XIAP overexpressing inflammatory breast cancer patients have high infiltration of immunosuppressive subsets and increased TNFR1 signaling targetable with Birinapant

OBJECTIVE

To assess the expression pattern of X-linked inhibitor of apoptosis protein (XIAP), a cellular stress sensor, and delineate the associated changes in the tumor immune microenvironment (TiME) for prognostic value and new therapeutic targets in inflammatory breast cancer (IBC).

METHODS

Immunohistochemistry was conducted to assess the spatial localization of immune subsets, XIAP, and PDL1 expression in IBC and non-inflammatory breast cancer (nIBC) pretreatment tumors (n = 142). Validation and further exploration were performed by gene expression analysis of patient tumors along with signaling studies in a co-culture model.

RESULTS

High XIAP in 37/81 IBC patients correlated significantly with high PD-L1, increased infiltration of FOXP3+ Tregs, CD163+ tumor-associated macrophages (TAMs), low CD8/CD163 ratio in both tumor stroma (TS) and invasive margins (IM), and higher CD8+ T cells and CD79α+ B cells in the IM. Gene set enrichment analysis identified cellular stress response- and inflammation-related genes along with tumor necrosis factor receptor 1 (TNFR1) expression in high-XIAP IBC tumors. Induction of TNFR1 and XIAP was observed when patient-derived SUM149 IBC cells were co-cultured with human macrophage-conditioned media simulating TAMs, further demonstrating that the TNF-α signaling pathway is a likely candidate governing TAM-induced XIAP overexpression in IBC cells. Finally, addition of Birinapant, a pan IAP antagonist, induced cell death in the pro-survival cytokine-enriched conditions.

CONCLUSION

Using immunophenotyping and gene expression analysis in patient biospecimens along with in silico modeling and a preclinical model with a pan-IAP antagonist, this study revealed an interplay between increased TAMs, TNF-α signaling, and XIAP activation during (immune) stress in IBC. These data demonstrate the potential of IAP antagonists as immunomodulators for improving IBC therapeutic regimens.

Identification of barriers at the primary care provider level to improve inflammatory breast cancer diagnosis and management

The purpose of this study, based in the United States, was to evaluate knowledge gaps and barriers related to diagnosis and care of inflammatory breast cancer (IBC), a rare but lethal breast cancer subtype, amongst Primary Care Providers (PCP) as they are often the first point of contact when patients notice initial symptoms. PCP participants in the Duke University Health System, federally qualified health center, corporate employee health and community practices, nearby academic medical center, Duke physician assistant and advanced practice nurse leadership program alumni were first selected in a convenience sample and for semi-structured interviews (n = 11). Based on these data, an online survey tool was developed and disseminated (n = 78) to assess salient measures of IBC diagnosis, health disparity factors, referral and care coordination practices, COVID-19 impact, and continuing medical education (CME). PCP reported access to care and knowledge gaps in symptom recognition (mean = 3.3, range 1-7) as major barriers. Only 31 % reported ever suspecting IBC in a patient. PCP (n = 49) responded being challenged with referral delays in diagnostic imaging. Additionally, since the COVID-19 pandemic started, 63 % reported breast cancer referral delays, and 33 % reported diagnosing less breast cancer. PCP stated interest in CME in their practice for improved diagnosis and patient care, which included online (53 %), lunch time or other in-service training (33 %), patient and provider-facing websites (32 %). Challenges communicating rare cancer information, gaps in confidence in diagnosing IBC, and timely follow-up with patients and specialists underscores the need for developing PCP educational modules to improve guideline-concordant care.

Cumulative environmental quality is associated with breast cancer incidence differentially by summary stage and urbanicity

Individual environmental contaminants have been associated with breast cancer; however, evaluations of multiple exposures simultaneously are limited. Herein, we evaluated associations between breast cancer summary stages and the Environmental Quality Index (EQI), which includes a range of environmental factors across five domains. The EQI (2000-2005) was linked to county-level age-standardized incidence rates (SIRs) obtained from the North Carolina Central Cancer Registry (2010-2014). Incidence rates and SIRs of total, in situ, localized, regional, and distant breast cancers were evaluated stratified by rural-urban status. In counties with poor environmental quality compared to those with good environmental quality, total breast cancer incidence was higher by 10.82 cases per 100,000 persons (95% CI 2.04, 19.60, p = 0.02). This association was most pronounced for localized breast cancer (β = 5.59, 95% CI 0.59, 10.58, p = 0.03). Higher incidence of early-stage disease (carcinoma in situ β = 5.25, 95% CI 2.34, 8.16, p = 0.00 and localized breast cancer β = 6.98, 95% CI 2.24, 11.73, p = 0.00) and total breast cancer (β = 11.44, 95% CI 3.01, 19.87, p = 0.01) occurred in counties with poor land quality, especially urban counties. Our analyses indicate significant associations between environmental quality and breast cancer incidence, which differ by breast cancer stage and urbanicity, identifying a critical need to assess cumulative environmental exposures in the context of cancer stage.

A Novel Preclinical Murine Model to Monitor Inflammatory Breast Cancer Tumor Growth and Lymphovascular Invasion

Inflammatory breast cancer (IBC), an understudied and lethal breast cancer, is often misdiagnosed due to its unique presentation of diffuse tumor cell clusters in the skin and dermal lymphatics. Here, we describe a window chamber technique in combination with a novel transgenic mouse model that has red fluorescent lymphatics (ProxTom RFP Nu/Nu) to simulate IBC clinicopathological hallmarks. Various breast cancer cells stably transfected to express green or red fluorescent reporters were transplanted into mice bearing dorsal skinfold window chambers. Intravital fluorescence microscopy and the in vivo imaging system (IVIS) were used to serially quantify local tumor growth, motility, length density of lymph and blood vessels, and degree of tumor cell lymphatic invasion over 0-140 h. This short-term, longitudinal imaging time frame in studying transient or dynamic events of diffuse and collectively migrating tumor cells in the local environment and quantitative analysis of the tumor area, motility, and vessel characteristics can be expanded to investigate other cancer cell types exhibiting lymphovascular invasion, a key step in metastatic dissemination. It was found that these models were able to effectively track tumor cluster migration and dissemination, which is a hallmark of IBC clinically, and was recapitulated in these mouse models.

Abstract P4-03-12: Cumulative Environmental Quality is Associated with Differential Breast Cancer Incidence by Summary Stage and Urbanicity

Background: Individual environmental contaminants have been associated with breast cancer; however, evaluations of multiple exposures simultaneously are limited. The USPA has constructed an environmental quality index (EQI), which contains county-level environmental exposure data across five overarching environmental domains (air, water, land, sociodemographic, and built environment). Unfortunately, the links made between breast cancer and the EQI are lacking because these analyses used total breast cancer incidence quantities, masking potential associations between EQI domains and specific stages of disease. In this study, we investigated if multiple exposures in broad EQI domains was associated with incidence of breast cancer, stratified by stage.

Methods: The EQI data was linked to county-level age-standardized incidence rates (SIRs) obtained from the North Carolina Central Cancer Registry/NC CCR (2010-2014), a reporting system for all cancer cases diagnosed in residents of the state. Incidence rates and SIRs of total, in situ, localized, regional, and distant breast cancers were evaluated stratified by rural-urban status. Associations between county-level age-adjusted cancer incidence rates for each summary stage were assessed using general linear models (SAS 9.3), linear models with a continuous outcome with a p-value cutoff for statistical significance set at p< 0.05. We also evaluated incidence rates by summary stage comparing across rural versus urban counties using Mann-Whitney rank tests, since not all stages were normally distributed, confirmed by the D’Agostino-Pearson normality test.

Results: In counties with poor environmental quality compared to those with good environmental quality, total breast cancer incidence was higher by 10.82 cases per 100,000 persons (95%CI: 2.04, 19.60, p=0.016). This association was most pronounced for localized breast cancer (β=5.59, 95%CI: 0.59, 10.58, p=0.029). Higher incidence of early-stage disease (carcinoma in situ β=5.25, 95%CI: 2.34, 8.16, p=0.001 and localized breast cancer β=6.98, 95%CI: 2.24, 11.73, p=0.004) and total breast cancer (β=11.44, 95%CI: 3.01, 19.87, p=0.008) occurred in counties with poor land quality, especially urban counties. Overall, NC counties averaged 21.6% percent African American (AA) which is higher than the US national average of 12.6% at the time of the U.S. 2010 Census. The percentage of AA in each county in bivariate analyses was associated with increased incidence of regional (incident cases 0.12 cases per % increase in AA population, 95% CI 0.01, 0.22, p=0.022) and distant breast cancers (incident cases 0.06 per % increase in AA population, 95% CI 0.02, 0.10, p=0.003) (Table 1). In addition, in stratified models, associations persisted and were strengthened in urban county models for regional breast cancer and in rural county models for distant breast cancer.

Conclusions: Environmental quality is variable across NC akin to variability across the US, as the interquartile range (25th-75th percentile) of total EQI in NC is -0.187 to 0.734 while the interquartile range is –0.606 to 0.706 for the US (USEPA), making NC EQI analyses generalizable to a number of states and counties across the U.S., although what drives poor environmental quality varied by region and by county. Our analyses indicate significant associations between EQI and breast cancer incidence, which differ by breast cancer stage and urbanicity, identifying a critical need to assess cumulative environmental exposures in the context of cancer stage. Funding: Duke Cancer Institute seed grant (GRD, KH) as part of the P30 Cancer Ctr grant; Duke Environmental Health Scholars Award and NIEHS T32-ESO21432-05 (LMG).

Table 1. Generalized linear model estimates and associated p-values for county characteristics, per 1% increase. Results are stratified by breast cancer stage and urbanicity. Bolded text indicates statistically significant estimates (p<0.05)

Citation Format: Larisa M Gearhart-Serna, Hillary Hsu, Oluwadamilola (Lola) Fayanju, Brittany Mills, Kate Hoffman, Gayathri R Devi. Cumulative Environmental Quality is Associated with Differential Breast Cancer Incidence by Summary Stage and Urbanicity [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P4-03-12.

Adaptive stress response genes associated with breast cancer subtypes and survival outcomes reveal race-related differences

Aggressive breast cancer variants, like triple negative and inflammatory breast cancer, contribute to disparities in survival and clinical outcomes among African American (AA) patients compared to White (W) patients. We previously identified the dominant role of anti-apoptotic protein XIAP in regulating tumor cell adaptive stress response (ASR) that promotes a hyperproliferative, drug resistant phenotype. Using The Cancer Genome Atlas (TCGA), we identified 46–88 ASR genes that are differentially expressed (2-fold-change and adjusted p-value < 0.05) depending on PAM50 breast cancer subtype. On average, 20% of all 226 ASR genes exhibited race-related differential expression. These genes were functionally relevant in cell cycle, DNA damage response, signal transduction, and regulation of cell death-related processes. Moreover, 23% of the differentially expressed ASR genes were associated with AA and/or W breast cancer patient survival. These identified genes represent potential therapeutic targets to improve breast cancer outcomes and mitigate associated health disparities.

