Jos H Beijnen

Utrecht University, Utrecht, Utrecht, Netherlands

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Publications (841)3177.76 Total impact

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    ABSTRACT: Background: The objective of this analysis was to determine the factors associated with early onset treatment-related toxicity in patients treated with capecitabine-based anticancer regimens in daily clinical care. Patients and methods: A total of 1463 patients previously included in a prospective cohort study and treated with standard-of-care capecitabine-based anticancer regimens (monotherapy or combined with other chemotherapy or radiotherapy) were analysed. Logistic regression models were developed to investigate associations between patient- and treatment-related factors and occurrence of early - i.e. cycle one or two - severe (grade ≥ 3) treatment-related toxicity, toxicity-related hospitalisation, and toxicity-related treatment discontinuation. Performance of models was evaluated using receiver-operating characteristic (ROC) curves and internal validity was explored using bootstrap analysis. Results: Among 1463 patients included, 231 patients (16%) experienced early severe toxicity, 132 patients (9%) were hospitalised for toxicity, and 146 patients (10%) discontinued treatment for toxicity; in total, 321 patients (22%) experienced any early toxicity-related adverse outcome. Predictors of early grade ≥3 toxicity, after adjustment for treatment regimen, were renal function (odds ratio [OR] 0.85 per 10 ml/min/1.73 m(2), p = 0.0007), body surface area (BSA) (OR 0.33 per m(2), p = 0.0053), age (OR 1.14 per decade, p = 0.0891), and elevated pre-treatment uracil concentrations (OR 2.41 per 10 ng/ml, p = 0.0046). Age was significantly associated with fatal treatment-related toxicity (OR 5.75, p = 0.0008). Area under the ROC curve (AUC) of a model to predict early grade ≥3 toxicity was 0.704 (95% confidence interval 0.666-0.743, optimism-corrected AUC 0.690). Conclusion: Renal function, BSA, and age, in addition to pre-treatment uracil, are associated with clinically relevant differences in risk of early severe toxicity in patients treated with capecitabine in routine clinical care.
    Full-text · Article · Feb 2016 · European journal of cancer (Oxford, England: 1990)
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    ABSTRACT: The objective of this study was to determine whether genotyping of MIR27A polymorphisms rs895819A>G and rs11671784C>T can be used to improve the predictive value of DPYD variants to identify patients at risk of severe fluoropyrimidine-associated toxicity (FP-toxicity). Patients treated previously in a prospective study with fluoropyrimidine-based chemotherapy were genotyped for rs895819 and rs11671784, and DPYD c.2846A>T, c.1679T>G, c.1129-5923C>G, and c.1601G>A. The predictive value of MIR27A variants for early-onset grade ≥3 FP-toxicity, alone or in combination with DPYD variants, was tested in multivariable logistic regression models. Random-effects meta-analysis was performed, including previously published data. 1592 patients were included. Allele frequencies of rs895819 and rs11671784 were 0.331 and 0.020, respectively. In DPYD wild type patients, MIR27A variants did not affect risk of FP-toxicity (OR 1.3 for ≥1 variant MIR27A allele vs. none, 95%CI 0.87-1.82, p=0.228). In contrast, in patients carrying DPYD variants, the presence of ≥1 rs895819 variant allele was associated with increased risk of FP-toxicity (OR 4.9, 95%CI 1.24-19.7, p=0.023). Rs11671784 was not associated with FP-toxicity (OR 2.9, p=0.253). Patients carrying a DPYD variant and rs895819 were at increased risk of FP-toxicity compared to patients wild type for rs895819 and DPYD (OR 2.4, 95%CI 1.27-4.37, p=0.007), while patients with a DPYD variant but without a MIR27A variant were not (OR 0.4, 95%CI 0.09-1.82, p=0.236). In meta-analysis, rs895819 remained significantly associated with FP-toxicity in DPYD variant allele carriers, OR 5.4 (95%CI 1.83-15.7, p=0.002). This study demonstrates the clinical validity of combined MIR27A/DPYD screening to identify patients at risk of severe FP-toxicity. This article is protected by copyright. All rights reserved.
