Jan H M Schellens

Universiteit Utrecht, Utrecht, Utrecht, Netherlands

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Publications (726)2827.83 Total impact

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    ABSTRACT: Pregnant patients with cancer are increasingly treated with anti-cancer drugs, although the specific impact of pregnancy-induced physiological changes on the pharmacokinetics (PK) of anti-cancer drugs and associated implications for optimal dose regimens remains unclear. Our objectives were to quantify changes in PK during pregnancy for four frequently used anti-cancer agents doxorubicin, epirubicin, docetaxel and paclitaxel, and to determine associated necessary dose adjustments. A pooled analysis of PK data was performed for pregnant (Pr) and non-pregnant (NPr) patients for doxorubicin (n = 16 Pr/59 NPr), epirubicin (n = 14 Pr/57 NPr), docetaxel (n = 3 Pr/32 NPr) and paclitaxel (n = 5 Pr/105 NPr). Compartmental nonlinear mixed effect models were used to describe the PK and gestational effects. Subsequently we derived optimized dose regimens aiming to match to the area-under-the-concentration-time-curve (AUC) in non-pregnant patients. The effect of pregnancy on volumes of distribution for doxorubicin, epirubicin, docetaxel and paclitaxel were estimated as fold-change of <1.32, <2.08, <1.37 and <4.21 respectively, with adequate precision (relative standard error [RSE] <37%). For doxorubicin, no gestational effect could be estimated on clearance. For epirubicin, docetaxel and paclitaxel a fold-change of 1.1 (RSE 9%), 1.19 (RSE 7%) and 1.92 (RSE 21%) were respectively estimated on clearance. Calculated dose adjustment-requirements for doxorubicin, epirubicin, docetaxel and paclitaxel were +5.5%, +8.0%, +16.9% and +37.8%, respectively. Estimated changes in infusion duration were marginal (<4.2%) except for paclitaxel (-21.4%). Clinicians should be aware of a decrease in drug exposure during pregnancy and should not a priori reduce dose. The decrease in exposure was most apparent for docetaxel and paclitaxel which is supported by known physiological changes during pregnancy. The suggested dose adaptations should only be implemented after conduct of further confirmatory studies of the PK during pregnancy.
    Annals of Oncology 04/2014; · 7.38 Impact Factor
  • Annals of Oncology 03/2014; · 7.38 Impact Factor
  • Vincent A de Weger, Jos H Beijnen, Jan H M Schellens
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    ABSTRACT: Paclitaxel and docetaxel are active against a range of human cancers. Their antitumor activity is based on stabilization of the microtubule dynamics and thereby disruption of the cell cycle. The taxanes are administered as intravenous solutions in a short administration schedule. Distribution of both taxanes is rapid, with large volumes of distribution and significant binding to plasma proteins. The metabolism of paclitaxel is mediated primarily by the P450 cytochrome enzymes CYP2C8 and CYP3A, whereas docetaxel is only metabolized by CYP3A4. The most common toxicities after intravenous administration are neutropenia, hypersensitivity reactions, neurotoxicity, and alopecia. Several new administration forms are in development; albumin-bound paclitaxel (Abraxane) has recently been registered. Oral formulations of taxanes have been developed, and several are now undergoing phase I trials. New formulations might improve efficacy and safety and could be easier to use.
