Kateřina Mičová

Abbreviations of metabolites used in targeted metabolomic analysis. Tables S2, S3. Results of analysis of CSF from confirmatory study: targeted analysis (Table S2) and untargeted (Table S3). Table S4. Twenty most discriminating features from untargeted analysis of brain tissue samples. Figure S1. Expression levels of insoluble tau proteins in brainstem of transgenic animals used for study. Figures S2, S3, S4, S5, S6, S7. OPLS-DA score scatterplots and S-plots built for targeted and untargeted metabolomics: CSF targeted (Fig. S2) and untargeted (Fig. S5) metabolomics, plasma targeted (Fig. S3) and untargeted (Fig. S6) metabolomics, brain tissue targeted (Fig. S4) and untargeted (Fig. S7) metabolomics. Figures S8, S9. OPLS-DA score scatterplots and S-plots built for targeted and untargeted metabolomics of CSF in confirmation study: targeted (Fig. S8) and untargeted (Fig. S9) metabolomics. Figure S10. Box plots of most discriminating features of brain tissue samples in untargeted metab...

Untargeted metabolite profiling using high-resolution mass spectrometry coupled with liquid chromatography (LC-HRMS), followed by data analysis with the Compound Discoverer 2.0™ software, was used to study the metabolism of imatinib in humans with chronic myeloid leukemia. Plasma samples from control (drug-free) and patient (treated with imatinib) groups were analyzed in full-scan mode and the unknown ions occurring only in the patient group were then, as potential imatinib metabolites, subjected to multi-stage fragmentation in order to elucidate their structure. The application of an untargeted approach, as described in this study, enabled the detection of 24 novel structurally unexpected metabolites. Several sulphur-containing compounds, probably originating after the reaction of reactive intermediates of imatinib with endogenous glutathione, were found and annotated as cysteine and cystine adducts. In the proposed mechanism, the cysteine adducts were formed after the rearrangemen...

With an increasing number of cancer patients receiving tyrosine kinase inhibitors (TKIs), therapeutic drug monitoring of these molecules is becoming more widespread today. It is mainly based on liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) methods with typical run times of several minutes. In an online solid phase extraction-MS/MS (SPE-MS/MS) system, the chromatography column is replaced with a reusable solid phase extraction (SPE) cartridge and the analysis time is shortened to less than half a minute. The aim of this study was to develop such a method and test the performance of this high-throughput system in the analysis of imatinib (IMA), nilotinib (NIL), and lapatinib (LAP) in human plasma. Samples were prepared by simple protein precipitation with methanol containing deuterated internal standards. After centrifugation, the supernatant was diluted 10 fold with a mixture of methanol and water (1:1). A C4 cartridge was used for SPE and the analytes were eluted by acetonitrile. All the analytes were measured within a wide calibration range (50-5000 ng/mL for nilotinib and imatinib, 100-10,000 ng/mL for lapatinib). The method was compared with the LC-MS/MS method by the analysis of 176 clinical samples. Intraday and interday inaccuracies within 15% and a coefficient of variation less than 15% were achieved for all the TKIs that were measured. Even though the matrix effects were higher in comparison with LC-MS/MS methods, their effect on the performance of the method was eliminated by the usage of deuterated internal standards. The total run time of the new method was 29 seconds for one analysis and the results were fully comparable with LC-MS/MS. Routine clinical practice requiring high-throughput methods for therapeutic drug monitoring of TKIs may benefit from the online SPE-MS/MS method that provides fast, low-cost analysis, and results that are comparable with conventional methods.

5-Ethynyl-2'-deoxyuridine (EdU) and 5-ethynyl-2'-deoxycytidine (EdC) are mainly used as markers of cellular replicational activity. Although EdU is employed as a replicational marker more frequently than EdC, its cytotoxicity is commonly much higher than the toxicity of EdC. To reveal the reason of the lower cytotoxicity of EdC, we performed a DNA analysis of five EdC-treated human cell lines. Surprisingly, not a single one of the tested cell lines contained a detectable amount of EdC in their DNA. Instead, the DNA of all the cell lines contained EdU. The content of incorporated EdU differed in particular cells and EdC-related cytotoxicity was directly proportional to the content of EdU. The results of experiments with the targeted inhibition of the cytidine deaminase (CDD) and dCMP deaminase activities indicated that the dominant role in the conversion pathway of EdC to EdUTP is played by CDD in HeLa cells. Our results also showed that the deamination itself was not able to...

The information about CML patients with a deep molecular response of ≥4.5 log reduction (MR(4.5)) in whom the dose of imatinib (IM) had to be reduced to relieve toxicity is insufficient. In 205 CML patients the dose of IM was reduced in 19 (31.2%) out of 61 patients with MR(4.5). The patients (12 pretreated with interferon-alpha) achieved MR(4.5) after an average of 27.7 months. The duration of MR(4.5) before the reduction of the dose was 16-123 (m=56.7) months. After the IM reduction (200mg daily - 400mg twice weekly for 15-90 (m=48) months) MR(4.5) or MMR was maintained in 14 (73.7%) and 2 (10.5%) patients, respectively. 3 patients who lost MMR (15.8%) after the discontinuation of IM regained MR(4.5) after the reintroduction of a lower dose. A lower dosage of IM should be tested for the management of side effects in patients with MR(4.5) in prospective studies.

