We observed that BMI ≥ 35.0 vs. 2 was associated with 108.3% (95% CI = 16.9%–270.9%) and 101.8% (95% CI = 17.0%–248.8%) higher expression in p-mTOR and normalized p-mTOR, i.e., p-mTOR/mTOR, respectively. Quartiles 4 vs. 1 of waist/hip ratio was associated with 41.8% (95% CI = 5.81%–89.9%) higher mTOR expression. Similar associations were observed for the body fat measurements, particularly in patients with estrogen receptor-negative (ER−) tumors, but not in those with ER+ tumors, although the differences in associations were not significant. This tumor-based study found positive associations between body fatness and mTOR pathway activation, evident by a p-mTOR expression, in breast cancer. Our findings suggest that mTOR inhibition can be a treatment strategy to prevent the recurrence of these tumors in obese individuals.

e13608 Background: Literature regarding racial differences in tumor immune responses in breast cancer remains sparse. To address this research gap, we assessed CD8+ T-cells in breast tumor samples from the Women’s Circle of Health Study (WCHS) population of predominantly Black breast cancer patients. We characterized and compared the density of CD8+ T cells, their prognostic value and their association with pharmacologic beta-blockers. Prior studies suggest that reducing adrenergic signaling through beta blockers can stimulate CD8+ T-cells. Methods: Tumor-infiltrating CD8+ T-cells were assessed by IHC staining of tissue microarray cores from 688 breast cancer patients, including 550 Blacks and 138 Whites. CD8+ T cells were scored with digital image analysis. Comparisons of demographic and clinical variables (including CD8+ T cell density) were made using the Mann-Whitney U or Kruskal-Wallis and Fisher’s exact tests. Associations with overall survival (OS) and disease-specific (DSS) survival were evaluated using the log-rank test of Cox regression. Analyses were performed in the overall sample and by disease sub-type. Results: Higher CD8+ T cell density was seen in Black women compared to White, with mean values of 756.2/mm2 and 292.4/mm2 respectively (p < 0.001). Within the overall population and in black women, CD8+ T cell density was significantly higher in younger patients, patients with high grade, and ER negative tumors. No significant associations were observed between CD8+ T cell density and OS or DSS. However, when stratified by subtype, Black patients with triple negative breast cancer and high CD8+ T cell density showed a trend towards improved OS in comparison to patients with low CD8+ T cell density (p = 0.065). 170 patients with information on beta blocker usage were analyzed. No significant associations were noted between CD8+ T cell density and beta blocker use. Conclusions: We observe a significantly higher CD8+ T cell density in Blacks compared to Whites, but this does not confer a survival advantage. Additionally, beta-blockers did not seem to enhance CD8+ T cell infiltration in tumors from Black patients. Our data raise the possibility that distinct mechanisms of immune cell action may occur in different racial groups. Future studies are needed to determine the functional properties of CD8+ T cells in Black women and to characterize additional immune cell subtypes that may also play a role.

The reprogramming of lipid metabolism is a hallmark of many cancers that has been shown to promote breast cancer progression. While several lipid signatures associated with breast cancer aggressiveness have been identified, a comprehensive lipidomic analysis specifically targeting the triple-negative subtype of breast cancer (TNBC) may be required to identify novel biomarkers and therapeutic targets for this most aggressive subtype of breast cancer that still lacks effective therapies. In this current study, our global LC-MS-based lipidomics platform was able to measure 684 named lipids across 15 lipid classes in 70 TNBC tumors. Multivariate survival analysis found that higher levels of sphingomyelins were significantly associated with better disease-free survival in TNBC patients. Furthermore, analysis of publicly available gene expression datasets identified that decreased production of ceramides and increased accumulation of sphingoid base intermediates by metabolic enzymes were associated with better survival outcomes in TNBC patients. Our LC-MS lipidomics profiling of TNBC tumors has, for the first time, identified sphingomyelins as a potential prognostic marker and implicated enzymes involved in sphingolipid metabolism as candidate therapeutic targets that warrant further investigation.

