Tumor heterogeneity and clinically invisible micrometastases in metastatic breast cancer-a call for enhanced surveillance strategies

The biology of metastatic breast cancer (MBC) is understudied, primarily due to the difficulty of procuring multiple samples from patients with oligometastatic breast cancer. We developed a rapid postmortem tissue procurement program that allows the collection and analysis of numerous metastatic lesions, subclinical locations, and potential pre-metastatic niches that fall within this scope. We conducted a rapid postmortem tissue collection study on 9 patients with MBC. Patients and their families consented to donate tissues immediately after death in an IRB-approved study. Various disease subtypes, progression histories, organ involvement, and final causes of death are reported. In patients with hormone receptor-positive (HR+) disease, estrogen receptor (ER), progesterone receptor (PR), HER2, and Ki-67 expression were heterogeneous across metastatic lesions within individual patients. Disease phenotype at the end of life trended toward complete loss of HR expression. Nearly all (n = 7) patients exhibited extensive tumor involvement of additional organs that had not been previously diagnosed clinically and were not retrospectively visible on recent imaging. Of these seven individuals, three included organs uncommonly associated with MBC: kidney, spleen, pancreas, and ovary. Finally, we identified clinically undetectable micrometastases in several organs uncommonly involved in MBC. Our findings raise several clinically relevant questions regarding the mechanisms of metastatic progression. Insights from this study argue for better surveillance strategies for monitoring MBC. We highlight the need to capture more accurate biomarker information in the context of heterogeneous disease and urge the consideration of treatment strategies that combine multiple targeted therapies.

PD-L1-expressing tumor-associated macrophages are immunostimulatory and associate with good clinical outcome in human breast cancer

Tumor-associated macrophages (TAMs) are the predominant cells that express programmed cell death ligand 1 (PD-L1) within human tumors in addition to cancer cells, and PD-L1+ TAMs are generally thought to be immunosuppressive within the tumor immune microenvironment (TIME). Using single-cell transcriptomic and spatial multiplex immunofluorescence analyses, we show that PD-L1+ TAMs are mature and immunostimulatory with spatial preference to T cells. In contrast, PD-L1- TAMs are immunosuppressive and spatially co-localize with cancer cells. Either higher density of PD-L1+ TAMs alone or ratio of PD-L1+/PD-L1- TAMs correlate with favorable clinical outcome in two independent cohorts of patients with breast cancer. Mechanistically, we show that PD-L1 is upregulated during the monocyte-to-macrophage maturation and differentiation process and does not require external IFN-γ stimulus. Functionally, PD-L1+ TAMs are more mature/activated and promote CD8+ T cells proliferation and cytotoxic capacity. Together, our findings reveal insights into the immunological significance of PD-L1 within the TIME.

Bow-tie architectures in biological and artificial neural networks: Implications for network evolution and assay design

Modern artificial neural networks (ANNs) have long been designed on foundations of mathematics as opposed to their original foundations of biomimicry. However, the structure and function of these modern ANNs are often analogous to real-life biological networks. We propose that the ubiquitous information-theoretic principles underlying the development of ANNs are similar to the principles guiding the macro-evolution of biological networks and that insights gained from one field can be applied to the other. We generate hypotheses on the bow-tie network structure of the Janus kinase - signal transducers and activators of transcription (JAK-STAT) pathway, additionally informed by the evolutionary considerations, and carry out ANN simulation experiments to demonstrate that an increase in the network's input and output complexity does not necessarily require a more complex intermediate layer. This observation should guide novel biomarker discovery-namely, to prioritize sections of the biological networks in which information is most compressed as opposed to biomarkers representing the periphery of the network.