Modern high resolution mass spectrometry offers unique identification capability in drug metabolism studies. In this work detailed imatinib metabolization in the plasma of patients with chronic myeloid leukemia is presented. The metabolites were separated by liquid chromatography on a C18 column with mass spectrometry detection via an Orbitrap Elite instrument (Thermo Scientific) based on exact mass measurement. A scan range of m/z 350-1200 resolution of 60,000 was applied (mass accuracy of 5ppm). The data were evaluated using the advanced software for mass spectrometry Mass Frontier and MetWorks. In all plasma samples, studied 90 metabolites in the concentration range of 0.0001-1μmol/L were identified by m/z values and confirmed by exact mass measurement of the MS(2) and MS(3) fragmentations. In order to achieve optimal clinical response and avoid toxicity, current therapeutic monitoring of parent drug is a useful tool for the individualization of treatment. Current high-resolution mass spectrometry possesses the potential to broaden this approach by monitoring number of potentially clinically relevant drug metabolites.

Modern high resolution mass spectrometry offers unique identification capability in drug metabolism studies. In this work detailed imatinib metabolization in the plasma of patients with chronic myeloid leukemia is presented. The metabolites were separated by liquid chromatography on a C18 column with mass spectrometry detection via an Orbitrap Elite instrument (Thermo Scientific) based on exact mass measurement. A scan range of m/z 350-1200 resolution of 60,000 was applied (mass accuracy of 5ppm). The data were evaluated using the advanced software for mass spectrometry Mass Frontier and MetWorks. In all plasma samples, studied 90 metabolites in the concentration range of 0.0001-1μmol/L were identified by m/z values and confirmed by exact mass measurement of the MS(2) and MS(3) fragmentations. In order to achieve optimal clinical response and avoid toxicity, current therapeutic monitoring of parent drug is a useful tool for the individualization of treatment. Current high-resolution mass spectrometry possesses the potential to broaden this approach by monitoring number of potentially clinically relevant drug metabolites.

The information about CML patients with a deep molecular response of ≥4.5 log reduction (MR(4.5)) in whom the dose of imatinib (IM) had to be reduced to relieve toxicity is insufficient. In 205 CML patients the dose of IM was reduced in 19 (31.2%) out of 61 patients with MR(4.5). The patients (12 pretreated with interferon-alpha) achieved MR(4.5) after an average of 27.7 months. The duration of MR(4.5) before the reduction of the dose was 16-123 (m=56.7) months. After the IM reduction (200mg daily - 400mg twice weekly for 15-90 (m=48) months) MR(4.5) or MMR was maintained in 14 (73.7%) and 2 (10.5%) patients, respectively. 3 patients who lost MMR (15.8%) after the discontinuation of IM regained MR(4.5) after the reintroduction of a lower dose. A lower dosage of IM should be tested for the management of side effects in patients with MR(4.5) in prospective studies.

Therapeutic drug monitoring is recommended for the optimal management of patients with several malignant diseases. The aim of this study was to develop and validate an isotope dilution direct injection mass spectrometry method for the high throughput determination of tyrosine kinase inhibitors in plasma from leukemic and cancer patients. The plasma for analysis was deproteinated by methanol and the centrifuged supernatant was directly injected to mass spectrometer without separation step. Multiple reaction monitoring modes on a hybrid triple quadrupole - linear ion trap mass spectrometer (5500 QTRAP) were used for the detection and quantification of imatinib, nilotinib, lapatinib, and dasatinib. We developed a fast method with analysis time of 55 s and 19s in multiple injection setting. The method was successfully validated and applied to the patient plasma samples. In order to overcome insufficient sensitivity of dasatinib, multiple reaction monitoring cube mode in linear ion trap ...

The aim of this study was to develop, validate and compare flow injection analysis (FIA) and ultra-high-performance liquid chromatography (LC)/tandem mass spectrometry methods for the determination of imatinib in plasma from patients with chronic myeloid leukemia. The plasma for analysis by both methods was deproteinated by methanol containing d8-imatinib. The separation was achieved on a 1.7 μm C18 column with a linear gradient (4 mM ammonium formiate and acetonitrile, pH 3.2). FIA was performed at flow rate of 0.03 mL/min (0.1% formic acid in methanol). Multiple reaction monitoring mode on the tandem mass spectrometer (API 4000, AB Sciex) in positive ESI were used for detection. The total analysis times were 3.2 (LC) and 0.75 min (FIA). Both methods were successfully validated and applied to the plasma patients samples. The limits of quantification were 4.1 and 30.8 ng/mL; imprecisions were less than 5.7% and recovery ranged between 93 and 105%, for the LC and FIA, respectively. The methods revealed an agreement with a mean difference of 1.46 ng/mL (SD 28.95 ng/mL). The high-throughput methods that were developed are suitable for the therapeutic drug monitoring of imatinib in plasma. They can be used in routine clinical practice.