    Anti-cancer drugs 03/2014; · 2.23 Impact Factor
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    ABSTRACT: Regorafenib has recently been approved for the treatment of colorectal cancer. A bioanalytical liquid chromatography-tandem mass spectrometric assay for this multikinase inhibitor was developed and validated in plasma. The concentration range of the assay was 25-25,000 ng/mL. Protein precipitation with acetonitrile was used as sample pre-treatment with sorafenib as internal standard. The extract was diluted with methanol (25%, v/v) and then injected onto the sub-2 µm particle, bridged ethylsilicia hybrid trifunctional bonded C18 column. Isocratic elution using 0.02% (v/v) formic acid in a methanol-water mixture was used. Compounds were monitored by a triple quadrupole mass spectrometer in the selected reaction monitoring mode after positive electrospray ionization. Double logarithmic calibration was used; within-day precisions, between-day precisions, and accuracies were 3.2-9.2, 4.1-12.3 and 94.8-103.0%, respectively. High drug stability was observed under all relevant storage conditions. The assay was used to measure drug concentrations in a pharmacokinetic study in wild-type FVB mice. Copyright © 2014 John Wiley & Sons, Ltd.
    Biomedical Chromatography 03/2014; · 1.95 Impact Factor
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    ABSTRACT: Although sarcomas account for only 1% of all solid tumors, patients with sarcomas comprise a larger proportion of patients entering phase I trials, due to the limited number of registered or active drugs for these diseases. To help in patient selection, we evaluated the utility of the predictive Royal Marsden Score which had been derived in carcinoma patients. In addition we analysed efficacy and toxicity regarding the sarcoma population enrolled in phase I trials. We used data from a European Database comprising 2182 patients treated in phase I trials in 14 European institutions between 2005 and 2007. 178 patients diagnosed with advanced sarcoma or other mesenchymal tumors were identified and accounted for 217 phase I trial participations during the study period. Histological type, class of drug, number of metastatic sites, high serum lactate dehydrogenase activity (LDH), low albumin and high white blood cell count were independent prognostic factors. Poor performance status (PS), liver metastases and high leucocyte count were associated with increased risk of early death. The class of drug used was the strongest predictor of progression-free survival (PFS) duration, inhibitors of angiogenesis and histone deacetylase giving the best results. Poor PS, high serum LDH and low lymphocyte count correlated with shorter PFS. In this heterogeneous population, PFS with investigational agents appeared comparable to that previously published for patients receiving standard treatments beyond first-line. Prognostic factors in sarcoma patients do not differ from a broader phase I population. Efficacy measures suggest that some patients with sarcoma derive benefit from therapy in this setting which could therefore be considered for patients with no remaining standard therapeutic option.
    Annals of Oncology 03/2014; · 7.38 Impact Factor
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    ABSTRACT: There is accumulating evidence for potential benefits of therapeutic drug monitoring (TDM) in the treatment of cancer with tyrosine kinase inhibitors (TKIs). Relationships between exposure and response (efficacy/toxicity) have been established for several TKIs. For example, the pharmacokinetic targets for efficacy of imatinib, sunitinib and pazopanib have been defined as trough plasma concentrations (C trough) of >1,000, >50 and >20,000 ng/mL for selected indications, respectively. Dose adjustment based on pharmacokinetic targets could therefore increase response rates and duration. Furthermore, with appropriate target concentrations defined, excessive side effects in patients using the current fixed dosing strategy may be prevented. This review provides a practical guideline for TDM for the currently approved TKIs at 28 February 2013. The focus of this article is on the elaboration of exposure and response relationships of TKIs with proposed pharmacokinetic targets, mainly C trough, and further on the interpretation of the pharmacokinetic targets with recommendations for dose titrations.
    Clinical Pharmacokinetics 02/2014; · 6.11 Impact Factor
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    ABSTRACT: Genetics has importantly added to our understanding of variability in drug response, especially in cancer treatment. Pharmacogenetics, aimed at predicting a patients' chance for effective and safe drug treatment by interrogating germline genetic variants, has moved from a monogenetic candidate gene to complex phenotype based genome-wide approaches. With the rapidly advancing sequencing technologies, decline in costs and swift turnaround times, large scale genomic information will become available in the clinical setting, facilitating implementation of pharmacogenetics.Clinical Pharmacology & Therapeutics (2014); accepted article preview online 21 January 2014 doi:10.1038/clpt.2014.13.