Analysis of polycyclic aromatic hydrocarbon intake in the US adult population from NHANES 2005-2014 identifies vulnerable subpopulations, suggests interaction between tobacco smoke exposure and sociodemographic factors

Polycyclic aromatic hydrocarbons (PAHs) are a toxic and ubiquitous class of environmental chemicals, products of fuel combustion from human and natural sources. The objective of this study was to identify vulnerable populations for high PAH exposure and variability, to better understand where to target PAH exposure reduction initiatives. Urinary metabolite data were collected from 9517 individuals from the U.S. CDC National Health and Nutrition Examination Survey years 2005-2014 for four parental PAHs naphthalene, fluorene, phenanthrene, and pyrene. We utilized these urinary biomarkers to estimate PAH intake, and regression models were fit for multiple demographic and lifestyle variables, to determine variable effects, interactions, odds of high versus low PAH intake. Smoking and secondhand smoke exposure accounted for the largest PAH intake rate variability (25.62%), and there were strongest interactions between race/ethnicity and smoking or SHS exposure, reflected in a much greater contribution of smoking to PAH intake in non-Hispanic Whites as compared to other races/ethnicities. Increased odds of high PAH intake were seen in older age groups, obese persons, college graduates, midrange incomes, smokers, and those who were SHS exposed. Among the non-smoking population, effects of other demographic factors lessened, suggesting a highly interactive nature. Our results suggest that there are demographic subpopulations with high PAH intake as a result of different smoking behaviors and potentially other exposures. This has human health, environmental justice, and regulatory implications wherein smoking cessation programs, SHS exposure regulations, and public health initiatives could be better targeted towards vulnerable subpopulations to meaningfully reduce PAH exposures.

Expression of X-Linked Inhibitor of Apoptosis Protein (XIAP) in Breast Cancer Is Associated with Shorter Survival and Resistance to Chemotherapy

XIAP, the most potent inhibitor of cell death pathways, is linked to chemotherapy resistance and tumor aggressiveness. Currently, multiple XIAP-targeting agents are in clinical trials. However, the characterization of XIAP expression in relation to clinicopathological variables in large clinical series of breast cancer is lacking. We retrospectively analyzed non-metastatic, non-inflammatory, primary, invasive breast cancer samples for XIAP mRNA (n = 2341) and protein (n = 367) expression. XIAP expression was analyzed as a continuous value and correlated with clinicopathological variables. XIAP mRNA expression was heterogeneous across samples and significantly associated with younger patients' age (≤50 years), pathological ductal type, lower tumor grade, node-positive status, HR+/HER2- status, and PAM50 luminal B subtype. Higher XIAP expression was associated with shorter DFS in uni- and multivariate analyses in 909 informative patients. Very similar correlations were observed at the protein level. This prognostic impact was significant in the HR+/HER2- but not in the TN subtype. Finally, XIAP mRNA expression was associated with lower pCR rate to anthracycline-based neoadjuvant chemotherapy in both uni- and multivariate analyses in 1203 informative patients. Higher XIAP expression in invasive breast cancer is independently associated with poorer prognosis and resistance to chemotherapy, suggesting the potential therapeutic benefit of targeting XIAP.

Coagulation, inflammation, and CD46 transgene expression in neonatal porcine islet xenotransplantation

BACKGROUND

Thrombosis is a known consequence of intraportal islet transplantation, particularly for xenogeneic islets. To define the origins of thrombosis after islet xenotransplantation and relate it to early inflammation, we examined porcine islets transplanted into non-human primates using a dual-transplant model to directly compare islet characteristics.

METHODS

α1,3-Galactosyltransferase gene-knockout (GTKO) islets with and without expression of the human complement regulatory transgene CD46 (hCD46) were studied. Biologically inert polyethylene microspheres were used to examine the generic pro-thrombotic effects of particle embolization. Immunohistochemistry was performed 1 and 24 hours after transplantation.

RESULTS

Xeno-islet transplantation activated both extrinsic and intrinsic coagulation pathways. The intrinsic pathway was also initiated by microsphere embolization, while extrinsic pathway tissue factor (TF) and platelet aggregation were more specific to engrafted islets. hCD46 expression significantly reduced TF, platelet, fibrin, and factor XIIIa accumulation in and around islets but did not alter intrinsic factor activation. Layers of TF⁺ cells emerged around islets within 24 hours, particularly co-localized with vimentin, and identified as CD3+ and CD68+ cells inflammatory cells.

CONCLUSIONS

These findings detail the origins of thrombosis following islet xenotransplantation, relate it to early immune activation, and suggest a role for transgenic hCD46 expression in its mitigation. Layers of TF-positive inflammatory cells and fibroblasts around islets at 24 hours may have important roles in the progressive events of thrombosis, inflammatory cell recruitment, rejection, and the ultimate outcome of transplanted grafts. These suggest that the strategies targeting these elements could yield more progress toward successful xenogeneic islet engraftment and survival.

Hymenolepis diminuta-based helminth therapy in C3(1)-TAg mice does not alter breast tumor onset or progression

Background and objectives

An individual's risk of breast cancer is profoundly affected by evolutionary mismatch. Mismatches in Western society known to increase the risk of breast cancer include a sedentary lifestyle and reproductive factors. Biota alteration, characterized by a loss of biodiversity from the ecosystem of the human body as a result of Western society, is a mismatch known to increase the risk of a variety of inflammation-related diseases, including colitis-associated colon cancer. However, the effect of biota alteration on breast cancer has not been evaluated.

Methodology

In this study, we utilized the C3(1)-TAg mouse model of breast cancer to evaluate the role of biota alteration in the development of breast cancer. This model has been used to recapitulate the role of exercise and pregnancy in reducing the risk of breast cancer. C3(1)-TAg mice were treated with Hymenolepis diminuta, a benign helminth that has been shown to reverse the effects of biota alteration in animal models.

Results

No effect of the helminth H. diminuta was observed. Neither the latency nor tumor growth was affected by the therapy, and no significant effects on tumor transcriptome were observed based on RNAseq analysis.

Conclusions and implications

These findings suggest that biota alteration, although known to affect a variety of Western-associated diseases, might not be a significant factor in the high rate of breast cancer observed in Western societies.

Lay summary

An almost complete loss of intestinal worms in high-income countries has led to increases in allergic disorders, autoimmune conditions, and perhaps colon cancer. However, in this study, results using laboratory mice suggest that loss of intestinal worms might not be associated with breast cancer.

A polycyclic aromatic hydrocarbon-enriched environmental chemical mixture enhances AhR, antiapoptotic signaling and a proliferative phenotype in breast cancer cells

Emerging evidence suggests the role of environmental chemicals, in particular endocrine-disrupting chemicals (EDCs), in progression of breast cancer and treatment resistance, which can impact survival outcomes. However, most research tends to focus on tumor etiology and the effect of single chemicals, offering little insight into the effects of realistic complex mixture exposures on tumor progression. Herein, we investigated the effect of a polycyclic aromatic hydrocarbon (PAH)-enriched EDC mixture in a panel of normal and breast cancer cells and in a tumor organoid model. Cells or organoids in culture were treated with EDC mixture at doses estimated from US adult intake of the top four PAH compounds within the mixture from the National Health and Nutrition Examination Survey database. We demonstrate that low-dose PAH mixture (6, 30 and 300 nM) increased aryl hydrocarbon receptor (AhR) expression and CYP activity in estrogen receptor (ER) positive but not normal mammary or ER-negative breast cancer cells, and that upregulated AhR signaling corresponded with increased cell proliferation and expression of antiapoptotic and antioxidant proteins XIAP and SOD1. We employed a mathematical model to validate PAH-mediated increases in AhR and XIAP expression in the MCF-7 ER-positive cell line. Furthermore, the PAH mixture caused significant growth increases in ER-negative breast cancer cell derived 3D tumor organoids, providing further evidence for the role of a natural-derived PAH mixture in enhancing a tumor proliferative phenotype. Together, our integrated cell signaling, computational and phenotype analysis reveals the underlying mechanisms of EDC mixtures in breast cancer progression and survival.

Birinapant Enhances Gemcitabine's Antitumor Efficacy in Triple-Negative Breast Cancer by Inducing Intrinsic Pathway-Dependent Apoptosis

Triple-negative breast cancer (TNBC) is the most aggressive subgroup of breast cancer, and patients with TNBC have few therapeutic options. Apoptosis resistance is a hallmark of human cancer, and apoptosis regulators have been targeted for drug development for cancer treatment. One class of apoptosis regulators is the inhibitors of apoptosis proteins (IAPs). Dysregulated IAP expression has been reported in many cancers, including breast cancer, and has been shown to be responsible for resistance to chemotherapy. Therefore, IAPs have become attractive molecular targets for cancer treatment. Here, we first investigated the antitumor efficacy of birinapant (TL32711), a biindole-based bivalent mimetic of second mitochondria-derived activator of caspases (SMACs), in TNBC. We found that birinapant as a single agent has differential antiproliferation effects in TNBC cells. We next assessed whether birinapant has a synergistic effect with commonly used anticancer drugs, including entinostat (class I histone deacetylase inhibitor), cisplatin, paclitaxel, voxtalisib (PI3K inhibitor), dasatinib (Src inhibitor), erlotinib (EGFR inhibitor), and gemcitabine, in TNBC. Among these tested drugs, gemcitabine showed a strong synergistic effect with birinapant. Birinapant significantly enhanced the antitumor activity of gemcitabine in TNBC both in vitro and in xenograft mouse models through activation of the intrinsic apoptosis pathway via degradation of cIAP2 and XIAP, leading to apoptotic cell death. Our findings demonstrate the therapeutic potential of birinapant to enhance the antitumor efficacy of gemcitabine in TNBC by targeting the IAP family of proteins.

Environmental Quality and Invasive Breast Cancer

Background: Breast cancer is a complex and multifactorial disease, and environmental factors have been suggested to increase its risk. However, prior research has largely focused on studying exposures to one factor/contaminant at a time, which does not reflect the real-world environment.Methods: Herein, we investigate associations between breast cancer and the environmental quality index (EQI), a comprehensive assessment of five domains of environmental quality (air, water, land, sociodemographic, and built environments) at the county level. Breast cancer diagnoses for North Carolina women were obtained from the North Carolina Central Cancer Registry (2009-2014) and the county of residence at the time of diagnosis was linked with the EQI. We evaluated the odds of localized, regional, or distant metastatic breast cancer in categories of environmental quality using women with carcinoma in situ as registry-based controls.Results: Overall environmental quality was generally not associated with invasive breast cancer; however, all breast cancer types tended to be inversely associated with land quality, particularly in more rural communities [distant metastatic breast cancer was 5%-8% more likely (OR, 1.08; 95% confidence interval, 1.02-1.14; P = 0.02) compared with carcinoma in situ].Conclusions: Cumulatively, our results suggest that some broad measures of environmental quality are associated with invasive breast cancer but that associations vary by environmental domain, cancer stage, subtype, and urbanicity.Impact: Our findings suggest that components of land quality (e.g., pesticide applications and animal facilities) warrant additional investigation in relation to invasive breast cancer.See all articles in this CEBP Focus section, "Environmental Carcinogenesis: Pathways to Prevention."

Abstract PR06: North Carolina environmental quality is associated with distant/metastatic breast cancer: Evidence for rural-urban disparities

Breast cancer is a complex and multifactorial disease, and there is increasing evidence of association between breast cancer incidence and environmental factors. This study sought to investigate the effects of cumulative environmental quality on aggressive breast cancer in North Carolina. We hypothesized that environmental quality plays a role in aggressive breast cancer incidence, and additionally that these effects vary by rural-urban context. The USEPA generates an environmental quality index (EQI), which contains county-level data on environmental quality across five domains—air, water, land, sociodemographic, and built. To address our hypothesis, we compared the odds of having distant/metastatic breast cancer versus ductal carcinoma in situ (DCIS) based on total and domain-specific EQI values, with cancer case information extracted from the North Carolina Central Cancer Registry (years 2009-2014) and based on staging criteria from the Surveillance, Epidemiology, and End Results Program (SEER). We used generalized estimating equation (GEE) models to generate odds ratios for having distant/metastatic breast cancer using DCIS patients as controls and quartiled EQI domain values, adjusting for individual age, BMI, and smoking status. We also stratified patients into rural-urban categories based on their county at diagnosis, representing more urbanized to more thinly populated areas. Each EQI domain is composed of several individual environmental factors, so we then investigated which of these individual factors were driving domain specific effects. Results show that there is an effect of environmental quality on distant/metastatic breast cancer. For example, patients residing in a county with the worst land environmental quality were 5% more likely to have distant/metastatic breast cancer than DCIS (OR 1.05, 95% CI 1.01-1.09, p=0.0063). This effect was stronger in more rural areas. Within the land domain, higher use of agricultural chemicals such as herbicides and insecticides had effects on increased distant/metastatic breast cancer incidence in more urban areas, whereas the number of animal facilities had a large effect in more rural areas. Additionally, patients residing in a county with the worst sociodemographic environmental quality were 6% more likely to have distant/metastatic breast cancer than DCIS (OR 1.06, 95% CI 1.02-1.09, p=0.0006), which was consistent across rural/urban areas. Within the sociodemographic domain, higher income and higher household value decreased odds of having distant/metastatic breast cancer regardless of whether the area was rural or urban. In conclusion, we have shown that cumulative environmental quality is associated with distant/metastatic breast cancer, and that these effects can differ by rural-urban area. This is relevant for further studies of environmental exposures associated with aggressive breast cancers.