Therapeutic drug monitoring is recommended for the optimal management of patients with several malignant diseases. The aim of this study was to develop and validate an isotope dilution direct injection mass spectrometry method for the high throughput determination of tyrosine kinase inhibitors in plasma from leukemic and cancer patients. The plasma for analysis was deproteinated by methanol and the centrifuged supernatant was directly injected to mass spectrometer without separation step. Multiple reaction monitoring modes on a hybrid triple quadrupole - linear ion trap mass spectrometer (5500 QTRAP) were used for the detection and quantification of imatinib, nilotinib, lapatinib, and dasatinib. We developed a fast method with analysis time of 55 s and 19s in multiple injection setting. The method was successfully validated and applied to the patient plasma samples. In order to overcome insufficient sensitivity of dasatinib, multiple reaction monitoring cube mode in linear ion trap (MRM(3)) was successfully applied. The limits of quantification were in the range 1.0-5.5 ng/ml. Imprecisions were lower than 6.9% and the accuracy of the quality control samples ranged between 99.0 and 107.9%. Isotope dilution direct injection mass spectrometry method allows high-throughput therapeutic drug monitoring of tyrosine kinase inhibitors in plasma. The method offers low-cost analyses as a result of its speed and the exclusion of separation step and can be advantageously used in routine clinical practice. The method can be applied on various drugs and biochemical markers with the use of triple quadrupole instruments.

The aim of this study was to develop, validate and compare flow injection analysis (FIA) and ultra-high-performance liquid chromatography (LC)/tandem mass spectrometry methods for the determination of imatinib in plasma from patients with chronic myeloid leukemia. The plasma for analysis by both methods was deproteinated by methanol containing d8-imatinib. The separation was achieved on a 1.7 μm C18 column with a linear gradient (4 mM ammonium formiate and acetonitrile, pH 3.2). FIA was performed at flow rate of 0.03 mL/min (0.1% formic acid in methanol). Multiple reaction monitoring mode on the tandem mass spectrometer (API 4000, AB Sciex) in positive ESI were used for detection. The total analysis times were 3.2 (LC) and 0.75 min (FIA). Both methods were successfully validated and applied to the plasma patients samples. The limits of quantification were 4.1 and 30.8 ng/mL; imprecisions were less than 5.7% and recovery ranged between 93 and 105%, for the LC and FIA, respectively. The methods revealed an agreement with a mean difference of 1.46 ng/mL (SD 28.95 ng/mL). The high-throughput methods that were developed are suitable for the therapeutic drug monitoring of imatinib in plasma. They can be used in routine clinical practice.

Despite the prognostic value of trough imatinib plasma levels (IPL) identified in some studies, no recommendations for the use of IPL results in routine management of CML patients have been issued. We report two patients in whom daily imatinib dose was increased from 400 to 600 or 800 mg because of low IPL found at various intervals from the beginning of treatment (7 measurements; mean IPL values = 616.33 and 764.5 ng/mL, respectively). Both patients achieved suboptimal response according to the European LeukemiaNet criteria (complete cytogenetic response was not achieved after 1 year of treatment in patient 1 and major molecular response after 47 months of standard-dose imatinib therapy in patient 2). In addition, we have demonstrated low hOCT-1 expression at diagnosis in both patients, retrospectively. Escalation of imatinib daily dose resulted in a significant increase of IPL (6 measurements; mean = 1790 and 1416.66 ng/mL, respectively) and in the achievement of complete cytogenetic response in patient 1 after 3 months and major molecular response within 15 and 6 months in both patients. Our cases demonstrate that low IPL identified at various non-predefined intervals from the beginning of therapy may be used for deciding on dose escalation in selected CML patients in the routine clinical setting, especially in cases with suboptimal treatment response.

Association of trough imatinib plasma levels (IPL) with cytogenetic or molecular response to treatment in patients with chronic myeloid leukemia (CML) was repeatedly reported. We analyzed their value in the routine clinical setting in 131 patients with chronic phase CML in whom imatinib was applied as first- or second-line treatment. A total of 1,118 measurements were obtained by ultra-performance liquid chromatography-tandem mass spectrometry assay in patients treated with daily dose of imatinib ranging from 100 to 800 mg. Samples were obtained from 1 to 96 h after drug ingestion. High inter (36%) and intraindividual variability (9-33%) of IPL was observed. For analysis of correlation of IPL with treatment response, two sets of samples were selected according to the European LeukemiaNet (ELN) criteria. The first set consisted of 241 samples taken 24 ± 2 h after dosing in 54 patients, and the second one consisted of 329 samples taken 24 ± 4 h after imatinib ingestion in 84 patients. In both sets, only patients treated with 400 mg imatinib once daily for at least 18 months were included. From multiple measurements in individual patients, mean IPL were used. In both sets, we were not able to demonstrate a statistically significant correlation between IPL and response to treatment according to the ELN. We believe that this was due to the differences in patients' compliance, leukemia biology, and other variables that are difficult to eliminate in the routine clinical practice. The use of IPL for prognostic estimation in CML treatment outside the clinical trials is probably limited.