Abstract P4-06-05: PanCancer profiling reveals population difference in breast cancer immune microenvironment

BACKGROUND. Breast Cancer (BC) outcome in patients (pts) of African ancestry (AA) is worse than pts of European ancestry (EA) despite accounting for socioeconomic status and access. AA have higher hormone receptor negative (HR-) and Triple Negative (TNBC) tumors, subtypes associated with stronger presence of tumor infiltrating lymphocytes (TILs). We hypothesize that BC Immune Microenvironment (IME) composition differs by ancestry, and describe IME from two independent datasets.

METHODS. Transcriptome data from the Cancer Genome Atlas (TCGA) (Group 1, Gp1) were used to estimate 22 IME cell types in BC samples by CIBERSORT. Clinical and overall survival (OS) data were accessed from XENA. Gp2 tissue samples were obtained from Women's Circle of Health study and Pathology Resource Network at Roswell Park Comprehensive Cancer Center and processed using NanoString™ PanCancer Immune Profiling panel, consisting of 770 immunity-related genes describing 24 IME cell types. Immune Dysfunction and Exclusion (TIDE) scores were derived from an algorithm by Jiang et al.

RESULTS. Gp1 consisted of 183 AA and 752 EA, with median age older in EA (54.5 vs 59). On CIBERSORT IME analysis by race, AA had higher IME infiltrates including macrophages (Mp), dendritic cells (DC) and TILs; notably T regulatory (Treg) and T Follicular Helper (Tfh) cells. The ratios of Tregs and Tfh to total TILs were also elevated. When stratified by subtypes, AAs with TNBC/Basal-like BC had higher Tregs and Tfh cells. CD8+ cells were higher in HR+ and high-grade AA pts only. CD4+/total T-cells was higher in AA across all subtypes, and predicted worse OS (HR 3.15[1.07-9.2]). Gp2 had 190 AA and 177 EA with comparable median age at diagnosis (53 versus 54) and tumor grade. By subtype, TNBC had significantly higher total TILs, CD45+, CD8+, exhausted CD8+, Treg, cytotoxic T cells, B, natural killer (NK), activated NK, DC and Mp; yet significantly lower mast cells and neutrophils (p <0.01). CD8+/Exhausted CD8+ and CD8+/Treg ratios were lower in TNBC and higher-grade tumors, and lowest in HR- grade III. Most of immune pathways were enriched in HR- tumors, with only exception being cell cycle genes being remarkably enriched in HR+ tissues (p <0.01). TIDE demonstrated high immune dysfunction in HR- and high exclusion in HR+ tumors. When compared to EA, AA had more TILs, including B, cytotoxic T-cells, exhausted CD8+, NK, activated NK and Tregs (p <0.01). Neutrophils, Mp and CD8+ were higher in EA. EA also had significantly higher ratio of immune cell types to total TILs across cytotoxic, exhausted CD8+ and Tregs, as well as persistent higher neutrophils, Mp and CD8+ ratios. CD8+/Treg ratio was higher in EA. Consistent with Gp1; CD4+/total T-cell ratio was higher in AA across all subtypes.

CONCLUSION. IME differed significantly by HR, grade and ancestry. Aggressive BC demonstrated stronger overall immune response but dysfunctional IME phenotype (higher Treg, lower granulocytes and mast cells ratios). AA had more TILs across all subtypes, but lower ratios of activator (CD8+, Cytotoxic) to suppressor TILs (Treg, exhausted CD8+), demonstrating immune tolerance and immune-desert model, exception being persistently high fraction of CD4+ ratio predicting worse OS.

Citation Format: Elkhanany A, Takabe K, Khoury T, Omilian A, Cheng D, Katsuta E, Davis W, Yan L, Hong C-C, Bandera E, Ambrosone C, Yao S. PanCancer profiling reveals population difference in breast cancer immune microenvironment [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-06-05.

Abstract P1-15-12: Axillary lymph node metastasis and HER2-receptor positivity significantly associate with recurrence and worse survival in breast cancer patients who achieved pathological complete response after neoadjuvant chemotherapy

BACKGROUND

Neoadjuvant chemotherapy (NAC) has become a common practice in breast cancer care since it not only expands the opportunity for breast conservation surgery, but also allows in vivo assessment of individual cancer biology. Patients who achieved pathological complete response (pCR) after NAC are known to have significantly improved outcomes than those who did not. To date, there has been no large study of factors that associate with tumor recurrence after patients had pCR following NAC. To identify such factors, we examined a cohort of 394 patients.

