BIRC5 expression by race, age and clinical factors in breast cancer patients

PURPOSE

Survivin/BIRC5 is a proliferation marker that is associated with poor prognosis in breast cancer and an attractive therapeutic target. However, BIRC5 has not been well studied among racially diverse populations where aggressive breast cancers are prevalent.

EXPERIMENTAL DESIGN

We studied BIRC5 expression in association with clinical and demographic variables and as a predictor of recurrence in 2174 participants in the Carolina Breast Cancer Study (CBCS), a population-based study that oversampled Black (n = 1113) and younger (< 50 years; n = 1137) participants with breast cancer. For comparison, similar analyses were conducted in The Cancer Genome Atlas [TCGA N = 1094, Black (n = 183), younger (n = 295)]. BIRC5 was evaluated as a continuous and categorical variable (highest quartile vs. lower three quartiles).

RESULTS

Univariate, continuous BIRC5 expression was higher in breast tumors from Black women relative to non-Black women in both estrogen receptor (ER)-positive and ER-negative tumors and in analyses stratified by stage (i.e., within Stage I, Stage II, and Stage III/IV tumors). Within CBCS and TCGA, BIRC5-high was associated with young age (< 50 years) and Black race, as well as hormone receptor-negative tumors, non-Luminal A PAM50 subtypes, advanced stage, and larger tumors (> 2 cm). Relative to BIRC5-low, BIRC5-high tumors were associated with poor 5-year recurrence-free survival (RFS) among ER-positive tumors, both in unadjusted models [HR (95% CI): 2.7 (1.6, 4.6)] and after adjustment for age and stage [Adjusted HR (95% CI): 1.87 (1.07, 3.25)]. However, this relationship was not observed among ER-negative tumors [Crude HR (95% CI): 0.7 (0.39, 1.2); Adjusted HR (95% CI): 0.67 (0.37, 1.2)].

CONCLUSION

Black and younger women with breast cancer have a higher burden of BIRC5-high tumors than older and non-Black women. Emerging anti-survivin treatment strategies may be an important future direction for equitable breast cancer outcomes.

Patterns of chemotherapy receipt among patients with hormone receptor-positive, HER2-negative breast cancer

BACKGROUND

Breast cancer chemotherapy utilization not only may differ by race and age, but also varies by genomic risk, tumor characteristics, and patient characteristics. Studies in demographically diverse populations with both clinical and genomic data are necessary to understand potential disparities by race and age.

METHODS

In the Carolina Breast Cancer Study Phase 3 (2008-2013), chemotherapy receipt (yes/no) and regimen type were assessed in association with age and race among hormone receptor (HR) positive and HER2-negative tumors (n = 1862). Odds ratios were estimated for the association between demographic factors and chemotherapy receipt.

RESULTS

Monotonic decreases in frequency of adjuvant chemotherapy receipt were observed over time during the study period, while neoadjuvant chemotherapy was stable. Younger age was associated with chemotherapy receipt (OR [95% CI]: 2.9 [2.4, 3.6]) and with anthracycline-based regimens (OR [95% CI]: 1.7 [1.3, 2.4]). Participants who had Medicaid (OR [95% CI]: 1.8 [1.3, 2.5]), lived in rural settings (OR [95% CI]: 1.4 [1.0, 2.0]), or were Black (OR [95% CI]: 1.5 [1.2, 1.8]) had slightly higher odds of chemotherapy, but these associations were non-significant with adjustment for stage and grade. Associations between younger age and chemotherapy receipt were strongest among women who did not receive genomic testing.

CONCLUSIONS

While race was not strongly associated with chemotherapy receipt, younger age remains a strong predictor of chemotherapy receipt, even with adjustment for clinical factors and among women who receive genomic testing.

Predicting early breast cancer recurrence from histopathological images in the Carolina Breast Cancer Study

Approaches for rapidly identifying patients at high risk of early breast cancer recurrence are needed. Image-based methods for prescreening hematoxylin and eosin (H&E) stained tumor slides could offer temporal and financial efficiency. We evaluated a data set of 704 1-mm tumor core H&E images (2-4 cores per case), corresponding to 202 participants (101 who recurred; 101 non-recurrent matched on age and follow-up time) from breast cancers diagnosed between 2008-2012 in the Carolina Breast Cancer Study. We leveraged deep learning to extract image information and trained a model to identify recurrence. Cross-validation accuracy for predicting recurrence was 62.4% [95% CI: 55.7, 69.1], similar to grade (65.8% [95% CI: 59.3, 72.3]) and ER status (66.3% [95% CI: 59.8, 72.8]). Interestingly, 70% (19/27) of early-recurrent low-intermediate grade tumors were identified by our image model. Relative to existing markers, image-based analyses provide complementary information for predicting early recurrence.

Differential distribution of actual and surrogate oncotype DX recurrence scores in breast cancer patients by age, menopausal status, race, and body mass index

PURPOSE

The Oncotype DX Recurrence Score (RS) is a widely used prognostic tool for estrogen receptor-positive breast cancer patients. Multiple surrogate models can predict RS with good accuracy. In this study we aimed to determine whether the RS and two surrogate indices were differentially distributed by age, menopausal status, race, and body mass index (BMI).

METHODS

516 breast cancer cases treated at a single institution were analyzed. Epidemiologic data, RS, tumor size, grade, and biomarker data were abstracted. Breast Cancer Prognostic Score (BCPS) and modified Magee equation 2 were used to calculate surrogate RS. Patients were stratified into different groups based on age, menopausal status, race, BMI, or a combination of strata. Mean and standard deviation were calculated for each group/subgroup.

RESULTS

Age below median (< 63) was associated with higher RS, especially in obese and Black patients. RS was also higher in obese and Black patients in the premenopausal subgroup. Black patients had a higher RS compared to White women in the premenopausal and non-obese subgroups. BMI < 30 was associated with higher RS, especially in older, postmenopausal, and Black patients. Some of these observations were replicated by the two surrogate models. The surrogate recurrence scores were higher in the younger age group, in non-obese older/postmenopausal women, and in younger/premenopausal obese individuals.

