Lung cancer is the leading cause of cancer death in the Netherlands. For years chemotherapy was the only (palliative) treatment, with a short survival of only months. Since the introduction of... Show moreLung cancer is the leading cause of cancer death in the Netherlands. For years chemotherapy was the only (palliative) treatment, with a short survival of only months. Since the introduction of immunotherapy in 2015, this survival has increased significantly, with the first results showing a survival of even a few years. However, the response rate is relatively low, the treatment is expensive and the (low percentage of) side effects are severe. Therefore a biomarker is needed to predict which patients would benefit of immunotherapy.This thesis is about the search for a new biomarker. With the use of the RNA of platelets, proteins, tumor markers in blood and a an electronic nose for exhaled breath, we tried to find a non-invasive biomarker for the prediction of response on immunotherapy and for the (future) use in clinical practice, some of which are promising. Show less
Degenerative diseases of the nervous system, such as Alzheimer's, Parkinson's and ALS, are severe, progressive and ultimately fatal. Most existing drugs for these neurodegenerative diseases only... Show moreDegenerative diseases of the nervous system, such as Alzheimer's, Parkinson's and ALS, are severe, progressive and ultimately fatal. Most existing drugs for these neurodegenerative diseases only temporarily relieve symptoms, increase mobility or relieve pain, but do not slow disease progression.This dissertation describes a method to efficiently carry out the development of new drugs that could inhibit disease progression in neurodegenerative diseases. Namely, by using pharmacodynamic biomarkers. These are signaling substances to measure the magnitude of a drug response.These biomarkers can be used in early clinical-pharmacological studies in healthy volunteers or small groups of patients to select the best drug candidates and their expected therapeutic doses as early as possible in the development stage. This helps to make informed choices to advance a potential new drug into large and expensive phase 2 and 3 (registration) studies, or conversely to discontinue development of a non-potential drug as early as possible. This biomarker method was applied in this dissertation to investigate 2 new drugs that could potentially slow disease progression in Alzheimer's and ALS (a RIPK1 inhibitor) or Parkinson's disease (a LRRK2 inhibitor). The research results from multiple early clinical-pharmacological studies in healthy volunteers and patients described in this thesis form the basis for larger phase 2 and 3 follow-up studies that have now been initiated with ALS patients and Parkinson's disease patients. Both with the goal of confirming whether these agents can indeed slow disease progression, which would represent a major breakthrough in the treatment of these conditions. Show less
Sepsis is a life-threatening condition caused by a dysregulated host response to infection, it is associated with significant morbidity, mortality, and with a high financial burden on global... Show moreSepsis is a life-threatening condition caused by a dysregulated host response to infection, it is associated with significant morbidity, mortality, and with a high financial burden on global healthcare systems. Bacterial infections are the primary cause of sepsis, but the growing prevalence of antimicrobial resistance complicates the effectiveness of antimicrobial treatments. Moreover, limited understanding of the host immune response during sepsis hinders the discovery of valuable biomarkers and drug targets. As such, there is an urgent need to improve the treatment of sepsis. To tackle this challenge, we have concentrated our efforts on optimizing current treatment strategies and on facilitating the discovery of novel host inflammatory response directed therapeutics. In this thesis, we have utilized quantitative pharmacological modeling approaches to assess the adequacy of current dose regimens and to evaluate antibiotic pharmacokinetic variability, thereby optimizing antimicrobial therapies for sepsis. Additionally, our researches had aimed to deepen our understanding of the underlying dynamics of sepsis pathology, enabling the identification of promising biomarkers and therapeutic targets for sepsis. Our work demonstrated how quantitative modeling strategies can support the design of optimized treatment strategies, and how systematic model-based integration of disease mechanisms can help to overcome the translational challenges in sepsis drug development. Show less
Antimicrobial drugs constitute a fundamental part of modern medicine. The global rise in antimicrobial resistance poses a major threat to global health. Optimising antimicrobial treatment... Show moreAntimicrobial drugs constitute a fundamental part of modern medicine. The global rise in antimicrobial resistance poses a major threat to global health. Optimising antimicrobial treatment strategies in patients offers an important direction to address this challenge. In this thesis, we describe how quantitative characterisation of the drug, the pathogen, and the patients, and how these three factors interact, can help to achieve this goal. To this end, we used a combination of state-of-the-art in silico model-based approaches to analyse and integrate experimental data from in vitro models, and clinical data from healthy volunteers and patients. We developed models describing infection site drug exposure, antimicrobial resistance evolution, and host response biomarker dynamics. We explored the impact of infection on pulmonary pharmacokinetics, evolutionary-based treatment strategies, and the utility host response biomarker for treatment monitoring. The work in this thesis builds towards developing novel strategies to optimise antimicrobial treatments and showcases the importance on interdisciplinary collaborations. Show less