METHODS

Patients diagnosed during 2007-16 with clinical stage I-III breast cancer who achieved pCR following NAC were identified from clinical records at four hospitals in urban Japan. Nearly 70% of patients received standard NAC regimen, which was a combination of anthracycline and taxane, with trastuzumab added as needed. pCR was defined as no pathological evidence of invasive cancer in the breast; residual ductal carcinoma in situ (DCIS) and residual axillary lymph node metastasis were included in this study. The median follow-up time was 63 months (range = 16-161 months). Outcomes were assessed by 5-year disease-free survival (DFS) and 5-year overall survival (OS).

RESULTS

Among the 394 patients with pCR, the breast cancer subtype was as follows: Luminal – 49 (12.4%), Luminal-HER2 – 97 (24.6%), HER2 – 117 (29.7%), and TNBC – 131 (33.2%). During follow up, 28 (7.1%) of the 394 patients had experienced tumor recurrence. In univariate Cox regression analysis, each of HER2-receptor status, pre-NAC tumor size, and pre-NAC axillary lymph node status were associated with recurrence. The hazard ratios, and their 95% confidence intervals (CI) and P values for these significant factors were as follows. HER2-receptor negative vs. positive: 2.5 (CI = 1.0-5.8; P = 0.036); cT1/2 vs. cT3/4: 2.2 (CI = 1.3-6.1; P = 0.008); cN0 vs. cN1-3: 9.5 (2.2-40.7; P = 0.002). However, age (<50 vs. ≥50 y), residual DCIS, post-NAC axillary lymph node status, type of mastectomy (total vs. partial), and adjuvant radiation therapy were not associated with recurrence. Of the 28 patients with recurrence, site of first event was local for 8, and brain and visceral for 10 each. Seven of the 10 patients with brain metastasis were HER2-receptor positive. Eleven of the 28 patients with recurrence had deceased, with a median post-recurrence survival duration of 40 months (range = 2–94 months). Shorter survival was associated with HER2-receptor positivity (P = 0.003).

CONCLUSION

Axillary lymph node metastasis before rather than after NAC, and HER2-receptor positivity are associated with tumor recurrence in patients who achieved pCR in breast cancer. HER2-receptor positive patients had higher risk for brain metastasis and shorter survival. Given the extreme rarity of local recurrence after pCR, we cannot help but speculate that omitting surgical removal of pCR tissue may be permissible when pCR has been diagnosed accurately.

Citation Format: Asaoka M, Narui K, Suganuma N, Chishima T, Yamada A, Kawai S, Uenaka N, Sato E, Katsuta E, Kawaguchi T, Takabe K, Ishikawa T. Axillary lymph node metastasis and HER2-receptor positivity significantly associate with recurrence and worse survival in breast cancer patients who achieved pathological complete response after neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-15-12.

Abstract P5-05-01: Metabolic enzyme PFKFB4 activates transcriptional coactivator SRC-3 to drive aggressive metastatic breast cancer

Background: Metabolic rewiring is one of the central hallmarks of cancer progression and survival to support anabolic and energetic demands. Tumor cells constantly alter their metabolic state in response to oncogenic stimuli, nutrient availability, and interaction with immune cells however the precise regulation that precedes the metabolic alteration is poorly understood. Here we report a direct interaction of glycolytic enzyme PFKFB4 with transcriptional coregulator SRC-3. PFKFB4 functions as a critical regulator of Warburg effect and our study reveals that upon glucose stimulation PFKFB4 activates SRC-3 driving an invasive-metastatic breast cancer.

Methods: Molecular experiments were performed to understand the transcriptional activation of SRC-3 by PFKFB4 enzyme. Chromatin immunoprecipitation and gene expression studies were performed to investigate the functions of PFKFB4/SRC-3 crosstalk on transcriptional regulation. Metabolomics and isotope tracing studies were performed to identify the metabolic adaptations regulated by PFKFB4/SRC-3 in breast tumors. PFKFB4-knockout was established using CRISPR-Cas9 system and functional studies were carried out to define its role in tumor cell proliferation, invasion-migration, and breast to lung metastasis. Human breast tumor samples were evaluated to identify the clinical importance of PFKFB4/SRC-3 crosstalk in patients.