Background Breast cancer subtype can be classified using standard clinical markers (estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2)), supplemented with additional markers. However, automated biomarker scoring and classification schemes have not been standardized. The aim of this study was to optimize tumor classification using automated methods in order to describe subtype frequency in the African American Breast Cancer Epidemiology and Risk (AMBER) consortium. Methods Using immunohistochemistry (IHC), we quantified the expression of ER, PR, HER2, the proliferation marker Ki67, and two basal-like biomarkers, epidermal growth factor receptor (EGFR) and cytokeratin (CK)5/6, in 1381 invasive breast tumors from African American women. RNA-based (prediction analysis of microarray 50 (PAM50)) subtype, available for 574 (42%) cases, was used to optimize classification. Subtype frequency was calculated, and associations between subtype and tumor characteristics were estimated using logistic regression. Results Relative to ER, PR and HER2 from medical records, central IHC staining and the addition of Ki67 or combined tumor grade improved accuracy for classifying PAM50-based luminal subtypes. Few triple negative cases (

Reproductive factors, particularly parity, have differential effects on breast cancer risk according to estrogen receptor (ER) status, especially among African American (AA) women. One mechanism could be through DNA methylation, leading to altered expression levels of genes important in cell fate decisions. Using the Illumina 450K BeadChip, we compared DNA methylation levels in paraffin-archived tumor samples from 383 AA and 350 European American (EA) women in the Women’s Circle of Health Study (WCHS). We combined 450K profiles with RNA-seq data and prioritized genes based on differential methylation by race, correlation between methylation and gene expression, and biological function. We measured tumor protein expression and assessed its relationship to DNA methylation. We evaluated associations between reproductive characteristics and DNA methylation using linear regression. 410 loci were differentially methylated by race, with the majority unique to ER− tumors. FOXA1 was hypermethylated in tumors from AA versus EA women with ER− cancer, and increased DNA methylation correlated with reduced RNA and protein expression. Importantly, parity was positively associated with FOXA1 methylation among AA women with ER− tumors (P = 0.022), as was number of births (P = 0.026), particularly among those who did not breastfeed (P = 0.008). These same relationships were not observed among EA women, although statistical power was more limited. Methylation and expression of FOXA1 is likely impacted by parity and breastfeeding. Because FOXA1 regulates a luminal gene expression signature in progenitor cells and represses the basal phenotype, this could be a mechanism that links these reproductive exposures with ER− breast cancer.

Kristopher Attwood,1 Daria Fleyshman,2 Laura Prendergast,2 Geraldine Paszkiewicz,2 Angela R Omilian,3 Wiam Bshara,3 Katerina Gurova2 1Department of Biostatistics and Bioinformatics, 2Department of Cell Stress Biology, 3Department of Pathology, Roswell Park Cancer Institute, Buffalo, NY, USA Abstract: Understanding the underlying reasons for tumor aggressiveness, such as why some tumors grow slowly and locally, while others rapidly progress to a lethal metastatic disease, is still limited. This is especially critical in breast cancer (BrCa) due to its high prevalence and also due to the possibility that it can be detected early. Several oncogenes and tumor suppressors have been identified and are used in the prognosis and treatment of BrCa. However, even with these markers, the outcome within BrCa subtypes is highly variable. Chromatin organization has long been acknowledged as a factor that plays an important role in tumor progression, but molecular mechanisms defining chromatin dynamics are largely missing. We have recently found that histone chaperone FACT (facilitates chromatin transcription) is overexpressed in ~18–20% of BrCa cases. FACT is elevated upon transformation of mammary epithelial cells and is essential for viability of tumor cells. BrCa cells with high FACT have a more aggressive transcriptional program than those with low FACT cells. Based on this we propose that FACT may be a marker of aggressive BrCa. In this study, we aimed to comprehensively characterize the pattern of FACT expression in BrCa in relation to other molecular and clinical prognostic markers. We developed and tested an assay for the detection and quantitation of protein levels of both FACT subunits, SSRP1, and SPT16, in clinical samples. We compared the value of mRNA and protein as potential markers of disease aggressiveness using a large cohort of patients (n=1092). We demonstrated that only SSRP1 immunohistochemical staining is a reliable indicator of FACT levels in tumor samples. High SSRP1 correlated with known markers of poor prognosis, such as negative hormone receptor status, presence of Her2, high-grade tumors, and tumors of later clinical stage. At the same time, no strong correlation between SSRP1 expression and survival was detected when all samples were analyzed together. Clear trend toward longer survival of patients with low or no SSRP1 expression in tumor samples was seen in several subgroups of patients, and most importantly significant association of high SSRP1 expression with shorter disease-free survival was detected in patients with early-stage and low-grade BrCa, the category of patients with the highest demand in predictive marker of disease progression. Keywords: SSRP1, SPT16, breast cancer, predictive marker, prognosis