CONCLUSIONS

Higher RS was observed in younger and premenopausal breast cancer patients, especially among the Black and obese subgroups, and in non-obese patients, especially among Black and older/postmenopausal women, suggesting more aggressive disease in these subgroups. Some statistical differences could be replicated by both surrogate models, suggesting that they may have utility in breast cancer epidemiology studies that do not have access to Oncotype DX RS or patient outcome data.

Reproducibility and intratumoral heterogeneity of the PAM50 breast cancer assay

BACKGROUND

The PAM50 assay is used routinely in clinical practice to determine breast cancer prognosis and management; however, research assessing how technical variation and intratumoral heterogeneity contribute to misclassification and reproducibility of these tests is limited.

METHODS

We evaluated the impact of intratumoral heterogeneity on the reproducibility of results for the PAM50 assay by testing RNA extracted from formalin-fixed paraffin embedded breast cancer blocks sampled at distinct spatial locations. Samples were classified according to intrinsic subtype (Luminal A, Luminal B, HER2-enriched, Basal-like, or Normal-like) and risk of recurrence with proliferation score (ROR-P, high, medium, or low). Intratumoral heterogeneity and technical reproducibility (replicate assays on the same RNA) were assessed as percent categorical agreement between paired intratumoral and replicate samples. Euclidean distances between samples, calculated across the PAM50 genes and the ROR-P score, were compared for concordant vs. discordant samples.

RESULTS

Technical replicates (N = 144) achieved 93% agreement for ROR-P group and 90% agreement on PAM50 subtype. For spatially distinct biological replicates (N = 40 intratumoral replicates), agreement was lower (81% for ROR-P and 76% for PAM50 subtype). The Euclidean distances between discordant technical replicates were bimodal, with discordant samples showing higher Euclidian distance and biologic heterogeneity.

CONCLUSION

The PAM50 assay achieved very high technical reproducibility for breast cancer subtyping and ROR-P, but intratumoral heterogeneity is revealed by the assay in a small proportion of cases.

A comparison of analytic approaches for investigating the obesity paradox in kidney cancer

PURPOSE

Body mass index (BMI) and kidney cancer mortality are inconsistently associated in the scientific literature. To understand how study design affects results, we contrasted associations between pre-diagnosis BMI and mortality under different analytic scenarios in a large, population-based prospective cohort study.

METHODS

Using data from the NIH-AARP Diet and Health Study (1995-2011), we constructed two cohorts: a "full at-risk" cohort with no kidney cancer history at baseline (n = 252,845) and an "incident cancer" subset who developed kidney cancer during follow-up (n = 1,652). Cox Proportional Hazards models estimated hazard ratios (HR) and 95% confidence intervals (CI) between pre-diagnosis BMI and mortality for different outcomes (all-cause and cancer-specific mortality), in the different cohorts (full at-risk vs. incident cancer cohort), and with different covariates (minimally vs. fully adjusted). For the incident cancer cohort, we also examined time to mortality using different timescales: from enrollment or diagnosis.

RESULTS

In the full at-risk study population, higher pre-diagnosis BMI was associated with greater cancer-specific mortality in fully adjusted multivariable models, particularly for obese participants [HR, (95% CI): 1.76, (1.38-2.25)]. This association was less pronounced in the incident cancer cohort [1.50, (1.09-2.07)]. BMI was not strongly associated with all-cause mortality in either cohort in fully adjusted models [full cohort: 1.03, (1.01, 1.06); incident cancer cohort: 1.20, (0.97, 1.48)].

CONCLUSIONS

Populations characterized by high adult BMI will likely experience greater population burdens of mortality from kidney cancer, partially because of higher rates of kidney cancer diagnosis. Questions regarding overall mortality burden and post-diagnosis cancer survivorship are distinct and require different study designs.

RNA-Based Classification of Homologous Recombination Deficiency in Racially Diverse Patients with Breast Cancer

BACKGROUND

Aberrant expression of DNA repair pathways such as homologous recombination (HR) can lead to DNA repair imbalance, genomic instability, and altered chemotherapy response. DNA repair imbalance may predict prognosis, but variation in DNA repair in diverse cohorts of breast cancer patients is understudied.

METHODS

To identify RNA-based patterns of DNA repair expression, we performed unsupervised clustering on 51 DNA repair-related genes in the Cancer Genome Atlas Breast Cancer [TCGA BRCA (n = 1,094)] and Carolina Breast Cancer Study [CBCS (n = 1,461)]. Using published DNA-based HR deficiency (HRD) scores (high-HRD ≥ 42) from TCGA, we trained an RNA-based supervised classifier. Unsupervised and supervised HRD classifiers were evaluated in association with demographics, tumor characteristics, and clinical outcomes.

RESULTS

: Unsupervised clustering on DNA repair genes identified four clusters of breast tumors, with one group having high expression of HR genes. Approximately 39.7% of CBCS and 29.3% of TCGA breast tumors had this unsupervised high-HRD (U-HRD) profile. A supervised HRD classifier (S-HRD) trained on TCGA had 84% sensitivity and 73% specificity to detect HRD-high samples. Both U-HRD and S-HRD tumors in CBCS had higher frequency of TP53 mutant-like status (45% and 41% enrichment) and basal-like subtype (63% and 58% enrichment). S-HRD high was more common among black patients. Among chemotherapy-treated participants, recurrence was associated with S-HRD high (HR: 2.38, 95% confidence interval = 1.50-3.78).

CONCLUSIONS

HRD is associated with poor prognosis and enriched in the tumors of black women.

IMPACT

RNA-level indicators of HRD are predictive of breast cancer outcomes in diverse populations.

Obesity and Breast Cancer Metastasis across Genomic Subtypes

BACKGROUND

Obese women have higher risk of aggressive breast tumors and distant metastasis. However, obesity has rarely been assessed in association with metastasis in diverse populations.

