Publications by authors named "Schaik R"

Background: Long-acting beta2-agonists (LABA) in combination with inhaled corticosteroids (ICS) are commonly used to treat asthma, however, some children lack response to the addition of LABA. This might be partially due to the presence of the Arg16Gly polymorphism, encoded by rs1042713 G>A in the ADRB2 gene. Carrying the A allele (Arg16) at this variant has been associated with an increased risk of exacerbations despite LABA treatment.

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Aligned with the mission of the Dutch Pharmacogenetics Working Group (DPWG) to promote the implementation of pharmacogenetics (PGx), this guideline is specifically designed to optimize pharmacotherapy of cholesterol lowering medication (statins) and glucose lowering medication (sulfonylureas). The SLCO1B1 c.521 T > C variant reduces the activity of the SLCO1B1 transporter involved in statin transport out of the blood into the liver.

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  • Alectinib is a treatment for ALK+ non-small cell lung cancer, but many patients experience drug-related toxicity requiring dose adjustments, potentially linked to genetic variants.
  • In a study of 215 patients, 47% had severe toxicity, with females being more affected and having higher drug levels. Additionally, specific genetic variants like PPAR-α 209G>A were associated with increased toxicity.
  • Identifying these genetic factors could help tailor treatments and reduce adverse effects, suggesting the need for pre-treatment genetic testing and possible dose modifications.
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Aims: A genotype-guided P2Y12-inhibitor de-escalation strategy, switching acute coronary syndrome (ACS) patients without a CYP2C19 loss-of-function allele from ticagrelor or prasugrel to clopidogrel, has shown to reduce bleeding risk without affecting effectivity of therapy by increasing ischemic risk. We estimated the cost-effectiveness of this personalized approach compared to standard dual antiplatelet therapy (DAPT; aspirin plus ticagrelor/prasugrel) in the Netherlands.

Methods And Results: We developed a one-year decision tree based on results of the FORCE-ACS registry, comparing a cohort of ACS patients who underwent genotyping with a cohort of ACS patients treated with standard DAPT.

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Pharmacogenetics promises to optimize treatment-related outcomes by informing optimal drug selection and dosing based on an individual's genotype in conjunction with other important clinical factors. Despite significant evidence of genetic associations with drug response, pharmacogenetic testing has not been widely implemented into clinical practice. Among the barriers to broad implementation are limited guidance for how to successfully integrate testing into clinical workflows and limited data on outcomes with pharmacogenetic implementation in clinical practice.

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  • Hypertensive disorders of pregnancy (HDP) are major contributors to complications in pregnancy, prompting research into the role of maternal tryptophan metabolites in placental health and development.
  • The study involved 911 women and assessed serum tryptophan metabolites early in pregnancy, analyzing their relationships with placental volume and vascular development, as well as odds of developing HDP.
  • Findings showed that higher kynurenine levels negatively impacted placental development, while increased levels of 5-hydroxytryptophan were linked to higher risks of early pregnancy hypertension and preeclampsia.
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The Immunosuppressive Drugs Scientific Committee of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology established the second consensus report to guide Therapeutic Drug Monitoring (TDM) of everolimus (EVR) and its optimal use in clinical practice 7 years after the first version was published in 2016. This version provides information focused on new developments that have arisen in the last 7 years. For the general aspects of the pharmacology and TDM of EVR that have retained their relevance, readers can refer to the 2016 document.

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  • - The study looks at whether stress hormones in pregnant women, called maternal vulnerability, can affect their baby's growth in the first trimester.
  • - Researchers found that higher levels of certain stress hormones in hair were linked to slower growth of the baby, while another substance called tryptophan was lower when stress was higher.
  • - The study used data from 132 pregnant women over a year to create a risk score for how vulnerable they are to stress and how it impacts their pregnancies.
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The ultimate goal of value-based laboratory medicine is maximizing the effectiveness of laboratory tests in improving patient outcomes, optimizing resources and minimizing unnecessary costs. This approach abandons the oversimplified notion of test volume and cost, in favor of emphasizing the clinical utility and quality of diagnostic tests in the clinical decision-making. Several key elements characterize value-based laboratory medicine, which can be summarized in some basic concepts, such as organization of diagnostics (including appropriateness, integrated diagnostics, networking, remote patient monitoring, disruptive innovations), translation of laboratory data into clinical information and measurable outcomes, sustainability, reimbursement, ethics (e.

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  • The study investigated whether using CYP2C19 genetic testing to guide medication choices improves outcomes for patients with acute coronary syndrome (ACS) compared to standard treatment.
  • Out of 5,321 ACS patients, those who were genotyped and had their medications tailored showed significantly lower bleeding rates while maintaining a similar risk of ischemic events compared to those on standard therapy.
  • The findings suggest that a personalized approach to antiplatelet therapy based on genetic markers can enhance safety without compromising efficacy in managing ACS.
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Background: The Alpe-DPD study (NCT02324452) demonstrated that prospective genotyping and dose-individualization using four alleles in DPYD (DPYD*2A/rs3918290, c.1236G > A/rs75017182, c.2846A > T/rs67376798 and c.