    No preview · Article · Jan 2016 · International Journal of Cancer
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    ABSTRACT: A quantitative bioanalytical liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay for afatinib, an irreversible inhibitor of the ErbB (erythroblastic leukemia viral oncogene homolog)) tyrosine kinase family, was developed and validated. Plasma samples were pre-treated using salting-out assisted liquid-liquid extraction (SALLE) with acetonitrile, magnesium chloride and a stable isotopically labeled internal standard. After dilution, the extract was directly injected into the reversed-phase liquid chromatographic system. The eluate was transferred into the electrospray interface with positive ionization and compounds were detected in the selected reaction monitoring mode of a triple quadrupole mass spectrometer.
    No preview · Article · Jan 2016 · Journal of chromatography. B, Analytical technologies in the biomedical and life sciences
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    ABSTRACT: Background: Elderly patients receiving anticancer drugs may have an increased risk to develop treatment-related toxicities compared to their younger peers. However, a potential pharmacokinetic (PK) basis for this increased risk has not consistently been established yet. Therefore, the objective of this study was to systematically review the influence of age on the PK of anticancer agents frequently administered to elderly breast cancer patients. Methods: A literature search was performed using the PubMed electronic database, Summary of Product Characteristics (SmPC) and available drug approval reviews, as published by EMA and FDA. Publications that describe age-related PK profiles of selected anticancer drugs against breast cancer, excluding endocrine compounds, were selected and included. Results: This review presents an overview of the available data that describe the influence of increasing age on the PK of selected anticancer drugs used for the treatment of breast cancer. Conclusions: Selected published data revealed differences in the effect and magnitude of increasing age on the PK of several anticancer drugs. There may be clinically-relevant, age-related PK differences for anthracyclines and platina agents. In the majority of cases, age is not a good surrogate marker for anticancer drug PK, and the physiological state of the individual patient may better be approached by looking at organ function, Charlson Comorbidity Score or geriatric functional assessment.
    Preview · Article · Jan 2016 · Cancers
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    ABSTRACT: Aim: Three intracellularly formed metabolites are responsible for the antineoplastic effect of capecitabine: 5-fluorouridine 5'-triphosphate (FUTP), 5-fluoro-2'-deoxyuridine 5'-triphosphate (FdUTP), and 5-fluoro-2'-deoxyuridine 5'-monophosphate (FdUMP). The objective of this study was to explore the pharmacokinetics of these intracellular metabolites during capecitabine treatment. Methods: Serial plasma and peripheral blood mononuclear cell (PBMC) samples were collected from 13 patients treated with capecitabine 1000 mg QD (group A) and 8 patients receiving capecitabine 850 mg/m(2) BID for fourteen days, every three weeks (group B). Samples were collected on day 1 and, for 4 patients of group B, also on day 14. The capecitabine and 5-fluorouracil (5-FU) plasma concentrations and intracellular metabolite concentrations were determined using LC-MS/MS. Pharmacokinetic parameters were estimated using non-compartmental analysis. Results: Only FUTP could be measured in the PBMC samples. The FdUTP and FdUMP concentrations were below the detection limits (LOD). No significant correlation was found between the plasma 5-FU and intracellular FUTP exposure. The FUTP concentration-time profiles demonstrated considerable inter-individual variation and accumulation of the metabolite in PBMCs. FUTP levels ranged between <LOD and 1.0 μM on day 1, and from 0.64 to 14 μM on day 14. The area under the FUTP concentration-time curve was significantly increased on day 14 of the treatment compared to day 1 (mean ±SD: 28 ±19 μM*h vs. 2.0 ±1.9 μM*h). Conclusions: To our knowledge, this is the first time that intracellular FUTP concentrations were measured in patients treated with capecitabine. During 14 days of treatment with capecitabine twice daily, intracellular accumulation of FUTP occurs.
    No preview · Article · Dec 2015 · British Journal of Clinical Pharmacology
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    ABSTRACT: Background: Pazopanib is approved for the treatment of renal cell carcinoma and soft tissue sarcoma. Analyses show increased benefit in patients with plasma trough concentrations ≥20.5 μg/ml compared with patients with lower concentrations. Methods & results: We developed a DBS assay as a patient friendly approach to guide treatment. The method was validated according to US FDA and EMA guidelines and European Bioanalysis Forum recommendations. Influence of spot homogeneity, spot volume and hematocrit were shown to be within acceptable limits. Analysis of paired clinical samples showed a good correlation between the measured plasma and DBS concentrations (R(2) of 0.872). Conclusion: The method was successfully validated, applied to paired clinical samples and is suitable for application to therapeutic drug monitoring of pazopanib.