Tumor-infiltrating exhausted CD8+ T cells dictate reduced survival in premenopausal estrogen receptor-positive breast cancer

CD8⁺ tumor-infiltrating lymphocytes (TILs) are associated with improved survival in triple-negative breast cancer (TNBC) yet have no association with survival in estrogen receptor–positive (ER⁺) BC. The basis for these contrasting findings remains elusive. We identified subsets of BC tumors infiltrated by CD8⁺ T cells with characteristic features of exhausted T cells (T_EX). Tumors with abundant CD8⁺ T_EX exhibited a distinct tumor microenvironment marked by amplified interferon-γ signaling–related pathways and higher programmed death ligand 1 expression. Paradoxically, higher levels of tumor-infiltrating CD8⁺ T_EX associated with decreased overall survival of patients with ER⁺ BC but not patients with TNBC. Moreover, high tumor expression of a CD8⁺ T_EX signature identified dramatically reduced survival in premenopausal, but not postmenopausal, patients with ER⁺ BC. Finally, we demonstrated the value of a tumor T_EX signature score in identifying high-risk premenopausal ER⁺ BC patients among those with intermediate Oncotype DX Breast Recurrence Scores. Our data highlight the complex relationship between CD8⁺ TILs, interferon-γ signaling, and ER status in BC patient survival. This work identifies tumor-infiltrating CD8⁺ T_EX as a key feature of reduced survival outcomes in premenopausal patients with early-stage ER⁺ BC.

Abstract 1689: Intranodal self-correlation analysis reveals differences in gene-to-gene interactions between lymph nodes draining cold vs. hot triple-negative breast tumors

Hot tumors (i.e., tumors with more infiltrating lymphocytes) are generally associated with better prognosis and response to immune checkpoint blockade therapies in TNBC. Higher tumor mutation burden (TMB) has been associated with hot tumors and considered a potential reason why hot tumors may have more tumor infiltrating lymphocytes (TILs) compared to cold tumors. However, TMB does not fully explain immune infiltration. We hypothesized that tumor draining lymph nodes (TDLNs) play an important role in lymphocyte infiltration into tumors. To study the functional features of LNs draining cold vs. hot tumors, we characterized the expression of 730 immune functional genes of 15 tumor-free TDLNs from paired cold (n = 7) and hot (n = 8) tumors based on low (<10%) or high (>60%) TIL percentages defined by pathologists in H&E stained slides. By standard differential gene expression (DGE) analysis, there were similar transcriptomic profiles in TDLNs between cold and hot cohorts. Since DGE analysis only provides comparison of average gene expression, it cannot compare gene-to-gene interactions. Therefore, to further investigate differences in intranodal gene-to-gene interactions, we implemented self-correlation analysis (i.e., generating clustered gene-to-gene correlations) to both cohorts. Results showed that TDLNs generally present weaker intranodal regulations (i.e., less significantly correlated gene pairs and smaller organized clusters) in the cold cohort. By further comparing specific gene-to-gene correlations, the GATA3-CXCR1 correlation in the cold cohort were found to be negative (rCold = -0.56), while positive (rHot = 0.90) in the hot cohort. Similar opposite correlations were also found in TBX21-CXCR1 pair (rCold = 0.85, rHot = -0.88). Since CXCR1 would be downregulated during the maturation of dendritic cells (DCs) and T cell differentiation, these results suggest that matured dendritic cells within TDLNs from cold tumors may preferably prime naïve CD4+ T cells to T helper 2 (Th2) cells. In contrast, TDLNs from hot tumors have an opposite preference to T helper 1 (Th1) cells. In addition, a positive CD4-STAT6 correlation (r = 0.88, p-value = 0.0084) was also observed, which further indicated a preference to Th2 cells in TDLNs from cold tumors. In summary, by applying intranodal self-correlation analysis to TDLNs from cold and hot tumors, opposite preferences of CD4+ naïve T cell differentiation in TDLNs are suggested. The weaker regulation and preference of Th2 cells in TDLNs from cold tumors may hinder lymphocyte infiltration into the tumor.