The focus of the described research in this thesis is on the oxidative stress response (Nrf2 pathway). The aim of the research presented in this thesis is to obtain more information concerning... Show moreThe focus of the described research in this thesis is on the oxidative stress response (Nrf2 pathway). The aim of the research presented in this thesis is to obtain more information concerning microRNAs which are involved in the Nrf2 pathway, to determine and evaluate the application of microRNAs for the construction of novel mechanistic biomarkers. Furthermore, we aimed to obtain a better understandingwith respect to the dynamics of the Nrf2 pathway to repeated xenobiotic exposure.To investigate the effect of overexpression of microRNAs on the Nrf2 pathway response in general and in combination with chemical exposure, a microRNA mimic screen was performed. In this screen overexpression of microRNAs was induced by using synthetic microRNA mimics. Since repeated exposure may drive adaptation programs and may lead to different responses between single and repeated exposures. The effect of a second exposure on the dynamics of the Nrf2 pathway activation was conducted. Final, results of a study are shown where a panel of structurally different phenolic compounds were used to demonstrate the proof-of-concept that Nrf2 pathway reporters can successfully be applied as biomarkers to characterize the specific pro-oxidant responses of chemicals. Show less
During this research project we studied circulating cells in the blood of people with cardiovascular disease, we investigated if these cells could be used as biomarkers for future cardiovascular... Show moreDuring this research project we studied circulating cells in the blood of people with cardiovascular disease, we investigated if these cells could be used as biomarkers for future cardiovascular incidents. We specifically looked at circulating immune cells such as monocytes, T cells and neutrophils. It was shown that both specific subsets of monocytes as well as neutrophils could be used to predict cardiovascular events in patients with cardiovascular disease. Surprisingly it was shown that different cell subsets were predictive for cardiovascular events in men and women. Investigating the difference between men and women further we show that the acute immune response in during cardiovascular disease is different between men and women. While the response in males was skewed towards a monocyte response, in women the acute response was skewed towards a T cell response. The research presented in this thesis shows that our knowledge of the gender specific immune response in cardiovascular disease is limited and further research is necessary. Show less
Part I describes the prognostic effect and interactions of the immune system in breast cancer patients. Part II of the thesis describes the prognostic effect of these prognostic immune parameters... Show morePart I describes the prognostic effect and interactions of the immune system in breast cancer patients. Part II of the thesis describes the prognostic effect of these prognostic immune parameters and biomarkers molecular subtypes and stem cell marker ALDH-1, which are known to be strong breast cancer prognostic factors, in elderly breast cancer patients compared to their younger counterparts. Show less
The aim of this thesis was to identify novel lifespan regulating loci that influence human longevity and population mortality. To this end, we performed two genome-wide association studies, one of... Show moreThe aim of this thesis was to identify novel lifespan regulating loci that influence human longevity and population mortality. To this end, we performed two genome-wide association studies, one of long-lived individuals from the family-based Leiden Longevity Study (LLS) and an extended one of long-lived individuals from multiple cohorts of European descent. Using the latter, we identified two genome-wide significant loci, the TOMM40/APOE/APOC1 locus and an intergenic locus on chromosome 5q33.3. In addition, our gene set analysis with the LLS data showed that genetic variation in genes involved in the insulin/IGF-1 signaling and telomere maintenance pathways is associated with human longevity. Since our genetic studies identified a limited number of longevity loci, we additionally examined whether leukocyte telomere length (LTL) could be used as a biomarker of healthy aging. We showed that LTL meets three of the four criteria for a biomarker of healthy aging in the LLS, i.e., LTL changes with chronological age and is associated with health, in this case immune-related parameters, and prospective mortality. To identify novel longevity loci, future research may benefit from a better definition of the healthy aging phenotype, combining study designs, and the use of novel methods and technologies, such as next-generation sequencing. Show less
