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 aim of this thesis was to investigate if a text-mining tool is suitable for collecting real-world data from electronic health records to evaluate cancer treatments in clinical practice. By... Show moreThe aim of this thesis was to investigate if a text-mining tool is suitable for collecting real-world data from electronic health records to evaluate cancer treatments in clinical practice. By investigating a range of use cases including treatments of patients with renal cell carcinoma, hepatocellular carcinoma, melanoma, breast cancer, and COVID-19, it showed that the text-mining tool is a suitable method of data needed for the evaluation of treatment patterns, effectiveness, safety, prognostic factors, and guideline adherence. The discussion showed that enhancing the data quality and actively using real-world data for treatment evaluation regarding treatment policies are some of the next steps. Show less
Pathogenic variants in PALB2 and CHEK2 are associated with an increased risk of breast cancer. By contrast, for missense variants of uncertain significance (VUS) in these genes, the associated... Show morePathogenic variants in PALB2 and CHEK2 are associated with an increased risk of breast cancer. By contrast, for missense variants of uncertain significance (VUS) in these genes, the associated breast cancer risk is often unclear. To aid in their clinical classification, functional assays that determine the impact of missense VUS on PALB2 and CHK2 protein function have been performed in this thesis. By means of these functional analyses, numerous missense VUS (in both PALB2 and CHEK2) have been identified that are, from a functional viewpoint, just as damaging as known pathogenic (i.e., truncating) variants. In agreement, we observe that the level of impaired protein function correlates with the degree of increased breast cancer risk. Overall, these findings suggest that damaging PALB2 and CHEK2 missense VUS are associated with a risk of breast cancer similar to that of protein-truncating variants in these genes. This indicates the urgency of expanding the functional characterization of missense VUS in both PALB2 and CHEK2 to further understand the associated cancer risk. Show less
This thesis deals with multiple aspects of breast cancer risk stratification after locoregional treatment. The first part of the thesis deals with the reproducibility of established... Show moreThis thesis deals with multiple aspects of breast cancer risk stratification after locoregional treatment. The first part of the thesis deals with the reproducibility of established pathological parameters that currently stratify breast cancer patients to low- or high risk, on the basis of which systemic therapies are considered. The reproducibility of estrogen receptor, progesterone receptor and HER2 is investigated. Additionally, prognostic implication of lymph vascular space invasion is assessed as well as its interobserver reproduciblity. Lastly, the reproducibility of Ki67 assays are determined. The second part of the thesis concerns investigations into the prognostic aspects of the tumor-associated stromal tissues. These tissues might be used to further improve breast cancer risk stratifications as well as help determine tumor susceptibility to systemic treatments. The prognostic implications of the tumor-stroma ratio is investigated. Proteomic studies into the tumor-associated stroma is described as well as a work-flow for investigating metabolic interactions between the tumor epithelium and tumor stroma. The prognostic significance of TGF-beta signaling is also investigated. Show less
Selection of patients who will likely respond or will develop relevant side effects has the potential to improve anticancer therapy. Considering the many contributing factors in drug disposition,... Show moreSelection of patients who will likely respond or will develop relevant side effects has the potential to improve anticancer therapy. Considering the many contributing factors in drug disposition, we hypothesized that variability in drug disposition could be better explained by phenotype, rather than by the genotype alone. In this thesis, phenotype tests in oncology were studied, with a focus on phenotype breath tests and CYP2D6 metabolism in breast cancer patients using tamoxifen. A review is given of phenotype studies published before 2011 addressing drug metabolizing enzymes in relation to anticancer drugs. The 13C-dextromethorphan-breath test was related to CYP2D6 genotype and serum concentrations of endoxifen, the active metabolite of tamoxifen. A 13C-dextromethorphan breath test was equally predictive of endoxifen levels as compared to the CYP2D6 genotype. We showed that there was no difference in CYP2D6 phenotype between metastasized patients and early breast cancer patients. Because endoxifen levels did not significantly differ between the two groups as well, our findings do not have clinical implications thus far. Show less
This thesis was divided in two parts. Part I demonstrated benefit of zoledronic acid addition to chemotherapy in terms of pathological response in postmenopausal women. Part II is all about... Show moreThis thesis was divided in two parts. Part I demonstrated benefit of zoledronic acid addition to chemotherapy in terms of pathological response in postmenopausal women. Part II is all about neoadjuvant endocrine therapy, and discusses the optimal duration of this treatment and the information on treatment efficacy that aromatase-inhibitor specific adverse events may provide. Show less
