Radiotherapy orchestrates natural killer cell dependent antitumor immune responses through CXCL8

Radiotherapy is a mainstay cancer therapy whose antitumor effects partially depend on T cell responses. However, the role of Natural Killer (NK) cells in radiotherapy remains unclear. Here, using a reverse translational approach, we show a central role of NK cells in the radiation-induced immune response involving a CXCL8/IL-8-dependent mechanism. In a randomized controlled pancreatic cancer trial, CXCL8 increased under radiotherapy, and NK cell positively correlated with prolonged overall survival. Accordingly, NK cells preferentially infiltrated irradiated pancreatic tumors and exhibited CD56^dim-like cytotoxic transcriptomic states. In experimental models, NF-κB and mTOR orchestrated radiation-induced CXCL8 secretion from tumor cells with senescence features causing directional migration of CD56^dim NK cells, thus linking senescence-associated CXCL8 release to innate immune surveillance of human tumors. Moreover, combined high-dose radiotherapy and adoptive NK cell transfer improved tumor control over monotherapies in xenografted mice, suggesting NK cells combined with radiotherapy as a rational cancer treatment strategy.

Combined inhibition of CXCL12 and PD-1 in MSS colorectal and pancreatic cancer: modulation of the microenvironment and clinical effects

BACKGROUND

Immunotherapy in microsatellite stable colorectal or pancreatic cancer has not shown promising results. It has been hypothesized that targeting immunosuppressive molecules like SDF1-alpha/CXCL12 could contribute to immunotherapy and animal models showed promising results on T cell activation and migration in combination with immune checkpoint inhibition.

METHODS

Here, we describe the successful application of anti-CXCL12 (NOX-A12) in patients with advanced stage pretreated metastatic colorectal and pancreatic cancer (OPERA trial). The treatment consisted of 2 weeks of anti-CXCL12 monotherapy with NOX-A12 followed by combination therapy with pembrolizumab (n=20 patients) until progression or intolerable toxicity had occurred.

RESULTS

The treatment was safe and well tolerated with 83.8% grade I/II, 15.5% grade III and 0.7% grade V adverse events. Of note, for a majority of patients, time on trial treatment was prolonged compared with their last standard treatment preceding trial participation. Systematic serial biopsies revealed distinct patterns of modulation. Tissue and clinical responses were associated with Th1-like tissue reactivity upon CXCL12 inhibition. A downregulation of a cytokine cassette of interleukin (IL)-2/IL-16/CXCL-10 was associated with tumor resistance and furthermore linked to a rare, CXCL12-associated CD14+CD15+promonocytic population. T cells showed aggregation and directed movement towards the tumor cells in responding tissues. Serum analyses detected homogeneous immunomodulatory patterns in all patients, regardless of tissue responses.

CONCLUSIONS

We demonstrate that the combination of CXCL12 inhibition and checkpoint inhibition is safe and grants further exploration of synergistic combinatorial strategies.

Abstract C02: Establishment of a human PDAC explant culture model for treatment prediction and characterization of the tumor microenvironment

Introduction: Pancreatic ductal adenocarcinoma (PDAC) is the fourth most common cause of death from cancer, with a 5-year survival of less than 8%. To date, the therapeutic approaches are chemotherapy regimens. Despite promising data from various preclinical models, new immunotherapeutic agents like checkpoint inhibitors (CPI), vaccines, oncolytic viruses, or TGFβ inhibitors do not show a benefit in the overall survival of patients. Thus, especially in PDAC and in respect to the immune system, there is an urgent need for sufficient preclinical systems that can mirror a human patient scenario. Therefore, we developed a human-based pipeline of whole explant tissue culture using PDAC to predict responses of the tumor to different types of treatments in a personalized manner.

Material and Methods: Human cancer tissue is taken into culture after surgery for several days. We tested different timings and technical variations (e.g., thickness of explants, medium changing protocols) to find superior conditions for tissue viability. In culture, the explants can be treated with (pre-) clinical-grade drugs and subsequently processed for quality controls via evaluation of the tissue integrity (on H&E slides) and cytokine stability. Also, histologic analyzes (e.g., cancer cells, T cells, B cells, macrophages) as well as multiplex cytokine analyzes are carried out. This combined approach enables us to study the impact of various drugs on the tissue in terms of tumor cell death, changes in the infiltration and activation of lymphocytes and macrophage polarization, etc. Results In vivo features of the tissue and the matrix architecture as well as the cytokine signatures are well maintained in the explants. Our model is reproducible among different explants of the same tissue in terms of infiltrating cells and cytokine expression. In addition, we were able to achieve an overview of the cytokine signature of PDAC in patients and to distinguish between clusters of patients by identifying different immune landscapes, for example, immunologically hot and cold subtypes.

Discussion: Our model is usable as a predictive system for the response of PDAC to different types of treatments and seems to be a reliable and sufficient preclinical extension alternative to mouse models, single-cell experiments, or organoid models. The whole context of the tissue is from human origin and we aim to expand our platform for multiscreening of drug responses for personalized decision-making. Furthermore, we described the tumor microenvironment in detail, unraveling the complex cytokine signature of PDAC, and subsequently identified different clusters of immune landscapes, which may be of prognostic value.