Whether estrogen receptor beta (ERβ) is a pro- or anti-oncogenic protein in breast cancer has been controversial. ERβ levels are high in ERα negative cancers including triple-negative breast cancer (TNBCs). Recent reports including the Cancer Genome Atlas (TCGA) show that about 80% of TNBC express mutant p53 (mut-p53) and it is the most predominant driver in these cancers. We tested the hypothesis that p53 status in breast cancer will have an important role in determining the duality of ERβ functions. We have shown that ERβ directly binds to p53 in human breast cancer cells. Using glutathione-S-transferase (GST)-pull down and co-imunoprecipitation assays, we have delineated the domains of both proteins that are required for the ERβ-p53 interaction. The DNA binding domain (DBD) along with the hinge domain of ERβ and the C-terminal regulatory domain of p53 are essential for the interaction. Using the highly sensitive proximity ligation assay (PLA), we show ERβ-p53 interaction in situ in breast cancer cells expressing either wild type (wt)- or mut-p53. ERβ and p53 antibodies validated for specificity were used. In multiple cell lines, a combination of proliferation and apoptosis assays, RNAi technology, quantitative chromatin immunoprecipitation (qChIP), and quantitative real-time PCR (qRT-PCR) showed that ERβ is pro-proliferative in the context of wt-p53, whereas it is anti-proliferative in the context of mut-p53. The results were recapitulated in isogenic MDA-MB-231 TNBC cells (generated by CRISPR technology) that differ only in the presence of wt-versus mut-p53. ERβ binds and sequesters mut-p53 from mut-p53−p73 complex leading to reactivation of tumor suppressor p73. Consistent with these data, combination of immunohistochemistry (IHC) and PLA in TNBC patient tumor tissue microarray (TMA) showed that patients with tumors expressing wt-p53/ high ERβ had worse prognosis, both in terms of overall survival (OS) and progression-free survival (PFS). On the contrary, tumors expressing mut-p53/ high ERβ were of smaller size and stage. These findings were complemented by data from our analysis of the mut-p53 subgroup of the basal-like tumors in the METABRIC dataset which showed that patients with tumors expressing higher levels of ERβ RNA (ESR2) had better prognosis. Surprisingly, 4-Hyroxy Tamoxifen (Tam) increased ERβ-mut-p53 interaction in TNBC cells and combination of doxorubicin (Adriamycin) and Tam decreased the IC50 of doxorubicin by 10 fold leading to increased apoptosis. These data have significant clinical implications in targeting ERβ and mutant p53 signaling pathways for therapeutic purposes especially in ERα negative cancers such as TNBC. Importantly, although at present Tam is not standard of care for TNBC, our data suggest a possibility for repurposing Tam therapy alone or in combination with chemotherapy to treat TNBC stratified based on p53 status. Citation Format: Gokul M. Das, Utpal K. Mukhopadhyay, Christina Adams, Nadi Wickramasekera, Rajesh Medisetty, Sanjay Bansal, Laxmi Silwal-Pandit, Anne-Lise Borresen-Dale, Austin Miller, Wendy M. Sweizig, Angela Omilian, Wiam Bshara, Alka Mukhopadhyay. p53 status as a determinant of functional duality of estrogen receptor beta in breast cancer: Therapeutic implications [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3748.