This abstract is also being presented as Poster A07.

Citation Format: Larisa M. Gearhart-Serna, Kate Hoffman, Brittany A. Mills, Gayathri R. Devi. North Carolina environmental quality is associated with distant/metastatic breast cancer: Evidence for rural-urban disparities [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr PR06.

Abstract B122: Spatial analysis of ductal carcinoma in situ, locoregional, and distant metastatic breast cancer in North Carolina: Evidence for rural-urban disparities

Introduction: A projected 8870 women will be diagnosed with breast cancer in North Carolina (NC) in 2019, with 1390 estimated deaths. However, breast cancer is a heterogenous disease, and investigating total incidence may hide differences in how sociodemographic factors impact the development of different subtypes of breast cancer, in particular early vs late stage aggressive phenotypes. The objective of this study was to investigate geographical variation of breast cancer in NC by stage, and to determine stage-specific associations with race and urbanicity. Methods: Breast cancer patient data were obtained from the NC Central Cancer Registry (NC CCR 2009-14) and stratified by stage and comprised of patients diagnosed with ductal carcinoma in situ (7975; DCIS), locoregional (38,200; combined localized, regional, and regional with direct extensions), or distant metastatic breast cancer (2073) based on derived summary staging defined by the Surveillance, Epidemiology, and End Results (SEER) program. Spatial distribution maps were generated in ArcMap 10.5.1 software for age-standardized incidence ratios (SIRs) by county using the NCCCR patient dataset described and age distributions from 2014 U.S. Census population estimates. Additionally, we stratified patients by rural-urban continuum code (RUCC), condensed for our purposes into three rural-urban categories: metropolitan urbanized, non-metro urbanized, and less populated. Results: DCIS, locoregional, and distant metastatic breast cancers all exhibited patterns of significantly different SIRs than expected based on state incidence rates in the northeastern region of NC, while DCIS and total breast cancer also had significantly different SIRs in the western region. Approximately 70% of patients inhabited metropolitan urbanized areas regardless of breast cancer stage, however, the highest incidence rates for all stages were consistently observed in less populated counties. Mean age at diagnosis for all stages was slightly higher in less populated areas, for example 61.4yrs DCIS and 62.8yrs distant metastatic breast cancer, than metropolitan areas, at 60.0yrs DCIS and 60.1yrs distant metastatic breast cancer. A higher percentage of distant metastatic breast cancer patients (29%) versus locoregional or DCIS patients (both 20%) in the dataset self-identified as Black, a pattern consistent across rural-urban categories. The percentage of current smokers was also higher for distant metastatic breast cancer cases (10%) than locoregional (6%) or DCIS cases (5%) across all rural-urban categories. Conclusions: Our results indicate that breast cancer incidence in NC varies geospatially by stage with incidence often higher in less populated areas. There were also age, race, and smoking status disparities across rural-urban stratifications and in patients with late stage breast cancer, which have the potential to contribute to poor survival outcomes in high risk patients.

Citation Format: Larisa M Gearhart-Serna, Kate Hoffman, Gayathri R Devi. Spatial analysis of ductal carcinoma in situ, locoregional, and distant metastatic breast cancer in North Carolina: Evidence for rural-urban disparities [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr B122.

Abstract A038: Current unmet needs in inflammatory breast cancer/IBC patient care: Analysis of open-ended responses from a community engagement session of clinicians, researchers, advocates, and patients at the Duke Consortium for IBC conference

Introduction: Inflammatory breast cancer (IBC) is an understudied and aggressive breast cancer subtype, accounting for 7-10% of all breast cancer-related deaths in the United States. IBC is more common among African American (AA) women, who also develop higher rates of treatment resistance when compared to other races and survival rates are lower after adjusting for nonbiologic and socioeconomic factors. IBC typically lacks a clinically apparent tumor mass, leading to misdiagnoses and treatment delays. There is little research on the IBC patient perspective regarding quality of care, cost, or side effects of therapy.

Methodology: In order to address critical needs in IBC clinical care and outreach across North Carolina and nationally, the Duke Consortium for IBC organized an interactive community engagement session. Attendees (n=174) at the local and national level included patients, advocates, NC government representatives and stakeholders (28%), health care providers (15%), staff (15%), academic research and clinical faculty from local universities and national IBC centers/laboratories (13%), trainees (9%), and other (16%). Facilitated small groups (3-8) discussed open-ended questions related to 1) gaps preventing timely diagnosis and treatment, 2) advocacy and grassroot programs, and 3) integrating research and outreach. Representative patients and facilitators/community partners were also contacted post-meeting for in-depth responses. All notes were recorded and thematic analysis using NVivo 12 Pro qualitative software was performed by three independent researchers. Grounded theory shaped both design and analysis.

Results: A total of 506 unique responses were recorded and six major themes were identified: barriers to care (57.7%), education (16.4%), outreach/awareness (43.3%), fundraising (6.3%), legislative process/priorities (1.4%), and “other” (3.0%). Within those themes, three topics emerged: a) provider education, b) barriers to diagnostic and/or treatment delays, and c) raising awareness of IBC and late disease breast cancer in communities.

Conclusions: This is the first report, to our knowledge, of a community engagement session and focused interviews that included clinicians, researchers, and patients/community stakeholders to address the unique needs and challenges for IBC patients. The study highlights the critical need to address lack of education around IBC at the provider and hospital level, and the need for better interaction with academic medical centers. Because treatment can be lengthy, social determinants, such as low socioeconomic status, may play an even larger role in patients with IBC. There is also a need for observational data on where knowledge gaps exist among providers and how missed diagnoses impact the patient in order to design improved interventions.

Funding in part to GRD from Duke (SOM-Interdisciplinary-Colloquium, Surgery, Pathology, Medicine, Cancer Institute); IBC Network Foundation; 1P20-CA202925-01A12- Projects (GRD, NB).

Citation Format: Gayathri R. Devi, Whitney Lane, Holly J. Hough, Kearston L. Ingraham, Larisa Gearhart, Nadine J. Barrett. Current unmet needs in inflammatory breast cancer/IBC patient care: Analysis of open-ended responses from a community engagement session of clinicians, researchers, advocates, and patients at the Duke Consortium for IBC conference [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr A038.

Abstract A023: Results from a town hall meeting: Inflammatory breast cancer listening session led by KOMEN scholars

Introduction: Cancer is the leading cause of death in North Carolina. While the incidence rate of breast cancer (BC) is higher in White women, African American and Latino women are more likely to die from BC than White women. Moreover, inflammatory breast cancer (IBC) is a rare and aggressive form of BC, and African Americans are more likely to be diagnosed with IBC compared to whites, have poor BC outcomes, and generally are less likely to get life-saving information and resources to reduce cancer risks. Additionally, work is needed to improve diagnosis rates and decrease time to treatment for IBC patients. Translational research scientists do not get exposure to community engagement opportunities that can add to their knowledge of the research spectrum around a particular disease. Engaging new researchers in this arena can add to addressing cancer disparities research.

Methods: An IBC listening session was conducted during the annual Women's Health Awareness Day conference sponsored by the National Institute of Environmental Health Sciences and North Carolina Central University. The session was developed by KOMEN translational health disparities researchers as part of their enhanced community engagement training program. Scholars created the marketing plan and listening session guide for the program with guidance and training from staff experts. Scholars were note takers, facilitators, and created summary reports that highlighted guiding questions for the session, which included the following questions: 1)What do you know about BC? 2) Are you aware of different types of breast cancers? 3) Have you heard of IBC? 4) How aware do you think people in your community are about BC and IBC? 5) Where do you get your information about BC and IBC? 6) What are ways we should educate the community with getting information on how to become aware about the signs and symptoms of IBC?

Results: There were 49 African American and Latina participants. Only 15 of 49 attendees had heard of IBC. Most women were aware of causes and symptoms of breast cancer; however, there was a lack of awareness around IBC. Those aware of IBC learned about it from their coworkers, doctors, or had family members die from the disease. Participants recommended more one-on-one education, patient self-advocacy sessions, making education and awareness available online, changing breast cancer communication to include IBC symptoms, and letting people know that you can have breast cancer without the presence of lumps.

Conclusion: Poor awareness, communication, and education around inflammatory breast cancer risk factors were substantial. There is significant need to raise awareness in diverse communities about inflammatory breast cancer risks, screening guidelines, diagnosis, and treatment options. Community-engaged research lead by under-represented researcher scholars in training can add to the translational research training experience.

Citation Format: Maria Dixion, Kearston L. Ingraham, Seronda A. Robinson, Jodie M. Fleming, Gayathri R. Devi, Holly Hough, Hamzah Kharabsheh, Dana M. Austin, Tia A. Tate, Artis Woodard, Joshua Alexander, Joan P. Packenham, Nadine J. Barrett, Kevin P. Williams. Results from a town hall meeting: Inflammatory breast cancer listening session led by KOMEN scholars [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr A023.

Abstract D093: Who carries the excess cancer risk burden: Implications of disparities in polycyclic aromatic hydrocarbon exposure

Polycyclic aromatic hydrocarbons (PAHs) are a toxic and ubiquitous class of environmental chemicals sourced from industrial practices, tobacco smoke, grilled and smoked meats, car exhaust, and other human and natural sources. Many PAHs are also considered carcinogenic. In this study, we sought to identify the most vulnerable populations for high PAH exposure in the U.S. and resultant excess cancer risk. Urinary biomarker data were collected from 2005-2014 by the U.S. CDC National Health and Nutrition Examination Survey for metabolites of four PAHs: naphthalene, fluorene, phenanthrene, and pyrene. We conducted reverse dosimetry modeling to estimate exposure to the four PAHs, singly and in sum, for each adult individual in the dataset, expressed as a daily intake rate. These were calculated using known excretion fractions and molecular weights specific to each PAH parent or metabolite compound, standardized adult urine output, and individual body weights. We then stratified these exposures by demographic factors (age, gender, race/ethnicity, education level, and family income), in addition to lifestyle factors (smoking status, exposure to secondhand smoke, and BMI). We analyzed these stratified demographic and lifestyle groups according to effect size, and analyzed subpopulations within each group by principal component analysis, so as to determine the most influential factors and the most vulnerable subpopulations for high PAH exposure. We then calculated lifetime excess cancer risk for subpopulations based on their PAH exposure using benzo(a)pyrene (BaP) toxic equivalency factors, BaP cancer slope factor, and a 70-year lifespan estimation. There were 8570 individuals in the final dataset, although smoking status information available for 3818 of these individuals. Unsurprisingly, smokers and those exposed to secondhand smoke had the highest total PAH intake rates. 36.9% of PAH exposure variance was explained by the demographic and lifestyle factors included in this analysis, with an additional 4.8% explained by smoking status and secondhand smoke exposure interactions with other demographic variables such as race/ethnicity. However, only 7.5% of the PAH exposure variance was explained when all smokers and those exposed to secondhand smoke were removed from the dataset, indicating the strength of association between tobacco smoke exposure and PAH intake. Demographic subpopulations such as those who did not complete high school, middle-income bracket ($45-75,000), and other Hispanic racial/ethnic identity had higher PAH exposure and resultant excess cancer risk, while higher income bracket (75,000+), those with a college degree, Asian identity, and females in general had lower PAH exposure levels and lower excess cancer risk. These results suggest that, in addition to smokers and those exposed to secondhand smoke, there are demographic subpopulations with disproportionately high PAH exposure and resultant excess cancer risk burden, which is a public health concern.