METHODS

In the Carolina Breast Cancer Study Phase 3 (2008-2013), waist-to-hip ratio (WHR), body mass index (BMI), and molecular subtype [PAM50 risk-of-recurrence (ROR) score] were assessed. Obesity measures were evaluated in association with metastasis within five years of diagnosis, overall and stratified by race and ROR score. Absolute risk of metastasis and risk differences between strata were calculated using the Kaplan-Meier estimator, adjusted for age, grade, stage, race, and ER status. Relative frequency of metastatic site and multiplicity were estimated in association with obesity using generalized linear models.

RESULTS

High-WHR was associated with higher risk of metastasis (5-year risk difference, RD, 4.3%; 95% confidence interval, 2.2-6.5). It was also associated with multiple metastases and metastases at all sites except brain. The 5-year risk of metastasis differed by race (11.2% and 6.9% in Black and non-Black, respectively) and ROR score (19.5% vs. 6.6% in high vs. low-to-intermediate ROR-PT). Non-Black women and those with low-to-intermediate ROR scores had similar risk in high- and low-WHR strata. However, among Black women and those with high ROR, risk of metastasis was elevated among high-WHR (RDBlack/non-Black = 4.6%, RDHigh/Low-Int = 3.1%). Patterns of metastasis were similar by BMI.

CONCLUSIONS

WHR is associated with metastatic risk, particularly among Black women and those with high-risk tumors.

IMPACT

Understanding how risk factors for metastasis interact may help in tailoring care plans and surveillance among patients with breast cancer.

Toward a digital analysis of environmental impacts on rodent mammary gland density during critical developmental windows

While mammographic breast density is associated with breast cancer risk in humans, there is no comparable surrogate risk measure in mouse and rat mammary glands following various environmental exposures. In the current study, mammary glands from mice and rats subjected to reproductive factors and exposures to environmental chemicals that have been shown to influence mammary gland development and/or susceptibility to mammary tumors were evaluated for histologic density by manual and automated digital methods. Digital histological density detected changes due to hormonal stimuli/reproductive factors (parity), dietary fat, and exposure to environmental chemicals, such as benzophenone-3 and a combination of perfluorooctanoic acid and zeranol. Thus, digital analysis of mammary gland density offers a high throughput method that can provide a highly reproducible means of comparing a measure of histological density across independent experiments, experimental systems, and laboratories. This methodology holds promise for the detection of environmental impacts on mammary gland structure in mice and rats that may be comparable to human breast density, thus potentially allowing comparisons between rodent models and human breast cancer studies.

The Landscape of Immune Microenvironments in Racially Diverse Breast Cancer Patients

BACKGROUND

Immunotherapy is a rapidly evolving treatment option in breast cancer; However, the breast cancer immune microenvironment is understudied in Black and younger (<50 years) patients.

METHODS

We used histologic and RNA-based immunoprofiling methods to characterize the breast cancer immune landscape in 1,952 tumors from the Carolina Breast Cancer Study (CBCS), a population-based study that oversampled Black (n = 1,030) and young women (n = 1,039). We evaluated immune response leveraging markers for 10 immune cell populations, compared profiles to those in The Cancer Genome Atlas (TCGA) Project [n = 1,095 tumors, Black (n = 183), and young women (n = 295)], and evaluated in association with clinical and demographic variables, including recurrence.

RESULTS

Consensus clustering identified three immune clusters in CBCS (adaptive-enriched, innate-enriched, or immune-quiet) that varied in frequency by race, age, tumor grade and subtype; however, only two clusters were identified in TCGA, which were predominantly comprised of adaptive-enriched and innate-enriched tumors. In CBCS, the strongest adaptive immune response was observed for basal-like, HER2-positive (HER2+), triple-negative breast cancer (TNBC), and high-grade tumors. Younger patients had higher proportions of adaptive-enriched tumors, particularly among estrogen receptor (ER)-negative (ER-) cases. Black patients had higher frequencies of both adaptive-enriched and innate-enriched tumors. Immune clusters were associated with recurrence among ER- tumors, with adaptive-enriched showing the best and innate-enriched showing the poorest 5-year recurrence-free survival.

CONCLUSIONS

These data suggest that immune microenvironments are intricately related to race, age, tumor subtype, and grade.

IMPACT

Given higher mortality among Black and young women, more defined immune classification using cell-type-specific panels could help explain higher recurrence and ultimately lead to targetable interventions.

Quantitative analysis of breast cancer tissue composition and associations with tumor subtype

The tumor microenvironment is an important determinant of breast cancer progression, but standard methods for describing the tumor microenvironment are lacking. Measures of microenvironment composition such as stromal area and immune infiltrate are labor-intensive and few large studies have systematically collected this data. However, digital histologic approaches are becoming more widely available, allowing high-throughput, quantitative estimation. We applied such methods to tissue microarrays of tumors from 1687 women (mean 4 cores per case) in the Carolina Breast Cancer Study Phase 3. Tumor composition was quantified as percentage of epithelium, stroma, adipose, and lymphocytic infiltrate (with the latter as presence/absence using a ≥1% cutoff). Composition proportions and presence/absence were evaluated in association with clinical and molecular features of breast cancer (intrinsic subtype and RNA-based risk of recurrence [ROR] scores) using multivariable linear and logistic regression. Lower stromal content was associated with aggressive tumor phenotypes, including triple-negative (31.1% vs. 41.6% in HR+/HER2-; RFD [95% CI]: -10.5%, [-13.1, -7.9]), Basal-like subtypes (29.0% vs. 44.0% in Luminal A; RFD [95% CI]: -14.9%, [-17.8, -12.0]), and high RNA-based PAM50 ROR scores (27.6% vs. 48.1% in ROR low; RFD [95% CI]: -20.5%, [24.3, 16.7]), after adjusting for age and race. HER2+ tumors also had lower stromal content, particularly among RNA-based HER2-enriched (35.2% vs. 44.0% in Luminal A; RFD [95% CI]: -8.8%, [-13.8, -3.8]). Similar associations were observed between immune infiltrate and tumor phenotypes. Quantitative digital image analysis of the breast cancer microenvironment showed significant associations with demographic characteristics and biological indicators of aggressive behavior.