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  • The Association for Molecular Pathology's Pharmacogenomics Working Group aims to establish key attributes and a standard set of genetic variants for clinical pharmacogenetic testing.
  • The document outlines two tiers of recommended genetic variants, which will guide clinical laboratories in creating pharmacogenomics assays.
  • Focused on dihydropyrimidine dehydrogenase (DPYD) testing, the recommendations encourage standardization while serving as a flexible reference rather than strict rules.
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The Dutch Pharmacogenetics Working Group (DPWG) aims to facilitate pharmacogenetics implementation in clinical practice by developing evidence-based guidelines to optimize pharmacotherapy based on pharmacogenetic test results. The current guideline describes the gene-drug interaction between CYP2D6 and venlafaxine, mirtazapine and duloxetine. In addition, the interaction between CYP2C19 and mirtazapine and moclobemide is presented.

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Beta-blockers are widely used medications for a variety of indications, including heart failure, myocardial infarction, cardiac arrhythmias, and hypertension. Genetic variability in pharmacokinetic (e.g.

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Background: The vital role of the maternal tryptophan (TRP) metabolism in maternal health and pregnancy is well established. However, non-medical maternal determinants influencing the TRP metabolism have been poorly investigated. We hypothesise that periconceptional maternal non-medical determinants alter the TRP metabolism, affecting both kynurenine (KP) and serotonin pathway (SP) metabolite concentrations.

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Immune checkpoint inhibitors (ICIs) represent the standard therapy for metastatic melanoma. However, a few patients do not respond to ICIs and reliable predictive biomarkers are needed. This pilot study investigates the association between mRNA levels of programmed cell death-1 (PD-1) ligand 1 (PD-L1), interferon-gamma (IFN-γ), and transforming growth factor-β (TGF-β) in circulating extracellular vesicles (EVs) and survival in 30 patients with metastatic melanoma treated with first line anti-PD-1 antibodies.

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Introduction: For patients with KRAS-mutated NSCLC who are treated with sotorasib, there is a lack of biomarkers to guide treatment decisions. We therefore investigated the clinical utility of pretreatment and on-treatment circulating tumor DNA (ctDNA) and treatment-emergent alterations on disease progression.

Methods: Patients with KRAS-mutated NSCLC treated with sotorasib were prospectively enrolled in our biomarker study (NCT05221372).

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  • The Dutch Pharmacogenetics Working Group (DPWG) is creating guidelines to improve the use of pharmacogenetics (PGx) in prescribing medications, focusing on genetic interactions with drugs like phenytoin, carbamazepine, oxcarbazepine, and lamotrigine.
  • Recommendations include adjusting phenytoin doses for patients with certain genetic markers (CYP2C9) and avoiding certain medications for patients with specific HLA alleles (like HLA-B*15:02) to reduce the risk of severe skin reactions.
  • The DPWG emphasizes the importance of genetic testing before starting these medications to help prevent adverse effects and promote safer drug use among at-risk populations.
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  • - Higher levels of 5-hydroxytryptophan (5-HTP) in pregnant women are linked to lower embryonic and fetal growth, increasing the risk of being small-for-gestational age (SGA), while higher kynurenine (KYN) levels are associated with a lower risk of SGA.
  • - Maternal tryptophan (TRP) metabolism plays an important role in the growth of embryos and fetuses, affecting both immune response and blood vessel function; disruptions in this metabolism can lead to negative outcomes for both mother and baby.
  • - The study analyzed data from over 1,100 women using blood samples and advanced ultrasound techniques to track embryonic and fetal growth, employing various statistical models to
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Tamoxifen is widely used in patients with hormone receptor-positive breast cancer. The polymorphic enzyme CYP2D6 is primarily responsible for metabolic activation of tamoxifen, resulting in substantial interindividual variability of plasma concentrations of its most important metabolite, Z-endoxifen. The Z-endoxifen concentration thresholds below which tamoxifen treatment is less efficacious have been proposed but not validated, and prospective trials of individualized tamoxifen treatment to achieve Z-endoxifen concentration thresholds are considered infeasible.

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Background: Identification of tumor-derived variants in circulating tumor DNA (ctDNA) has potential as a sensitive and reliable surrogate for tumor tissue-based routine diagnostic testing. However, variations in pre(analytical) procedures affect the efficiency of ctDNA recovery. Here, an external quality assessment (EQA) was performed to determine the performance of ctDNA mutation detection work flows that are used in current diagnostic settings across laboratories within the Dutch COIN consortium (ctDNA on the road to implementation in The Netherlands).

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Neutropenia is the major dose-limiting toxicity of irinotecan-based therapy. The objective of this study was to assess whether inclusion of germline genetic variants into a population pharmacokinetic/pharmacodynamic model can improve prediction of irinotecan-induced grade 4 neutropenia and identify novel variants of clinical value. A semimechanistic population pharmacokinetic/pharmacodynamic model was used to predict neutrophil response over time in 197 patients receiving irinotecan.

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Single nucleotide polymorphisms (SNPs) in the cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) gene, an inhibitor of T-cell priming, are associated with auto and alloimmunity. Studies implied a role for these SNPs as surrogate markers for immunotherapy-outcome in patients with melanoma. However, no predictive SNPs are defined to date.

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