Citation Format: Larisa M Gearhart-Serna, Moises Tacam, Jr., Theodore A Slotkin, Gayathri R Devi. Who carries the excess cancer risk burden: Implications of disparities in polycyclic aromatic hydrocarbon exposure [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr D093.

Abstract B034: Improving patient-centered care for inflammatory breast cancer: Strategies for addressing barriers faced by patients, researchers, and providers

Introduction: Inflammatory breast cancer (IBC) is a rare but the most lethal breast cancer often misdiagnosed as mastitis or dermatitis since majority of cases lack a clinically apparent tumor mass and present with progressive breast erythema and skin edema. Further exacerbating this is its incidence, more often, in premenopausal women who have yet to initiate regular screening, and/or its manifestation in women of color, in whom the signs of disease may be more subtle. Thus, the goal of this research is to understand IBC awareness and knowledge of clinical signs related to diagnosis and treatment amongst the general public, patients, and primary care providers in order to design effective interventions to improve patient care. Methods: Responses (500+ unique) were collected from a facilitated session and representative post meeting interviews including researchers, clinicians, patients, and community stakeholders on open-ended questions related to IBC diagnosis, treatment barriers, and strategies to improve patient care. For thematic analysis, responses were subdivided into patient/community, provider, and organizational level using NVivo 12 Pro qualitative software. Grounded theory shaped both design and analysis. Results: Based on participant responses, barriers at the patient/community level (69.4%) were recognized to be the greatest. The primary factor identified was related to living in a rural community/distance to a treatment center (21.1%). At the organizational level, obstacles included limited or no access to an appropriate treatment center (42.2%), lack of IBC-specific standard of care (20.0%), lack of central source of information about IBC (20.0%) and need for trained patient navigators (8.9%). This analysis highlighted that patients often experience multiple misdiagnoses before finding a physician that correctly recognizes IBC - 79.4% responses indicated a lack of education among primary care providers (79.4%), misdiagnoses due to patients not fitting the typical breast cancer profile (13.1%), and a dearth in communication between physicians and patients (7.5%). This study also identified specific strategies, which included developing culturally tailored IBC media campaign and community-facing patient navigation to address barriers such as social support and care for patients in rural or underserved communities. Conclusions: Taken together, three themes in IBC care were identified- a) barriers to timely diagnosis and treatment, b) strategies for community engagement, and c) the need for provider education. These datasets have led to the development of survey instruments to assess gaps of knowledge during diagnosis and treatment in IBC patients and primary care providers including physicians, physician assistants, and nurse practitioners in the community. Supported by Duke SOM Interdisciplinary Colloquium (GRD); DCI Behavioral and Health Survey Research Core Award (GRD, LF, AT); C-REP 1P20-CA202925-01A12 (GRD, HH, LGS, NB); T32 Surgical Oncology training (WL).

Citation Format: Larisa Gerahart-Serna, Whitney Lane, Laura Fish, Anh N Tran, Gayathri R Devi, Holly Hough, Kearston L Ingraham. Improving patient-centered care for inflammatory breast cancer: Strategies for addressing barriers faced by patients, researchers, and providers [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr B034.

Abstract IA18: North Carolina Central University and Duke Cancer Institute's collaborative cancer research and education program: Connecting cancer disparities translational research, clinical trials operations, and community engagement

Three interrelated contributors to cancer disparities include the lack of diversity among investigators contributing to cancer research, the deficiency of minority participation in clinical trials and bio-banking, and the need to advance community engagement as a vital component of the translational research spectrum. The North Carolina Central University and Duke Cancer Institute's Cancer Disparities Translational Research Partnership (NCCU-DCI CDTRP) (P20 PACHE), through its Cancer Research and Education Program (C-REP), provides a Translational Immersion Experience (TIE) that spans the full translational research spectrum, for traditionally under-represented PhD students, postdoctoral fellows, and early-stage investigators. The goals of TIE are to (1) provide cancer disparities research training with an emphasis on translational laboratory science including high-throughput screening/drug discovery, (2) equip trainees with unique training and education in the operational infrastructure that supports clinical research and trials, (3) highlight strategies to increase diverse participation in clinical trials and bio banking, and (4) learn and apply principles of community engagement through community-based programs and outreach. Using multimodal training techniques, the TIE program provides training and education in real-life settings that expose trainees to the full translational research spectrum across two diseases that disproportionality affect African Americans at significantly higher rates, prostate cancer and inflammatory breast cancer. The overarching goal is to bolster our trainees' experiences and training to contribute to innovative technologies and discoveries and provide access to training that spans beyond the traditional curriculum in areas of high need in translational cancer disparities research such as minority accrual and clinical trials operations. The program includes evidence-based workshops in healthy mentor-mentee relationships, building and sustaining resilience, and sharpening grantwriting skills coupled with ongoing external evaluation to provide real-time feedback on the program. We present the preliminary evaluation data based on the first cohort of the C-REP TIE program.

Citation Format: Kevin P. Williams, Nadine J. Barrett, Carla E. Oldham, Holly Hough, Artis Woodard, Jennifer Freedman, Gayathri R. Devi, Steven R. Patierno. North Carolina Central University and Duke Cancer Institute's collaborative cancer research and education program: Connecting cancer disparities translational research, clinical trials operations, and community engagement [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr IA18.

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

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

Citation Format: Gayathri R Devi, Muthana Al Abo, Larisa Gearhart-Serna, Joseph Geradts, Shannon J McCall, Savitri Krishnamurthy. Identification of a tumor cell adaptive stress response signaling pathway, which drives aggressive breast cancer phenotype and therapeutic resistance, in African American patients with locally advanced breast cancer subtypes [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr B035.

Abstract C100: Identification and functional characterization of a novel GLI1 splice variant in breast cancer

The purpose of this study is to investigate the biologic significance of novel GLI1 splice variants in breast cancer. African American (AA) women suffer a disproportionately high burden of basal-like breast cancer, an aggressive subtype that has no targeted therapy (1). About 15-20% of breast cancers are triple-negative/basal-like, are associated with poor clinical outcomes and show disproportionately higher prevalence in younger women of African descent (2-4). The Hedgehog (Hh)/GLI1 developmental pathway has emerged as a therapeutic target in many cancers, including breast cancer studies from our lab (5, 6). Overexpression of the main Hh transcriptional mediator GLI1, correlates with poor patient prognosis and relapse. The human GLI1 transcript undergoes alternative splicing producing two shorter isoforms, an N-terminal deletion variant (GLI1ΔN) (7) and a truncated GLI1 (tGLI1) (8), which have been reported to have different patterns of tissue expression and function. tGLI1 has been identified as being highly expressed in several cancers, including in breast cancer (9). We performed in silico analysis of the NCBI database for evidence of additional human GLI1 transcripts and identified a novel GLI1 splice variant, GLI1-X2, that has an in-frame deletion of the entire exon 10-zinc finger 5 domain of the GLI1 gene. Our preliminary data show that GLI1-X2 is expressed in basal-like breast cancers at substantially higher levels than GLI1, tGLI1, or GLI1ΔN. To our knowledge, we are the first to demonstrate expression of GLI1-X2 in any model and our findings expand the GLI1 family of zinc finger transcription factors. Our objectives are to examine the expression differences of the GLI1 splice variants in basal-like and luminal breast cancer cell models, AA and White patient samples and to investigate the biologic function of GLI1-X2 in breast cancer. Previous studies report that GLI1ΔN and tGLI1 proteins retain intact functional zinc finger domains. Thus, we hypothesize that the loss of zinc-finger 5 is critical for GLI1-X2's functional role and regulation of downstream target genes in breast cancer. As the biologic significance of GLI1-X2 in normal and cancer biology is unknown, this proposed work is the first to characterize its function and potential role in cancer.

Citation Format: Maria S. Dixon, Lhoucine Chdid, David R. Lamson, Michael T. Tarpley, Helen O. Oladapo, Jodie M. Fleming, Jennifer A. Freedman, Gayathri R. Devi, Kevin P. Williams. Identification and functional characterization of a novel GLI1 splice variant in breast cancer [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C100.

Abstract P1-03-03: Multichannel serial imaging of transgenic, preclinical murine models provides the first quantitative analysis of the unusual growth kinetics and lymph-vascular invasion of patient-derived inflammatory breast cancer cells and tumor emboli

Background: Lymphovascular invasion (LVI), a critical feature of advanced cancers, is a major route of metastatic dissemination. Of the clinically-distinct types of breast cancer, the most lethal variant is inflammatory breast cancer (IBC) where LVI is a histopathological hallmark. Majority of IBC patients lack a distinct, solid tumor and instead present with diffuse tumor cell clusters cells, also termed as tumor emboli, in the breast and dermal lymphatics, which contributes to the clinical breast-skin symptoms and postulated to provide an efficient path to metastatic spread. The steps in lymphatic dissemination are challenging to study in vitro, and in vivo models are limited. Our goal was to develop new in vivo models that would enable direct visualization and quantitation of local tumor cell growth and tumor-lymphatic vessel interactions for improved understanding of the unique IBC tumor biology and for drug discovery.

Methods: mCherry/GFP-expressing non-IBC (4T1, E0771) and IBC cells derived from patient untreated primary tumors (SUM149/basal and SUM190/Her2+) were implanted into the fascia in the center of a window chamber in the skin-fold or mammary fat pad. In order to allow direct study of tumor cell–lymphatic vessel interaction, we generated transgenic nude mice with fluorescent lymphatics [tdTomato fluorophore under control of a Prox1 promoter, encodes a transcription factor (prospero-related homeobox 1) necessary for the formation and maintenance of lymphatic vessels]. Multichannel microscopy was employed to serially quantify tumor growth, tumor spread and lymph-tumor interactions. Using this model, we also optimized implantation and live imaging of pre-formed IBC-cell derived tumor emboli generated by simulating the lymphatic sheer stress in culture.

Results: Compared to non-IBC cells, which formed solid tumors that increased in size over a 14 day period, IBC models exhibited a diffuse and disseminating phenotype, within 24h, rather than a centralized tumor mass, similar to the disease presentation in patients. Using a threshold analysis in ImageJ, we quantified tumor area (as a metric of tumor growth), the tumor motility, and the linear density of lymph and blood vessels. Briefly, we binarized each fluorescent channel image such that the tumor or lymph signal was positive; then, an algorithm drew regions of interest (ROIs) around each defined tumor-cell cluster. The ROIs were used to calculate the parameters describing tumor growth and motility (distance of the tumor from the center of mass (CM)), and the area moment (the movement of the clusters relative to the CM) at each timepoint. The linear vascular density was calculated from the distance of segments drawn through the center of large vessels for each mouse, which provided quantitative data describing tumor cell or IBC emboli and lymphovascular interactions, suggesting that there is a specific microenvironment necessary for the unique phenotype and dissemination pattern exhibited by IBC tumor cells.

Conclusions: Despite the poor prognosis of IBC, the clinical implications of how and why tumor emboli form and how they survive to migrate into the lymphatics is not defined. These in vivo models provide in-depth imaging and quantitative measurements of locoregional invasion, tumor cell-lymphatic or endothelial vessel interactions of implanted tumor cells or tumor emboli. This model has the potential to be extended to study other cancer cell types exhibiting LVI as well as a screening metric for IBC therapies.