Results:Molecular studies revealed that PFKFB4 enzyme phosphorylates SRC-3 at serine 857 (S857) enhancing its transcriptional activity, whereas either suppression of PFKFB4 or ectopic expression of a phosphorylation-deficient SRC-3 mutant S857A (SRC-3S857A) significantly abolished SRC-3-mediated transcriptional output (p<0.000001). Functionally, PFKFB4-driven SRC-3 activation drives glucose flux towards the pentose phosphate pathway enabling purine synthesis by transcriptionally upregulating the expression of enzyme transketolase (TKT). Deletion of PFKFB4 by CRISPR-Cas9 system resulted in significantly reduced proliferation (p<0.05) and migration-invasion (p<0.001) compared to wildtype breast tumor cells. Ablation of SRC-3 or PFKFB4 suppressed in vivo breast tumor growth and prevents metastasis to the lung from an orthotopic setting (p<0.0001). PFKFB4 and phosphorylated SRC-3 levels are significantly increased in breast tumors (p=0.02), whereas, in patients with the basal subtype, PFKFB4 and SRC-3 drive a common protein signature that correlates with the poor survival of TNBC patients (p=0.03).

Conclusion:Our data suggest that the Warburg pathway enzyme PFKFB4 acts as a molecular fulcrum that couples sugar metabolism to transcriptional activation by stimulating SRC-3 to promote aggressive metastatic tumors. It also provides first evidence how Warburg pathway drives aggressive breast tumorigenesis by directly activating powerful oncogene SRC-3. Our work suggests that targeting the PFKFB4–SRC-3 axis may be therapeutically valuable in breast tumors that are notably dependent on glucose metabolism.

(This work is funded by grants from Susan G. Komen and NCI to S.D.)

Citation Format: Dasgupta S, Anand V, John H, Sawant Dessai A, Katsuta E, Takabe K, O'Malley B. Metabolic enzyme PFKFB4 activates transcriptional coactivator SRC-3 to drive aggressive metastatic breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-05-01.

Abstract P3-08-05: High APOBEC3C-H gene expression in tumor associates with better survival in breast cancer

Background

APOBEC3 (A3) enzymes are strong mutagenic factors. A3B has been well described as an active mutator in breast cancer, whereas the roles of the other APOBEC3s (A3A, C-H) are unclear. While mutations may directly drive cancer progression, they can indirectly suppress cancer growth by generating neoantigens. To elucidate this, we comprehensively analyzed all APOBEC3s for their association with mutations and immune activity in breast cancer.

Methods

RNA seq.-based gene expression data for 1091 primary carcinomas and 113 adjacent normal tissues was from TCGA. Patients were divided into high and low groups by top and bottom gene expression tertiles. Tumor immune features like cytolytic activity, T cell receptor (TCR) diversity, and cell fractions were quantified from gene expression data. Data for some of these features, mutation-related aspects, and survival outcomes were obtained from the Pan-Cancer Atlas. Gene expression data for 55 breast cancer cell-lines was from Cancer Cell Line Encycolpedia. Cox regression and Spearman methods were respectively used for survival and correlation analyses. Welch's t test was used for group comparison. P <0.05 was deemed significant. Hallmark gene-sets were used for enrichment analysis with recommended 25% FDR.

Results

A3B and A3C together represented most (91%) of A3 gene expression in breast cancer cell-lines. In TCGA patients, expression of only A3B was increased by 4.5x in tumors compared to normal tissue, whereas levels for other A3 genes were unchanged. Surprisingly, tumor A3B or A3A levels had no significant association with overall (OS) or disease-specific survival (DSS), whereas for each of A3C-H, higher expression was significantly associated with improved OS (hazard ratios of 0.45-0.66) or DSS (0.43-0.61). The prognostic benefit of high A3C-H expression was also seen in survival analyses of two meta-datasets of microarray-based gene expression (KMPlot and SurvExpress). A3A and A3B levels correlated with both mutation burden and neoantigen load (Spearman ρ = 0.28-0.34), which respectively were 2.0-2.9x higher in high compared to low expressors. But there was no association of expression with mutation burden or neoantigen load for A3C-H. On the other hand, A3C-H levels correlated positively with tumor leukocyte fraction (ρ = 0.29-0.70) and its lymphocyte subset (ρ = 0.20-0.50), whereas the correlation was poor for A3B (ρ = 0.10 & -0.01 respectively). Expression of genes of immune function like interferon response and complement activation was enriched in high A3C-H expressors. It was not so for A3B, for which enrichment was instead observed for cell proliferation. Both CD4 and CD8 T cells were significantly more (2.3-4.0x & 2.1-5.4x resp.), and TCR diversity significantly higher (1.3-2.1x) in A3C-H high expressors. Concordantly, for each of A3C-H, expression correlated with tumor immune cytolytic activity (ρ = 0.31-0.79), which was increased 3.1-7.9x in high compared to low expressors.

Conclusions

These findings suggest that in spite of A3C-H being known as DNA mutators, an increase in their expression confers a survival benefit in breast cancer. Their increased expression likely reflects a heightened anti-cancer immune response, and may be useful for disease prognosis and monitoring immunotherapy.