Citation Format: Azaz Ahmed, Dyke Ferber, Meggy Suarez-Carmona, Bénédicte Lenoir, Rosa Klotz, Thilo Hackert, Nathalia Giese, Inka Zörnig, Dirk Jäger, Niels Halama. Establishment of a human PDAC explant culture model for treatment prediction and characterization of the tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr C02.

CCR5 status and metastatic progression in colorectal cancer

Multiple reports have highlighted the importance of the local immunological cellular composition (i.e. the density of effector T cells and macrophage polarization state) in predicting clinical outcome in advanced metastatic stage of colorectal cancer. However, in spite of the general association between a high effector T cell density and improved outcome, our recent work has revealed a specific lymphocyte-driven cancer cell-supporting signal. Indeed, lymphocyte-derived CCL5 supports CCR5-positive tumor cell proliferation and thereby fosters tumor growth in metastatic liver lesions. Upon systematic analysis of CCR5 expression by tumor cells using immunohistochemistry, we observed that the intensity of CCR5 increases with primary tumor size and peaks in T4 tumors. In liver metastases however, though CCR5 expression intensity is globally heightened compared to primary tumors, alterations in the expression patterns appear, leading to “patchiness” of the stain. CCR5 patchiness is, therefore, a signature of liver metastases in our cohort (n = 97 specimens) and relates to globally decreased expression intensity, but does not influence the extent of the response to CCR5 inhibitor Maraviroc in patients. Moreover, CCR5 patchiness relates to a poor immune landscape characterized by a low cytotoxic-to-regulatory T cell ratio at the invasive margin and enriched cellular and molecular markers of macrophage M2 polarization. Finally, because higher numbers of PD-1- and CTLA-4-positive cells surround tumors with patchy CCR5 expression, one can speculate that these tumors potentially respond to immune checkpoint blockade. This hypothesis is corroborated by the prolonged disease-free survival and disease-specific survival observed in patients with low gene expression of CCR5 in metastases from two publically available cohorts. These observations highlight the complex role of the CCL5-CCR5 axis in CRC metastatic progression and warrant further investigations.

Abstract A069: NIM15 blockade – A new stroma-targeting approach for the treatment of epithelial ovarian cancer

Despite the immense research over the past decade in the cancer immunology field, which has led to several clinical trials and FDA and EMA approvals of biologicals for the reinvigoration of T-cell-mediated cancer cell killing in diverse tumor entities, the long-term survival of patients with advanced epithelial ovarian cancer is still devastating. These results therefore imply the need for a more intensive investigation of the tumor microenvironment in this cancer type in order to enhance disease outcome and improve the effectiveness of current immunotherapeutics. We herein show for the first time efficacy data of a novel treatment approach for the specific targeting of the stromal tumor compartment in a human tissue explant culture model of high-grade serous ovarian cancer. Antibody-mediated blockade of NIM15, a protein suspected to be predominantly expressed by tumor-associated macrophages and cancer-associated-fibroblasts in ovarian cancer, has the potential to polarize the immune landscape in a subset of patients from a stromal-dense and immunosuppressive one into a Th1-M1-supportive microenvironment, as measured by cytokine pattern analyses and semiautomated immune cell quantification. Abrogating the effects of secreted NIM15 unleashes in vitro proliferation of T-cell subsets and increases the production of cytokines and chemokines involved in innate and adaptive antitumor immune responses in our tissue culture explant model. In order to unravel the mechanistic relations behind the observed effects, we plan further experiments to prove whether these might be due to a disruption of the collagen-dense tumor stroma and a repolarization of the secretory profile of tumor-associated macrophages and fibroblasts. In summary, we hope to develop a pharmacologic tool that converts immune-depleted, “cold” cancer types into T-cell infiltrated ones and therewith provide a rationale for combination treatment approaches, like anti-PD1 blockade or adoptive cell transfer, to further ameliorate the so far poor response of metastasized, refractory ovarian cancer.

Citation Format: Dyke Ferber, Meggy Suarez-Carmona, Frank Momburg, Marten Meyer, Rebecca Rothenheber, Bénédicte M.A. Lenoir, Sarah Schott, Inka Zoernig, Dirk Jäger, Niels Halama. NIM15 blockade – A new stroma-targeting approach for the treatment of epithelial ovarian cancer [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A069.

Abstract A171: A fully human tissue-based ex vivo cell migration analysis model to study T-cell infiltration and distribution in colorectal cancer liver metastases