The aims of this thesis were to gain insight into specific disease processes in Huntington__s Disease (HD) and to identify biomarkers. To achieve these aims, cognitive functioning, structural brain... Show moreThe aims of this thesis were to gain insight into specific disease processes in Huntington__s Disease (HD) and to identify biomarkers. To achieve these aims, cognitive functioning, structural brain characteristics and intrinstic functional brain connectivity of premanifest and early HD subjects were examined. Cortical, subcortical and the intermediate white matter brain tissue shows evidence of structural and functional decline. We found evidence that disease processes, such as altered metabolism, excessive iron accumulation and cell loss, play a role in the changes. We conclude that changes occur throughout the brain from the earliest disease phase onwards. Hence, both premanifest and manifest HD should not be regarded as a disorder of the basal ganglia, but as a disease affecting the whole brain. Candidate biomarkers that have the potential to objectively reflect the early changes and the progressive nature of the disease are measures of subcortical atrophy, integrity of white matter pathways and of intrinsic functional brain connectivity. Iron, creatine, and N-acetylaspartate concentrations in the caudate nucleus and putamen may prove to be useful as markers of disease state for objectifying transitional disease processes from premanifest to manifest HD. Visuospatial working memory could be applied as a state marker for stage two HD. Show less
The aim of this thesis was to find potential MRI biomarkers for Huntington__s disease (HD). Therefore, after an overview of the current literature on MRI biomarkers, followed by examinations of... Show moreThe aim of this thesis was to find potential MRI biomarkers for Huntington__s disease (HD). Therefore, after an overview of the current literature on MRI biomarkers, followed by examinations of volumetric MRI, magnetization transfer imaging (MTI), diffusion tensor imaging (DTI) and magnetic resonance spectroscopy (MRS) were applied in patients in different disease stages of HD. The main conclusions demonstrate that choosing the optimal biomarker for evaluating therapeutic effects is dependent on the disease stage and therapeutic compound. To evaluate the premanifest stages of the disease volumetric MRI and DTI are most suitable. When the transition period is the desired timeframe for evaluation, also MRS can be very useful, especially if the compound in question has a direct potential influence on certain pathogenic pathways which in turn have an impact on specific metabolites. Future research should focus on combining multiple imaging techniques; __multimodal imaging__. A composite MRI biomarker has the potential to distinguish between disease groups more accurately than a single biomarker and in this way improve the evaluation of therapeutic compounds. Show less
This thesis describes the development of a novel alcohol clamp, a new method to obtain stable plasma levels of alcohol and its application in CNS-research. The method might have several advantages... Show moreThis thesis describes the development of a novel alcohol clamp, a new method to obtain stable plasma levels of alcohol and its application in CNS-research. The method might have several advantages that were explored in subsequent studies described in this thesis. The stability of the alcohol clamp was used to examine functional effect profiles and time-dependence of different CNS-effects. The tests to examine these effects were chosen based upon a prior review of the literature, during which the most sensitive CNS-tests were selected. Hereafter, we studied the alcohol clamping method as a tool to compare alcohol disposition capacities between different (ethnic) populations and as a tool to compare their different CNS-responses to multiple stable alcohol levels. We also investigated whether the clamping method could be useful as a future benchmarking entity in CNS-research, based on its fMRI effects on the brain at rest and its efficacy on tremor symptoms. Finally, we employed the method in an interaction study with a compound that is in development for addictive disorders including alcoholism. This thesis has examined several examples of situations where the alcohol clamp has been a useful research instrument during alcohol research and in early drug development. Show less
Survival rates after surgical treatment of gastric, colon and rectal cancer can improve with preoperative and/or postoperative adjuvant treatment with chemo- and/or radiotherapy. The role of... Show moreSurvival rates after surgical treatment of gastric, colon and rectal cancer can improve with preoperative and/or postoperative adjuvant treatment with chemo- and/or radiotherapy. The role of epigenetic aberrancies such as DNA methylation is established to play a pivotal role in gastrointestinal carcinogenesis and malignant progression. This thesis describes novel epigenetic biomarkers that could tailor (neo)adjuvant treatment regimens to the patients who would benefit from them. The same markers could further be used to exclude those patients who would not gain more survival-years and would be unnecessarily