Citation Format: Asaoka M, Patnaik SK, Katsuta E, Kawaguchi T, Ishikawa T, Takabe K. High APOBEC3C-H gene expression in tumor associates with better survival in breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-08-05.

Abstract P2-02-04: CD73 expression regulated by estrogen signaling associates with poor prognosis in estrogen receptor (ER)-positive breast cancer

Introduction: CD73, a cell surface enzyme, catalyzes the generation of adenosine from ATP and ADP in the tumor microenvironment along with CD39. Accumulated extracellular adenosine functions as immune-suppressor, and also binds to adenosine receptors which promotes angiogenesis and cell proliferation that results in accelerate cancer progression. However, the clinical significance and molecular function of CD73 expression in breast cancer remains unclear.

Methods: Utilizing publicly available breast cancer cohorts of The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO), clinical significance as well as underlying mechanisms were investigated. Molecular experiments were carried out in MCF7 cells, ER-positive breast cancer cell line, to investigate the role of estrogen signaling on CD73/CD39 expression.

Results: In treatment naïve TCGA cohort, CD73 expression level was significantly lower in ER-positive breast cancers compared to ER-negative tumors. Higher CD73 expression was associated with worse overall survival in whole cohort (p=0.021) and ER-positive tumors (p=0.003), but not in ER-negative tumors. Gene Set Enrichment Analysis revealed that estrogen response gene sets (Early; NES=-1.57, p=0.043, Late; NES=-1.61, p=0.021) were significantly enriched in CD73 low expressing ER-positive tumors, suggesting estrogen signaling may repress CD73 expression. To test this hypothesis, we analyzed the expression of CD73 and CD39 in MCF7 cells treated with estrogen, tamoxifen or both. Our data revealed that estrogen treatment suppressed CD73 and CD39 expression, whereas tamoxifen treatment enhanced expression of the genes. These findings suggest that CD73 and CD39 gene expression is suppressed by estrogen signaling, whereas binding of ER antagonists such as tamoxifen can remove the repressive effect on gene expression. On the other hand, epithelial-mesenchymal transition (EMT) (Normalized Enrichment Score; NES=2.41, p<0.001) and angiogenesis (NES=2.33, p<0.001) gene sets were significantly enriched in CD73 high expressing ER-positive tumors. CIBERSORT, which is an algorithm to estimate infiltrating immune cells by gene expression, demonstrated that CD73 high expressing ER-positive tumors have less infiltrating CD8-positive T cells, memory B cells and plasma cells, implying that CD73 high expressing tumors have immune suppressive environment, which is in agreement with the notion that CD73 high tumors are immunosuppressive. Finally, we found that CD73 expression was significantly elevated post-chemotherapy compared to tumors prior to the treatment (p=0.007), and CD73 high expression patients showed worse relapse-free survival in neoadjuvant chemotherapy patients cohort (p=0.003).

Conclusion: Molecular studies revealed that CD73 expression is regulated by estrogen signaling. Increased expression of CD73 significantly correlates with worse outcomes in ER-positive breast cancer patients. This may be due to upregulated pro-metastatic gene signatures such as EMT and angiogenesis as well as less infiltration of anti-cancer immune cells by adenosine generated by CD73 in the tumor microenvironment. Our data reveals an intriguing mechanism which may be responsible for recurrence and metastasis of ER-positive breast cancer.

Citation Format: Katsuta E, Anand V, Yan L, Dasgupta S, Takabe K. CD73 expression regulated by estrogen signaling associates with poor prognosis in estrogen receptor (ER)-positive breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-02-04.

Abstract P3-06-16: The pattern of alpha- and beta- adrenergic receptor expression impacts breast cancer outcome

BACKGROUND. Chronic stress promotes myriad of genomic changes collectively termed conserved transcriptional response to adversity (CTRA), contributing to a pro-tumorogenic and immunosuppressive tumor microenvironment (TME). Adrenergic stimulation is one mechanism of CTRA, and adrenergic receptor (AR) modulators are currently repurposed in cancer trials. However, the impact of AR expression on TME and overall survival outcome (OS) in breast cancer (BC) remains unclear. We asked whether AR expression in tumor samples predicts prognosis in BC patients (pts) and whether it correlated to expression in normal cells.

METHODS. Public RNA expression data accessed from The Cancer Genome Atlas (TCGA), and fed to deconvolutional algorithm CIBERSORT, estimating 22 immune cell proportions. Clinical and OS data were accessed from XENA. Differential gene expression obtained for 115 CTRA genes known to correlate with stress. Cytolytic activity (CY) appended from Rooney et al.