T-cell exclusion by tumors is one of the major obstacles for cancer immunotherapies. In colorectal cancer liver metastasis (CRC-LM) patients, effector T-cells are mainly found in the invasive margin and not in the tumor epithelium. Such T-cell exclusion might hinder an effective antitumor immune response and could account for therapy failures with immune checkpoint inhibitors, which is observed in the majority of CRC-LM patients. As T-cell infiltration and distribution are difficult to detect in patients, little is known about detailed immunotherapy effects on tumor-infiltrating lymphocytes (TIL). Therefore, we established a fully human tissue-based ex vivo cell migration analysis model to monitor T-cell infiltration and positioning in the authentic tumor microenvironment of CRC-LM patients. In brief, we isolated T-cells from fresh resected CRC-LM patient tissue samples, labeled the cells with a fluorescent dye and returned the labeled T-cells to the tissues, which were cultured for a certain time period. Besides autologous T-cells, several tissue samples were treated with non-autologous labeled T-cells isolated from a healthy donor. After tissue processing, immunostaining and cell quantification, we observed that remigration of the labeled autologous and donor T-cells into the tissues was significantly associated with numbers of endogenous TIL. The labeled autologous and donor T-cells showed a similar distribution pattern to endogenous TIL with highest densities in the invasive margin of patient tissues. No relevant changes in tumor cell numbers or apoptosis protein concentrations could be observed by both treatments. Furthermore, quantification of the chemokines CXCL9, CXCL10 and CCL5 showed significant associations with labeled autologous and donor T-cell infiltration. Interestingly, treatment with a PD1 inhibitor did not support infiltration of exogenous or endogenous T-cells into the tumor epithelium. Our findings highlight that infiltrating T-cells in CRC-LM are always positioned into the invasive margin independently of the T-cell´s origin. Especially microenvironmental factors such as CXCL9, CXCL10 and CCL5 seem to be involved in this process, preventing T-cell contact with the tumor epithelium, which could also not be abrogated by immune checkpoint inhibition. The similar infiltration and distribution pattern of T-cells in the ex vivo and in vivo settings highlights the functionality and reliability of the human tissue-based cell migration analysis model, emphasizing its use for studying therapy effects on TIL in CRC-LM patient tissues.

Citation Format: Anna Berthel, Meggy Suarez-Carmona, Jakob N. Kather, Rodrigo Rojas-Moraleda, Pornpimol Chaorentong, Nektarios A. Valous, Fee Klupp, Martin Schneider, Alexis Ulrich, Markus Buechler, Inka Zoernig, Dirk Jaeger, Niels Halama. A fully human tissue-based ex vivo cell migration analysis model to study T-cell infiltration and distribution in colorectal cancer liver metastases [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A171.

Abstract A114: Omental fat in ovarian cancer induces metabolic and immune alterations

Epithelial ovarian cancer (EOC) is an immunogenic tumor entity, as evidenced by multiple correlative studies indicating the impact of intraepithelial tumor-infiltrating T lymphocyte (TIL) density on patient outcome. Immunotherapy trials have generated modest results so far and chemotherapy remains standard of care. In this study, we focus on EOC metastases invading the omentum. Our aim is to characterize their immune landscape with the goal of identifying specific targetable characteristics of these metastases, which are the most prevalent and relate to high morbidity.We used a cohort of 120 ovarian cancer specimens for histologic analysis, cytokine, or metabolic profiling. Furthermore, we developed an EOC tissue explant culture model and treated whole-tissue explants with drugs before assessing immune cell density, distribution, and activation status. Finally, we cultured macrophages isolated from patient-derived ascites to study their response to various treatments.Samples were classified into omental metastases and primary tumors (based on the presence of fat on histologic sections). We observed that omental metastases are characterized by an inflamed microenvironment orchestrated by macrophages and are infiltrated by high amounts of TILs with low expression of activation markers, and a skewed localization around fat patches. These TILs express high amounts of the tumor-supporting CCL5 chemokine. Macrophages storing fatty acids in the form of big vacuoles were found in these fatty tumors as well. Targeting macrophages using the CCR5 inhibitor maraviroc in whole tissue explants effectively restored T-cell distribution across the tissue and slightly affected macrophage polarization specifically in fat-containing tumors. Inhibiting fatty acid import in macrophages more dramatically affected the cytokine landscape, also specifically in fat-containing tumors, and established a Th1-supporting environment permeable to T-cell expansion and activation. In brief, omental metastases are characterized by: (a) a smoldering inflammatory reaction and high macrophage density, (b) increased T-cell accumulation around fatty areas away from cancer cells, and (c) T-cell exhaustion accompanied by CCL5 expression. Treatment of EOC explants revealed that macrophages infiltrating omental metastases can be repolarized in situ, leading to TIL expansion and activation.

Citation Format: Meggy Suarez-Carmona, Nektarios A. Valous, Pornpimol Charoentong, Jakob N. Kather, Mareike Hampel, Bénédicte M.A. Lenoir, Dyke Ferber, Sarah Schott, Sabine Kess, Inka Zoernig, Dirk Jaeger, Niels Halama. Omental fat in ovarian cancer induces metabolic and immune alterations [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A114.

Abstract A086: Omental fat in ovarian cancer induces lymphangiogenesis

Ovarian cancer metastasis occurs by direct multifocal seeding into the peritoneum as well as by migration through the lymphatic system. High-grade ovarian carcinoma patients often present with distant metastases. Significant risk factors for the development of those are stage, grade, and lymph node involvement. The increase of the number of lymphatic vessels seems to be implicated in ovarian tumor progression. While the tropism of ovarian cancer cells for fat is well described, the potential impact of an adipose-rich microenvironment on the dissemination of metastasis via lymphatic vessels has never been investigated. So far, in this study, we examined the effect of omental fat on lymphangiogenesis in ovarian carcinoma. For that we used a cohort of 80 ovarian cancer specimens. We observed a higher number of tumor-associated vessels and principally lymphatic vessels in ovarian cancer in contact with the omentum. These lymphatic vessels are predominantly localized along the fat tissue. A higher secretion of VEGF-C is observed in ovarian tissues containing fat compared to the ones without fat, giving a potential explanation to the observed increase of lymphatic vessels in fatty tissues. We also developed a healthy fat tissue explant culture model and treated whole tissue explants with ascites. Herein, we saw an increase of the number of adipose-derived stem cells (ADSCs). These ADSCs express lymphatic markers such as D2-40 and Lyve-1. We also observed an impact of fat supernatant on the proliferation, migration and tube formation of lymphatic endothelial cells in vitro. In conclusion, we can say that omental fat in ovarian cancer seems to have an impact on lymphangiogenesis. The close contact of ascites with fat tissue seems to lead to a differentiation of adipose-derived stem cells into lymphatic endothelial cells. Further investigations must be performed to understand the exact mechanisms underlying this phenomenon.