Racial differences in breast cancer outcomes by hepatocyte growth factor pathway expression

PURPOSE

Black women have a 40% increased risk of breast cancer-related mortality. These outcome disparities may reflect differences in tumor pathways and a lack of targetable therapies for specific subtypes that are more common in Black women. Hepatocyte growth factor (HGF) is a targetable pathway that promotes breast cancer tumorigenesis, is associated with basal-like breast cancer, and is differentially expressed by race. This study assessed whether a 38-gene HGF expression signature is associated with recurrence and survival in Black and non-Black women.

METHODS

Study participants included 1957 invasive breast cancer cases from the Carolina Breast Cancer Study. The HGF signature was evaluated in association with recurrence (n = 1251, 171 recurrences), overall, and breast cancer-specific mortality (n = 706, 190/328 breast cancer/overall deaths) using Cox proportional hazard models.

RESULTS

Women with HGF-positive tumors had higher recurrence rates [HR 1.88, 95% CI (1.19, 2.98)], breast cancer-specific mortality [HR 1.90, 95% CI (1.26, 2.85)], and overall mortality [HR 1.69; 95% CI (1.17, 2.43)]. Among Black women, HGF positivity was significantly associated with higher 5-year rate of recurrence [HR 1.73; 95% CI (1.01, 2.99)], but this association was not significant in non-Black women [HR 1.68; 95% CI (0.72, 3.90)]. Among Black women, HGF-positive tumors had elevated breast cancer-specific mortality [HR 1.80, 95% CI (1.05, 3.09)], which was not significant in non-Black women [HR 1.52; 95% CI (0.78, 2.99)].

CONCLUSION

This multi-gene HGF signature is a poor-prognosis feature for breast cancer and may identify patients who could benefit from HGF-targeted treatments, an unmet need for Black and triple-negative patients.

Hepatocyte growth factor pathway expression in breast cancer by race and subtype

BACKGROUND

African American women have the highest risk of breast cancer mortality compared to other racial groups. Differences in tumor characteristics have been implicated as a possible cause; however, the tumor microenvironment may also contribute to this disparity in mortality. Hepatocyte growth factor (HGF) is a stroma-derived marker of the tumor microenvironment that may affect tumor progression differentially by race.

OBJECTIVE

To examine whether an HGF gene expression signature is differentially expressed by race and tumor characteristics.

METHODS

Invasive breast tumors from 1957 patients were assessed for a 38-gene RNA-based HGF gene expression signature. Participants were black (n = 1033) and non-black (n = 924) women from the population-based Carolina Breast Cancer Study (1993-2013). Generalized linear models were used to estimate the relative frequency differences (RFD) in HGF status by race, clinical, and demographic factors.

RESULTS

Thirty-two percent of tumors were positive for the HGF signature. Black women were more likely [42% vs. 21%; RFD = + 19.93% (95% CI 16.00, 23.87)] to have HGF-positive tumors compared to non-black women. Triple-negative patients had a higher frequency of HGF positivity [82% vs. 13% in non-triple-negative; RFD = + 65.85% (95% CI 61.71, 69.98)], and HGF positivity was a defining feature of basal-like subtype [92% vs. 8% in non-basal; RFD = + 81.84% (95% CI 78.84, 84.83)]. HGF positivity was associated with younger age, stage, higher grade, and high genomic risk of recurrence (ROR-PT) score.

CONCLUSION

HGF expression is a defining feature of basal-like tumors, and its association with black race and young women suggests it may be a candidate pathway for understanding breast cancer disparities.

Abstract 2347: Metabolomics profiling of formalin-fixed paraffin-embedded prostate tissues

The metabolic landscape of the prostate changes with malignant transformation, and metabolomics is a means of identifying diagnostic and prognostic biomarkers for prostate cancer. Epidemiology and registry studies containing archival formalin-fixed paraffin-embedded (FFPE) specimens are a rich resource for this work but this method of tissue preservation presents a challenge due to loss of metabolites. We optimized global metabolic profiling in FFPE tissue and identified metabolites distinguishing tumor from normal prostate tissue, and aggressive from non-aggressive prostate cancer.

For optimization of metabolomics in FFPE tissues, we obtained matched frozen and FFPE tumor tissue from 62 prostate cancer cases who underwent radical prostatectomy (RP) at the University of North Carolina (UNC) hospital, of which 24 also had adjacent normal prostate tissue. To identify metabolites associated with tumor aggressiveness, we obtained matched tumor and normal FFPE tissue from 60 prostate cancer patients (Gleason ≥4+3, n=30; Gleason ≤3+4, n=30) who underwent RP participating in the UNC Health Registry/Cancer Survivorship Cohort. Following log transformation and imputation of missing values with the minimum observed value for each compound, Welch's two-sample t-test was used to identify biochemicals that differed significantly between groups. Random forest analysis evaluated predictive accuracy of metabolites for distinguishing tumor from normal prostate tissue.

We identified 768 compounds of known identity in frozen and 119 in matched FFPE tissues. Therefore, only 15% of the metabolites detected in frozen samples were recovered from corresponding FFPE tissue, with 80% of these common to both FFPE and matched frozen tissues. We found a predictive accuracy of 78% and 67% for frozen and FFPE tissue, respectively, for distinguishing tumor from normal. Of 39 metabolites significantly altered between matched tumor and normal FFPE tissue, 47% belonged to the lipid class, and despite a greater number of significantly altered metabolites in frozen tissue (246), the proportion belonging to the lipid class was similar (50%). Citrate, integral to normal prostate metabolism, and citrulline, involved in nitric oxide synthesis, had significantly lower levels in aggressive versus non-aggressive tumors. Cell membrane phospholipids were found at significantly higher levels in aggressive tumors.