Citation Format: Weihua Guo, Minhui Lim, Jiayi Tan, Lei Wang, Ting-fang He, Shawn Solomon, Colt A. Egelston, Diana L. Simons, Daniel Schmolze, James Waisman, Peter P. Lee. Intranodal self-correlation analysis reveals differences in gene-to-gene interactions between lymph nodes draining cold vs. hot triple-negative breast tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1689.

Organ specificity dictates tumor immune infiltration and composition in metastatic breast cancer; lessons from a rapid autopsy tissue collection study

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Background: Immune composition in the tumor microenvironment (TME) of patient tumors has proven to play a central role in the propensity of tumors to metastasize and respond to therapy. Evidence has suggested that the metastatic TME is immune aberrant, however limited sample size and numbers has made assessment of the immune TME in the development of multi-organ metastases difficult. Here we utilize a rapid autopsy tissue collection protocol to assess the infiltration and composition of the immune TME in numerous metastatic tissue sites, paired disease-free tissue sites, and the associated tissue draining lymph nodes. Methods: Post-mortem tissues were collected from six metastatic breast cancer patients shortly after death through City of Hope’s “Legacy Project for Rapid Tissue Donation” Program. The average post mortem interval (PMI) for tissue collection was 6 hours. Collected specimens include metastatic lesions and paired non-cancer samples from every cancer-involved organ, disease-free specimens from non-involved major organs, distant and tumor-draining lymph nodes (both cancer-infiltrated and disease free), as well as blood. Immediately following collection, specimens were processed into single cell suspension for flow cytometry. Over 80 immune cell phenotypes were assessed, including CD8+ and CD4+ T cell subsets, B cell subsets, natural killer (NK) cells, tumor associated macrophages (TAMs), dendritic cell subsets, and other cells. Results: Tumor infiltrated tissues were found to have comparable immune cell densities and composition compared to paired disease-free tissues of the same organ type. However, immune cell densities in metastatic tissues and disease-free tissues were significantly different between organ types, with lung immune infiltration consistently being greater than liver tissues. Differences in immune composition between tissue sites were also observed. Notably, liver tissues favored the presence of central memory CD8+ T cells, while lung tissues favored the presence of CD8+ tissue resident memory T cells. Relative to disease-free lung tissues, tumor infiltrated lungs contained diminished frequencies of CD8+ tissue resident memory T cells and altered B cell phenotypes. Conclusions: These data suggest that immune monitoring and trafficking of metastatic tissues site is dictated by organ type, which can be altered in composition by tumor infiltration. Further studies such as these may reveal organ-specific mechanisms of response to therapeutic interventions.

Breast cancer induces systemic immune changes on cytokine signaling in peripheral blood monocytes and lymphocytes

Background

It is increasingly recognized that cancer progression induces systemic immune changes in the host. Alterations in number and function of immune cells have been identified in cancer patients’ peripheral blood and lymphoid organs. Recently, we found dysregulated cytokine signaling in peripheral blood T cells from breast cancer (BC) patients, even those with localized disease.

Methods

We used phosphoflow cytometry to determine the clinical significance of cytokine signaling responsiveness in peripheral blood monocytes from non-metastatic BC patients at diagnosis. We also examined the correlation between cytokine signaling in peripheral monocytes and the number of tumor-infiltrating macrophages in paired breast tumors.

Findings

Our results show that cytokine (IFNγ) signaling may also be dysregulated in peripheral blood monocytes at diagnosis, specifically in BC patients who later relapsed. Some patients exhibited concurrent cytokine signaling defects in monocytes and lymphocytes at diagnosis, which predict the risk of future relapse in two independent cohorts of BC patients. Moreover, IFNγ signaling negatively correlates with expression of CSF1R on monocytes, thus modulating their ability to infiltrate into tumors.

Interpretation

Our results demonstrate that tumor-induced systemic immune changes are evident in peripheral blood immune cells for both myeloid and lymphoid lineages, and point to cytokine signaling responsiveness as important biomarkers to evaluate the overall immune status of BC patients.