    Clinical Pharmacology &#38 Therapeutics 01/2014; · 6.85 Impact Factor
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    ABSTRACT: A quantitative bioanalytical liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay for sepantronium bromide (YM155), an inhibitor of survivin, was developed and validated. Under reduced light exposure, plasma samples were pre-treated using protein precipitation with acetonitrile containing AT7519 as internal standard. After dilution with water, 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 detected in the selected reaction monitoring mode of a triple quadrupole mass spectrometer. The assay was validated in a 0.5-100ng/ml calibration range with r(2)=0.9981±0.0007 using double logarithmic calibration (n=5). Within day precisions (n=6) were 3.6-8.8% and between day (3 days; n=18) precisions 6.5-11.1%. Accuracies were between 92 and 111% for the whole calibration range. The light sensitive drug sepantronium was sufficiently stable under all relevant analytical conditions. Finally, the assay was successfully used to determine plasma drug levels in mice after administration of sepantronium bromide by continuous infusion from subcutaneously implanted osmotic pumps.
    Journal of pharmaceutical and biomedical analysis 01/2014; 92C:144-148. · 2.45 Impact Factor
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    ABSTRACT: Concomitant use of complementary and alternative medicine (CAM) and anticancer drugs can affect the pharmacokinetics of anticancer drugs by inhibiting the metabolizing enzyme cytochrome P450 3A4 (CYP3A4) (EC Several in vitro studies determined whether CAM can inhibit CYP3A4, but these studies revealed contradictory results. A plausible explanation for these conflicting results is the use only of a single model CYP3A4 substrate in each study. Therefore, the objective was to determine the potential of selected CAM (β-carotene, Echinacea, garlic, Ginkgo biloba, ginseng, grape seed extract, green tea extract, milk thistle, saw palmetto, valerian, vitamin B6, B12 and C) to inhibit CYP3A4-mediated metabolism of different substrates: 7-benzyloxy-4-trifluoromethyl-coumarin (BFC), midazolam and docetaxel. The effect of CAM on CYP3A4-mediated metabolism of an anticancer drug has never been determined before in vitro, which makes this study unique. The oncolytic CYP3A4 substrate docetaxel was used to establish the predictive value of the model substrates for pharmacokinetic interactions between CAM and anticancer drugs in vitro, and to more closely predict these interactions in vivo. The inhibition of CYP3A4-mediated metabolism of 7-benzyloxy-4-trifluoromethyl-coumarin (BFC) by CAM was assessed in Supersomes, using the fluorometric CYP3A4 inhibition assay. In human liver microsomes (HLM) the inhibition of CYP3A4-mediated metabolism of midazolam and docetaxel was determined, using liquid-chromatography coupled to tandem mass spectrometry (LC-MS/MS). The results confirmed grape seed and green tea as potent inhibitors and milk thistle as moderate inhibitor of CYP3A4-mediated metabolism of BFC, midazolam and docetaxel. Clinical studies are required to determine the clinical relevance of the determined CYP3A4 inhibition by grape seed, green tea and milk thistle.