Common patterns of altered metabolites in tumor vs. normal prostate were observed irrespective of tissue preservation method, despite loss of a large proportion of metabolites during the process of FFPE. As such, FFPE studies are feasible particularly when lipid metabolism is of interest as this class appears one of the best preserved in FFPE. This work will pave the way for incorporating metabolomics profiling of FFPE specimens into epidemiology and registry-based studies of prostate cancer.

Citation Format: Sophia Rachael Halliday, Linnea T. Olsson, Alina Hamilton, Sivapriya Ramamoorthy, Jason Kitchen, Erin Kirk, Laura Farnan, Adrian Gerstel, Melissa A. Troester, Jannette T. Bensen, Sara E. Wobker, Emma Allott. Metabolomics profiling of formalin-fixed paraffin-embedded prostate tissues [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 2347.

Protein-based immune profiles of basal-like vs. luminal breast cancers

Tumor-infiltrating lymphocytes play an important, but incompletely understood role in chemotherapy response and prognosis. In breast cancer, there appear to be distinct immune responses by subtype, but most studies have used limited numbers of protein markers or bulk sequencing of RNA to characterize immune response, in which spatial organization cannot be assessed. To identify immune phenotypes of Basal-like vs. Luminal breast cancer we used the GeoMx® (NanoString) platform to perform digital spatial profiling of immune-related proteins in tumor whole sections and tissue microarrays (TMA). Visualization of CD45, CD68, or pan-Cytokeratin by immunofluorescence was used to select regions of interest in formalin-fixed paraffin embedded tissue sections. Forty-four antibodies representing stromal markers and multiple immune cell types were applied to quantify the tumor microenvironment. In whole tumor slides, immune hot spots (CD45+) had increased expression of many immune markers, suggesting a diverse and robust immune response. In epithelium-enriched areas, immune signals were also detectable and varied by subtype, with regulatory T-cell (Treg) markers (CD4, CD25, and FOXP3) being higher in Basal-like vs. Luminal breast cancer. Extending these findings to TMAs with more patients (n = 75), we confirmed subtype-specific immune profiles, including enrichment of Treg markers in Basal-likes. This work demonstrated that immune responses can be detected in epithelium-rich tissue, and that TMAs are a viable approach for obtaining important immunoprofiling data. In addition, we found that immune marker expression is associated with breast cancer subtype, suggesting possible prognostic, or targetable differences.

Investigating survivin as a novel target in black women with breast cancer

594

Background: Black women with breast cancer have higher mortality than White women. Differences in tumor biology contribute to racial disparities in breast cancer outcomes. BIRC5 gene encodes survivin, an inhibitor of apoptosis protein, and an independent marker of poor prognosis in breast cancer. Cancer patients have anti-survivin antibodies and circulating survivin-specific T cells, suggesting that survivin may be targetable. Several ongoing antibody-mediated, vaccine strategies that target survivin are being developed. Nevertheless, most survivin studies were conducted in cohorts of White women. To date, the prevalence and/or role of survivin expression in breast tumors from Black women has not been studied. Methods: Associations between BIRC5 expression, clinicopathological and molecular features were measured in the population-based Carolina Breast Cancer Study (CBCS) and The Cancer Genome Atlas (TCGA) breast cancer cohort. Gene expression was measured by Nanostring RNA counting and split into BIRC5 high (4th quartile) and low categories based on log2 gene expression values. Relative frequency differences (RFD) for the association between BIRC5 high and clinicopathologic features were estimated. RNA based p53 mutant status and homologous recombination deficiency (HRD) status were included in RFD analysis. Receiver operating characteristic (ROC) curves were used to illustrate the potential of BIRC5 expression to distinguish patients who achieved pathological complete response (pCR) after receiving neoadjuvant chemotherapy in CBCS (133 Black, 49 non-Black). Results: BIRC5 gene expression was significantly increased in tumors from 966 Black patients compared to 1,497 non-Black (p < 0.00001), adjusting for stage and subtype. BIRC5 high tumors were significantly more expressed in higher stage and basal-like breast cancer subtypes. BIRC5 high tumors were also significantly enriched for expression of genes involved in p53 loss and HRD. Furthermore, in an analysis of 182 CBCS patients, BIRC5 gene expression alone predicted pCR with similar overall AUC to ROR-PT multigene signatures (AUC 0.62 vs 0.64). Conclusions: Our study shows that survivin expression is particularly high in breast tumors from Black women. This was associated with more aggressive clinicopathological features in addition to p53 mutant and HRD status. Black women with breast cancer represent an area of unmet clinical need and could potentially benefit from anti-survivin targetable treatment strategies. Further studies are needed to help close this gap which constitutes the largest disparity among cancer-specific diseases.[Table: see text]