Citation Format: Bénédicte M.A. Lenoir, Dyke Ferber, Victor Starrach, Meggy Suarez-Carmona, Sarah Schott, Inka Zoernig, Dirk Jäger, Niels Halama. Omental fat in ovarian cancer induces lymphangiogenesis [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A086.

Topography of cancer-associated immune cells in human solid tumors

Lymphoid and myeloid cells are abundant in the tumor microenvironment, can be quantified by immunohistochemistry and shape the disease course of human solid tumors. Yet, there is no comprehensive understanding of spatial immune infiltration patterns (‘topography’) across cancer entities and across various immune cell types. In this study, we systematically measure the topography of multiple immune cell types in 965 histological tissue slides from N = 177 patients in a pan-cancer cohort. We provide a definition of inflamed (‘hot’), non-inflamed (‘cold’) and immune excluded patterns and investigate how these patterns differ between immune cell types and between cancer types. In an independent cohort of N = 287 colorectal cancer patients, we show that hot, cold and excluded topographies for effector lymphocytes (CD8) and tumor-associated macrophages (CD163) alone are not prognostic, but that a bivariate classification system can stratify patients. Our study adds evidence to consider immune topographies as biomarkers for patients with solid tumors.

High-Throughput Screening of Combinatorial Immunotherapies with Patient-Specific In Silico Models of Metastatic Colorectal Cancer

Solid tumors are rich ecosystems of numerous different cell types whose interactions lead to immune escape and resistance to immunotherapy in virtually all patients with metastatic cancer. Here, we have developed a 3D model of human solid tumor tissue that includes tumor cells, fibroblasts, and myeloid and lymphoid immune cells and can represent over a million cells over clinically relevant timeframes. This model accurately reproduced key features of the tissue architecture of human colorectal cancer and could be informed by individual patient data, yielding in silico tumor explants. Stratification of growth kinetics of these explants corresponded to significantly different overall survival in a cohort of patients with metastatic colorectal cancer. We used the model to simulate the effect of chemotherapy, immunotherapies, and cell migration inhibitors alone and in combination. We classified tumors according to tumor and host characteristics, showing that optimal treatment strategies markedly differed between these classes. This platform can complement other patient-specific ex vivo models and can be used for high-throughput screening of combinatorial immunotherapies.Significance: This patient-informed in silico tumor growth model allows testing of different cancer treatment strategies and immunotherapies on a cell/tissue level in a clinically relevant scenario. Cancer Res; 78(17); 5155-63. ©2018 AACR.

Large-scale database mining reveals hidden trends and future directions for cancer immunotherapy

Cancer immunotherapy has fundamentally changed the landscape of oncology in recent years and significant resources are invested into immunotherapy research. It is in the interests of researchers and clinicians to identify promising and less promising trends in this field in order to rationally allocate resources. This requires a quantitative large-scale analysis of cancer immunotherapy related databases.

We developed a novel tool for text mining, statistical analysis and data visualization of scientific literature data. We used this tool to analyze 72002 cancer immunotherapy publications and 1469 clinical trials from public databases. All source codes are available under an open access license.

The contribution of specific topics within the cancer immunotherapy field has markedly shifted over the years. We show that the focus is moving from cell-based therapy and vaccination towards checkpoint inhibitors, with these trends reaching statistical significance. Rapidly growing subfields include the combination of chemotherapy with checkpoint blockade. Translational studies have shifted from hematological and skin neoplasms to gastrointestinal and lung cancer and from tumor antigens and angiogenesis to tumor stroma and apoptosis.

This work highlights the importance of unbiased large-scale database mining to assess trends in cancer research and cancer immunotherapy in particular. Researchers, clinicians and funding agencies should be aware of quantitative trends in the immunotherapy field, allocate resources to the most promising areas and find new approaches for currently immature topics.