    The Journal of pharmacy and pharmacology. 01/2014;
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    ABSTRACT: A sensitive and selective HPLC-MS/MS assay was used to analyze steady-state serum concentrations of tamoxifen, N-desmethyltamoxifen (E)-endoxifen, (Z)-endoxifen, N-desmethyl-4'-hydroxytamoxifen, 4-hydroxytamoxifen, and 4'-hydroxytamoxifen to support therapeutic drug monitoring (TDM) in patients treated with tamoxifen according to standard of care. When the (Z)-endoxifen serum concentration was below the predefined therapeutic threshold concentration of 5.9 ng/mL, the clinician was advised to increase the tamoxifen dose and to collect another serum sample. Paired serum samples from patients at one dose level at different time points during the tamoxifen treatment were used to assess the intra-patient variability. A total of 251 serum samples were analyzed, obtained from 205 patients. Of these patients, 197 used 20 mg tamoxifen per day and 8 patients used 10 mg/day. There was wide variability in tamoxifen and metabolite concentrations within the dosing groups. The threshold concentration for (Z)-endoxifen was reached in one patient (12 %) in the 10 mg group, in 153 patients (78 %) in the 20 mg group, and in 26 (96 %) of the patients who received a dose increase to 30 or 40 mg/day. Dose increase from 20 to 30 or 40 mg per day resulted in a significant increase in the mean serum concentrations of all analytes (p < 0.001). The mean intra-patient variability was between 10 and 20 % for all analytes. These results support the suitability of TDM for optimizing the tamoxifen treatment. It is shown that tamoxifen dose is related to (Z)-endoxifen exposure and increasing this dose leads to a higher serum concentration of tamoxifen and its metabolites. The low intra-patient variability suggests that only one serum sample is needed for TDM, making this a relatively noninvasive way to optimize the patient's treatment.
    Breast Cancer Research and Treatment 01/2014; · 4.47 Impact Factor
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    ABSTRACT: This work describes a first population pharmacokinetic (PK) model for free and total cefazolin during pregnancy, which can be used for dose regimen optimization. Secondly, analysis of PK studies in pregnant patients is challenging due to study design limitations. We therefore developed a semiphysiological modeling approach, which leveraged gestation-induced changes in creatinine clearance (CrCL) into a population PK model. This model was then compared to the conventional empirical covariate model. First, a base two-compartmental PK model with a linear protein binding was developed. The empirical covariate model for gestational changes consisted of a linear relationship between CL and gestational age. The semiphysiological model was based on the base population PK model and a separately developed mixed-effect model for gestation-induced change in CrCL. Estimates for baseline clearance (CL) were 0.119 L/min (RSE 58%) and 0.142 L/min (RSE 44%) for the empirical and semiphysiological models, respectively. Both models described the available PK data comparably well. However, as the semiphysiological model was based on prior knowledge of gestation-induced changes in renal function, this model may have improved predictive performance. This work demonstrates how a hybrid semiphysiological population PK approach may be of relevance in order to derive more informative inferences.
    BioMed research international. 01/2014; 2014:897216.
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    BioMed Research International 01/2014; 2014:1-9. · 2.88 Impact Factor
  • S Bins, J H M Schellens, E E Voest, S Sleijfer
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    ABSTRACT: - New possibilities for genetic diagnostics are rapidly assuming a place in oncological clinical practice. - Due to specific genetic aberrations, solid tumours characterised by their histological origin can now be further classified into subgroups.- The further sub-classification of tumours has led to the development of therapies that target these genetic changes.- Clinical research into these drugs in genetically characterised patient groups should be carried out more efficiently than is currently the case in oncological drug studies.- In both primary tumours and metastases, the heterogeneity of the tumour genome and the changes within this make the identification of important genetic aberrations more difficult. - In the Netherlands a network of hospitals and institutions is being set up - the Center for Personalized Cancer Treatment - to facilitate genome studies of tumours and clinical oncology studies and aimed at making the development of drugs more efficient.
    Nederlands tijdschrift voor geneeskunde 01/2014; 158:A6801.
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    ABSTRACT: High cancer mortality rates in low- and middle-income countries (LMICs) have raised concerns regarding access to oncology medicines. Essential medicines are those which satisfy the primary health care needs and provide a basis for public procurement or reimbursement decisions in LMICs. We explored selection of oncology medicines in LMICs through investigating national essential medicines lists (NEMLs) for cancer treatments. Recently updated NEMLs were retrieved for 76 countries. Oncology medicines were classified based on therapeutic categories. Countries were clustered based on geographic regions, income levels and burden of cancer (mortality and morbidity). Indicators of frequency (number of medicines), diversity (number of therapeutic (sub)categories) and more importantly absence were measured and compared across countries using parametric and nonparametric tests. The overall median number of oncology medicines on NEMLs was 16 (interquartile range = 23) chosen predominantly from subcategories of 'antineoplastic agents', with substantial variation across regions and income groups. Five countries did not select any oncology medicine and 68% did not have any 'hormones and related agents' on their NEMLs. Newer technologies like targeted therapies were infrequently incorporated. The cluster of countries suffering most from the burden of cancer selected more essential oncology medicines and diversified further. The observed selection of oncology essential medicines can reflect insufficiencies and inequalities in access to cancer treatments at least in the public sector of LMICs. Further resources need to be allocated from governments and international organizations to tackle the problem of access to oncology medicines in these countries.