Abstract SS1-05: Racial differences in breast cancer immune microenvironments

Background: Black women suffer 40% higher mortality from breast cancer (BC) compared to non-Hispanic white women, and the underlying causes of these disparities remain uncertain. Growing evidence supports the importance of the immune microenvironment in BC survival, but immune response differences by race are poorly understood. We sought to characterize the immune microenvironment of BC to evaluate how phenotypes of immune response vary across race and tumor intrinsic subtype to impact clinical outcomes. Methods: We leveraged the Carolina Breast Cancer Study (CBCS), a large population-based study that oversampled young (≤50) and black women with invasive breast cancer and collected tumor tissue on &gt;95% of participants. We curated a 48-gene panel representative of 13 individual immune cell types, and performed NanoString gene expression profiling on tissue from 1957 BC patients, including 1033 (53%) Black and 924 (47%) Non-Black women. Consensus clustering was used to identify phenotypes of immune response, and individual immune cell scores were calculated as the median expression of cell-type markers. Immune phenotypes and cell-type scores were compared against validated protein markers and H&E-based quantification of TILs from corresponding tissue microarrays (TMAs). We estimated associations of immune classes with BC intrinsic subtype, ROR-PT scores (calculated as low, medium and high), age and race using relative frequency differences (RFDs), adjusting for age and tumor stage. Cell type scores were compared by race using Welch’s t-tests and adjusted for multiple comparisons with the Benjamani-Hochberg procedure. Results: We identified three BC immune phenotypes primarily defined by features related to an Adaptive-enriched, Innate-enriched, or a Quiet immune microenvironment. These expression-based groups correlated with histological evidence of immune cells from corresponding TMAs. Similarly, expression-based cell scores correlated strongly with protein-based quantification of immune cells from corresponding TMAs (e.g. B-cell score vs. CD19 immunofluorescence, rho=0.75; ICOS RNA counts vs. protein; Rho=0.76). Both Adaptive-enriched and Innate-enriched tumors were associated with high ROR-PT scores [RFD for Adaptive-enriched vs. Quiet: 24.1% (95% CI 19.3-28.8); Innate-enriched vs. Quiet RFD: 13.1 (95% CI 9.1-17); frequencies: 37.2%, 26.2% and 10% for Adaptive, Innate and Quiet, respectively], the basal-like intrinsic subtype [RFD for Adaptive-enriched vs. Quiet: 19.4% (95% CI 14.3-24.6); Innate-enriched vs. Quiet RFD: 9.8 (95% CI 5.6-14.1); frequencies: 43.4%, 27.4% and 8.9% respectively] and Black race [RFD for Adaptive-enriched vs. Quiet: 16.1% (95% CI 10.3-21.9); Innate-enriched vs. Quiet RFD: 9.5 (95% CI 3.9-15); frequencies 60.5%, 53.5% and 42.5% respectively]. After adjusting for tumor subtype, the Adaptive-enriched class remained associated with Black race (RFD for Adaptive-Enriched vs Quiet: 7.5% (95% CI 1.4-13.6). Conversely, tumors in the immune-quiet group were primarily non-basal (90%) with low ROR-PT scores (86.7%). Within the Adaptive-enriched class, Black women displayed decreased CD8 T cell scores (p=0.05) but increased T-reg cell scores (p=0.02) relative to Non-Black women. Conclusion: Immune response appears to be intricately related to race and tumor subtype, with black women having strong associations with adaptive-enriched and innate-enriched immune microenvironments. Differences in CD8 T cell and Treg expression suggest that even within broad classes of immune response, racial differences in specific cell-type distributions exist. Immune response differences may be targetable to improve treatment response, and therefore it is important to identify race- and subtype-specific differences in immune microenvironments.

Citation Format: Alina M Hamilton, Linnea T Olsson, Benjamin C Calhoun, Katherine A Hoadley, Melissa A Troester. Racial differences in breast cancer immune microenvironments [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 SS1-05.

Abstract PD11-06: Associations between obesity and metastasis in the Carolina breast cancer study

Background. Metastatic disease accounts for the majority of breast cancer-specific mortality, and identifying women who are most at risk for metastasis remains an important challenge. Genomic risk scores are valuable tools in assessing risk of recurrence but have rarely been applied to assess risk of distant metastasis in large, diverse population-based cohorts. Such cohorts can identify important modifiers of the relationship between tumor genomics and metastasis. In particular, obesity at diagnosis has been implicated as a risk factor for breast cancer metastasis. Waist-to-hip ratio (WHR), as a measure of central adiposity, appears to increase risk of breast cancer mortality. It is important to understand how obesity impacts risk of metastasis and modifies other known prognostic factors. Methods. Data from the Carolina Breast Cancer Study, a prospective cohort of women with incident breast cancer that oversampled young women and black women such that each represented 50% of the study population, were used to study metastasis within five years of follow up (n=239 incident metastases in 2767 eligible participants with stage I-III disease). PAM50-derived risk-of-recurrence (ROR-PT) scores were measured using a research version of the 50-gene assay, and represent a multigene classifier incorporating tumor subtype, size, and proliferation score. Women with de novo metastasis (identified at diagnosis, n=109) were excluded, as incident and de novo metastases have different prognosis. Obesity was defined by WHR (&gt; 0.85). Absolute risk within strata and risk differences between strata were calculated using the Kaplan-Meier estimator; models were adjusted with inverse probability weights conditional on grade, stage, age, and race, where appropriate. To examine the association between obesity and site or multiplicity of metastasis, relative frequency differences were estimated using generalized linear models. Results. The overall risk of metastasis in CBCS differed significantly by race (11.2% in Black women and 6.8% in non-Black women and was associated with higher ROR-PT score (19.8% in high ROR-PT vs. 6.5% in low or medium ROR-PT). 48.2% of women were classified as obese by WHR. Women with high WHR had a significantly higher absolute risk of metastasis (11.2%, 95% CI: 9.4, 13.0) relative to those with lower WHR (6.9, 95% CI: 5.6, 8.2). However, the effects of WHR on risk seemed to be isolated to those with high risk tumors. Non-obese and obese women with low-to-medium ROR-PT scores had similar risk of metastasis [RDLowMed (95% CI) = 1.5% (-1.5, 4.4)], while obese women with high ROR-PT scores had substantially higher risk of metastasis than non-obese women [RDHigh (95% CI) = 13.1% (4.3, 21.9); 26.2% vs. 13.1%]. Considering site of metastasis, more metastases were observed among women with high WHR at every site except brain. More occurrences of multiple metastases were also observed among obese women. Conclusions. Consistent with previous studies, we observed racial disparities in metastasis, with Black women having higher 5-year metastatic risk and with women with high ROR-PT scores also having higher risk. Obesity, herein measured by WHR, is an important predictor of metastatic risk and may modify the relationship between genomic risk scores and risk of metastasis.

Citation Format: Linnea T Olsson, Andrea Walens, Alina M Hamilton, Halei C Benefield, Kevin P Williams, Jodie M Fleming, Stephen D Hursting, Melissa A Troester. Associations between obesity and metastasis in the Carolina breast cancer study [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 PD11-06.

