| 1. |
- Berglund, Erik, et al.
(författare)
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Intracellular concentration of the tyrosine kinase inhibitor imatinib in gastrointestinal stromal tumor cells.
- 2014
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Ingår i: Anti-Cancer Drugs. - 0959-4973 .- 1473-5741. ; 25:4, s. 415-22
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Tidskriftsartikel (refereegranskat)abstract
- Gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm in the gastrointestinal tract. In most GISTs, the underlying mechanism is a gain-of-function mutation in the KIT or the PDGFRA gene. Imatinib is a tyrosine kinase inhibitor that specifically blocks the intracellular ATP-binding sites of these receptors. A correlation exists between plasma levels of imatinib and progression-free survival, but it is not known whether the plasma concentration correlates with the intracellular drug concentration. We determined intracellular imatinib levels in two GIST cell lines: the imatinib-sensitive GIST882 and the imatinib-resistant GIST48. After exposing the GIST cells to imatinib, the intracellular concentrations were evaluated using LC-MS (TOF). The concentration of imatinib in clinical samples from three patients was also determined to assess the validity and reliability of the method in the clinical setting. Determination of imatinib uptake fits within detection levels and values are highly reproducible. The GIST48 cells showed significantly lower imatinib uptake compared with GIST882 in therapeutic doses, indicating a possible difference in uptake mechanisms. Furthermore, imatinib accumulated in the tumor tissues and showed intratumoral regional differences. These data show, for the first time, a feasible and reproducible technique to measure intracellular imatinib levels in experimental and clinical settings. The difference in the intracellular imatinib concentration between the cell lines and clinical samples indicates that drug transporters may contribute toward resistance mechanisms in GIST cells. This highlights the importance of further clinical studies to quantify drug transporter expression and measure intracellular imatinib levels in GIST patients.
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| 2. |
- Skoglund, Karin, et al.
(författare)
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In vivo CYP3A activity and pharmacokinetics of imatinib in relation to therapeutic outcome in chronic myeloid leukemia patients
- 2016
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Ingår i: Therapeutic Drug Monitoring. - 0163-4356 .- 1536-3694. ; 38:2, s. 230-238
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: CYP3A metabolic activity varies between individuals and is therefore a possible candidate of influence on the therapeutic outcome of the tyrosine kinase inhibitor imatinib in chronic myeloid leukemia (CML) patients. The aim of this study was to investigate the influence of CYP3A metabolic activity on the plasma concentration and outcome of imatinib in CML patients.METHODS: Forty-three CML patients were phenotyped for CYP3A activity using quinine as a probe drug and evaluated for clinical response parameters. Plasma concentrations of imatinib and its main metabolite, CGP74588, were determined using liquid chromatography-mass spectrometry.RESULTS: Patients with optimal response to imatinib after 12 months of therapy did not differ in CYP3A activity compared to non-optimal responders (quinine metabolic ratio of 14.69 and 14.70, respectively; P=0.966). Neither the imatinib plasma concentration nor the CGP74588/imatinib ratio was significantly associated with CYP3A activity.CONCLUSIONS: CYP3A activity does not influence imatinib plasma concentrations or the therapeutic outcome. These results indicate that even though imatinib is metabolized by CYP3A enzymes, this activity is not the rate-limiting step in imatinib metabolism and excretion. Future studies should focus on other pharmacokinetic processes so as to identify the major contributor to patient variability in imatinib plasma concentrations.
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| 3. |
- Skoglund, Karin, et al.
(författare)
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In Vivo Cytochrome P450 3A Isoenzyme Activity and Pharmacokinetics of Imatinib in Relation to Therapeutic Outcome in Patients With Chronic Myeloid Leukemia
- 2016
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Ingår i: Therapeutic Drug Monitoring. - : LIPPINCOTT WILLIAMS & WILKINS. - 0163-4356 .- 1536-3694. ; 38:2, s. 230-238
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Tidskriftsartikel (refereegranskat)abstract
- Background: Cytochrome P450 3A (CYP3A) isoenzyme metabolic activity varies between individuals and is therefore a possible candidate of influence on the therapeutic outcome of the tyrosine kinase inhibitor imatinib in patients with chronic myeloid leukemia (CML). The aim of this study was to investigate the influence of CYP3A metabolic activity on the plasma concentration and outcome of imatinib in patients with CML. Methods: Forty-three patients with CML were phenotyped for CYP3A activity using quinine as a probe drug and evaluated for clinical response parameters. Plasma concentrations of imatinib and its main metabolite, CGP74588, were determined using liquid chromatography-mass spectrometry. Results: Patients with optimal response to imatinib after 12 months of therapy did not differ in CYP3A activity compared to nonoptimal responders (quinine metabolic ratio of 14.69 and 14.70, respectively; P = 0.966). Neither the imatinib plasma concentration nor the CGP74588/imatinib ratio was significantly associated with CYP3A activity. Conclusions: The CYP3A activity does not influence imatinib plasma concentrations or the therapeutic outcome. These results indicate that although imatinib is metabolized by CYP3A enzymes, this activity is not the rate-limiting step in imatinib metabolism and excretion. Future studies should focus on other pharmacokinetic processes so as to identify the major contributor to patient variability in imatinib plasma concentrations.
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| 4. |
- Ubhayasekera, S. J. Kumari A., et al.
(författare)
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Simultaneous quantification of imatinib and CGP74588 in human plasma by liquid chromatography-time of flight mass spectrometry (LC-TOF-MS)
- 2016
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Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9660 .- 1759-9679. ; 8:15, s. 3046-3054
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Tidskriftsartikel (refereegranskat)abstract
- Imatinib mesylate is widely used for the treatment of different types of cancer, such as chronic myelogenous leukemia and gastrointestinal stromal tumors. It is a tyrosine kinase inhibitor that binds to the active site of the enzyme inhibiting it. In clinical toxicology, a fast and sensitive quantification method for monitoring the imatinib concentration in blood can be very useful for personalized treatments. The aim of this study was to propose an alternative novel analytical method (LC-TOF-MS) for the quantification of intracellular imatinib and its main metabolite in human plasma. The method is simple and fast. It has sufficient sensitivity for the quantification of imatinib and its main metabolite CGP74588 in a smaller volume of plasma. The linearity of the method was evaluated over the range of concentrations (0.02-5 mu g mL(-1)) of imatinib and CGP74588 in human plasma. The correlation coefficients (r(2)) were close to 1 for both analytes. The limit of quantification was 0.02 mu g mL(-1) for both imatinib and CGP74588. A number of (>50) chronic myelogenous leukemia patient plasma samples have been analyzed by this method obtaining values ranging from 0.19-4.53 and 0.03-0.84 mu g mL(-1) for imatinib and CGP74588, respectively. This novel method allows a specific, sensitive and reliable simultaneous determination of intracellular imatinib and CGP74588 in a single chromatographic run, which is suitable for routine clinical practice.
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