    Annals of Oncology 01/2014; 25(1):270-6. · 7.38 Impact Factor
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    ABSTRACT: Aim To quantify the effect of food on the systemic exposure of lapatinib at steady state when administered 1 h before and after meals, and to observe the safety and tolerability of lapatinib under these conditions in patients with advanced solid tumours. Methods This was a three-treatment, randomised, three-sequence cross-over study. Lapatinib was administered 1 h after a low- [B] or a high-fat [C] meal and systemic exposure was compared with that obtained following administration 1 h before a low-fat meal [A]. Results In total, 25 patients were included, of whom 12 were evaluable for the pharmacokinetic analysis. Both low-fat and high-fat meals affected lapatinib exposure. Lapatinib AUC0-24 increased following lapatinib administration 1 h after a low-fat meal by 1.80-fold (90 % CI: 1.37-2.37) and after a high-fat meal by 2.61-fold (90 % CI: 1.98-3.43). Lapatinib Cmax increased following lapatinib administration 1 h after a low-fat meal by 1.90-fold (90 % CI: 1.49-2.43) and after a high-fat meal by 2.66-fold (90 % CI: 2.08-3.41). The most commonly occurring treatment-related toxicity was diarrhoea (8/25, 32 % CTCAE grade 1 and 2/25, 8 % grade 2) and one treatment-related grade ≥ 3 event occurred (fatigue grade 3, 4 %). Conclusions Both low-fat and high-fat food consumed 1 h before lapatinib administration increased lapatinib systemic exposure compared with lapatinib administration 1 h before a low-fat meal. In order to administer lapatinib in a fasted state, it is advised to administer the drug 1 h before a meal.
    Investigational New Drugs 12/2013; · 3.50 Impact Factor
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    ABSTRACT: An oral extended-release (ER) formulation of capecitabine was developed for twice daily dosing, theoretically providing a continuous exposure to capecitabine, thus avoiding the undesirable in-between dosing gap inherent to the dosing schedule of the marketed capecitabine immediate-release formulation (Xeloda(®) ). The target 12-hour in vivo release profile was correlated to an in vitro dissolution profile using an in vitro-in vivo correlation model based on the pharmacokinetic (PK) and dissolution characteristics of Xeloda(®) . Making use of the slow dissolution characteristics of amorphous capecitabine as reported previously and screening of a panel of ER excipients, an ER formulation was designed. Kollidon(®) SR induced the most prominent ER. Moreover, it was shown that tablets prepared from CoSD capecitabine and Kollidon(®) SR have an additional threefold delay in dissolution compared with tablets prepared from the same but only physically mixed components. Therefore, a prototype tablet formulation composed of co-spray-dried capecitabine and Kollidon(®) SR (98/2%, w/w) mixed with colloidal silicon dioxide (0.5%, w/w) and magnesium stearate (2.5%, w/w) was defined. This prototype shows similar dissolution characteristics as the modelled dissolution profile. Currently, the in vivo PK of our designed ER capecitabine formulations is investigated in a clinical study. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci.