In Silico Modeling of Immunotherapy and Stroma-Targeting Therapies in Human Colorectal Cancer

Despite the fact that the local immunological microenvironment shapes the prognosis of colorectal cancer, immunotherapy has shown no benefit for the vast majority of colorectal cancer patients. A better understanding of the complex immunological interplay within the microenvironment is required. In this study, we utilized wet lab migration experiments and quantitative histological data of human colorectal cancer tissue samples (n = 20) including tumor cells, lymphocytes, stroma, and necrosis to generate a multiagent spatial model. The resulting data accurately reflected a wide range of situations of successful and failed immune surveillance. Validation of simulated tissue outcomes on an independent set of human colorectal cancer specimens (n = 37) revealed the model recapitulated the spatial layout typically found in human tumors. Stroma slowed down tumor growth in a lymphocyte-deprived environment but promoted immune escape in a lymphocyte-enriched environment. A subgroup of tumors with less stroma and high numbers of immune cells showed high rates of tumor control. These findings were validated using data from colorectal cancer patients (n = 261). Low-density stroma and high lymphocyte levels showed increased overall survival (hazard ratio 0.322, P = 0.0219) as compared with high stroma and high lymphocyte levels. To guide immunotherapy in colorectal cancer, simulation of immunotherapy in preestablished tumors showed that a complex landscape with optimal stroma permeabilization and immune cell activation is able to markedly increase therapy response in silico These results can help guide the rational design of complex therapeutic interventions, which target the colorectal cancer microenvironment. Cancer Res; 77(22); 6442-52. ©2017 AACR.

Abstract 3021: CCR5 inhibition: macrophage repolarization therapy for colorectal cancer

In patients with metastatic colorectal cancer (CRC), the local immune response influences the clinical course. An in-depth analysis of the invasive margin of human CRC liver metastases revealed a distinct immunological microenvironment. Within this microenvironment, two distinct subsets of myeloid cells induce an influx of T cells into the invasive margin via CXCL9/CXCL10. CCL5 is produced by these T cells and stimulates pro-tumoral effects via CCR5, creating an exploitive loop. CCR5 was found on macrophages, lymphocytes and on the vast majority of tumor cells. Inhibition of CCR5 in patient-derived functional in vitro organotypic culture models showed a promising macrophage repolarization with anti-tumoral effects. These effects are mediated by activation of an antiviral program in macrophages, leading to interferon and reactive oxygen species production and subsequent selective tumor cell death. These anti-tumoral effects were confirmed in a phase I trial with a CCR5 antagonist in 14 patients with liver metastases of advanced refractory CRC. Treatment with the oral CCR5 Inhibitor was very well tolerated and objective responses were seen, especially in combination with previously ineffective chemotherapy. Biopsies revealed mitigation of tumor-promoting inflammation within the tumor tissue, confirming the validity of the explant model and highlighting the feasbility of this approach. It furthermore shows the proof-of-concept for macrophage repolarization in cancer patients.

Citation Format: Niels Halama, Inka Zoernig, Anna Berthel, Christoph Kahlert, Fee Klupp, Meggy Suarez-Carmona, Karsten Brand, Juergen Krauss, Felix Lasitschka, Alexis Ulrich, Juergen Weitz, Martin Schneider, Markus Buechler, Laurence Zitvogel, Thomas Herrmann, Axel Benner, Christina Kunz, Stephan Luecke, Christoph Springfeld, Christine S. Falk, Dirk Jaeger. CCR5 inhibition: macrophage repolarization therapy for colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3021. doi:10.1158/1538-7445.AM2017-3021

TGFBR2-dependent alterations of exosomal cargo and functions in DNA mismatch repair-deficient HCT116 colorectal cancer cells

BACKGROUND

Colorectal cancers (CRCs) that lack DNA mismatch repair function exhibit the microsatellite unstable (MSI) phenotype and are characterized by the accumulation of frameshift mutations at short repetitive DNA sequences (microsatellites). These tumors recurrently show inactivating frameshift mutations in the tumor suppressor Transforming Growth Factor Beta Receptor Type 2 (TGFBR2) thereby abrogating downstream signaling. How altered TGFBR2 signaling affects exosome-mediated communication between MSI tumor cells and their environment has not been resolved. Here, we report on molecular alterations of exosomes shed by MSI cells and the biological response evoked in recipient cells.

METHODS

Exosomes were isolated and characterized by electron microscopy, nanoparticle tracking, and western blot analysis. TGFBR2-dependent effects on the cargo and functions of exosomes were studied in a MSI CRC model cell line enabling reconstituted and inducible TGFBR2 expression and signaling. Microsatellite frameshift mutations in exosomal and cellular DNA were examined by PCR-based DNA fragment analysis and exosomal protein profiles were identified by mass spectrometry. Uptake of fluorescent-labeled exosomes by hepatoma recipient cells was monitored by confocal microscopy. TGFBR2-dependent exosomal effects on secreted cytokine levels of recipient cells were analyzed by Luminex technology and ELISA.

RESULTS

Frameshift mutation patterns in microsatellite stretches of TGFBR2 and other MSI target genes were found to be reflected in the cargo of MSI CRC-derived exosomes. At the proteome level, reconstituted TGFBR2 expression and signaling uncovered two protein subsets exclusively occurring in exosomes derived from TGFBR2-deficient (14 proteins) or TGFBR2-proficient (five proteins) MSI donor cells. Uptake of these exosomes by recipient cells caused increased secretion (2-6 fold) of specific cytokines (Interleukin-4, Stem Cell Factor, Platelet-derived Growth Factor-B), depending on the TGFBR2 expression status of the tumor cell.