RESULTS. 1,211 pts had clinical and genomic data, including 114 pts with normal breast (BN) samples. When compared to BC, BN samples were enriched for ARG1, PTGS2, VCAM1, CSF1, as well as all ARs (ADR A1A, A1B, A1D, A2A, A2B, A2C, B1, B2, B3). There was significant correlation between BC and BN samples in A2A, B1, B2, IFN-γ, PTGS2 (Spearman ρ -0.2, -0.27, -0.2, 0.28, 0.29, P<0.01). On survival analysis, worse OS was associated with higher expression of A1B and A2C (HR 1.1[1-1.22], 1.1[1-1.17]), while higher B1 predicted better OS (HR 0.86[0.79-0.93]). OS impact persisted after quantile separation (HR for higher to lower quantiles of A1B, A2C and B1 were 1.47[1.1-2], 1.38[1.01-1.9], 0.69[0.49-0.0.95]). Co-expression of A1B and A2C predicted significantly worse OS than either alone (HR 1.53[1.1-2.2]). Results persisted after adjusting for age. For TME analysis between quantiles, higher A1B and A2C expression correlated with higher regulatory T (Treg) cells (OR 1.42[1.1-1.86]), fewer resting and activated dendritic cells (DCs) and memory CD4+ cells, and lower CY (OR 0.81[0.64-0.9]). In comparison, higher B1 correlated with higher tumor infiltrating lymphocytes (TILs), M1 macrophages (M1), M1/M2 ratio (OR 1.45[1.14-1.84], 3.64[1.03-12.8], 1.86[1.46-2.36]), lower M2 and Treg (0.42[0.33-0.53], 0.65[0.49-0.85]), and higher CY (OR 1.89[1.49-2.38]). CY also correlated with IFN-γ, MMP9 and CSF1 (Spearman ρ 0.75, 0.59, 0.3 p<0.001). Higher M2 and lower M1/M2 ratio were independently associated with a poorer OS, persisting after control for B1 (HR 1.78[1.27-2.47], 1.5[1.08-2.08]). T-cell exhaustion (Tex) genes CD274, PDCD1, CTLA4, IDO1, LAG3 and HAVCR2 were all lower in ADR-α (OR for A1B was 0.69, 0.73, 0.68, 0.87, 0.61, 0.69) and higher in ADR-β (OR for B1 was 1.46, 1.32, 1.29, 1.42, 1.26, 1.4).

CONCLUSIONS. AR genes were similarly expressed across normal and tumor samples from BC pts. Pts with higher ADR-α expression had worse OS (higher Treg, lower CY) while higher ADR-β expression pts had better OS (higher TILs, M1, M1/M2, lower Treg, M2). Tex genes were higher in ADR-β, likely due to higher TILs. These findings illustrate the potential impact of chronic stress on TME and clinical outcome, potentially helping to discern pts who can benefit most from AR modulation.

Citation Format: Elkhanany A, Katsuta E, Repasky E, Takabe K. The pattern of alpha- and beta- adrenergic receptor expression impacts breast cancer outcome [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-06-16.

Abstract P3-06-15: Young breast cancer patients demonstrate worse survival associated with aggressive oncogene expression but not with mutation load, tumor heterogeneity or pro-tumor immune cell infiltrations

INTRODUCTION: Young breast cancer patients have more aggressive subtypes and higher mortality rates. This study investigates the biologic, immunologic, and oncogenic differences between Young (≤40 yo) and Non-Young (>40 yo) patients with breast cancer.

MATERIALS/METHODS: The Cancer Genome Atlas (TCGA; n=1095) and the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC; n=1894) were used for analysis. Gene Set Enrichment Analysis (GSEA) was performed on breast cancer patients in TCGA. We calculated mutation load using both TCGA and METABRIC. We also calculated the Cytolytic Activity Score (CYT), Mutant-Allele Tumor Heterogeneity (MATH), T-Cell Receptor (TCR)-Richness, and Ki67 mRNA expression in TCGA.