In this thesis the feasibility of tailored follow-up for early-stage breast cancer patients is evaluated. In order to do so, we first determined the risk of locoregional recurrence (LRR) dependent... Show moreIn this thesis the feasibility of tailored follow-up for early-stage breast cancer patients is evaluated. In order to do so, we first determined the risk of locoregional recurrence (LRR) dependent on local treatment in a large cohort of low-risk breast cancer patients, treated with adequate modern systemic therapy. In the second part we evaluated both patients__ and professionals__ needs and preferences for breast cancer follow-up and we reviewed the literature on cost effectiveness of known follow-up schedules. Finally we prospectively examined whether the implementation of a tailored follow-up programme, based on a prognostic index for LRR, is feasible and acceptable to patients and professionals. The results show that in general, implementation of minimised tailored follow-up seems feasible, but professionals tend to more frequent follow-up. Patients accept less intensive follow-up schedules and follow-up by a nurse practitioner. Given the low risk of LRR, tailoring should not only be done based on this risk, but individually, based on the presence of treatment related side effects, either physical or psychosocial. If patients do not experience side effects, annual planned mammography and telephone contact coordinated by a single professional, preferably a specialised nurse, suffice in case of easily accessible information and on demand visits. Show less
Tissue Factor (TF) is a membrane protein that is responsible for the initiation of the coagulation. In addition to its coagulant activity, it can also signal through a member of G-protein coupled... Show moreTissue Factor (TF) is a membrane protein that is responsible for the initiation of the coagulation. In addition to its coagulant activity, it can also signal through a member of G-protein coupled receptor family, PARs, thus play a role in breast cancer growth and angiogenesis. The switch between signaling and coagulant TF regulated by the oxidation/reduction of an allosteric disulfide bond which resides in TF antigen. A decade ago, it was discovered that TF RNA can be alternatively spliced to form a soluble protein called Alternatively Spliced Tissue Factor (asTF). This protein is non-coagulant. However, it plays a major role in breast cancer growth via inducing cancer cell proliferation. The mechanism lying behind behind this phenomenon is asTF's capability to ligate integrins thus it can initiate integrin signaling. Moreover, both TF and asTF can synergize with estrogen pathway thus providing a complex regulation of breast cancer progression. Show less
Currently, 35-45% of newly diagnosed breast cancer patients in developed countries is aged 65 years and older. Older women with breast cancer comprise a heterogeneous group due to large differences... Show moreCurrently, 35-45% of newly diagnosed breast cancer patients in developed countries is aged 65 years and older. Older women with breast cancer comprise a heterogeneous group due to large differences with regard to concomitant diseases, physiological reserve and functional status. Current guidelines for breast cancer are based on studies that were mostly performed in younger patients. Therefore, treatment of older women with breast cancer is not evidence-based, and it cannot be expected that clinical trials will fill this gap of knowledge in the near future. The aim of this thesis was to investigate several aspects of breast cancer treatment in older women. In Part I, several aspects of treatment in older breast cancer patients were assessed. Part II assessed methodological aspects of studying breast cancer in older patients. This thesis has shown that older patients are at increased risk for overdiagnosis of breast cancer due to population screening, with potential harmful effects due to the increased risk of complications of treatment. Despite changing treatment strategies, breast cancer prognosis of older women has not improved. Current treatment strategies and decisions tools are insufficient. Observational studies will become increasingly important in this patient population, the use of accurate methods will be essential. Show less
Not all hormone receptor positive breast cancer patients benefit from tamoxifen treatment, but may be nonetheless exposed to its side effects (e.g. hot flashes). Tamoxifen needs bioactivation by... Show moreNot all hormone receptor positive breast cancer patients benefit from tamoxifen treatment, but may be nonetheless exposed to its side effects (e.g. hot flashes). Tamoxifen needs bioactivation by formation of the metabolite endoxifen, which is mainly catalyzed by the enzyme CYP2D6. In this thesis, we studied the variation in tamoxifen metabolism in relation to endoxifen serum concentration, tamoxifen efficacy and side effects, focusing on CYP2D6 activity and pharmacogenetics. The importance of good methodology for genotyping and endoxifen measurement was exemplified. In a large trial population, no association between CYP2D6 genotype and disease free survival or the occurence of hot flashes was found, although polymorphisms in the estrogen receptor-1 and UGT2B15 might be related to clinical outcome. Adherence, but not the concomitant use of CYP2D6 inhibiting medication was associated with breast cancer recurrence. CYP2D6 genotype and endoxifen-guided tamoxifen dose escalation led to an increase in endoxifen serum levels and a new 13C-Dextromethorphan breath test was used for phenotyping CYP2D6, which correlated well with CYP2D6 genotype and endoxifen levels. Finally, the CYP2D6 phenotype and endoxifen serum levels are currently prospectively related to breast cancer recurrence. This may lead to therapeutic drug monitoring and selection of patients who benefit most from tamoxifen. 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