Supported by DOD-Breakthrough-W81XWH-17-1-029, IBC Research Foundation, DCI pilot funds, IBC Network Foundation, Duke Surgery Gardner Award.

Citation Format: Ashlyn Rickard, Pranalee Patel, Scott J Sauer, Mark W Dewhirst, Gregory M Palmer, Gayathri R Devi. Multichannel serial imaging of transgenic, preclinical murine models provides the first quantitative analysis of the unusual growth kinetics and lymph-vascular invasion of patient-derived inflammatory breast cancer cells and tumor emboli [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 P1-03-03.

Extent of axillary surgery in inflammatory breast cancer: a survival analysis of 3500 patients

PURPOSE

Inflammatory breast cancer (IBC) is an aggressive variant for which axillary lymph node (LN) dissection following neoadjuvant chemotherapy (NACT) remains standard of care. But with increasingly effective systemic therapy, it is unclear whether more limited axillary surgery may be appropriate in some IBC patients. We sought to examine whether extent of axillary LN surgery was associated with overall survival (OS) for IBC.

METHODS

Female breast cancer patients with non-metastatic IBC (cT4d) diagnosed 2010-2014 were identified in the National Cancer Data Base. Cox proportional hazards modeling was used to estimate the association between extent of axillary surgery (≤ 9 vs ≥ 10 LNs removed) and OS after adjusting for covariates, including post-NACT nodal status (ypN0 vs ypN1-3) and radiotherapy receipt (yes/no).

RESULTS

3471 patients were included: 597 (17.2%) had cN0 disease, 1833 (52.8%) had cN1 disease, and 1041 (30%) had cN2-3 disease. 49.9% of cN0 patients were confirmed to be ypN0 on post-NACT surgical pathology. Being ypN0 (vs ypN1-3) was associated with improved adjusted OS for all patients. Radiotherapy was associated with improved adjusted OS for cN1 and cN2-3 patients but not for cN0 patients. Regardless of ypN status, there was a trend towards improved adjusted OS with having ≥ 10 (vs ≤ 9) LNs removed for cN2-3 patients (HR 0.78, 95% CI 0.60-1.01, p = 0.06) but not for cN0 patients (p = 0.83).

CONCLUSIONS

A majority of IBC patients in our study presented with node-positive disease, and for those presenting with cN2-3 disease, more extensive axillary surgery is potentially associated with improved survival. For cN0 patients, however, more extensive axillary surgery was not associated with a survival benefit, suggesting an opportunity for more personalized care.

The role of human CD46 in early xenoislet engraftment in a dual transplant model

BACKGROUND

Membrane cofactor protein CD46 attenuates the complement cascade by facilitating cleavage of C3b and C4b. In solid organ xenotransplantation, organs expressing CD46 have been shown to resist hyperacute rejection. However, the incremental value of human CD46 expression for islet xenotransplantation remains poorly defined.

METHODS

This study attempted to delineate the role of CD46 in early neonatal porcine islet engraftment by comparing Gal-knocked out (GKO) and hCD46-transgenic (GKO/CD46) islets in a dual transplant model. Seven rhesus macaques underwent dual transplant and were sacrificed at 1 hour (n = 4) or 24 hours (n = 3). Both hemilivers were recovered and fixed for immunohistochemistry (CD46, insulin, neutrophil elastase, platelet, IgM, IgG, C3d, C4d, CD68, Caspase 3). Quantitative immunohistochemical analysis was performed using the Aperio Imagescope.

RESULTS

Within 1 hour of intraportal infusion of xenografts, no differences were observed between the two types of islets in terms of platelet, antibody, or complement deposition. Cellular infiltration and islet apoptotic activity were also similar at 1 hour. At 24 hours, GKO/CD46 islets demonstrated significantly less platelet deposition (P = 0.01) and neutrophil infiltration (P = 0.01) compared to GKO islets. In contrast, C3d (P = 0.38) and C4d (P = 0.45) deposition was equal between the two genotypes.

CONCLUSIONS

Our findings suggest that expression of hCD46 on NPIs potentially provides a measurable incremental survival advantage in vivo by reducing early thrombo-inflammatory events associated with instant blood-mediated inflammatory reaction (IBMIR) following intraportal islet infusion.

Perspectives on Inflammatory Breast Cancer (IBC) Research, Clinical Management and Community Engagement from the Duke IBC Consortium

Inflammatory breast cancer (IBC) is an understudied and aggressive form of breast cancer with a poor prognosis, accounting for 2-6% of new breast cancer diagnoses but 10% of all breast cancer-related deaths in the United States. Currently there are no therapeutic regimens developed specifically for IBC, and it is critical to recognize that all aspects of treating IBC - including staging, diagnosis, and therapy - are vastly different than other breast cancers. In December 2014, under the umbrella of an interdisciplinary initiative supported by the Duke School of Medicine, researchers, clinicians, research administrators, and patient advocates formed the Duke Consortium for IBC to address the needs of patients in North Carolina (an ethnically and economically diverse state with 100 counties) and across the Southeastern United States. The primary goal of this group is to translate research into action and improve both awareness and patient care through collaborations with local, national and international IBC programs. The consortium held its inaugural meeting on Feb 28, 2018, which also marked Rare Disease Day and convened national research experts, clinicians, patients, advocates, government representatives, foundation leaders, staff, and trainees. The meeting focused on new developments and challenges in the clinical management of IBC, research challenges and opportunities, and an interactive session to garner input from patients, advocates, and community partners that would inform a strategic plan toward continuing improvements in IBC patient care, research, and education.

Assessing Cancer Risk Associated with Aquatic Polycyclic Aromatic Hydrocarbon Pollution Reveals Dietary Routes of Exposure and Vulnerable Populations

Polycyclic aromatic hydrocarbon (PAH) exposure is widespread, and many PAHs are considered carcinogenic. The PAH-contaminated AWI Superfund site in Virginia provides a model for studying a complex PAH mixture and its extrapolation to cancer risk and PAH exposure in the general population. We examined cancer risk at the Superfund site due to sediment-derived PAHs and then evaluated PAH sources in the general population and potentially vulnerable subpopulations upon PAH mixture exposure. The PAH mixture was assessed for potential carcinogenicity using the US EPA's OncoLogic™ ranking tool and the US EPA list of priority PAHs. Cancer risk due to PAH exposure was calculated for Superfund site users and compared to the US EPA assessment. Human intake and health endpoints of PAHs within the mixture were extracted from USEtox® chemical fate database, while mean intake exposure was calculated for U.S. adults for select PAHs using NHANES database urinary biomarkers. Eleven PAH compounds within the mixture were of carcinogenic concern, and seven PAHs conveyed significant excess cancer risk at the Superfund site and in the general population, wherein PAH-contaminated seafood ingestion was a main contributor. Other dietary sources of PAHs derived from PAH-contaminated soil or water could also play a role in total exposure. Vulnerable populations to PAH exposure and coinciding increased cancer risk may include, in addition to smokers, children and non-Hispanic blacks, which is a public health concern.

Abstract 4457: Determining the role of novel GLI1 splice variants in breast cancer

The purpose of this study is to investigate the biological significance of novel GLI1 splice variants in breast cancer. 15-20% of breast cancers are triple negative/basal-like, are associated with poor clinical outcomes and show disproportionately higher prevalence in younger women of African descent. The Hedgehog (Hh)/GLI1 developmental pathway has emerged as a therapeutic target in many cancers including studies on breast cancer such as those from our lab. Overexpression of the main Hh transcriptional mediator GLI1 correlates with poor patient prognosis and relapse. The human GLI1 transcript undergoes alternative splicing producing two shorter isoforms, an N-terminal deletion variant (GLI1ΔN) and a truncated GLI1 (tGLI1) which have been reported to have different patterns of tissue expression and function. tGLI1 has been identified as being highly expressed in several cancers, including in breast cancer. We undertook an in silico analysis of the NCBI database for evidence of additional human GLI1 transcripts and have identified novel GLI1 splice variants that we have subsequently shown to be highly expressed in breast cancer cell lines. Our objectives were to examine expression differences between GLI1 splice variants in basal-like and luminal breast cancer cell models, AA and White patient samples and to investigate the biological function of GLI1 splice variants in breast cancer. In our studies, we have utilized phenotypic and functional assays to examine the functional impact of these novel isoforms. Our preliminary data suggest that these newly identified GLI1 isoforms are expressed in basal-like breast cancers at substantially higher levels than GLI1, tGLI1 or GLI1ΔN. Previous studies assessing GLI1 expression have not considered these new isoforms and the relative contribution of each to breast cancer aggressiveness and require further investigation.

Citation Format: Maria S. Dixon, Lhoucine Chdid, David Lamson, Michael Tarpley, Jodie M. Fleming, Jennifer A. Freedman, Gayathri R. Devi, Kevin P. Williams. Determining the role of novel GLI1 splice variants in breast cancer [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 4457.

Abstract B47: Efficacy of GLI antagonists in triple-negative inflammatory breast cancer 2D and 3D models

Our objective was to investigate the differential effects of specific GLI1 antagonists in triple-negative inflammatory breast cancer 2D and 3D cell culture systems. Inflammatory breast cancer (IBC) accounts for 15% of all breast cancer deaths. IBC is a unique form of locally advanced breast cancer, an aggressive and highly invasive breast cancer having one of the worst clinical outcomes among breast cancers. African-American, American-Indian, and Arab-American women are disproportionately affected by IBC (1-3). Compared to non-IBC, IBC has a higher incidence of the triple-negative (TN) phenotype for which there are few treatment options. There are currently limited strategies for targeting IBC; thus, IBC patients continue to have worse survival outcomes than non-IBC breast cancer patients. GLI1 (glioma-associated oncogene homolog 1), the terminal effector of the hedgehog (Hh) pathway, has emerged as a potential therapeutic target for TN breast cancers including IBC (4). There is overwhelming evidence for GLI1 activation across many tumor types, including aggressive breast cancers, and its importance for tumor progression. Nuclear expression of GLI1 has been shown to be a strong predictor of poor prognosis in pancreatic cancer and brain gliomas and correlates with aggressiveness in basal-like breast cancer. In our studies, we utilized various automated phenotypic and functional assays (5) to examine the efficacy of GLI antagonists with varying mechanism of action for effects on IBC cell proliferation and growth in 2D and 3D cell culture systems. We are also assessing by high-throughput transcriptome sequencing (RNA-seq) gene expression differences in IBC cell lines after treatment with GLI antagonists. In both our 2D and 3D cell culture systems, TN-IBC cell lines were highly sensitive to two GLI antagonists, JK184 and GANT61. JK184 and GANT61 showed significant but differential effects on TN-IBC cell proliferation, colony formation, cell motility, and spheroid formation.

This study was supported in part by Department of Defense award W81WXH-13-1-0141, NIH award P20CA202924, Komen Graduate Training in Disparities Research award GTDR16377604, Developmental Funds from Duke School of Medicine and Duke Cancer Institute (as part of the P30CA014236 and Cancer and Environment Program supported by Mr and Mrs Fred and Alice Stanback P3917733).

References:

1. Anderson WF, Schairer C, Chen BE, et al. Epidemiology of inflammatory breast cancer (IBC). Breast Dis 2006;22(-1):9-23.

2. Woodward WA, Cristofanilli M. Inflammatory breast cancer. Semin Radiat Oncol 2009;19(4):256-65.

3. Hirko KA, Soliman AS, Banerjee M, et al. Characterizing inflammatory breast cancer among Arab Americans in the California, Detroit and New Jersey Surveillance, Epidemiology and End Results (SEER) registries (1988-2008). SpringerPlus. 2013;2(1).

4. Thomas Z, Gibson W, Sexton J, et al. Targeting GLI1 expression in human inflammatory breast cancer cells enhances apoptosis and attenuates migration. Br J Cancer. 2011;104:1575-86.