CONCLUSION

Our results indicate that the coding MSI phenotype of DNA mismatch repair-deficient CRC cells is maintained in their exosomal DNA. Moreover, we uncovered that a recurrent MSI tumor driver mutation like TGFBR2 can reprogram the protein content of MSI cell-derived exosomes and in turn modulate the cytokine secretion profile of recipient cells. Apart from its diagnostic potential, these TGFBR2-dependent exosomal molecular and proteomic signatures might help to understand the signaling routes used by MSI tumors. Fricke et al. uncovered coding microsatellite instability-associated mutations of colorectal tumor driver genes like TGFBR2 in MSI tumor cellderived exosomes. Depending on the TGFBR2 expression status of their donor cells, shed exosomes show distinct proteomic signatures and promote altered cytokine secretion profiles in recipient cells.

Abstract A110: Detailed resolution analysis reveals spatial heterogeneity of T cell distribution in the invasive margin of colorectal cancer liver metastases

On a broader scale T cell density and localization in colorectal cancer liver metastases (CRC-LM) have prognostic and predictive implications, while T cell distribution at higher resolutions has not been fully investigated. As the invasive front of CRC-LM represents a clear border between malignant tissue and adjacent normal liver tissue, a detailed resolution analysis of T cell distribution in this region could be performed. Tissue areas of 1 square millimeter size from different patients were analyzed by high-throughput whole slide imaging technology, showing distinct density patterns of T cell localization in relation to the malignant tissue across the invasive margins. Unsupervised clustering revealed specific groups of patients with T cell aggregates limited to a given distance from the tumor. Furthermore, regions with T cells in close contact to the tumor usually had elevated T cell numbers further away from the tumor, whereas the intermediate area showed limited enrichment. There seems to be a distance of around 10 to 30 micrometer from the tumor where a decrease in T cells is common. Interestingly, 68 percent of distant T cells were identified to be in close contact with tumor-associated macrophages. Therefore, the spatial heterogeneity of T cell distribution in the invasive margin could be accounted for interactions with immunosuppressive cells, cell-matrix interactions or chemotactic fields potentially generated by tumor or endothelial cells, which is currently investigated. Whether the presence of the observed patterns has clinical importance and might change under therapy remains to be seen. In summary, this high resolution analysis of T cell distribution within the invasive front of CRC-LM reveals insights into the detailed localization of T cells and possible spatial immunosuppressive hurdles that need to be overcome by immunotherapies. The analysis of reversal of these spatial profiles could serve as a biomarker for successful therapies.

Citation Format: Anna Berthel, Inka Zoernig, Meggy Suarez-Carmona, Christoph Kahlert, Fee Klupp, Alexis Ulrich, Juergen Weitz, Dirk Jaeger, Halama Niels. Detailed resolution analysis reveals spatial heterogeneity of T cell distribution in the invasive margin of colorectal cancer liver metastases [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr A110.

Abstract A102: The fat in ovarian cancer: Immune-dependent tumor-promoting effects

Because of the particular anatomy of ovaries, which are in close contact with the adipocyte-rich omentum, ovarian cancer frequently presents itself with established metastasis-like disseminated tumor islets along the omentum.

The tropism of ovarian cancer cells for fat is well described. Indeed, adipocyte-derived free fatty acids have been causatively linked to cancer cell proliferation and invasive properties. Obesity is additionally linked to increased risk of ovarian cancer onset and, in ovarian cancer patients, to worse outcome. However, there is to our knowledge no clear association between omentum-anchored dissemination and the anti-tumor immune response.

Here we describe an unsuspected association between the presence peritoneal fat in ovarian tumors and massive tumor infiltration by T cells. Still, this massive T cell influx seems to fail in its anti-tumor activity since (1) tumor-infiltrating T cells seem to be hijacked away from tumor cells and accumulate around fatty areas and (2) tumor-infiltrating T cells display an exhausted phenotype.

In this presentation, we also describe a new model of tissue culture of explants from primary human tumors that are treated with various drugs in an attempt to circumvent this fat-derived immune exhaustion and restore an efficient anti-tumor immune response.

Citation Format: Meggy Suarez-Carmona, Anita Heinzelmann, Nektarios A. Valous, Mareike Hampel, Anna Berthel, Sarah Schott, Inka Zörnig, Dirk Jäger, Niels Halama. The fat in ovarian cancer: Immune-dependent tumor-promoting effects [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr A102.

Abstract B037: Macrophage repolarization therapy in metastatic colorectal cancer: CCR5 inhibition

The influence of the local immune response on the clinical course of colorectal cancer (CRC) has been analyzed extensively. Analyzing the invasive margin of human CRC liver metastases, we identified a protumoral mechanism of T-cell-derived CCL5 that leads to immune cell exploitation by tumor cells. Two distinct subsets of myeloid cells produce CXCL9/CXCL10, which induce an influx of T cells into the invasive margin. CCL5 is produced by these exhausted T cells and stimulates tumor cell proliferation and invasive behavior via CCR5 on tumor cells and macrophages. CCR5 inhibition in patient-derived functional in vitro organotypic culture models induced macrophage repolarization with anti-tumoral effects. These immunomodulatory and anti-tumoral effects of CCR5 blockade then could be confirmed in a phase I trial with a CCR5 antagonist in advanced refractory CRC patients with liver metastases. Amelioration of tumor-promoting inflammation on the tumor tissue level and objective tumor responses in advanced metastatic CRC patients were observed.