    No preview · Article · Dec 2015 · Bioanalysis
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    ABSTRACT: Objective To investigate the efficacy of bevacizumab and trastuzumab combined with docetaxel, oxaliplatin, and capecitabine (B-DOCT) as first-line treatment of advanced human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC). Methods In this multicentre, single-arm, phase II study, tumor HER2 status was determined centrally prior to treatment. Patients with advanced HER2-positive adenocarcinoma of the stomach or gastroesophageal junction (immunohistochemistry 3+ or immunohistochemistry 2+/silver in-situ hybridization positive) were treated with six cycles of bevacizumab 7.5 mg/kg (day 1), docetaxel 50 mg/m(2) (day 1), oxaliplatin 100 mg/m(2) (day 1), capecitabine 850 mg/m(2) b.i.d. (days 1-14), and trastuzumab 6 mg/kg (day 1) every three weeks, followed by maintenance with bevacizumab, capecitabine, and trastuzumab until disease progression. The primary objective was to demonstrate an improvement of progression-free survival (PFS) to >7.6 months (observed in the ToGA trial) determined according to the lower limit of the 95 % confidence interval (CI). Secondary endpoints were safety, objective response rate (ORR), and overall survival (OS). Results Twenty-five patients with HER2-positive tumors were treated with B-DOCT between March 2011 and September 2014. At a median follow-up of 17 months, median PFS was 10.8 months (95%CI: 9.0-NA), OS was 17.9 months (95%CI: 12.4-NA). One-year PFS and OS were 52 % and 79 %, respectively. The ORR was 74 % (95%CI: 52-90 %). Two patients became resectable during treatment with B-DOCT and achieved a pathological complete response. The most common treatment-related grade ≥ 3 adverse events were: neutropenia (16 %), diarrhoea (16 %), and hypertension (16 %). Conclusions B-DOCT is a safe and active combination in HER2-positive GC, supporting further investigations of DOC with HER2/vascular endothelial growth factor (VEGF) inhibition in HER2-positive GC.
    No preview · Article · Dec 2015 · Investigational New Drugs
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    ABSTRACT: Herein we describe a case of a 62-year-old female in good clinical condition with non-small-cell lung cancer who was treated with crizotinib. After 24 days of crizotinib therapy she presented with acute liver failure. Serum aspartate aminotransferase and alanine aminotransferase levels had increased from normal prior to crizotinib start to 2053 IU/L and 6194 IU/L, respectively. Total bilirubin and prothrombin time (PT-INR) increased up to 443 IU/L and 5.33, respectively, and symptoms of hepatic encephalopathy and hepatorenal syndrome emerged. Despite crizotinib discontinuation and intensive supportive therapy, the patient died 40 days after treatment with crizotinib was initiated due to acute liver failure with massive liver cell necrosis.
    No preview · Article · Dec 2015
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    ABSTRACT: In a mouse tumour model for hereditary breast cancer, we previously explored the anti-cancer effects of docetaxel, ritonavir and the combination of both and studied the effect of ritonavir on the intratumoural concentration of docetaxel. The objective of the current study was to apply pharmacokinetic (PK)-pharmacodynamic (PD) modelling on this previous study to further elucidate and quantify the effects of docetaxel when co-administered with ritonavir. PK models of docetaxel and ritonavir in plasma and in tumour were developed. The effect of ritonavir on docetaxel concentration in the systemic circulation of Cyp3a knock-out mice and in the implanted tumour (with inherent Cyp3a expression) was studied, respectively. Subsequently, we designed a tumour growth inhibition model that included the inhibitory effects of both docetaxel and ritonavir. Ritonavir decreased docetaxel systemic clearance with 8% (relative standard error 0.4%) in the co-treated group compared to that in the docetaxel only-treated group. The docetaxel concentration in tumour tissues was significantly increased by ritonavir with mean area under the concentration-time curve 2.5-fold higher when combined with ritonavir. Observed tumour volume profiles in mice could be properly described by the PK/PD model. In the co-treated group, the enhanced anti-tumour effect was mainly due to increased docetaxel tumour concentration; however, we demonstrated a small but significant anti-tumour effect of ritonavir addition (p value <0.001). In conclusion, we showed that the increased anti-tumour effect observed when docetaxel is combined with ritonavir is mainly caused by enhanced docetaxel tumour concentration and to a minor extent by a direct anti-tumour effect of ritonavir.