exposed to the morbidity/mortality of additional chemo- and/or radiation therapy. Currently, nodal status is the single most important prognostic indicator in gastrointestinal cancers however this can only be reliably assessed by the pathologist after surgery. Currently, neoadjuvant regimens are more and more being studied and shown to be of benefit. This development necessitates biomarkers that are available before the operation. An important derived conclusion from this thesis is that the preoperative availability of primary tumor DNA methylation biomarkers holds great potential for tailoring neoadjuvant therapy. The thesis also describes technical advancements that will enable primary tumor DNA methylation assessment in small amounts of tissue as preoperative diagnostic tumor biopsies harvested during gastroscopy or colonoscopy Show less
Replicative ageing of fibroblasts has often been used as a model for organismal ageing. The general assumption that the ageing process is mirrored by cellular senescence in vitro is based on lower... Show moreReplicative ageing of fibroblasts has often been used as a model for organismal ageing. The general assumption that the ageing process is mirrored by cellular senescence in vitro is based on lower replicative capacity of human fibroblasts from donors of higher chronological age, but these inverse relations have not been reported unequivocally. The relation between chronological age and fibroblast growth characteristics was assessed in nonagenarian subjects of the Leiden 85+ Study. A high remaining replicative capacity impressively showed that even in the very elderly a crucial number of cells with high mitotic capacity are left to give rise to fibroblast strains with the capacity for more than 100 population doublings. During the course of fibroblast growth in vitro, beta-galactosidase activity has been shown to be a reliable biomarker for replicative senescence. In myoblast cultures the relation between mixed cultures and clonal cultures was studied, showing marked heterogeneity between clonal cultures that all had a significantly lower replicative capacity when compared to mixed cultures, indicating heterogeneity of cells within one tissue compartment in their in vivo history. In a formal review on the replicative capacity of fibroblasts from patients suffering from accelerated ageing syndromes, age related diseases and donor age it was found that except for premature ageing syndromes, the replicative capacity of fibroblasts in vitro does not mirror key characteristics of human life histories. Show less
Although cannabis is especially known for its recreational use as a __soft drug__, its potential therapeutic properties have been recognized for hundreds of years. Since the isolation of THC from... Show moreAlthough cannabis is especially known for its recreational use as a __soft drug__, its potential therapeutic properties have been recognized for hundreds of years. Since the isolation of THC from Cannabis sativa L, the discovery of cannabinoid receptors and their natural ligands (endocannabinoids) the interest in the development of novel cannabinoids as medicine is accelerating. This thesis describes useful cannabis-biomarkers and the clinical pharmacology of some cannabinoid agonists and antagonists in early phase drug development. This includes a novel mode of pure intrapulmonary THC administration that can be used as a benchmark for novel CB1/CB2-agonists, or to demonstrate inhibitory activity of CB1-antagonists. In addition, the pharmacodynamics and pharmacokinetics of two novel CB1/CB2 agonists are evaluated and compared with the pharmacodynamic effect profile of THC. The clinical trials carried out for this research were performed at the Centre for Human Drug Research, Leiden, The Netherlands. Show less
The muscular dystrophies are a group of neuromuscular disorders characterized by progres_sive muscle weakness and wasting. Although the underlying genetic defects of a large number of muscular... Show moreThe muscular dystrophies are a group of neuromuscular disorders characterized by progres_sive muscle weakness and wasting. Although the underlying genetic defects of a large number of muscular dystrophies are now know, the molecular mechanisms resulting in the devastating effects of the disease are not yet clear. Furthermore, the muscular dystrophies differ in clinical presentation and severity. The processes responsible for this di_vergence are largely unknown as well. In this thesis, gene expression profiling has been applied to study the molecular and cellular mechanisms and subsequent biological processes that play a role in muscular dystrophy. To characterize the processes associated with regeneration, we have compared gene expression levels in hindlimb muscle tissue of mdx and control mice in a temporal study. Additionally, we have determined the gene expression profiles of dif_ferentiating human myoblasts in vitro, since regeneration processes recapitulate myogenesis. We also set out to compare gene expression levels of different mouse models for muscular dystrophy to find common and distinct molecular mechanisms that underlie different forms of muscular dystrophy. Accordingly, we first had to determine the effects of genetic background variation between inbred mouse strains, and to study the feasibility of alternative experimental designs. Show less