RESULTS: There were 97 and 116 Young patients and 994 and 1788 Non-Young patients in the TCGA and METABRIC databases respectively. Young patients had a lower DFS (p=0.012) in TCGA. Young patients had a lower DSS (p<0.001) in METABRIC. There were less Stage I (13.5% vs 17.3%) and II (54.2% vs 58.3%) patients and more Stage III (31.2% vs 22.4%) patients in the Young group. There were more basal-like subtypes in the Young in TCGA (17.8% vs 16.1%) and METABRIC (28.4% vs 9.3%). Mutation load in TCGA was lower in the Young (p=0.030), but not significantly different in the METABRIC database. MATH, which reflects tumor heterogeneity, was not significantly different between the groups. These results were unexpected since Young patients have a higher proportion of basal-like subtype which is known to be rich in mutations and more immunogenic. In TCGA, Young patients were found to have higher amounts of activated dendritic cells (p=0.049). In METABRIC, Young patients had higher amounts of Plasma cells (p=0.016), CD4 memory-activated T-cells (p<0.001), NK resting cells (p=0.015), and M1 Macrophages (p=0.002). We also found that regulatory T-cells (p=0.029), activated NK cells (p=0.016), M2 Macrophages (p<0.001), and resting Mast cells (p=0.006) were lower in the Young. This unexpectedly showed that anti-tumor immune cells were more enriched in Young patients. Indeed, the CYT, which reflects tumor killing activity, and TCR-Richness, which reflects T-cell function, were both significantly higher in Young patients (p=0.034, p=0.004, respectively), which was opposite from what we expected due to its biological aggressiveness. GSEA was then used to analyze the TCGA database to clarify gene sets that are enriched in Young patients. Of the 50 Hallmark gene sets analyzed, 4 gene sets were found to be enriched in Young patients; G2M Checkpoint (p=0.002), Hallmark MYC Targets V1 (p=0.004), HALLMARK E2F Targets (p=0.035), and Hallmark Unfolded Protein Response (p=0.038). Ki67 which reflects cell proliferation was significantly higher in Young vs Non-Young patients (p=0.004).

CONCLUSIONS: Both TCGA and METABRIC cohorts demonstrated that Young patients have more basal-like subtype and significantly worse survival. Our results support the notion that Young patients have more aggressive cancer not because of mutations, tumor heterogeneity or immune cell infiltrations, but because of aggressive oncogene expressions.

Citation Format: Young JS, Asaoka M, Katsuta E, Kawaguchi T, Qi Q, Liu S, Yan L, Takabe K. Young breast cancer patients demonstrate worse survival associated with aggressive oncogene expression but not with mutation load, tumor heterogeneity or pro-tumor immune cell infiltrations [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-06-15.

Abstract P1-01-06: Targeting the SphK1/S1P/S1PR1 axis that connects obesity, chronic inflammation, and breast cancer metastasis

Introduction: Obesity with associated inflammation is now recognized as a risk factor for breast cancer and increased incidence of distant metastases. However, the link between obesity and breast cancer progression remains poorly understood. There is growing evidence that sphingosine-1-phosphate (S1P), a pleiotropic bioactive sphingolipid metabolite enriched both in blood and lymphatic fluid is involved in inflammation, obesity, and breast cancer progression. Our hypothesis is that obesity increases levels of S1P in both tumor and its microenvironment, which play a role in obesity-induced inflammation and breast cancer metastasis. The aim of this study is to test this hypothesis in in vitro and in vivo as well as patient settings.

Methods: Levels of sphingolipids including S1P in serum from breast cancer patients were quantified. Orthotopically-implanted E0771 syngeneic breast cancer and MMTV-PyMT transgenic breast cancer mouse models were used. Mice were fed with normal or high-fat diet (HFD). FTY720 was administered orally (1 mg/kg/day). To examine pre-metastatic niche formation, a mouse model utilizing tail vein injection of E0771 cells was used. In this model, mice were treated with conditioned media from E0771 breast cancer cells overexpressing SphK1 (K1-CM) or that from E0771 cells cultured with the vector control (CT-CM), prior to tail vein injections of naive E0771 cells. S1P levels were determined by electrospray ionization-tandem mass spectrometry.

Results: We found that obesity significantly increased S1P levels in serum from breast cancer patients. In animal breast cancer models, HFD upregulated expression of sphingosine kinase 1 (SphK1), the enzyme that produces S1P, and its receptor S1PR1 in syngeneic and spontaneous breast tumors. HFD also significantly increased S1P in breast tumors and in the tumor interstitial fluid, which is a component of the tumor microenvironment and bathes cancer cells in the tumor. Targeting the SphK1/S1P/S1PR1 axis with FTY720/fingolimod attenuated obesity-induced key pro-inflammatory cytokines, macrophage infiltration, and tumor progression. In addition, S1P produced by tumor SphK1 primed lung pre-metastatic niches, increased macrophage recruitment into the lung, and induced IL-6 and signaling pathways important for lung metastatic colonization. FTY720 suppressed HFD-induced lung IL-6 and macrophage infiltration as well as S1P-mediated signaling pathways and dramatically reduced formation of metastatic foci. In tumor bearing mice, FTY720 also suppressed obesity-related inflammation, S1P signaling, pulmonary metastasis, and prolonged survival.

