A deeper understanding of the parameters driving response and resistance to immunotherapy is needed to improve the low response rates observed in breast cancer patients. Research into immunotherapy... Show moreA deeper understanding of the parameters driving response and resistance to immunotherapy is needed to improve the low response rates observed in breast cancer patients. Research into immunotherapy response has predominantly focused on T cells, however effective immune responses require tightly regulated crosstalk between innate and adaptive immune cells. By combining profiling of blood and tumors from metastatic breast cancer patients with mechanistic studies in mouse models, we uncovered the critical role of eosinophils in immunotherapy response, and we provide proof-of-principle for eosinophil engagement to enhance immunotherapy efficacy. Focusing on resistance mechanisms to immunotherapy, we demonstrate that neoadjuvant immunotherapy triggers persistent and systemic regulatory T cell activation which blunts therapeutic efficacy against metastatic spread of breast tumors. In addition, we demonstrate that neutrophils in the tumor microenvironment pose a barrier to immunotherapy response through T cell suppression. Lastly, we demonstrate that combining the immunomodulatory agent PD1-IL2v with cisplatin is a powerful approach to induce a broad activation of systemic and intratumoral adaptive and innate immunity, resulting in effective immunotherapy responses. Overall, this work identifies several key players and their interconnectivities in anti-tumor immunity and tumor-induced immunosuppression that may be therapeutically exploited to improve immunotherapy responses for breast cancer patients. Show less
The immune system plays a dual role in cancer development. Besides the potential to eliminate cancer cells, immunoregulatory mechanisms exist that counteract anti-tumor immunity.Research in this... Show moreThe immune system plays a dual role in cancer development. Besides the potential to eliminate cancer cells, immunoregulatory mechanisms exist that counteract anti-tumor immunity.Research in this thesis focusses on the role of regulatory T cells (Tregs), a type of adaptive immune cell that plays a major role in tumor-associated immunosuppression. Specifically, the role of Tregs was investigated during the development of primary- and metastatic breast cancer, and in the context of novel immunotherapeutics. This was done by using advanced genetically engineered mouse models that recapitulate human breast cancer.The results in this thesis describe that breast tumors are, already early in their development, able to mobilise Tregs in the tumor-draining lymph nodes, thereby creating a local immunosuppressive niche leading to increased lymph node metastasis. In addition, it was found that the immunotherapeutic treatments anti-PD1 and anti-CTLA4 inadvertently activate Tregs, resulting in a diminished efficacy of this treatment in mice bearing breast tumors. Finally, we describe a mechanism by which intratumoral macrophages are critical promote the intratumoral accumulation of Tregs in breast tumors.Insights from this thesis may eventually contribute to the development of therapeutic applications that are aimed at overcoming immunoregulatory mechanisms in breast cancer. Show less
Tumors are complex ecosystems containing not just cancer cells, but a large variety of cell types, including immune cells. Moreover, tumors have a systemic influence: they can signal long distances... Show moreTumors are complex ecosystems containing not just cancer cells, but a large variety of cell types, including immune cells. Moreover, tumors have a systemic influence: they can signal long distances using soluble molecules and hijack non-neoplastic cells (such as immune cells) in distant organs for their own benefit, thus maximising their metastatic potential. The phenotype of immune cells in tumors and in systemic environments is therefore a key determinant of cancer progression and response to therapy.This thesis aims to understand what governs the tumor-immune ecosystem. We argue that cancer-intrinsic genetic aberrations have a dominant role in determining the tumor immune contexture, as well as systemic inflammatory activation. Understanding the intricate connection between the genetics of breast cancer and anti-tumor immune responses will help develop personalised immune intervention strategies for cancer, tailored to the genetic makeup of a patient’s tumor. Furthermore, we examine in detail the role of neutrophils in cancer-induced systemic inflammation, and how they influence the progression and spread of breast cancer. While tumors can be highly heterogeneous in nature, we show that neutrophils themselves also have a tremendous phenotypic diversity. Mapping this heterogeneity in neutrophil phenotypes may help to utilise these cells in cancer immunotherapy. Show less
In summary, this thesis focused on the understanding the underlying mechanisms driving TNBC metastatic progression. We established DUB activity profiling methods and identified UCHL1 as a candidate... Show moreIn summary, this thesis focused on the understanding the underlying mechanisms driving TNBC metastatic progression. We established DUB activity profiling methods and identified UCHL1 as a candidate oncoprotein that promotes TGFβ-induced breast cancer metastasis. Importantly, we found UCHL1 activity inhibitor as a potential drug for TNBC therapy and developed UCHL1 activity-based probe. For vemurafenib-resistance melanoma, we provided insights that targeting TGFβ signaling may help to overcome drug resistant phenotype. Show less