    Journal of Pharmaceutical Sciences 12/2013; · 3.13 Impact Factor
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    ABSTRACT: The objectives of this study were to evaluate the plasma concentrations of the tyrosine kinase inhibitors (TKIs), imatinib, erlotinib, and sunitinib, in a cohort of patients with cancer in routine clinical practice and to find the possible factors related to plasma concentrations below the target level. An observational study was performed in an unselected cohort of patients using TKIs for cancer treatment. Randomly timed plasma samples were drawn together with regular laboratory investigations during routine outpatient clinic visits. The plasma concentrations of TKIs were determined using a validated high-performance liquid chromatography coupled with tandem mass spectrometry detection method. Trough concentrations were estimated using the interval between the last dose intake and blood sampling and the mean elimination half-life of the TKIs and were compared with target trough concentrations. Outpatient medical records were reviewed to collect data on patient- and medication-related factors that could have contributed to the variation in TKI plasma concentrations. Only 26.8%, 88.9%, and 51.4% of the calculated trough plasma concentrations of imatinib, erlotinib, and sunitinib samples, respectively, reached the predefined target concentration (imatinib: 1100 ng/mL, erlotinib: 500 ng/mL, and sunitinib: 50 ng/mL). Interpatient variability was high with coefficients of variation of 39.1%, 40.1%, and 29.2% for imatinib, erlotinib, and sunitinib, respectively. High variation in plasma concentrations could only partly be explained by patient- or medication related factors. Almost half of the plasma concentrations in the outpatient population seemed to be below the target level with a risk of treatment failure. It is not possible to predict which patients are at a risk of plasma concentrations below the target level based on patient- or medication-related factors. Thus, therapeutic drug monitoring could play a crucial role in routine cancer care to identify patients that are in need of individual adjusted dosages. Further research is required to investigate the safety and efficacy of therapeutic drug monitoring.
    Therapeutic drug monitoring 12/2013; · 2.43 Impact Factor
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    ABSTRACT: Structural uncertainty relates to differences in model structure and parameterization. For many published health economic analyses in oncology, substantial differences in model structure exist, leading to differences in analysis outcomes and potentially impacting decision-making processes. The objectives of this analysis were (1) to identify differences in model structure and parameterization for cost-effectiveness analyses (CEAs) comparing tamoxifen and anastrazole for adjuvant breast cancer (ABC) treatment; and (2) to quantify the impact of these differences on analysis outcome metrics. The analysis consisted of four steps: (1) review of the literature for identification of eligible CEAs; (2) definition and implementation of a base model structure, which included the core structural components for all identified CEAs; (3) definition and implementation of changes or additions in the base model structure or parameterization; and (4) quantification of the impact of changes in model structure or parameterizations on the analysis outcome metrics life-years gained (LYG), incremental costs (IC) and the incremental cost-effectiveness ratio (ICER). Eleven CEA analyses comparing anastrazole and tamoxifen as ABC treatment were identified. The base model consisted of the following health states: (1) on treatment; (2) off treatment; (3) local recurrence; (4) metastatic disease; (5) death due to breast cancer; and (6) death due to other causes. The base model estimates of anastrazole versus tamoxifen for the LYG, IC and ICER were 0.263 years, 3,647 and 13,868/LYG, respectively. In the published models that were evaluated, differences in model structure included the addition of different recurrence health states, and associated transition rates were identified. Differences in parameterization were related to the incidences of recurrence, local recurrence to metastatic disease, and metastatic disease to death. The separate impact of these model components on the LYG ranged from 0.207 to 0.356 years, while incremental costs ranged from 3,490 to 3,714 and ICERs ranged from 9,804/LYG to 17,966/LYG. When we re-analyzed the published CEAs in our framework by including their respective model properties, the LYG ranged from 0.207 to 0.383 years, IC ranged from 3,556 to 3,731 and ICERs ranged from 9,683/LYG to 17,570/LYG. Differences in model structure and parameterization lead to substantial differences in analysis outcome metrics. This analysis supports the need for more guidance regarding structural uncertainty and the use of standardized disease-specific models for health economic analyses of adjuvant endocrine breast cancer therapies. The developed approach in the current analysis could potentially serve as a template for further evaluations of structural uncertainty and development of disease-specific models.