    No preview · Article · Nov 2015 · The AAPS Journal
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    ABSTRACT: Purpose: Fluoropyrimidines are frequently prescribed anticancer drugs. A polymorphism in the fluoropyrimidine metabolizing enzyme dihydropyrimidine dehydrogenase (DPD; ie, DPYD*2A) is strongly associated with fluoropyrimidine-induced severe and life-threatening toxicity. This study determined the feasibility, safety, and cost of DPYD*2A genotype-guided dosing. Patients and methods: Patients intended to be treated with fluoropyrimidine-based chemotherapy were prospectively genotyped for DPYD*2A before start of therapy. Variant allele carriers received an initial dose reduction of ≥ 50% followed by dose titration based on tolerance. Toxicity was the primary end point and was compared with historical controls (ie, DPYD*2A variant allele carriers receiving standard dose described in literature) and with DPYD*2A wild-type patients treated with the standard dose in this study. Secondary end points included a model-based cost analysis, as well as pharmacokinetic and DPD enzyme activity analyses. Results: A total of 2,038 patients were prospectively screened for DPYD*2A, of whom 22 (1.1%) were heterozygous polymorphic. DPYD*2A variant allele carriers were treated with a median dose-intensity of 48% (range, 17% to 91%). The risk of grade ≥ 3 toxicity was thereby significantly reduced from 73% (95% CI, 58% to 85%) in historical controls (n = 48) to 28% (95% CI, 10% to 53%) by genotype-guided dosing (P < .001); drug-induced death was reduced from 10% to 0%. Adequate treatment of genotype-guided dosing was further demonstrated by a similar incidence of grade ≥ 3 toxicity compared with wild-type patients receiving the standard dose (23%; P = .64) and by similar systemic fluorouracil (active drug) exposure. Furthermore, average total treatment cost per patient was lower for screening (€2,772 [$3,767]) than for nonscreening (€2,817 [$3,828]), outweighing screening costs. Conclusion: DPYD*2A is strongly associated with fluoropyrimidine-induced severe and life-threatening toxicity. DPYD*2A genotype-guided dosing results in adequate systemic drug exposure and significantly improves safety of fluoropyrimidine therapy for the individual patient. On a population level, upfront genotyping seemed cost saving.
    No preview · Article · Nov 2015 · Journal of Clinical Oncology
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    ABSTRACT: Background Moderate diagnostic accuracy of MRI and initial cerebrospinal fluid (CSF) cytology analysis results in at least 10%–15% false negative diagnoses of leptomeningeal metastases (LM) of solid tumors, thus postponing start of therapy. The aim of this prospective clinical study was to determine the diagnostic value of epithelial cell adhesion molecule (EpCAM)–based flow cytometry versus cytology in CSF for the diagnosis of LM in patients with epithelial tumors.
    No preview · Article · Nov 2015 · Neuro-Oncology
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    ABSTRACT: Treatment with monoclonal antibodies is becoming increasingly important in clinical oncology. These antibodies specifically inhibit signaling pathways in tumor growth and/or induce immunological responses against tumor cells. By combining monoclonal antibodies several pathways may be targeted simultaneously, potentially leading to additive or synergistic effects. Theoretically, antibodies are very suitable for use in combination therapy, because of limited overlapping toxicity and lack of pharmacokinetic interactions. In this article an overview is given of preclinical and clinical data on twenty-five different combinations of antibodies in oncology. Some of these combinations have proven clinical benefit, for example the combination of trastuzumab and pertuzumab in HER2-positive breast cancer, which exemplifies an additive or synergistic effect on antitumor activity in clinical studies and the combination of nivolumab and ipilimumab, which results in significant increases in progression-free and overall survival in patients with advanced melanoma. However, other combinations may lead to unfavorable results, such as bevacizumab with cetuximab or panitumumab in advanced colorectal cancer. These combinations result in shorter progression-free survival and increased toxicity compared to therapy with a single antibody. In summary, the different published studies showed widely varying results, depending on the combination of antibodies, indication and patient population. More preclinical and clinical studies are necessary to unravel the mechanisms behind synergistic or antagonistic effects of combining monoclonal antibodies. Most research on combination therapies is still in an early stage, but it is expected that for several tumor types the use of combination therapy of antibodies will become standard of care in the near future.