5. Williams KP, Allensworth JL, Ingram SM, et al. Quantitative high-throughput efficacy profiling of approved oncology drugs in inflammatory breast cancer models of acquired drug resistance and re-sensitization. Cancer Lett 2013;337:77-89.

Citation Format: Helen Oladapo, Xiaojia Ji, Hassan Shehata, Mike Tarpley, Lhoucine Chdid, David Lamson, Xuhui Bao, Scott Sauer, Gayathri R. Devi, Kevin P. Williams. Efficacy of GLI antagonists in triple-negative inflammatory breast cancer 2D and 3D models [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr B47.

Early barriers to neonatal porcine islet engraftment in a dual transplant model

Porcine islet xenografts have the potential to provide an inexhaustible source of islets for β cell replacement. Proof-of-concept has been established in nonhuman primates. However, significant barriers to xenoislet transplantation remain, including the poorly understood instant blood-mediated inflammatory reaction and a thorough understanding of early xeno-specific immune responses. A paucity of data exist comparing xeno-specific immune responses with alloislet (AI) responses in primates. We recently developed a dual islet transplant model, which enables direct histologic comparison of early engraftment immunobiology. In this study, we investigate early immune responses to neonatal porcine islet (NPI) xenografts compared with rhesus islet allografts at 1 hour, 24 hours, and 7 days. Within the first 24 hours after intraportal infusion, we identified greater apoptosis (caspase 3 activity and TUNEL [terminal deoxynucleotidyl transferase dUTP nick end labeling])-positive cells) of NPIs compared with AIs. Macrophage infiltration was significantly greater at 24 hours compared with 1 hour in both NPI (wild-type) and AIs. At 7 days, IgM and macrophages were highly specific for NPIs (α1,3-galactosyltransferase knockout) compared with AIs. These findings demonstrate an augmented macrophage and antibody response toward xenografts compared with allografts. These data may inform future immune or genetic manipulations required to improve xenoislet engraftment.

Inflammatory breast cancer tumor emboli express high levels of anti-apoptotic proteins: use of a quantitative high content and high-throughput 3D IBC spheroid assay to identify targeting strategies

Inflammatory breast cancer (IBC) is one of the most lethal breast cancer variants; with existing therapy, 5-yr survival rate is only 35%. Current barriers to successful treatment of IBC include frequent infiltration and the presence of tumor cell clusters, termed tumor emboli, within the breast parenchyma and lymphatics. Prior studies have identified the role of anti-apoptotic signaling, in particular hyperactivation of NFκB and its target genes, in IBC pathobiology and therapeutic resistance. The objectives of this study were to: (1) determine if IBC tumor emboli express anti-apoptotic proteins and (2) develop a high content, multiparametric assay to assess the morphology of the IBC 3D spheroids and to optimize a high throughput format to screen for compounds that can inhibit the formation of the IBC tumor clusters/embolic structures. Immunohistochemical analysis of IBC patient tumor samples with documented tumor emboli revealed high NFκB (p65) staining along with expression of XIAP, a potent anti-apoptotic protein known to interact with NFκB signaling in enhancing survival of malignant cells. Subsequently, the high content assay developed allowed for simultaneous imaging and morphometric analysis, including count and viability of spheroids derived from SUM149, rSUM149 and SUM190 cells and its application to evaluate XIAP and NFκB inhibitory agents. We demonstrate the efficacy of the off-patent drug disulfiram when chelated with copper, which we had previously reported to inhibit NFκB signaling, was highly effective in disrupting both IBC spheroids and emboli grown in vitro. Taken together, these results identify a high-throughput approach to target tumor spheroid formation for drug discovery. Finally, disulfiram is a safe and approved drug for management of alcohol abuse, warranting its evaluation for repurposing in IBC therapy.

Advancement of multidisciplinary education and research in translational sciences: MERITS program development at Duke University

INTRODUCTION

The Duke Multidisciplinary Education and Research in Translational Sciences Program provides educational resources for faculty and trainees in translational research.

METHODS

To aid in program development, we assessed perceptions of translational science through focus groups targeting different career stages.

RESULTS

In total, 3 essential themes emerged: collaboration, movement toward application, and public health impact. Facilitators and barriers varied among groups.

CONCLUSION

Training programs must provide specific strategies for collaboration and selectively accelerating discoveries to therapies.

XIAP Regulation by MNK Links MAPK and NFκB Signaling to Determine an Aggressive Breast Cancer Phenotype

Hyperactivation of the NFκB pathway is a distinct feature of inflammatory breast cancer (IBC), a highly proliferative and lethal disease. Gene expression studies in IBC patient tissue have linked EGFR (EGFR/HER2)-mediated MAPK signaling to NFκB hyperactivity, but the mechanism(s) by which this occurs remain unclear. Here, we report that the X-linked inhibitor of apoptosis protein (XIAP) plays a central role in linking these two pathways. XIAP overexpression correlated with poor prognoses in breast cancer patients and was frequently observed in untreated IBC patient primary tumors. XIAP drove constitutive NFκB transcriptional activity, which mediated ALDH positivity (a marker of stem-like cells), in vivo tumor growth, and an IBC expression signature in patient-derived IBC cells. Using pathway inhibitors and mathematical models, we defined a new role for the MAPK interacting (Ser/Thr)-kinase (MNK) in enhancing XIAP expression and downstream NFκB signaling. Furthermore, targeted XIAP knockdown and treatment with a MNK inhibitor decreased tumor cell migration in a dorsal skin fold window chamber murine model that allowed for intravital imaging of local tumor growth and migration. Together, our results indicate a novel role for XIAP in the molecular cross-talk between MAPK and NFκB pathways in aggressive tumor growth, which has the potential to be therapeutically exploited.Significance: Signaling by the MNK kinase is essential in inflammatory breast cancer, and it can be targeted to inhibit XIAP-NFκB signaling and the aggressive phenotype of this malignancy. Cancer Res; 78(7); 1726-38. ©2018 AACR.

Scientific Summary from the Morgan Welch MD Anderson Cancer Center Inflammatory Breast Cancer (IBC) Program 10th Anniversary Conference

In 2006, a remarkable collaboration between University of Texas MD Anderson Cancer Center clinicians and Texas and New Mexico State legislators led to the formation of a dedicated IBC Research Program and Clinic at MD Anderson. This initiative provided funding and infrastructure to foster coordination of an IBC World Consortium of national and international experts, and launch the first ever IBC international conference in 2008, which brought together experts from around the world to facilitate collaborations and accelerate progress. Indeed great progress has been made since then. National and international experts in IBC convened at the 10^th Anniversary Conference of the MD Anderson IBC Clinic and Research Program and presented the most extensive sequencing analysis to date comparing IBC to non-IBC, gene- and protein-based immunoprofiling of IBC versus non-IBC patients, and converging lines of evidence on the specific role of the microenvironment in IBC. Novel models, unique metabolic mechanisms, and prominent survival pathways have been identified and were presented. Multiple clinical trials based on the work of the last decade are in progress or in development. The important challenges ahead were discussed. This progress and a coordinated summary of these works are presented herein.

Bisphenol A activates EGFR and ERK promoting proliferation, tumor spheroid formation and resistance to EGFR pathway inhibition in estrogen receptor-negative inflammatory breast cancer cells

Emerging evidence from epidemiological studies suggests a link between environmental chemical exposure and progression of aggressive breast cancer subtypes. Of all clinically distinct types of breast cancers, the most lethal phenotypic variant is inflammatory breast cancer (IBC). Overexpression of epidermal growth factor receptors (EGFR/HER2) along with estrogen receptor (ER) negativity is common in IBC tumor cells, which instead of a solid mass present as rapidly proliferating diffuse tumor cell clusters. Our previous studies have demonstrated a role of an adaptive response of increased antioxidants in acquired resistance to EGFR-targeting drugs in IBC. Environmental chemicals are known to induce oxidative stress resulting in perturbations in signal transduction pathways. It is therefore of interest to identify chemicals that can potentiate EGFR mitogenic effects in IBC. Herein, we assessed in ER-negative IBC cells a subset of chemicals from the EPA ToxCast set for their effect on EGFR activation and in multiple cancer phenotypic assays. We demonstrated that endocrine-disrupting chemicals such as bisphenol A (BPA) and 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane can increase EGFR/ERK signaling. BPA also caused a corresponding increase in expression of SOD1 and anti-apoptotic Bcl-2, key markers of antioxidant and anti-apoptotic processes. BPA potentiated clonogenic growth and tumor spheroid formation in vitro, reflecting IBC-specific pathological characteristics. Furthermore, we identified that BPA was able to attenuate the inhibitory effect of an EGFR targeted drug in a longer-term anchorage-independent growth assay. These findings provide a potential mechanistic basis for environmental chemicals such as BPA in potentiating a hyperproliferative and death-resistant phenotype in cancer cells by activating mitogenic pathways to which the tumor cells are addicted for survival.

Photothermal ablation of inflammatory breast cancer tumor emboli using plasmonic gold nanostars

Inflammatory breast cancer (IBC) is rare, but it is the most aggressive subtype of breast cancer. IBC has a unique presentation of diffuse tumor cell clusters called tumor emboli in the dermis of the chest wall that block lymph vessels causing a painful, erythematous, and edematous breast. Lack of effective therapeutic treatments has caused mortality rates of this cancer to reach 20%–30% in case of women with stage III–IV disease. Plasmonic nanoparticles, via photothermal ablation, are emerging as lead candidates in next-generation cancer treatment for site-specific cell death. Plasmonic gold nanostars (GNS) have an extremely large two-photon luminescence cross-section that allows real-time imaging through multiphoton microscopy, as well as superior photothermal conversion efficiency with highly concentrated heating due to its tip-enhanced plasmonic effect. To effectively study the use of GNS as a clinically plausible treatment of IBC, accurate three-dimensional (3D) preclinical models are needed. Here, we demonstrate a unique in vitro preclinical model that mimics the tumor emboli structures assumed by IBC in vivo using IBC cell lines SUM149 and SUM190. Furthermore, we demonstrate that GNS are endocytosed into multiple cancer cell lines irrespective of receptor status or drug resistance and that these nanoparticles penetrate the tumor embolic core in 3D culture, allowing effective photothermal ablation of the IBC tumor emboli. These results not only provide an avenue for optimizing the diagnostic and therapeutic application of GNS in the treatment of IBC but also support the continuous development of 3D in vitro models for investigating the efficacy of photothermal therapy as well as to further evaluate photothermal therapy in an IBC in vivo model.

Bisphenol A activates EGFR and ERK promoting proliferation, tumor spheroid formation and resistance to EGFR pathway inhibition in estrogen receptor-negative inflammatory breast cancer cells

Emerging evidence from epidemiological studies suggests a link between environmental chemical exposure and progression of aggressive breast cancer subtypes. Of all clinically distinct types of breast cancers, the most lethal phenotypic variant is inflammatory breast cancer (IBC). Overexpression of epidermal growth factor receptors (EGFR/HER2) along with estrogen receptor (ER) negativity is common in IBC tumor cells, which instead of a solid mass present as rapidly proliferating diffuse tumor cell clusters. Our previous studies have demonstrated a role of an adaptive response of increased antioxidants in acquired resistance to EGFR-targeting drugs in IBC. Environmental chemicals are known to induce oxidative stress resulting in perturbations in signal transduction pathways. It is therefore of interest to identify chemicals that can potentiate EGFR mitogenic effects in IBC. Herein, we assessed in ER-negative IBC cells a subset of chemicals from the EPA ToxCast set for their effect on EGFR activation and in multiple cancer phenotypic assays. We demonstrated that endocrine-disrupting chemicals such as bisphenol A (BPA) and 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane can increase EGFR/ERK signaling. BPA also caused a corresponding increase in expression of SOD1 and anti-apoptotic Bcl-2, key markers of antioxidant and anti-apoptotic processes. BPA potentiated clonogenic growth and tumor spheroid formation in vitro, reflecting IBC-specific pathological characteristics. Furthermore, we identified that BPA was able to attenuate the inhibitory effect of an EGFR targeted drug in a longer-term anchorage-independent growth assay. These findings provide a potential mechanistic basis for environmental chemicals such as BPA in potentiating a hyperproliferative and death-resistant phenotype in cancer cells by activating mitogenic pathways to which the tumor cells are addicted for survival.