Funding

This study was supported by the Department of Defense Breast Cancer Research Program (BCRP), The V Foundation, Stand Up to Cancer (SU2C), and Breast Cancer Research Foundation (BCRF).

Resident memory CD8+ T cells within cancer islands mediate survival in breast cancer patients

CD8+ tumor-infiltrating lymphocytes (TILs) correlate with relapse-free survival (RFS) in most cancer types, including breast cancer. However, subset composition, functional status, and spatial location of CD8+ TILs in relation to RFS in human breast tumors remain unclear. Spatial tissue analysis via quantitative immunofluorescence showed that infiltration of CD8+ T cells into cancer islands was more significantly associated with RFS than CD8+ T cell infiltration into either tumor stroma or total tumor. Localization into cancer islands within tumors is mediated by expression of the integrin CD103, which is a marker for tissue-resident memory T cells (TRMs). Analysis of fresh tumor samples revealed that CD8+ TRMs are functionally similar to other CD8+ TILs, suggesting that the basis of their protective effect is their spatial distribution rather than functional differences. Indeed, CD103+ TRMs, as compared with CD103-CD8+ TILs, are enriched within cancer islands, and CD8+ TRM proximity to cancer cells drives the association of CD8+ TIL densities with RFS. Together, these findings reveal the importance of cancer island-localized CD8+ TRMs in surveillance of the breast tumor microenvironment and as a critical determinant of RFS in patients with breast cancer.

Connecting blood and intratumoral Treg cell activity in predicting future relapse in breast cancer

Regulatory T (T_reg) cells play a major role in the development of an immunosuppressive tumor microenvironment. The origin of intratumoral T_reg cells and their relationship with peripheral blood T_reg cells remain unclear. T_reg cells consist of at least three functionally distinct subpopulations. Here we show that peripheral blood CD45RA^-FOXP3^hi T_reg cells (T_reg II cells) are phenotypically closest to intratumoral T_reg cells, including in their expression of CCR8. Analyses of T cell antigen receptor repertoires further support the hypothesis that intratumoral T_reg cells may originate primarily from peripheral blood T_reg II cells. Moreover, the signaling responsiveness of peripheral blood T_reg II cells to immunosuppressive, T helper type 1 (T_H1) and T helper type 2 (T_H2) cytokines reflects intratumoral immunosuppressive potential, and predicts future relapse in two independent cohorts of patients with breast cancer. Together, our findings give important insights into the relationship between peripheral blood T_reg cells and intratumoral T_reg cells, and highlight cytokine signaling responsiveness as a key determinant of intratumoral immunosuppressive potential and clinical outcome.

Human breast tumor-infiltrating CD8+ T cells retain polyfunctionality despite PD-1 expression

Functional CD8⁺ T cells in human tumors play a clear role in clinical prognosis and response to immunotherapeutic interventions. PD-1 expression in T cells involved in chronic infections and tumors such as melanoma often correlates with a state of T-cell exhaustion. Here we interrogate CD8⁺ tumor-infiltrating lymphocytes (TILs) from human breast and melanoma tumors to explore their functional state. Despite expression of exhaustion hallmarks, such as PD-1 expression, human breast tumor CD8⁺ TILs retain robust capacity for production of effector cytokines and degranulation capacity. In contrast, melanoma CD8⁺ TILs display dramatic reduction of cytokine production and degranulation capacity. We show that CD8⁺ TILs from human breast tumors can potently kill cancer cells via bi-specific antibodies. Our data demonstrate that CD8⁺ TILs in human breast tumors retain polyfunctionality, despite PD-1 expression, and suggest that they may be harnessed for effective immunotherapies.

Expression of the checkpoint molecule programmed cell death protein 1 (PD-1) is considered a marker of T cells exhaustion. Here the authors show that CD8T cells isolated from breast cancer patients are perfectly functional despite PD-1 expression while those isolated from melanoma patients are not.