    PharmacoEconomics 11/2013; · 2.86 Impact Factor
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    ABSTRACT: Azacitidine is a cytidine analog used in the treatment of myelodysplastic syndromes, chronic myelomonocytic leukemia and acute myeloid leukemia. The pharmacological effect of azacitidine arises after incorporation into the DNA and RNA. To this end, the drug first has to be converted into its triphosphate forms. This paper describes the development of an assay for quantitative determination of azacitidine triphosphate (aza-CTP) in peripheral blood mononuclear cells (PBMCs). To quantify aza-CTP, separation from the endogenous nucleotides cytidine triphosphate (CTP) and uridine triphosphate (UTP) is required. This was a challenge as the structures of these nucleotides are highly similar and the monoisotopic molecular masses of aza-CTP, UTP and the naturally occurring [(13)C]- and [(15)N]-isotopes of CTP differ less than 0.02Da. Efforts to select a specific MS(2)-fragment for aza-CTP using a triple quadrupole mass spectrometer remained without success. Therefore, we investigated the feasibility to separate these highly resembling nucleotides based on accurate mass spectrometry using a linear trap quadrupole (LTQ) coupled with an Orbitrap. The LTQ-Orbitrap was able to differentiate between aza-CTP and the endogenous nucleotides UTP and [(13)C]-CTP. There was no baseline resolution between aza-CTP and [(15)N]-CTP, but the [(15)N]-CTP interference was low. For quantification, extracted ion chromatograms were obtained for the accurate m/z window of the aza-CTP product ion. The assay was able to determine aza-CTP concentrations in PBMC lysate from 40.7 to 281nM. Assuming that an average cell suspension extracted from 16mL blood contains 10 to 42 million PBMCs per mL, this range corresponds with 2.58/10.9-17.8/74.9pmol aza-CTP per million PBMCs. Intra-assay accuracies were between -1.1 and 9.5% deviation and coefficient of variation values were ≤13.2%. The assay was successfully applied to quantify aza-CTP in samples from two patients treated with azacitidine. Aza-CTP concentrations up to 19.0pmol per million PBMCs were measured. This is the first time that aza-CTP concentrations were quantified in PBMCs from patients treated with azacitidine.
    Journal of pharmaceutical and biomedical analysis 11/2013; 90C:7-14. · 2.45 Impact Factor
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    ABSTRACT: The wide inter-patient variability in drug exposure partly explains the toxicity and efficacy profile of sunitinib treatment. In this prospective study cytochrome P450 (CYP) 3A and adenosine triphosphate binding cassette (ABC) B1 phenotypes were correlated to the pharmacokinetics of sunitinib and its active metabolite N-desethylsunitinib. A correlation analysis was performed between sunitinib pharmacokinetics and 1'OH-midazolam/midazolam ratio and parameters derived from technetium-99m-2-methoxy isobutyl isonitrile ((99m)Tc-MIBI) scans, respectively. A population pharmacokinetic model using non-linear mixed-effects modeling software NONMEM was built, which included the phenotype tests as covariate. In 52 patients, the mean trough concentration of sunitinib plus metabolite increased from 21.4 ng/mL at day 1 of a cycle to 88.1 ng/mL in the fourth week of treatment. A trend for a correlation was observed between (99m)Tc-MIBI elimination constant and trough concentrations of N-desethylsunitinib; however, this was not significant. Correlations were found between 1'OH-midazolam/midazolam ratio and sunitinib clearance (P = 0.008) and day 1 N-desethylsunitinib trough concentrations (P = 0.005), respectively. Moreover, patients suffering from grade 3 toxicities had significant lower clearance of sunitinib than patients without grade 3 toxicities (34.4 vs. 41.4 L/h; P = 0.025). Phenotype tests for ABCB1 and CYP3A4 did not explain inter-individual variability of sunitinib exposure sufficiently. However, the correlation between sunitinib clearance and the occurrence of severe toxicity suggests a direct exposure-toxicity relationship.