Abstract P2-04-21: Suppression of immune response by X-linked inhibitor of apoptosis protein-nuclear factor kappa-light-chain-enhancer of activated B cells tumor cell signaling

This abstract was withdrawn by the authors.

Abstract P3-16-02: Nanotheranostics using plasmonic gold nanostars to target inflammatory breast cancer cells and tumor emboli

Introduction: Due to the aggressive nature of inflammatory breast cancer (IBC) and insensitive imaging techniques, patients diagnosed with IBC have a poor prognosis. IBC's unique ability to form emboli leads to rapid growth and distant invasion. New therapies aimed at disrupting the formation of tumor emboli are needed. Gold nanostars (GNS) are unique nanoparticles that can be imaged in real time with high sensitivity, and are rapidly endocytosed into cancer cells. Due to their sharp spikes, GNS exhibit plasmonic properties, which strongly enhance the electromagnetic field upon laser excitation. In addition to their use as highly intense and stable fluorescent labels, these nanoparticles can be photothermally activated to trigger cellular ablation. The use of GNS as an imaging and therapeutic modality for IBC should be investigated.

Methods: IBC (SUM-149/SUM190), non-IBC (BT474M1/MD-MBA-231), and drug resistant isotype variant (rSUM-149) cell lines were incubated with GNS, stained with Hoechst33342, and imaged with multiphoton microscopy (MPM). The dose and time dependent effects of GNS on SUM-149 proliferation was assessed with MTT assays. Photothermal treatment was performed on GNS-labeled IBC, non-IBC, and drug resistant cancer cell lines. The effects of photothermal therapy on cell viability were assessed using fluorescein diacetate and propidium iodide. Using a tumor emboli model, SUM-149, rSUM-149, and SUM-190 tumor emboli were labeled with GNS on the 3rd day of embolic maturation. Emboli were sectioned, stained with H/E, and imaged with MPM to demonstrate the depth of GNS penetrance. The potential for photothermal ablation of the GNS-labeled tumor emboli was assessed using various laser intensities. Propidium iodide was used to examine emboli viability following treatment.

Results: In all cell lines, GNS displayed rapid cellular uptake without nuclear involvement. MTT assay showed that GNS concentrations of 0.15 and 0.20 nM caused decreases in cell proliferation at 6 and 12 hours. Proliferative capacity was unaltered at 24 hours for all concentrations, however this may be due to spectrophotometric interference with high intracellular GNS concentrations. Live/dead staining confirmed effective photothermal treatment in all cultures with a clear zone of cellular death. For tumor emboli studies, GNS allowed bright fluorescent monitoring of tumor emboli using MPM, and cross sectional imaging demonstrated GNS penetrance into the embolic core. Photothermal ablation of GNS-labeled tumor emboli was successfully demonstrated following laser irradiation. Cell death was confirmed with propidium iodide.

Conclusion: Gold nanostars provide a highly fluorescent intracellular label for cancer cell lines, and tumor emboli without significantly altering cell proliferation. Furthermore, the inherent optical properties of the GNS allows for a combined therapeutic application following phototoactivation. This is the first study to demonstrate the nanothernostic application of GNS in IBC tumor emboli. Prior studies have shown the effectiveness of photothermal ablation in in vivo sarcoma models; we are currently extending our studies to an IBC mouse model.

Supported by the P30 Cancer Center Support Grant (GRD) and Duke Exploratory Funds (TVD).

Citation Format: Shammas RL, Fales AM, Crawford BM, Hollenbeck ST, Vo-Dinh T, Devi GR. Nanotheranostics using plasmonic gold nanostars to target inflammatory breast cancer cells and tumor emboli [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-16-02.

Abstract B44: Immune pathway dysregulations in inflammatory breast cancer health disparity

Background: Inflammatory breast cancer (IBC) is a distinct, aggressive and the most lethal form of breast cancer. Furthermore, data from population-based registries, when stratified by race and compared to other locally advanced breast cancers, suggest that IBC has a disproportionately high incidence, prevalence & shorter median survival time in African Americans (AA) compared to Caucasian American (CA) patients. IBC health disparities that are independent of external factors like differences in income, screening rates, and access to health care suggest a biological component to poor outcomes. IBC pathobiology is also unique wherein instead of a solid tumor, tightly packed tumor cell clusters/emboli are formed with a propensity for lymphatic dissemination. The underlying mechanisms for this extremely aggressive breast cancer phenotype are largely unknown and, therefore, present a major impediment to identifying the molecular underpinnings for health disparities in IBC patients.

Methods and Results: In order to understand how IBC cells evade cell death signals in the host microenvironment, we conducted comparative analysis of the largest collection of untreated primary tumor samples of IBC (N=137), along with stage- and subtype-matched non-IBC (N=252) and normal breast tissue. Results reveal that pretreatment tumor tissue samples from IBC patients have a heightened expression of adaptive stress response genes comprised of high levels of the nuclear transcription factor, NFkappaB, and its target genes in the anti-apoptotic and immune/inflammatory pathways that correlate with cell survival. In addition, guided by analysis based on presence of tumor infiltrating leukocytes in IBC (N=69) and non-IBC (N=62) patient samples, we have identified a set of pathways and genes that have the ability to distinguish the immune responses in IBC and non-IBC patients in a subtype independent manner. In particular, interferon alpha/beta and NFκB signaling pathways were differentially regulated in IBC vs. non-IBC. Gene expression driven analysis of enrichment of leukocyte subsets reveal specific differences in plasma cells and effector memory CD8 cells in IBC bulk tumor samples. Preliminary data analysis of gene expression data sets from laser microdissected epithelium and stromal compartments of AA and CA breast cancer patients also show enrichment of plasma cells, effector memory CD4+, and M1 macrophages. Studies are ongoing to characterize these immune profiles that are unique and distinguishable in IBC patients and further identify race-related differences. Most importantly, we discovered that the constitutive NFκB hyperactivation observed in IBC tumor cells is driven by stress-mediated translational upregulation of the most potent anti-apoptotic protein, XIAP. Interestingly, XIAP:NFκB overexpressing cells are highly resistant to immunotherapy mediated cell death. These data strongly suggest that in IBC, host immune phenotype promotes outgrowth of cell death resistant population and specific tumor cell pro-survival signaling mechanisms that enhances invasion and lymphatic dissemination. We have developed novel in vitro IBC tumor emboli culture model and a transgenic mouse bearing red fluorescent lymphatic vasculature that allow recapitulating host factors to define tumor cell signaling mechanisms on immune effector function and the resultant invasive phenotype.

Conclusions: As the incidence is rising and targets for therapy are scant, IBC has the potential to become a major public health disparity concern. This study reveals that the immune factors in the host microenvironment may interact with underlying IBC genetics to promote the aggressive nature of the tumor, and more specifically, these factors may be one of the sources of biologic variation between patients of different ethnicities leading to IBC disparity outcomes. Supported in part by Duke IBC Consortium, DCI NIH CAO14236 development funds (GRD), DoD W81XWH-13-1-0047 (GRD).

Citation Format: Gayathri R. Devi, Eun-Sil Shelley Hwang, John Stewart, Michael A. Morse, Steven Van Laere. Immune pathway dysregulations in inflammatory breast cancer health disparity. [abstract]. In: Proceedings of the Ninth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2016 Sep 25-28; Fort Lauderdale, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(2 Suppl):Abstract nr B44.

Three-dimensional culture systems in cancer research: Focus on tumor spheroid model

Cancer cells propagated in three-dimensional (3D) culture systems exhibit physiologically relevant cell-cell and cell-matrix interactions, gene expression and signaling pathway profiles, heterogeneity and structural complexity that reflect in vivo tumors. In recent years, development of various 3D models has improved the study of host-tumor interaction and use of high-throughput screening platforms for anti-cancer drug discovery and development. This review attempts to summarize the various 3D culture systems, with an emphasis on the most well characterized and widely applied model - multicellular tumor spheroids. This review also highlights the various techniques to generate tumor spheroids, methods to characterize them, and its applicability in cancer research.

X-linked inhibitor of apoptosis protein mediates tumor cell resistance to antibody-dependent cellular cytotoxicity

Inflammatory breast cancer (IBC) is the deadliest, distinct subtype of breast cancer. High expression of epidermal growth factor receptors [EGFR or human epidermal growth factor receptor 2 (HER2)] in IBC tumors has prompted trials of anti-EGFR/HER2 monoclonal antibodies to inhibit oncogenic signaling; however, de novo and acquired therapeutic resistance is common. Another critical function of these antibodies is to mediate antibody-dependent cellular cytotoxicity (ADCC), which enables immune effector cells to engage tumors and deliver granzymes, activating executioner caspases. We hypothesized that high expression of anti-apoptotic molecules in tumors would render them resistant to ADCC. Herein, we demonstrate that the most potent caspase inhibitor, X-linked inhibitor of apoptosis protein (XIAP), overexpressed in IBC, drives resistance to ADCC mediated by cetuximab (anti-EGFR) and trastuzumab (anti-HER2). Overexpression of XIAP in parental IBC cell lines enhances resistance to ADCC; conversely, targeted downregulation of XIAP in ADCC-resistant IBC cells renders them sensitive. As hypothesized, this ADCC resistance is in part a result of the ability of XIAP to inhibit caspase activity; however, we also unexpectedly found that resistance was dependent on XIAP-mediated, caspase-independent suppression of reactive oxygen species (ROS) accumulation, which otherwise occurs during ADCC. Transcriptome analysis supported these observations by revealing modulation of genes involved in immunosuppression and oxidative stress response in XIAP-overexpressing, ADCC-resistant cells. We conclude that XIAP is a critical modulator of ADCC responsiveness, operating through both caspase-dependent and -independent mechanisms. These results suggest that strategies targeting the effects of XIAP on caspase activation and ROS suppression have the potential to enhance the activity of monoclonal antibody-based immunotherapy.

Abstract P6-14-05: A novel link between anti-apoptotic signaling, NFκB, and SMAD7 in IBC pathobiology

Background: Inflammatory breast cancer (IBC) has the highest lethality amongst all subtypes of breast cancer and develops rapid therapeutic resistance. High NFκB activation has been identified as a distinct molecular determinant in IBC pathobiology; however, the precise sequence of its activation and functional consequence in IBC remains unknown. Our previous work identified increased expression of the X-linked inhibitor of apoptosis protein (XIAP) due to altered translation in IBC, while other studies have noted a crosstalk between XIAP and NFκB. We hypothesized that XIAP drives NFκB activation in IBC promoting therapeutic resistance and tumorigenesis.

Methods: NFκB phosphorylation, nuclear translocation, and target gene expression were evaluated in triple-negative SUM149 IBC cells with targeted overexpression or knockdown of XIAP. Using specific point mutants, we assessed the domain and mechanism of XIAP-mediated NFκB activation in IBC. We evaluated proliferation and viability in 2D and 3D culture of SUM149 cells treated with JSH-23, a small molecule inhibitor of NFκB nuclear translocation. We monitored the effects of XIAP overexpression or knockdown on in vivo tumorigenicity in IBC xenograft models by measuring tumor growth and NFκB signaling. IHC analysis of XIAP and NFκB was performed on tumor microarrays containing both non-IBC and IBC.