    No preview · Article · Nov 2015 · Cancer Treatment Reviews
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    ABSTRACT: Purpose: The prognosis of gastroesophageal cancer is poor, and current regimens are associated with limited efficacy. The purpose of this study was to explore the safety and preliminary efficacy of docetaxel, oxaliplatin plus capecitabine for advanced cancer of the stomach or the gastroesophageal junction (GEJ). Secondary objectives included pharmacokinetic and pharmacogenetic analyses. Methods: Patients were treated in escalating dose levels with docetaxel and oxaliplatin (both on day 1), plus capecitabine b.i.d. on days 1-14 every 3 weeks, to determine the dose-limiting toxicity and maximum tolerated dose (MTD). An expansion cohort was treated at the MTD. A total of ten polymorphisms in pharmacokinetic and pharmacodynamic candidate genes were analyzed and tested for association with treatment outcome. Results: A total of 34 evaluable patients were enrolled. The MTD was docetaxel 50 mg/m(2), oxaliplatin 100 mg/m(2) plus capecitabine 850 mg/m(2) b.i.d. The median number of treatment cycles was 6 (range 2-8). Grade ≥ 3 toxicities included neutropenia (24 %), leukocytopenia (15 %), febrile neutropenia (12 %), fatigue (9 %) and diarrhea (6 %). The overall response rate was 45 %; two patients achieved a complete response. Median progression-free survival and overall survival were 6.5 months (95 % CI 5.4-7.6) and 11.0 months (95 % CI 7.9-14.1), respectively. The polymorphisms ERCC1 354C>T, TYMS 1053C>T and rs2612091 in ENOSF1 were associated with severe toxicity; ERCC1 354C>T and ERCC2 2251A>C were associated with poor progression-free survival. Conclusion: Docetaxel, oxaliplatin plus capecitabine are a well-tolerable, safe and effective treatment regimen for patients with advanced cancer of the stomach or GEJ. Pharmacogenetic markers in pharmacokinetic and pharmacodynamic candidate genes may be predictive for treatment outcome.
    No preview · Article · Oct 2015 · Cancer Chemotherapy and Pharmacology
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    ABSTRACT: The best-known cause of intolerance to fluoropyrimidines is dihydropyrimidine dehydrogenase (DPD) deficiency, which can result from deleterious polymorphisms in the gene encoding DPD (DPYD), including DPYD*2A and c.2846A>T. Three other variants—DPYD c.1679T>G, c.1236G>A/HapB3, and c.1601G>A—have been associated with DPD deficiency, but no definitive evidence for the clinical validity of these variants is available. The primary objective of this systematic review and meta-analysis was to assess the clinical validity of c.1679T>G, c.1236G>A/HapB3, and c.1601G>A as predictors of severe fluoropyrimidine-associated toxicity.
    No preview · Article · Oct 2015 · The Lancet Oncology
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    ABSTRACT: A validated simple, fast and sensitive bio-analytical assay for ibrutinib and its dihydrodiol metabolite in human and mouse plasma was set up. Sample preparation was performed by protein precipitation, and addition of the respective deuterated internal standards, followed by LC-MS/MS analysis. Separation was performed on a 3.5μm particle-size, bridged ethylene hybrid column with gradient elution by 0.1% v/v formic acid and acetonitrile. The full eluate was transferred to an electrospray interface in positive ionization mode, and subsequently analyzed by a triple quadrupole mass spectrometer by selected reaction monitoring. The assay was validated in a 5-5000 ng/ml calibration range. Both ibrutinib and dihydrodiol-ibrutinib were deemed stable under refrigerated or frozen storage conditions. At room temperature, ibrutinib showed a not earlier described instability, and revealed rapid degradation at 37°C. Finally, the assay was used for a pharmacokinetic study of plasma levels in treated FVB mice.