Despite extensive studies to unravel molecular mechanisms underlying breast cancer metastasis, still 3500 women die of the results of this disease in the Netherlands each year. Improving our... Show moreDespite extensive studies to unravel molecular mechanisms underlying breast cancer metastasis, still 3500 women die of the results of this disease in the Netherlands each year. Improving our understanding of metastasis formation remains a challenge for further drug development. The scope of this thesis is the identification of novel candidate metastasis genes, with a main focus on candidate genes affecting tumor cell migration. For that purpose, a live cell imaging-based random cell migration assay that is suitable for screening has been developed. In addition, a mouse breast cancer model that allows to study tumor cell autonomous processes of metastasis formation is described. A RNA-interference tumor cell migration screen has been done and resulted in the identification of novel regulators of tumor cell migration that show clinical relevance in a breast cancer patient cohort. In addition, focused research has been conducted on two previously identified candidate metastasis genes to determine their role in breast cancer metastasis. Show less
Despite major advances in breast cancer diagnostics and treatment over the years, the disease is still a leading cause of death in women worldwide. Primary breast tumors can be treated relatively... Show moreDespite major advances in breast cancer diagnostics and treatment over the years, the disease is still a leading cause of death in women worldwide. Primary breast tumors can be treated relatively well with radiation, surgery, chemotherapy or a combination of these treatments. The occurrence of distant metastases derived from the primary tumor however, results in a considerable decrease in disease prognosis. Metastasis formation occurs through a series of distinct cell biological steps (outlined above). Understanding the molecular mechanisms that underlie each of these steps will help in the development of more successful anti-metastasis treatments. In this thesis, both in vitro and in vivo studies are described that aim at unraveling some of the processes involved in metastasis formation: signaling by components of the focal adhesions and cell migration. Show less
In het proefschrift van Martine van Miltenburg wordt het onderzoek naar de rol van FAK en annexine A1 in borstkankerontwikkeling en uitzaaiing (metastasering) beschreven. E__n van de... Show moreIn het proefschrift van Martine van Miltenburg wordt het onderzoek naar de rol van FAK en annexine A1 in borstkankerontwikkeling en uitzaaiing (metastasering) beschreven. E__n van de sleutelprocessen bij de metastasering is de verandering van het rustige fenotype van kankercellen naar het beweeglijke fenotype. Een belangrijke ontdekking is dat het eiwit annexine A1 een belangrijke rol speelt in metastasering van basale borstkanker. Verhoogde expressie van annexine A1 draagt bij aan beweeglijkheid en daarmee agressief gedrag van tumorcellen. Hoe hoger de expressie van annexine A1, hoe meer uitzaaiingen, simpel gezegd. Wanneer annexine A1 wordt uitgeschakeld in deze cellen verandert de cel van het agressieve gedrag naar een ___rustige___ tumorcel, en ontstaan er beduidend minder uitzaaiingen. Ondanks de veelbelovende resultaten is het geen optie om remming van annexine A1 als anti-kanker therapie te gebruiken omdat annexine A1 ook in gezonde lichaamscellen een belangrijke functie heeft. Maar de onderzoekers denken wel dat annexine A1 een ___marker___ voor basale borstkanker kan worden. Doordat annexine A1 specifiek in basale borstkanker verhoogd tot expressie komt zou het als marker wellicht goed gebruikt kunnen worden om dit relatief agressieve type borstkanker type te bepalen bij pati__nten. Show less
In order to form a distant metastasis, a cancer cell has to migrate out of the primary tumor, intravasate into a blood or a lymphatic vessel, subsequently survive in the absence of cell-cell and... Show moreIn order to form a distant metastasis, a cancer cell has to migrate out of the primary tumor, intravasate into a blood or a lymphatic vessel, subsequently survive in the absence of cell-cell and cell-matrix interactions, extravasate the blood or lymphatic vessel, migrate through the target organ and finally proliferate to grow out into a full metastasis. During all of these processes, specific kinases are involved in the concerted activation of distinct signaling pathways. We hypothesised that the protein tyrosine kinase FAK plays a crucial role in one or multiple of the processes involved in the formation of metastases. Therefore, the overall aim of the studies described in this thesis was to investigate the role of the non-receptor protein tyrosine kinase FAK in the distinct processes involved in tumorigenesis and metastasis and to unravel the involved downstream signaling pathways. Moreover, the potential of a combined therapy of the inhibition of FAK and exposure to the cytostatic doxorubicin was tested, as well as dissection of the intracellular events downstream of FAK. Show less