Complex phenotyping of PD-1+ CD39+ exhausted CD8+ T cells in human carcinomas

CD8+ T cell infiltration into solid tumors has been shown to correlate with patient prognosis in numerous carcinomas. Furthermore, response to checkpoint blockade therapies has been linked to an induction of T cell function and rescue of T cell exhaustion in patients. Expression of both PD-1 and CD39 on exhausted CD8+ T cells has been described in murine models of chronic disease and recently human carcinomas. Here we profile breast tumor, melanoma, and chronic lymphocytic leukemia (CLL) for the frequency and phenotype of exhausted CD8+ T cells. We find that the frequency of exhausted CD8+ T cells is highest in melanoma among these tumor types which may suggest correlation with mutational burden. Functional analysis of PD-1+ CD39+ cells in human tumors shows significant reduction of IFNγ, TNFα, and IL-2 production as assessed by intracellular flow cytometry. Further phenotyping of exhausted CD8+ T cells revealed a loss of expression of both the IL-7 receptor alpha (CD127) and KLRG1, suggesting terminal differentiation of these cells. PD-1+ CD39+ T cells also expressed CD103 suggesting potential similarities with differentiation into a peripheral resident memory phenotype. Indeed PD-1+ CD39+ exhausted T cells were only identified in peripheral tissues where cancer cells were present, such as solid tumors, tumor positive tumor draining lymph nodes, and one CLL patient, but not identified in the circulation or tumor negative tumor draining lymph nodes of patients. Finally, single cell and T cell receptor sequencing revealed distinct transcriptional and clonal signatures of PD-1+ CD39+ CD8+ T cells suggesting them to be a unique population in response to tumor antigen.

MHC class I loaded ligands from breast cancer cell lines: A potential HLA-I-typed antigen collection

To build a catalog of peptides presented by breast cancer cells, we undertook systematic MHC class I immunoprecipitation followed by elution of MHC class I-loaded peptides in breast cancer cells. We determined the sequence of 3196 MHC class I ligands representing 1921 proteins from a panel of 20 breast cancer cell lines. After removing duplicate peptides, i.e., the same peptide eluted from more than one cell line, the total number of unique peptides was 2740. Of the unique peptides eluted, more than 1750 had been previously identified, and of these, sixteen have been shown to be immunogenic. Importantly, half of these immunogenic peptides were shared between different breast cancer cell lines. MHC class I binding probability was used to plot the distribution of the eluted peptides in accordance with the binding score for each breast cancer cell line. We also determined that the tested breast cancer cells presented 89 mutation-containing peptides and peptides derived from aberrantly translated genes, 7 of which were shared between four or two different cell lines. Overall, the high throughput identification of MHC class I-loaded peptides is an effective strategy for systematic characterization of cancer peptides, and could be employed for design of multi-peptide anticancer vaccines.

SIGNIFICANCE

By employing proteomic analyses of eluted peptides from breast cancer cells, the current study has built an initial HLA-I-typed antigen collection for breast cancer research. It was also determined that immunogenic epitopes can be identified using established cell lines and that shared immunogenic peptides can be found in different cancer types such as breast cancer and leukemia. Importantly, out of 3196 eluted peptides that included duplicate peptides in different cells 89 peptides either contained mutation in their sequence or were derived from aberrant translation suggesting that mutation-containing epitopes are on the order of 2-3% in breast cancer cells. Finally, our results suggest that interfering with MHC class I function is one of the mechanisms of how tumor cells escape immune system attack.