    No preview · Article · Oct 2015 · Journal of pharmaceutical and biomedical analysis
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    ABSTRACT: We aimed to clarify the roles of the multidrug transporters ABCB1 and ABCG2 in oral availability and brain accumulation of ceritinib, an oral anaplastic lymphoma kinase (ALK) inhibitor used to treat metastatic non-small cell lung cancer (NSCLC) after progression on crizotinib. Importantly, NSCLC is prone to form brain metastases. Transport of ceritinib by human (h) ABCB1 or hABCG2 or mouse (m) Abcg2 was assessed in vitro. To study the single and combined roles of Abcb1a/1b and Abcg2 in ceritinib disposition in vivo, we used appropriate knockout mouse strains. Ceritinib was very efficiently transported by hABCB1, and efficiently by hABCG2 and mAbcg2 in vitro, and transport was specifically inhibited by the ABCB1 inhibitor zosuquidar and ABCG2 inhibitor Ko143, respectively. Absorption and 24-h oral availability were not significantly affected by the absence of Abcb1 and/or Abcg2, but the brain concentrations were greatly increased (>38-fold) in Abcb1a/1b(-/-) mice at 3 and 24h after oral administration of 20mg/kg ceritinib. The brain concentrations increased another ∼3-fold (to >90-fold) in Abcb1a/1b;Abcg2(-/-) mice, indicating that there was a significant additional effect of Abcg2-mediated transport of ceritinib as well in vivo. Overall, brain accumulation, but not the 24-h oral availability of ceritinib were profoundly restricted by Abcb1a/1b and Abcg2, with Abcb1a/1b being the dominant efflux protein. Our data suggest that coadministration of ceritinib with a dual ABCB1 and ABCG2 inhibitor may improve treatment of brain (micro) metastases positioned behind a functionally intact blood-brain barrier, and possibly also of tumors resistant to ceritinib due to ABCB1 or ABCG2 overexpression.
    No preview · Article · Sep 2015 · Pharmacological Research

  • No preview · Article · Sep 2015 · European geriatric medicine
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    ABSTRACT: We aimed to clarify the roles of the multidrug-detoxifying proteins ABCB1, ABCG2, ABCC2, and CYP3A in oral availability and brain accumulation of cabazitaxel, a taxane developed for improved therapy of docetaxel-resistant prostate cancer. Cabazitaxel pharmacokinetics were studied in Abcb1a/1b, Abcg2, Abcc2, Cyp3a, and combination knockout mice. We found that human ABCB1, but not ABCG2, transported cabazitaxel in vitro. Upon oral cabazitaxel administration, total plasma levels were greatly increased due to binding to plasma carboxylesterase Ces1c, which is highly upregulated in several knockout strains. Ces1c inhibition and in vivo hepatic Ces1c knockdown reversed these effects. Correcting for Ces1c effects, Abcb1a/1b, Abcg2, and Abcc2 did not restrict cabazitaxel oral availability, whereas Abcb1a/1b, but not Abcg2, dramatically reduced cabazitaxel brain accumulation (>10-fold). Coadministration of the ABCB1 inhibitor elacridar completely reversed this brain accumulation effect. After correction for Ces1c effects, Cyp3a knockout mice demonstrated a strong (6-fold) increase in cabazitaxel oral availability, which was completely reversed by transgenic human CYP3A4 in intestine and liver. Cabazitaxel markedly inhibited mouse Ces1c, but human CES1 and CES2 only weakly. Ces1c upregulation can thus complicate preclinical cabazitaxel studies. In summary, ABCB1 limits cabazitaxel brain accumulation and therefore potentially therapeutic efficacy against (micro)metastases or primary tumors positioned wholly or partly behind a functional blood-brain barrier. This can be reversed with elacridar coadministration, and similar effects may apply to ABCB1-expressing tumors. CYP3A4 profoundly reduces the oral availability of cabazitaxel. This may potentially be greatly improved by coadministering ritonavir or other CYP3A inhibitors, suggesting the option of patient-friendly oral cabazitaxel therapy.