Citation Format: Niels Halama, Inka Zoernig, Anna Berthel, Christoph Kahlert, Fee Klupp, Meggy Suarez-Carmona, Juergen Krauss, Karsten Brand, Felix Lasitschka, Tina Lerchl, Claudia Luckner-Minden, Alexis Ulrich, Juergen Weitz, Martin Schneider, Markus W. Buechler, Laurence Zitvogel, Thomas Herrmann, Axel Benner, Christina Kunz, Stephan Luecke, Christoph Springfeld, Christine Falk, Dirk Jaeger. Macrophage repolarization therapy in metastatic colorectal cancer: CCR5 inhibition [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr B037.

Tumoral Immune Cell Exploitation in Colorectal Cancer Metastases Can Be Targeted Effectively by Anti-CCR5 Therapy in Cancer Patients

The immune response influences the clinical course of colorectal cancer (CRC). Analyzing the invasive margin of human CRC liver metastases, we identified a mechanism of immune cell exploitation by tumor cells. While two distinct subsets of myeloid cells induce an influx of T cells into the invasive margin via CXCL9/CXCL10, CCL5 is produced by these T cells and stimulates pro-tumoral effects via CCR5. CCR5 blockade in patient-derived functional in vitro organotypic culture models showed a macrophage repolarization with anti-tumoral effects. These anti-tumoral effects were then confirmed in a phase I trial with a CCR5 antagonist in patients with liver metastases of advanced refractory CRC. Mitigation of tumor-promoting inflammation within the tumor tissue and objective tumor responses in CRC were observed.

Soluble factors regulated by epithelial-mesenchymal transition mediate tumour angiogenesis and myeloid cell recruitment

Epithelial-mesenchymal transition (EMT) programmes provide cancer cells with invasive and survival capacities that might favour metastatic dissemination. Whilst signalling cascades triggering EMT have been extensively studied, the impact of EMT on the crosstalk between tumour cells and the tumour microenvironment remains elusive. We aimed to identify EMT-regulated soluble factors that facilitate the recruitment of host cells in the tumour. Our findings indicate that EMT phenotypes relate to the induction of a panel of secreted mediators, namely IL-8, IL-6, sICAM-1, PAI-1 and GM-CSF, and implicate the EMT-transcription factor Snail as a regulator of this process. We further show that EMT-derived soluble factors are pro-angiogenic in vivo (in the mouse ear sponge assay), ex vivo (in the rat aortic ring assay) and in vitro (in a chemotaxis assay). Additionally, conditioned medium from EMT-positive cells stimulates the recruitment of myeloid cells. In a bank of 40 triple-negative breast cancers, tumours presenting features of EMT were significantly more angiogenic and infiltrated by a higher quantity of myeloid cells compared to tumours with little or no EMT. Taken together, our results show that EMT programmes trigger the expression of soluble mediators in cancer cells that stimulate angiogenesis and recruit myeloid cells in vivo, which might in turn favour cancer spread.

Carcinogenic HPV infection in the cervical squamo-columnar junction

Recent studies have suggested the involvement of a unique population of cells at the cervical squamo-columnar junction (SCJ) in the pathogenesis of early (squamous intraepithelial lesion or SIL) and advanced (squamous cell and adeno-carcinomas) cervical neoplasia. However, there is little evidence to date showing that SCJ cells harbour carcinogenic HPV or are instrumental in the initial phases of neoplasia. This study was designed to (1) determine if normal-appearing SCJ cells contained evidence of carcinogenic HPV infection and (2) trace their transition to early SIL. Sections of cervix from high-risk reproductive age women were selected and SCJ cells were analysed by using several techniques which increasingly implicated HPV infection: HPV DNA (genotyping and in situ hybridization)/RNA (PCR), immunostaining for HPV16 E2 (an early marker of HPV infection), p16(ink4), Ki67, and HPV L1 protein. In 22 cases with a history of SIL and no evidence of preneoplastic lesion in the excision specimen, HPV DNA was isolated from eight of ten with visible SCJ cells, six of which were HPV16/18 DNA-positive. In five of these latter cases, the SCJ cells were positive for p16(ink4) and/or HPV E2. Transcriptionally active HPV infection (E6/E7 mRNAs) was also detected in microdissected SCJ cells. Early squamous atypia associated with the SCJ cells demonstrated in addition diffuse p16(ink4) immunoreactivity, elevated proliferative index, and rare L1 antigen positivity. We present for the first time direct evidence that normal-appearing SCJ cells can be infected by carcinogenic HPV. They initially express HPV E2 and their progression to SIL is heralded by an expanding metaplastic progeny with increased proliferation and p16(ink4) expression. Whether certain SCJs are more vulnerable than others to carcinogenic HPV genotypes and what variables determine transition to high-grade SIL remain unresolved, but the common event appears to be a vulnerable cell at the SCJ.