Results: Knockdown of XIAP significantly decreased NFκB activation in IBC cells. Domain analysis revealed the necessity of the BIR1 domain of XIAP and TAB1:IKKβ complex formation in activating NFκB. NFκB antagonism inhibited proliferation of cells and sensitized therapy-resistant, XIAP overexpressing cells to targeted therapy. Loss of XIAP inhibited tumor growth of SUM149 tumor cells, correlating with decreased ALDH activity and varied epithelial-mesenchymal characteristics in these cells, while overexpression of XIAP significantly enhanced tumor growth of SUM149 cells. Further analysis revealed altered SMAD7 expression in XIAP knockdown cells, revealing crosstalk between XIAP, NFκB, and TGFβ signaling in IBC. IHC analysis of XIAP expression in invasive non-IBC tumors correlated with triple-negative status as well as increased grade and stage of tumors. In IBC tumors, XIAP expression associated with increased NFκB.

Conclusions: In summary, our studies reveal that XIAP expression is necessary for NFκB activation in IBC and is critical for IBC development and progression. This study provides a novel insight into how an anti-apoptotic protein may regulate survival signaling and disease progression and may guide further research into innovative inhibitors of this interaction.

Citation Format: Myron K Evans, Scott J Sauer, Amy J Aldrich, Joseph Geradts, Peter Vermeulen, Luc Dirix, Steven Van Laere, Gayathri R Devi. A novel link between anti-apoptotic signaling, NFκB, and SMAD7 in IBC pathobiology [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-14-05.

Modulation of murine breast tumor vascularity, hypoxia and chemotherapeutic response by exercise

Exercise has been shown to improve postischemia perfusion of normal tissues; we investigated whether these effects extend to solid tumors. Estrogen receptor-negative (ER-, 4T1) and ER+ (E0771) tumor cells were implanted orthotopically into syngeneic mice (BALB/c, N = 11-12 per group) randomly assigned to exercise or sedentary control. Tumor growth, perfusion, hypoxia, and components of the angiogenic and apoptotic cascades were assessed by MRI, immunohistochemistry, western blotting, and quantitative polymerase chain reaction and analyzed with one-way and repeated measures analysis of variance and linear regression. All statistical tests were two-sided. Exercise statistically significantly reduced tumor growth and was associated with a 1.4-fold increase in apoptosis (sedentary vs exercise: 1544 cells/mm(2), 95% CI = 1223 to 1865 vs 2168 cells/mm(2), 95% CI = 1620 to 2717; P = .048), increased microvessel density (P = .004), vessel maturity (P = .006) and perfusion, and reduced intratumoral hypoxia (P = .012), compared with sedentary controls. We also tested whether exercise could improve chemotherapy (cyclophosphamide) efficacy. Exercise plus chemotherapy prolonged growth delay compared with chemotherapy alone (P < .001) in the orthotopic 4T1 model (n = 17 per group). Exercise is a potential novel adjuvant treatment of breast cancer.

Disulfiram (DSF) acts as a copper ionophore to induce copper-dependent oxidative stress and mediate anti-tumor efficacy in inflammatory breast cancer

Cancer cells often have increased levels of reactive oxygen species (ROS); however, acquisition of redox adaptive mechanisms allows for evasion of ROS-mediated death. Inflammatory breast cancer (IBC) is a distinct, advanced BC subtype characterized by high rates of residual disease and recurrence despite advances in multimodality treatment. Using a cellular model of IBC, we identified an oxidative stress response (OSR) signature in surviving IBC cells after administration of an acute dose of an ROS inducer. Metagene analysis of patient samples revealed significantly higher OSR scores in IBC tumor samples compared to normal or non-IBC tissues, which may contribute to the poor response of IBC tumors to common treatment strategies, which often rely heavily on ROS induction. To combat this adaptation, we utilized a potent redox modulator, the FDA-approved small molecule Disulfiram (DSF), alone and in combination with copper. DSF forms a complex with copper (DSF-Cu) increasing intracellular copper concentration both in vitro and in vivo, bypassing the need for membrane transporters. DSF-Cu antagonized NFκB signaling, aldehyde dehydrogenase activity and antioxidant levels, inducing oxidative stress-mediated apoptosis in multiple IBC cellular models. In vivo, DSF-Cu significantly inhibited tumor growth without significant toxicity, causing apoptosis only in tumor cells. These results indicate that IBC tumors are highly redox adapted, which may render them resistant to ROS-inducing therapies. DSF, through redox modulation, may be a useful approach to enhance chemo- and/or radio-sensitivity for advanced BC subtypes where therapeutic resistance is an impediment to durable responses to current standard of care.

Mn porphyrin in combination with ascorbate acts as a pro-oxidant and mediates caspase-independent cancer cell death

Resistance to therapy-mediated apoptosis in inflammatory breast cancer, an aggressive and distinct subtype of breast cancer, was recently attributed to increased superoxide dismutase (SOD) expression, glutathione (GSH) content, and decreased accumulation of reactive species. In this study, we demonstrate the unique ability of two Mn(III) N-substituted pyridylporphyrin (MnP)-based SOD mimics (MnTE-2-PyP(5+) and MnTnBuOE-2-PyP(5+)) to catalyze oxidation of ascorbate, leading to the production of excessive levels of peroxide, and in turn cell death. The accumulation of peroxide, as a consequence of MnP+ascorbate treatment, was fully reversed by the administration of exogenous catalase, showing that hydrogen peroxide is essential for cell death. Cell death as a consequence of the action of MnP+ascorbate corresponded to decreases in GSH levels, prosurvival signaling (p-NF-κB, p-ERK1/2), and in expression of X-linked inhibitor of apoptosis protein, the most potent caspase inhibitor. Although markers of classical apoptosis were observed, including PARP cleavage and annexin V staining, administration of a pan-caspase inhibitor, Q-VD-OPh, did not reverse the observed cytotoxicity. MnP+ascorbate-treated cells showed nuclear translocation of apoptosis-inducing factor, suggesting the possibility of a mechanism of caspase-independent cell death. Pharmacological ascorbate has already shown promise in recently completed phase I clinical trials, in which its oxidation and subsequent peroxide formation was catalyzed by endogenous metalloproteins. The catalysis of ascorbate oxidation by an optimized metal-based catalyst (such as MnP) carries a large therapeutic potential as an anticancer agent by itself or in combination with other modalities such as radio- and chemotherapy.

Quantitative high-throughput efficacy profiling of approved oncology drugs in inflammatory breast cancer models of acquired drug resistance and re-sensitization

Although there is no standard treatment protocol for inflammatory breast cancer (IBC), multi-modality treatment has improved survival. In this study we profiled the NCI approved oncology drug set in a qHTS format to identify those that are efficacious in basal type and ErbB2 overexpressing IBC models. Further, we characterized the sensitivity of an acquired therapeutic resistance model to the oncology drugs. We observed that lapatinib-induced acquired resistance in SUM149 cells led to cross-resistance to other targeted- and chemotherapeutic drugs. Removal of the primary drug to which the model was developed led to re-sensitization to multiple drugs to a degree comparable to the parental cell line; this coincided with the cells regaining the ability to accumulate ROS and reduced expression of anti-apoptotic factors and the antioxidant SOD2. We suggest that our findings provide a unique IBC model system for gaining an understanding of acquired therapeutic resistance and the effect of redox adaptation on anti-cancer drug efficacy.

Novel adenoviral vector induces T-cell responses despite anti-adenoviral neutralizing antibodies in colorectal cancer patients

First-generation, E1-deleted adenovirus subtype 5 (Ad5)-based vectors, although promising platforms for use as cancer vaccines, are impeded in activity by naturally occurring or induced Ad-specific neutralizing antibodies. Ad5-based vectors with deletions of the E1 and the E2b regions (Ad5 [E1-, E2b-]), the latter encoding the DNA polymerase and the pre-terminal protein, by virtue of diminished late phase viral protein expression, were hypothesized to avoid immunological clearance and induce more potent immune responses against the encoded tumor antigen transgene in Ad-immune hosts. Indeed, multiple homologous immunizations with Ad5 [E1-, E2b-]-CEA(6D), encoding the tumor antigen carcinoembryonic antigen (CEA), induced CEA-specific cell-mediated immune (CMI) responses with antitumor activity in mice despite the presence of preexisting or induced Ad5-neutralizing antibody. In the present phase I/II study, cohorts of patients with advanced colorectal cancer were immunized with escalating doses of Ad5 [E1-, E2b-]-CEA(6D). CEA-specific CMI responses were observed despite the presence of preexisting Ad5 immunity in a majority (61.3 %) of patients. Importantly, there was minimal toxicity, and overall patient survival (48 % at 12 months) was similar regardless of preexisting Ad5 neutralizing antibody titers. The results demonstrate that, in cancer patients, the novel Ad5 [E1-, E2b-] gene delivery platform generates significant CMI responses to the tumor antigen CEA in the setting of both naturally acquired and immunization-induced Ad5-specific immunity.

Abstract 951: Cross-resistance and re-sensitization to multiple drugs in an IBC model of lapatinib acquired resistance parallels redox adaptation

Inflammatory breast cancer (IBC) is characterized by rapid progression from onset of disease, therefore an early and aggressive multimodal therapy is essential to improve outcome. IBC tumors are frequently ErbB2- and EGFR-positive, and the use of trastuzumab in combination with lapatinib has seen clinical success; however, de novo and acquired resistance to these agents due to interplay between different members of the ErbB family is a significant challenge. In addition, it is well recognized that there is paucity of IBC cellular models. We have characterized a novel isogenic-derived progression model of lapatinib drug resistance (rSUM149) and re-sensitization (rrSUM149). Four IBC cell lines representing either HER2 overexpression or basal-type were profiled to identify approved oncology drugs from that can act as potent inhibitors of IBC cell proliferation. In our present study, rSUM149 cells showed cross-resistance to a number of the drugs previously shown to act on the parental cells. We show that long term removal of lapatinib, the primary drug against which resistance was developed from rSUM149 cells led to isolation of a population of cells (rrSUM149) that are then re-sensitized to multiple drugs, behaving in a manner comparable to the parental SUM149 cell line. Recently, we identified that the lapatinib-resistant rSUM149 had increased levels of anti-apoptotic proteins, increased antioxidant expression (superoxide dismutase and GSH), and decreased ability to accumulate reactive oxygen species (ROS), all of which lead to inhibition of drug-induced apoptosis. We had previously validated this finding with the observations that: (i). Overexpressing XIAP in therapy-sensitive IBC cells renders them therapy-resistant and this corresponds to low ROS accumulation in response to oxidative stress; (ii). specific XIAP inhibition using siRNA or XIAP small molecule inhibitors reversed drug resistance, decreased the antioxidants involved in redox-adaptation and increased significant ROS accumulation leading to IBC cell death. In our results presented herein, re-sensitization was accompanied by a decrease in expression of the apoptosis inhibitor XIAP and antioxidant SOD2; assessment of ROS following challenge with lapatinib revealed that the ability to accumulate ROS was restored to the cells through those changes. This mechanistic phenotype supports our current observations of cross-resistance to multiple drugs, which is also commonly seen in patients. These results strengthen the need for novel strategies to modulate cellular redox to overcome drug resistance in IBC.

*Joint corresponding authors (GRD & KPW). Supported in part by NIH grant CA137844 (KPW), American Cancer Society grant RSG-08-290-01-CCE (GRD), DCI Cancer and Environment Initiative award, Duke Uni (GRD). Additional funding; Golden LEAF Foundation and BIOIMPACT Initiative of the State of NC.

Citation Format: Gayathri R. Devi, Jennifer L. Allensworth, Shalonda M. Ingram, Ginger R. Smith, Amy J. Aldrich, Kevin P. Williams. Cross-resistance and re-sensitization to multiple drugs in an IBC model of lapatinib acquired resistance parallels redox adaptation. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 951. doi:10.1158/1538-7445.AM2013-951