Abstract PO-090: Protein-based immune profiles of basal-like vs luminal breast cancers

Background: Tumor infiltrating lymphocytes (TILs) play an important, but incompletely understood role in chemotherapy response and prognosis. In breast cancer, there appear to be distinct immune responses by subtype, but most studies have used limited numbers of protein markers or bulk sequencing of RNA to characterize immune response, in which spatial organization cannot be assessed. Methods: To identify immune phenotypes of Basal-like vs. Luminal breast cancer we used the GeoMx® (NanoString) platform to perform digital spatial profiling (DSP) of immune-related proteins in tumor whole sections and tissue microarrays (TMA). Visualization of CD45, CD68, or pan-Cytokeratin by immunofluorescence was used to select regions of interest (ROIs) in formalin-fixed paraffin embedded tissue sections. 44 antibodies representing stromal markers and multiple immune cell types were applied to quantify the tumor microenvironment. Results: In whole tumor slides, immune hot spots (CD45+) had increased expression of many immune markers, suggesting a diverse and robust immune response. In epithelium-enriched areas, immune signals were also detectable and varied by subtype, with Regulatory T cell (Treg) markers (CD4, CD25, FOXP3) being higher in Basal-like vs. Luminal breast cancer. Extending these findings to TMAs with more patients (n=75), we confirmed subtype-specific immune profiles, including enrichment of Treg markers in Basal-likes. Conclusion: This work demonstrated that immune responses can be detected in epithelium-rich tissue, and that TMAs are a viable approach for obtaining important immunoprofiling data. In addition, we found that immune marker expression is associated with BC subtype, suggesting possible prognostic or targetable differences.

Citation Format: Andrea Walens, Linnea T. Olsson, Xiaohua Gao, Alina M. Hamilton, Erin L. Kirk, Stephanie M. Cohen, Bentley R. Midkiff, Yongjuan Xia, Mark E. Sherman, Nana Nikolaishvili-Feinberg, Katherine A. Hoadley, Melissa A. Troester, Benjamin C. Calhoun. Protein-based immune profiles of basal-like vs luminal breast cancers [abstract]. In: Proceedings of the AACR Virtual Special Conference on Tumor Heterogeneity: From Single Cells to Clinical Impact; 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr PO-090.

Abstract PO-068: Intratumoral heterogeneity of prognostic multigene signatures for breast cancer

Background Multigene assays for breast cancer are becoming more commonly used for research, diagnostic, and treatment-selection purposes. These assays are commonly based on a single tumor sample, so this study assesses whether clinically-relevant multigene scores are subject to misclassification due to technical variation or intratumoral heterogeneity. Methods Using FFPE blocks, tumors from 37 patients were sampled at different pathologist-selected spatial locations, targeting regions with distinct histological appearance. A second pathologist assessed mitotic activity and presence of immune infiltration for each specimen. Gene expression was quantified using the PAM50 assay. Samples were classified with respect to intrinsic subtype (Luminal A, Luminal B, HER2-enriched, or Basal-like) and risk of recurrence with proliferation score (ROR-P, high vs. med/low). Euclidean distances between samples were calculated across the 50 genes, and the distribution of Euclidean distances were compared for samples that were concordant vs. discordant for each multigene classifier for PAM50 or ROR-P. Results Of the 37 tumors, 11 had samples with discordant PAM50 subtype and 7 had samples with discordant ROR-P group (75% and 83% agreement, respectively). The Euclidean distance between paired samples with discordant PAM50 intrinsic subtype or ROR-P score was significantly greater than that among concordant tumors. Samples discordant for ROR-P had more heterogeneity in histological characteristics, while discordance of PAM50 subtype call was generally not predicted by heterogeneity of these histological characteristics. Conclusion The concordance of PAM50 subtype calls and ROR-P, despite oversampling of heterogenous-appearing tumor regions, demonstrates reproducibility of the PAM50 classifier for breast cancer tumor intrinsic subtyping. However, assay sampling strategies for histologically heterogeneous tumors merit further consideration.

Citation Format: Amber N. Hurson, Alina Hamilton, Linnea T. Olsson, Erin L. Kirk, Benjamin C. Calhoun, Joseph Geradts, Mark E. Sherman, Melissa A. Troester. Intratumoral heterogeneity of prognostic multigene signatures for breast cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Tumor Heterogeneity: From Single Cells to Clinical Impact; 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr PO-068.

Abstract 1184: Association of immune microenvironment and race in the Carolina Breast Cancer Study

Background: High levels of tumor infiltrating lymphocytes have been associated with favorable prognosis in triple negative and HER2-positive breast cancer (BC), especially in tumors with high mutation burden. Recently, our group showed that TP53 functional defects are strongly associated with black race in the Carolina Breast Cancer Study (CBCS). However, the immune microenvironment has been inconsistently associated with racial disparities in BC.

Methods: To characterize immune phenotypes in BC, we curated a 50-gene NanoString immune panel and validated the gene set using RNA sequencing data from The Cancer Genome Atlas (TCGA). We applied the NanoString panel in the CBCS and estimated associations with immune infiltrates, BC intrinsic subtype, proliferation scores, p53 mutation signature and race using relative frequency differences (RFDs) as the measure of association.

Results: Our 50-gene immune panel produced sample groupings in TCGA similar to that observed with the deconvolution algorithm, CIBERSORT. In CBCS (n=1208), we identified three immune groups primarily defined by features related to either adaptive immunity, innate immunity, or a quiet immune environment. Confirming that our expression-based groups reflect the tumor immune microenvironment, these immune groups correlated with histological evidence of immune cells from H&E slides in both TCGA and CBCS. The adaptive-enriched group was strongly associated with young age (≤50 years), high tumor grade, higher proliferation scores and the basal-like intrinsic subtype. TP53 mutant-like status was strongly associated with the adaptive-enriched immune group (RFD: 25.3%, p&lt;0.0001), adjusting for age, race, and stage. Conversely, tumors in the innate and immune-quiet groups were primarily luminal (67.7%) and TP53 WT-like (60.2%). Black race was associated with the adaptive-enriched immune phenotype, even after adjusting for age and tumor stage (RFD: 7.6%, p=0.031).