CD8+ tissue resident memory T cells are associated with good prognosis in breast cancer patients

CD8+ Tumor Infiltrating Lymphocytes (TILs) have been shown to correlate with patient prognosis in breast cancer. Recently, resident memory T cells (TRM) have been established as a potent functional subset of memory T cells that exist in peripheral tissue without recirculation. We assayed CD8+ T cells from fresh breast tumors to phenotype memory T cells and found them to be almost exclusively made up of effector memory T cells. Further profiling by examining expression of CD103 and CD69 showed that on average 40% of CD8+ TILs are composed of TRM. Functional analysis of these T cells showed robust production of IFNγ and TNFα by these TRMs suggesting that despite existence in the tumor microenvironment TRMs maintain functional potency. To examine if CD8+ TRM have prognostic value in breast cancer patients, we examined a set of primary tumors from ‘good’ and ‘bad’ outcome patients, which we defined as having a relapse in more than 5 years after diagnosis or in less than 3 years after diagnosis respectively. In good outcome patients TRMs represented 60% of CD8+ T cells found in cancer islands, while only 20% of such in bad outcome patients. Similarly, CD8+ TRMs were observed in higher numbers in both the cancer islands and stroma of good outcome patient tumors in comparison to bad outcome patient tumors. This observed significance was greater than that found for CD8+ T cells in general, highlighting the importance of TRM in affecting patient outcome. Finally we showed that TRMs also exist in non-cancerous breast tissue and are found within the mammary ducts associated with epithelial cells perhaps in surveillance of potential pathogens. We suggest that TRMs are a potential vaccine target for preventing recurrence and metastasis in cancer patients.

IL6 Signaling in Peripheral Blood T Cells Predicts Clinical Outcome in Breast Cancer

IL6 is a pleiotropic cytokine with both pro- and anti-inflammatory properties, which acts directly on cancer cells to promote their survival and proliferation. Elevated serum IL6 levels negatively correlate with survival of cancer patients, which is generally attributed to the direct effects of IL6 on cancer cells. How IL6 modulates the host immune response in cancer patients is unclear. Here, we show the IL6 signaling response in peripheral blood T cells is impaired in breast cancer patients and is associated with blunted Th17 differentiation. The mechanism identified involved downregulation of gp130 and IL6Rα in breast cancer patients and was independent of plasma IL6 levels. Importantly, defective IL6 signaling in peripheral blood T cells at diagnosis correlated with worse relapse-free survival. These results indicate that intact IL6 signaling in T cells is important for controlling cancer progression. Furthermore, they highlight a potential for IL6 signaling response in peripheral blood T cells at diagnosis as a predictive biomarker for clinical outcome of breast cancer patients. Cancer Res; 77(5); 1119-26. ©2016 AACR.

Spatial organization of dendritic cells within tumor draining lymph nodes impacts clinical outcome in breast cancer patients

BACKGROUND

Dendritic cells (DCs) are important mediators of anti-tumor immune responses. We hypothesized that an in-depth analysis of dendritic cells and their spatial relationships to each other as well as to other immune cells within tumor draining lymph nodes (TDLNs) could provide a better understanding of immune function and dysregulation in cancer.

METHODS

We analyzed immune cells within TDLNs from 59 breast cancer patients with at least 5 years of clinical follow-up using immunohistochemical staining with a novel quantitative image analysis system. We developed algorithms to analyze spatial distribution patterns of immune cells in cancer versus healthy intra-mammary lymph nodes (HLNs) to derive information about possible mechanisms underlying immune-dysregulation in breast cancer. We used the non-parametric Mann-Whitney test for inter-group comparisons, Wilcoxon Matched-Pairs Signed Ranks test for intra-group comparisons and log-rank (Mantel-Cox) test for Kaplan Maier analyses.

RESULTS

Degree of clustering of DCs (in terms of spatial proximity of the cells to each other) was reduced in TDLNs compared to HLNs. While there were more numerous DC clusters in TDLNs compared to HLNs,DC clusters within TDLNs tended to have fewer member DCs and also consisted of fewer cells displaying the DC maturity marker CD83. The average number of T cells within a standardized radius of a clustered DC was increased compared to that of an unclustered DC, suggesting that DC clustering was associated with T cell interaction. Furthermore, the number of T cells within the radius of a clustered DC was reduced in tumor-positive TDLNs compared to HLNs. Importantly, clinical outcome analysis revealed that DC clustering in tumor-positive TDLNs correlated with the duration of disease-free survival in breast cancer patients.