Background: Women of African ancestry (AA) have higher breast cancer mortality than other US racial/ethnic groups, attributed to a number of social and economic factors. However, breast tumors in AA women are more likely to present with higher grade and lacking estrogen receptor (ER) expression compared to those from women of European ancestry (EA), suggesting the importance of tumor factors in breast cancer disparities. Emerging evidence suggests that stromal tumor-infiltrating lymphocytes (TIL-str) have a role in immune response to therapy and prognosis of breast cancer. The objective of this study was to examine associations between risk factors for breast cancer and TIL-str, with consideration of tumor characteristics. Methods: We reviewed the hematoxylin and eosin slides from surgical or biopsy tumor blocks of invasive breast cancer from 1,385 cases (986 AA and 399 EA women, aged 20-75 years) in the Women's Circle of Health Study, a multicenter case-control study in New York and New Jersey. In-person interviews were conducted at diagnosis to obtain data on demographics, family histories, hormone use, and reproductive and menstrual histories. Anthropometric measurements were taken by trained staff. TIL-str were scored as 0%, 1%, and 10% to 100% in increments of 10%. Linear regressions were performed to estimate differences in TIL-str scores (β). Results: In univariate analysis, TIL-str was higher in tumors from AA than those from EA women overall (mean score = 21.5% vs. 12.5; P Conclusion: Self-reported African compared to European ancestry is independently associated with higher TIL-str scores in breast tumors. Our findings suggest that immune response may play a role in the differences in breast cancer biology and outcomes between AA and EA women. (Funding: The Breast Cancer Research Foundation; NIH P01CA151135, R01CA100598, R01CA185623, P30CA072720, K07CA201334; US Army Medical Research and Material Command DAMD-17-01-1-0334) Citation Format: Ting-Yuan D. Cheng, Rochelle Payne Ondracek, Song Yao, Warren Davis, Angela Omilian, Mateusz Opyrchal, Elisa V. Bandera, Michael J. Higgins, Christine B. Ambrosone, Thaer Khoury. Differences in stromal tumor-infiltrating lymphocytes in breast cancer from women of African and European ancestry after accounting for tumor characteristics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3242.

623 Background: Focal adhesion kinase (FAK) is an attractive therapeutic target in solid cancers, but there is no method for patient selection based on FAK expression nor biomarker for therapeutic response. Previous FAK expression studies were not standardized and showed varying correlations. This single-institution study aims to define FAK expression patterns in colorectal cancer (CRC) and correlate with patient outcomes and expression in other solid cancers. Methods: We analyzed 635 samples from 298 patients (pt) with CRC using tissue microarrays (TMAs) stained for FAK and scored 0-3 by a single pathologist. The TMAs contained samples of 298 primary tumors with 290 matching normal tissue and 47 matching metastases. As an internal control, we examined FAK and outcomes in 135 breast cancer pt and 145 melanoma pt. FAK expression and pt outcomes were evaluated using Kruskal-Wallis exact and Wilcoxon signed-rank tests. Results: FAK expression correlated with aggressive phenotype in CRC primaries. Matching normal colon had lower FAK than primaries (Mean FAK 0.61 vs 1.87, p < 0.001). Higher primary tumor FAK was associated with higher tumor stage; the 88 T1-2 primaries had a mean FAK 1.54, compared to FAK 2.06 in the 99 T3-4 tumors (p < 0.001). There was no difference in FAK among Stage II-IV pt, nor between mean FAK in the primaries (1.87) versus metastases (1.73). When FAK was dichotomized as high vs low (high = FAK > 2), high primary tumor FAK was associated with shorter overall survival (OS). Median OS was 91 months (95% CI 73-130) in high FAK (n = 122 pt) vs 155 months (95% CI 124-196) in low FAK (n = 176 pt), p = 0.007. The OS rates at 5 and 10 years in high FAK were 65% and 43%, vs 79% and 61% in low FAK. FAK in CRC metastases did not correlate with OS (p = 0.945). In contrast, when CRC was compared to breast cancer and melanoma, FAK did not show the same correlations in outcome. Conclusions: For the first time, by standardizing FAK quantification, we have identified that FAK expression in the primary correlates with outcome in CRC. These data may have implications in selection of patients for adjuvant therapy. Normal colon and earlier stage CRC had lower FAK expression compared to more advanced stages, suggesting a therapeutic window for FAK as a target.