    No preview · Article · Aug 2015 · Molecular Pharmaceutics
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    ABSTRACT: Colorectal cancer has been characterized as a genetically heterogeneous disease, with a large diversity in molecular pathogenesis resulting in differential responses to therapy. However, the currently available validated biomarkers KRAS, BRAF, and microsatellite instability do not sufficiently cover this extensive heterogeneity and are therefore not suitable to successfully guide personalized treatment. Recent studies have focused on novel targets and rationally designed combination strategies. Furthermore, a more comprehensive analysis of the underlying biology of the disease revealed distinct phenotypic differences within subgroups of patients harboring the same genetic driver mutation with both prognostic and predictive relevance. Accordingly, patient stratification based on molecular intrinsic subtypes rather than on single gene aberrations holds promise to improve the clinical outcome of patients with colorectal cancer.
    Full-text · Article · Aug 2015 · Current Colorectal Cancer Reports
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    ABSTRACT: Computerized Adaptive Testing (CAT) of cognitive function, selects for every individual patient, only items of appropriate difficulty to estimate his or her level of cognitive impairment. Therefore, CAT has the potential to combine brevity with precision. We retrospectively examined the evaluation of treatment effects of cholinesterase inhibitors by CAT using longitudinal data from 643 patients from a Dutch teaching hospital who were diagnosed with Alzheimer disease or Lewy Body disease. The Cambridge Cognitive Examination (CAMCOG) was administered before treatment initiation and after intervals of six months of treatment. A previously validated CAT was simulated using 47 CAMCOG items. Results demonstrated that the CAT required a median number of 17 items (inter-quartile range 16–20), or a corresponding 64% test reduction, to estimate patients’ global cognitive impairment levels. At the same time, intraclass correlations between global cognitive impairment levels as estimated by CAT or based on all 47 CAMCOG items, ranged from 0.93 at baseline to 0.91–0.94 at follow-up measurements. Slightly more people had substantial decline on the original CAMCOG (N = 31/285, 11%) than on the CAT (N = 17/285, 6%). We conclude that CAT saves time, does not lose much precision, and therefore deserves a role in the evaluation of treatment effects in dementia. Copyright © 2015 John Wiley & Sons, Ltd.
    Full-text · Article · Aug 2015

Publication Stats

22k Citations
3,177.76 Total Impact Points


  • 1988-2016
    • Utrecht University
      • • Department of Pharmaceutical Sciences
      • • Faculty of Science
      • • Division of Biomedical Analysis
      • • Division of Toxicology
      Utrecht, Utrecht, Netherlands
  • 1991-2015
    • Slotervaartziekenhuis
      Amsterdamo, North Holland, Netherlands
  • 1991-2014
    • Netherlands Cancer Institute
      • • Department of Clinical Pharmacology
      • • Department of Medical Oncology
      • • Division of Experimental Therapy
      • • Division of Molecular Biology
      Amsterdamo, North Holland, Netherlands
  • 2013
    • B.P. Koirala Institute of Health Sciences
      • Department of Biochemistry
      Dharan, Eastern Region, Nepal
  • 2010-2012
    • Slotervaart Ziekenhuis Amsterdam
      Amsterdamo, North Holland, Netherlands
  • 2011
    • VU University Medical Center
      • Department of Clinical Pharmacology and Pharmacy
      Amsterdamo, North Holland, Netherlands
  • 2007
    • University of Groningen
      Groningen, Groningen, Netherlands
    • VU University Amsterdam
      Amsterdamo, North Holland, Netherlands
    • University of Florence
      Florens, Tuscany, Italy
    • University Medical Center Utrecht
      Utrecht, Utrecht, Netherlands
  • 2005
    • University of Amsterdam
      Amsterdamo, North Holland, Netherlands
  • 2002
    • Pfizer Inc.
      New York, New York, United States
  • 1998
    • Erasmus MC
      • Department of Internal Oncology
      Rotterdam, South Holland, Netherlands
  • 1996
    • Centro de Investigación del Cáncer
      Helmantica, Castille and León, Spain
  • 1995
    • Medisch Spectrum Twente
      Enschede, Overijssel, Netherlands