Conclusion: Our results highlight a critical role for circulating S1P produced by tumor and the SphK1/S1P/S1PR1 axis in obesity-related inflammation, metastatic niche formation and breast cancer metastasis and suggest that targeting the SphK1/S1P/S1PR1 axis would be a useful therapeutic for obesity promoted metastatic breast cancer.

Citation Format: Nagahashi M, Yamada A, Aoyagi T, Huang W-C, Terracina KP, Hait N, Allegood JC, Tsuchida J, Nakajima M, Katsuta E, Milstien S, Wakai T, Spiegel S, Takabe K. Targeting the SphK1/S1P/S1PR1 axis that connects obesity, chronic inflammation, and breast cancer metastasis [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-01-06.

Abstract P5-05-06: Development of advanced pre-clinical in vivo models of metastatic breast cancer

Backgrounds: The fact that we continue to lose 40,000 women with breast cancer every year in the US despite the recent advance in basic research clearly demonstrate disconnect in translation of basic research findings to clinic. This is largely due to lack of appropriate animal model that mimic clinical conditions for preclinical studies that result in high failure rate of clinical trials. To date, we had established many syngeneic mouse models, which are not free from limitations; 1) few clinically relevant animal models with bone metastasis have been established, 2) syngeneic mouse model cannot address human cancer genomics and tumor heterogeneity. Patient-Derived Xenograft (PDX) model has emerged as pre-clinical model to address these issues, however, it suffers low tumor take rate of around 20-40%, and lack metastatic model. Here, we describe development of orthotopic implantation, and bone and liver metastatic breast cancer mouse models to overcome these limitations.

Methods: 1) 4T1.2-luc3 cells that has metastatic potential to the bone were orthotropically inoculated as a syngeneic mouse model, imaged with IVIS and MRI. 2) Patient tumor tissues of 1mm(3) were implanted surgically into dorsal subcutaneous space (SQ), or orthotropically into mammary fat pat #2 and #4 (MFP).

Results: 1) We established a syngeneic breast cancer bone metastasis model. Primary tumors were surgically resected days after 4T1.2-luc3 cells were orthotopically implanted under direct vision. Removal of primary tumor allowed bioluminescent visualization and quantification of bone metastasis by IVIS. We found that MRI was effective in evaluating bone metastasis and bone related events in these mice. MRI allows differentiation of bone metastasis from metastasis to the surrounding organs with bone destruction image, whereas conventional bioluminescence imaging shows only existence of cancer cells. 2) The overall tumor take rate of the tumor in PDX model was 46.0% (74/161 implantation site). Take rate from triple-negative breast cancer tumors was 56.1% (74/132), on the other hand, that from ER positive tumors was 0% (0/39). Tumor take rate was significantly better in MFP implantation than SQ (39.5%, 30/76 vs 51.2%, 44/85, p<0.01). Tumor weight were significantly heavier in MFP compared to SQ (0.072g vs 0.328g, p<0.00001). With more passage, the difference in tumor weight between SQ and MFP was significantly increased(p<0.0001). Finally, we developed a PDX breast cancer liver metastasis model by surgically implanting tissue fragment into liver using direct vision technique. We found MRI to be very useful as a living imaging modality to evaluate cancer progression in the deeply located metastatic sites of PDX models.

Conclusions: We have established orthotropic syngeneic breast cancer bone metastasis model as well as improved breast cancer PDX model with synchronous liver metastasis utilizing MRI. Our novel models could be powerful tools for preclinical studies.

Citation Format: Okano M, Kawaguchi T, Okano I, Katsuta E, Takabe K. Development of advanced pre-clinical in vivo models of metastatic breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-05-06.

Abstract P4-06-12: Murine radical mastectomy model for preclinical study of adjuvant systemic therapies

Background:

Current standard of care of breast cancer is removal of primary tumor followed by systemic adjuvant therapy to reduce recurrence and to prolong survival. However, vast majority of the preclinical studies that use murine models evaluate the drug response of primary tumors either in mammary pads or subcutaneous tissues. Lately it has been shown that the genetic profiles of metastatic lung tumors are significantly different from that of their primary mammary tumors, let alone subcutaneous tumors. Therefore we hypothesized that the responses of metastatic tumors rather than primary mammary tumors need to be evaluated for a systemic therapy. However there are few reports of murine mastectomy models used for preclinical study.