    Clinical Pharmacokinetics 11/2013; · 6.11 Impact Factor

Publication Stats

11k Citations
2,827.83 Total Impact Points


  • 1995–2014
    • Universiteit Utrecht
      • • Department of Pharmaceutical Sciences
      • • Division of Biomedical Analysis
      • • Division of Toxicology
      • • Division of Veterinary Pharmaceuticals, Pharmacology and Toxicology
      Utrecht, Utrecht, Netherlands
  • 1993–2014
    • Netherlands Cancer Institute
      • • Department of Clinical Pharmacology
      • • Division of Molecular Pathology
      • • Department of Medical Oncology
      • • Division of Experimental Therapy
      • • Division of Molecular Biology
      • • Department of Neuro-oncology
      Amsterdamo, North Holland, Netherlands
  • 2013
    • University of Amsterdam
      • Faculty of Medicine AMC
      Amsterdamo, North Holland, Netherlands
    • Rijnstate Hospital
      Arnheim, Gelderland, Netherlands
  • 1994–2013
    • Slotervaartziekenhuis
      Amsterdamo, North Holland, Netherlands
  • 2012
    • Nederlands Jeugd Instituut
      Utrecht, Utrecht, Netherlands
    • Queen's University Belfast
      • Centre for Cancer Research and Cell Biology
      Béal Feirste, N Ireland, United Kingdom
  • 2009–2012
    • University Medical Center Utrecht
      Utrecht, Utrecht, Netherlands
  • 2001–2012
    • Uppsala University
      • Department of Pharmacy
      Uppsala, Uppsala, Sweden
  • 2011
    • Dana-Farber Cancer Institute
      • Carole M. and Philip L. Lowe Center for Thoracic Oncology
      Boston, MA, United States
    • Cantonal Hospital of Schwyz
      Schwyz, Schwyz, Switzerland
  • 2007–2011
    • Kantonsspital St. Gallen
      San Gallo, Saint Gallen, Switzerland
    • Leiden University Medical Centre
      • Department of Clinical Pharmacy and Toxicology
      Leyden, South Holland, Netherlands
    • Insitute de Cancérologie de l'Ouest - Centre René Gauducheau
      Naoned, Pays de la Loire, France
  • 2010
    • Institute of Cancer Research
      Londinium, England, United Kingdom
  • 2002–2010
    • Academisch Medisch Centrum Universiteit van Amsterdam
      • Department of Medical Oncology
      Amsterdam, North Holland, Netherlands
    • Institut de Cancérologie Gustave Roussy
      • Department of Radiotherapy
      Île-de-France, France
  • 2008–2009
    • Astellas Pharmaceutical
      Northbrook, Illinois, Japan
    • Atrium Medisch Centrum Parkstad
      Heerlen, Limburg, Netherlands
  • 2004
    • University of Washington Seattle
      • Department of Medicine
      Seattle, WA, United States
    • VU University Medical Center
      Amsterdamo, North Holland, Netherlands
  • 2002–2004
    • Wyeth
      New Johnsonville, Tennessee, United States
  • 2003
    • Centre Jean Perrin
      Clermont, Auvergne, France
    • University of Antwerp
      Antwerpen, Flanders, Belgium
  • 1999–2001
    • Institut Bergonié
      Burdeos, Aquitaine, France
  • 1996–1999
    • Erasmus MC
      • Department of Internal Oncology
      Rotterdam, South Holland, Netherlands
  • 1998
    • University of Glasgow
      Glasgow, Scotland, United Kingdom
  • 1991
    • Leiden University
      Leyden, South Holland, Netherlands