Conclusions: Our immune panel defines groups of BCs according to type of immune infiltration. Consistent with previous literature, we show that adaptive immunity is associated with aggressive breast tumors in CBCS. In addition, our data suggest an immunomodulatory effect of TP53 functional status–a variable we have previously associated with race in the CBCS. We provide evidence for a role of the immune microenvironment in racial disparities of BC. Further characterization of individual immune cell populations by race could reveal potential targets for BC intervention strategies that improve survivorship disparities.

Citation Format: Alina M. Hamilton, Linnea T. Olsson, Benjamin C. Calhoun, Katherine A. Hoadley, Melissa A. Troester. Association of immune microenvironment and race in the Carolina Breast Cancer Study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1184.

Using Digital Pathology to Understand Epithelial Characteristics of Benign Breast Disease among Women Undergoing Diagnostic Image-Guided Breast Biopsy

Delayed terminal duct lobular unit (TDLU) involution is associated with elevated mammographic breast density (MD). Both are independent breast cancer risk factors among women with benign breast disease (BBD). Prior digital analyses of normal breast tissues revealed that epithelial nuclear density (END) and TDLU involution are inversely correlated. Accordingly, we examined associations of END, TDLU involution, and MD in BBD clinical biopsies. This study included digitized images of 262 representative image-guided hematoxylin and eosin-stained biopsies from 224 women diagnosed with BBD, enrolled within the cross-sectional BREAST-Stamp project that were visually assessed for TDLU involution (TDLU count/100 mm², median TDLU span and median acini count per TDLU). A digital algorithm estimated nuclei count per unit epithelial area, or END. Single X-ray absorptiometry of prebiopsy ipsilateral craniocaudal digital mammograms measured global and localized MD surrounding the biopsy region. Adjusted ordinal logistic regression models assessed relationships between tertiles of TDLU and END measures. Analysis of covariance examined mean differences in MD across END tertiles. TDLU measures were positively associated with increasing END tertiles [TDLU count/100 mm², OR_T3vsT1: 3.42, 95% confidence interval (CI), 1.87-6.28; acini count/TDLU_T3vsT1, OR: 2.40, 95% CI, 1.39-4.15]. END was significantly associated with localized, but not, global MD. Relationships were most apparent among patients with nonproliferative BBD. These findings suggest that quantitative END reflects different but complementary information to the histologic information captured by visual TDLU and radiologic MD measures and merits continued evaluation in assessing cellularity of breast parenchyma to understand the etiology of BBD.

Vascular density of histologically benign breast tissue from women with breast cancer: associations with tissue composition and tumor characteristics

In breast tumors, it is well established that intratumoral angiogenesis is crucial for malignant progression, but little is known about the vascular characteristics of extratumoral, cancer-adjacent breast. Genome-wide transcriptional data suggest that extratumoral microenvironments may influence breast cancer phenotypes; thus, histologic features of cancer-adjacent tissue may also have clinical implications. To this end, we developed a digital algorithm to quantitate vascular density in approximately 300 histologically benign tissue specimens from breast cancer patients enrolled in the UNC Normal Breast Study (NBS). Specimens were stained for CD31, and vascular content was compared to demographic variables, tissue composition metrics, and tumor molecular features. We observed that the vascular density of cancer-adjacent breast was significantly higher in older and obese women, and was strongly associated with breast adipose tissue content. Consistent with observations that older and heavier women experience higher frequencies of ER+ disease, higher extratumoral vessel density was also significantly associated with positive prognostic tumor features such as lower stage, negative nodal status, and smaller size (<2 cm). These results reveal biological relationships between extratumoral vascular content and body size, breast tissue composition, and tumor characteristics, and suggest biological plausibility for the relationship between weight gain (and corresponding breast tissue changes) and breast cancer progression.

Race-associated biological differences among luminal A and basal-like breast cancers in the Carolina Breast Cancer Study

BACKGROUND

We examined racial differences in the expression of eight genes and their associations with risk of recurrence among 478 white and 495 black women who participated in the Carolina Breast Cancer Study Phase 3.

METHODS

Breast tumor samples were analyzed for PAM50 subtype and for eight genes previously found to be differentially expressed by race and associated with breast cancer survival: ACOX2, MUC1, FAM177A1, GSTT2, PSPH, PSPHL, SQLE, and TYMS. The expression of these genes according to race was assessed using linear regression and each gene was evaluated in association with recurrence using Cox regression.

RESULTS

Compared to white women, black women had lower expression of MUC1, a suspected good prognosis gene, and higher expression of GSTT2, PSPHL, SQLE, and TYMS, suspected poor prognosis genes, after adjustment for age and PAM50 subtype. High expression (greater than median versus less than or equal to median) of FAM177A1 and PSPH was associated with a 63% increase (hazard ratio (HR) = 1.63, 95% confidence interval (CI) = 1.09-2.46) and 76% increase (HR = 1.76, 95% CI = 1.15-2.68), respectively, in risk of recurrence after adjustment for age, race, PAM50 subtype, and ROR-PT score. Log₂-transformed SQLE expression was associated with a 20% increase (HR = 1.20, 95% CI = 1.03-1.41) in recurrence risk after adjustment. A continuous multi-gene score comprised of eight genes was also associated with increased risk of recurrence among all women (HR = 1.11, 95% CI = 1.04-1.19) and among white (HR = 1.14, 95% CI = 1.03-1.27) and black (HR = 1.11, 95% CI = 1.02-1.20) women.

CONCLUSIONS

Racial differences in gene expression may contribute to the survival disparity observed between black and white women diagnosed with breast cancer.