Methods:

Murine mammary adenocarcinoma 4T1-luc2 cells were inoculated into #2 right mammary fat pad under direct vision as previously described (Katsuta et al, JSR 2016). The tumor burden was quantified by bioluminescence IVIS imaging system. Novel platinum drug, Triplatin, or Vehicle was administrated every 4 days for 3 times from the day after inoculation. Amount of lung metastases were quantified ex vivo by IVIS imaging. Then we compared the growth of metastatic tumors between two methods of radical mastectomy; midline incision method and Halsted incision method, which were performed 8 days after inoculation. Triplatin or Vehicle was administered 2 days after mastectomies.

Results:

First we compared the two methods of chest mammary tumor removal; midline incision method and Halsted incision method. There was no significant difference in weight of resected tumors between these two techniques (p=0.751), however, the bioluminescence in midline incision model was significantly higher than Halsted incision model at the first day after operations (p=0.003). Only 1 out of 7 cases (14%) after Halsted incision method developed local recurrence, whereas all (100%) the animals that underwent midline incision method developed recurrence within 30 days after operation (p<0.001). No mice developed respiratory failure due to wound closure of wide skin defect. We then examined the effect of Triplatin on chest mammary tumor and lung metastasis. There was no significant difference in bioluminescence from chest mammary tumors between treatment group and non-treatment, however, ex vivo bioluminescence of lung metastases demonstrated that treatment group mice had significantly less tumor burden in lung than non-treatment group. Utilizing Halsted incision method with less local recurrence, we found that lung metastases were significantly less in treatment group than non-treatment group in live animals monitored by bioluminescence.

Conclusion:

We have established an improved murine chest mammary tumor resection model. Effects on metastases, as opposed to primary tumor should be evaluated for the preclinical study of adjuvant systemic therapy, since they may not be the same.

Citation Format: Katsuta E, Takabe K. Murine radical mastectomy model for preclinical study of adjuvant systemic therapies [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 P4-06-12.

Abstract P3-06-07: Combination of doxorubicin with S1P signaling modulator FTY720 significantly suppressed obesity-associated breast cancer

Background:

Obesity is one of the biggest health issues in the US. It has been shown that obesity-associated breast cancer is more aggressive with poor prognosis, which is partly explained by the low-grade inflammation caused by obesity. Recently we have published that sphingosine-1-phosphate (S1P), a signaling lipid mediator, link inflammation and cancer in colitis-associated colon cancer model. We hypothesized that addition of S1P modulator that block S1P signaling thus suppress the effect of obesity-mediated inflammation should enhance anti-cancer effect of doxorubicin, which is a typical anti-cancer drug for breast cancer used as a standard of care.

Methods:

Female B6.cg-Lepob (OB/OB) mice fed with high fat diet for 2 weeks prior to implantation of cancer cells were used as an obesity model, and litter mate control mice fed with normal diet were used as a control. 1 x 106 murine mammary adenocarcinoma E0771 cells were inoculated into #2 rt. fat pads as previously described (Katsuta et al JSR 2016). 9 days after inoculation, both OB/OB and control mice were randomized into 4 groups in each group; vehicle, Doxorubicin, FTY720 and Combination of Doxorubicin and FTY720. Doxorubicin was administrated by i.p. injection at a dose of 5 mg/kg on Day 0 and 3. FTY720 was administered everyday by gavage at a dose of 1 mg/kg during the entire course. Tumor growths were measured daily by caliper measurements. Tumor weights were measured on 21 days after cell inoculation.

Results:

The body weight of obesity model was significantly heavier than control mice at the time of cancer cell inoculation (44.1 g vs 19.4 g; p < 0.001). In non-treatment group, tumor weight in obesity group was significant heavier than control mice[KT1] (1232 mg vs 966 mg; p = 0.049), which is consistent with the dogma that obesity worsen cancer progression. As expected, tumor weight in non-treatment group is heavier than any treatment group, and that in combination treatment of doxorubicin and FTY720 is lightest in both of obesity group and control group. Interestingly, tumor reduction rate in obesity group compared with non-treatment group is significant greater than control group (Doxorubicin: 83% vs 19%, p = 0.001; FTY720: 80% vs 46%, p = 0.027, Doxorubicin + FTY720: 93% vs 64%, p = 0.011). Over 15 % weight loss were seen in obesity doxorubicin group and obesity combination treatment group.

Conclusion:

Modification of S1P signaling by FTY720 was shown to enhance the effect of doxorubicin particularly in obese mice, which implicate a novel approach to treat obesity-associated breast cancer.

Citation Format: Katsuta E, Takabe K. Combination of doxorubicin with S1P signaling modulator FTY720 significantly suppressed obesity-associated breast cancer [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 P3-06-07.