ΔNp63 isoform-mediated β-defensin family up-regulation is associated with (lymph)angiogenesis and poor prognosis in patients with squamous cell carcinoma

Beside a role in normal development/differentiation, high p63 immunoreactivity is also frequently observed in squamous cell carcinoma (SCC). Due to the complexity of the gene, the role of each p63 isotype in tumorigenesis is still confusing. Constitutively produced or induced in inflammatory conditions, human beta-defensins (HβDs) are cationic peptides involved in host defenses against bacteria, viruses and fungi. Here, we investigated both the role of p63 proteins in the regulation of HβDs and the implication of these antimicrobial peptides in tumor (lymph)angiogenesis. Thus, in contrast to TAp63 isotypes, we observed that ΔNp63 proteins (α, β, γ) induce HβD1, 2 and 4 expression. Similar results were observed in cancer tissues and cell lines. We next demonstrated that ΔNp63-overexpressing SCC are associated with both a poor prognosis and a high tumor vascularisation and lymphangiogenesis. Moreover, we showed that HβDs exert a chemotactic activity for (lymphatic) endothelial cells in a CCR6-dependent manner. The ability of HβDs to enhance (lymph)angiogenesis in vivo was also evaluated. We observed that HβDs increase the vessel number and induce a significant increase in relative vascular area compared to negative control. Taken together, the results of this study suggest that ΔNp63-regulated HβD could promote tumor (lymph)angiogenesis in SCC microenvironment.

Abstract 3954: Regulation of pro-angiogenic and pro-inflammatory cytokines in tumor cells: Implication of epithelial-to-mesenchymal transitions

Increasing data suggest a contribution of epithelial-to-mesenchymal transitions in specific steps of the metastatic cascade, particularly in tumor invasion and intravasation, and in the release of circulating tumor cells (CTCs) in the blood stream. The completion of these steps largely relies on interactions disseminating tumor cells establish with host cells. Because cytokines are particularly implicated in tumor-host cross-talks, we have examined whether EMT programs could be involved in the regulation of pro-inflammatory and pro-angiogenic cytokines which could favor angiogenesis, intravasation and CTC release.

To investigate EMT implication in cytokine regulation, we used two cell lines, MDA-MB-468 (a mammary adenocarcinoma cell line) and A549 (a lung carcinoma cell line). These cell lines were shown to undergo EMT-changes following EGF and TGF-β treatment respectively, characterized by an upregulation of vimentin, snail and slug, and a downregulation of E-cadherin. A cytokine array on cell supernatant showed that EMT induction in these cell lines is associated with the upregulation of a consistant panel of cytokines. We then confirmed that interleukin-8 (IL-8), interleukin-6 (IL-6) and Granulocyte Monocyte-Colony Stimulating Factor (GM-CSF) are upregulated during EMT in the two carcinoma cell lines by RT-qPCR and ELISA. Emphasizing a functional role of such regulations, conditioned medium from EMT-induced MDA-468 cells was shown to stimulate HUVEC cell migration in a boyden chamber assay.

In order to investigate whether slug and snail EMT transcription factors are involved in the regulation of IL-8, IL-6 and GM-CSF, we used both siRNA and cDNA transfection approaches. Combined repression of snail and slug inhibited the EMT-associated upregulation of IL-8, IL-6 and GM-CSF, suggesting that snail and slug are necessary for this process. Ectopic expression of each transcription factor was not sufficient to induce cytokines expression. However, ectopic expression of a proteasome degradation-resistant mutant of snail was sufficient to induce expression of IL-6, IL-8 and GM-CSF, suggesting that the stabilization of snail is necessary to regulate the expression of these cytokines.

We thus here demonstrate that EMT is associated with an overexpression of specific pro-angiogenic and pro-inflammatory cytokines. We further emphasize a role of snail and slug transcription factors in this regulatory process. These data suggest that EMT programs could directly contribute to the stimulation of angiogenesis and inflammatory cell recruitment in the tumor microenvironment. The impact of such regulations on angiogenesis and the metastatic spread is currently under investigation.

Citation Format: Meggy Suarez-Carmona, Morgane Bourcy, Jean-Michel Foidart, Philippe Delvenne, Agnès Noël, Myriam Polette, Christine Gilles. Regulation of pro-angiogenic and pro-inflammatory cytokines in tumor cells: Implication of epithelial-to-mesenchymal transitions . [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 3954. doi:10.1158/1538-7445.AM2013-3954

Regulation of p63 isoforms by snail and slug transcription factors in human squamous cell carcinoma

TP63 is a p53-related gene that contains two alternative promoters, which give rise to transcripts that encode proteins with (TAp63) or without (DeltaNp63) an amino-transactivating domain. Whereas the expression of p63 is required for proper development of epithelial structures, the role of p63 in tumorigenesis remains unclear. Here, we investigated the role of Snail and Slug transcription factors, known to promote epithelial-to-mesenchymal transitions during development and cancer, in the regulation of p63 isoforms in human squamous cell carcinoma (SCC). In the present study, we observed that the expressions of DeltaN and TAp63 isoforms were, respectively, down- and up-regulated by both Snail and Slug. However, the induction of TAp63 was not directly caused by these two transcription factors but resulted from the loss of DeltaNp63, which acts as dominant-negative inhibitor of TAp63. In SCC cell lines and cancer tissues, high expression of Snail and Slug was also significantly associated with altered p63 expression. Finally, we showed that DeltaNp63 silencing reduced cell-cell adhesion and increased the migratory properties of cancer cells. These data suggest that the disruption of p63 expression induced by Snail and Slug plays a crucial role in tumor progression. Therefore, p63 and its regulating factors could constitute novel prognosis markers in patients with SCC and attractive targets for the therapeutic modulation of neoplastic cell invasiveness.