CONCLUSIONS

These findings are the first to describe the spatial organization of DCs within TDLNs and their association with survival outcome. In addition, we characterized specific changes in number, size, maturity, and T cell co-localization of such clusters. Strategies to enhance DC function in-vivo, including maturation and clustering, may provide additional tools for developing more efficacious DC cancer vaccines.

Abstract A51: Identification of cytokine network signaling abnormalities in immune cells from cancer patients

The innate and adaptive immune systems have the capacity to recognize and eliminate transformed cells while the ability of tumors to evade and abrogate immune functions appears to be a requisite for disease progression. Abnormalities in essentially every immune population have been documented in cancer patients and murine tumor models. Thus, the immune system is a crucial target for cancer therapeutics in order to achieve a true cure.

The cytokine JAK-STAT signaling network is a key instrument of immune system communication and directs a multitude of immune functions. Because of the integral role in regulation of immune functions as well as the intricate crosstalk that occurs within cytokine signaling networks, alterations in these networks in cancer patients are likely to be key contributing factors in immune dysfunction.

We have previously shown that IFNα and IFNγ signaling are impaired in lymphocytes from breast cancer, melanoma, and gastrointestinal cancer patients. In this study we sought to determine whether additional cytokine signaling pathways are altered in immune cells from cancer patients. Phospho-flow cytometry was used to measure STAT phosphorylation in response to 10 cytokines from the IFN, gp130, γC, and the IL3 cytokine families, to provide a broad picture of the global cytokine network in peripheral blood immune cells. Included in this analysis were patient cohorts with various carcinomas including breast, lung, gastrointestinal, and melanoma, as well as patients with psoriasis, an epidermal hyperplasia resulting from chronic inflammatory cytokine production by persistently activated immune cells.

Preliminary analysis of our study has revealed that compared with healthy controls, cancer and psoriasis patients exhibit altered responses to multiple additional cytokines in various immune cell subsets. We hypothesize that chronic inflammation which occurs in the settings of both cancer and psoriasis contributes to cytokine signaling defects and are exploring the mechanisms and the functional consequences of these defects on T cell function.

Understanding how alterations in cytokine responsiveness contribute to immune dysfunction will enable correction of these signaling defects to restore anti-tumor immune function and enhance the ability of the host immune response to control cancer.

This work was supported by the U.S. Army Medical Research and Materiel Command under W81XWH-10-1-0616 and W81XWH-06-1-0417, NIH Molecular and Cellular Immunobiology Training Grant No. 5 T32 AI07290-24, and NIH R01 CA130817.

Citation Format: Andrea K. Miyahira, Diana L. Simons, Frederick Dirbas, Ellie Guardino, Shruti Sheth, Robert Carlson, Peter P. Lee. Identification of cytokine network signaling abnormalities in immune cells from cancer patients. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr A51.

PRC2/EED-EZH2 complex is up-regulated in breast cancer lymph node metastasis compared to primary tumor and correlates with tumor proliferation in situ

BACKGROUND

Lymph node metastasis is a key event in the progression of breast cancer. Therefore it is important to understand the underlying mechanisms which facilitate regional lymph node metastatic progression.

METHODOLOGY/PRINCIPAL FINDINGS

We performed gene expression profiling of purified tumor cells from human breast tumor and lymph node metastasis. By microarray network analysis, we found an increased expression of polycomb repression complex 2 (PRC2) core subunits EED and EZH2 in lymph node metastatic tumor cells over primary tumor cells which were validated through real-time PCR. Additionally, immunohistochemical (IHC) staining and quantitative image analysis of whole tissue sections showed a significant increase of EZH2 expressing tumor cells in lymph nodes over paired primary breast tumors, which strongly correlated with tumor cell proliferation in situ. We further explored the mechanisms of PRC2 gene up-regulation in metastatic tumor cells and found up-regulation of E2F genes, MYC targets and down-regulation of tumor suppressor gene E-cadherin targets in lymph node metastasis through GSEA analyses. Using IHC, the expression of potential EZH2 target, E-cadherin was examined in paired primary/lymph node samples and was found to be significantly decreased in lymph node metastases over paired primary tumors.

CONCLUSIONS/SIGNIFICANCE

This study identified an over expression of the epigenetic silencing complex PRC2/EED-EZH2 in breast cancer lymph node metastasis as compared to primary tumor and its positive association with tumor cell proliferation in situ. Concurrently, PRC2 target protein E-cadherin was significant decreased in lymph node metastases, suggesting PRC2 promotes epithelial mesenchymal transition (EMT) in lymph node metastatic process through repression of E-cadherin. These results indicate that epigenetic regulation mediated by PRC2 proteins may provide additional advantage for the outgrowth of metastatic tumor cells in lymph nodes. This opens up epigenetic drug development possibilities for the treatment and prevention of lymph node metastasis in breast cancer.

Altered local and systemic immune profiles underlie lymph node metastasis in breast cancer patients

Cancer-mediated immune dysfunction contributes to tumor progression and correlates with patient outcome. Metastasis to tumor draining lymph nodes (TDLNs) is an important step in breast cancer progression and is used to predict patient outcome and survival. Although lymph nodes are important immune organs, the role of immune cells in TDLNs has not been thoroughly investigated. We hypothesized that the host immune response in node negative (NN) patients is more intact and thereby can resist tumor invasion compared to node positive (NP) patients. As such, lymph node metastasis requires breakdown of the host immune response in addition to escape of cancer cells from the tumor. To investigate the immunological differences between NN and NP breast cancer patients, we purified and profiled immune cells from the three major compartments where cancer and immune cells interact: tumor, TDLNs and peripheral blood. Significant down-regulation of genes associated with immune-related pathways and up-regulation of genes associated with tumor-promoting pathways was consistently observed in NP patients' TDLNs compared to NN patients. Importantly, these signatures were seen even in NP patients' tumor-free TDLNs, suggesting that such immune changes are not driven solely by local tumor invasion. Furthermore, similar patterns were also observed in NP patients' tumor and blood immune cells, suggesting that immunological differences between NN and NP patients are systemic. Together, these findings suggest that alterations in overall immune function may underlie risk for LN metastasis in breast cancer patients.

Interferon signaling patterns in peripheral blood lymphocytes may predict clinical outcome after high-dose interferon therapy in melanoma patients

Background

High-dose Interferon (HDI) therapy produces a clinical response and achieves relapse-free survival in 20-33% of patients with operable high risk or metastatic melanoma. However, patients may develop significant side effects frequently necessitating dose reduction or discontinuation of therapy. We recently showed that peripheral blood lymphocytes (PBL) from some melanoma patients have impaired interferon (IFN) signaling which could be restored with high concentrations of IFN. This exploratory study evaluated IFN signaling in PBL of melanoma patients to assess whether the restoration of PBL IFN signaling may predict a beneficial effect for HDI in melanoma patients.

Methods

PBL from 14 melanoma patients harvested on Day 0 and Day 29 of neoadjuvant HDI induction therapy were analyzed using phosflow to assess their interferon signaling patterns through IFN-α induced phosphorylation of STAT1-Y701.

Results

Patients who had a clinical response to HDI showed a lower PBL interferon signaling capacity than non-responders at baseline (Day 0). Additionally, clinical responders and patients with good long-term outcome showed a significant increase in their PBL interferon signaling from Day 0 to Day 29 compared to clinical non-responders and patients that developed metastatic disease. The differences in STAT1 activation from pre- to post- HDI treatment could distinguish between patients who were inclined to have a favorable or unfavorable outcome.

Conclusion

While the sample size is small, these results suggest that interferon signaling patterns in PBL correlate with clinical responses and may predict clinical outcome after HDI in patients with melanoma. A larger confirmatory study is warranted, which may yield a novel approach to select patients for HDI therapy.