liu.seSearch for publications in DiVA
Change search
Refine search result
1 - 21 of 21
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Coulthard, Sally A
    et al.
    Newcastle University.
    Redfern, Christopher P F
    Linköping University, Department of Medical and Health Sciences, Pharmacology. Linköping University, Faculty of Health Sciences.
    Lindqvist Appell, Malin
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Skoglund, Karin
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Jakobsen Falk, Ingrid
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Hall, Andrew G
    Newcastle University.
    Taylor, Gordon A
    Newcastle University.
    Hogarth, Linda A
    Newcastle University.
    Increased Sensitivity to Thiopurines in Methylthioadenosine Phosphorylase-Deleted Cancers2011In: MOLECULAR CANCER THERAPEUTICS, ISSN 1535-7163, Vol. 10, no 3, p. 495-504Article in journal (Refereed)
    Abstract [en]

    The thiopurines, 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG), are used in the treatment of leukemia. Incorporation of deoxythioguanosine nucleotides (dG(s)) into the DNA of thiopurine-treated cells causes cell death, but there is also evidence that thiopurine metabolites, particularly the 6-MP metabolite methylthioinosine monophosphate (MeTIMP), inhibit de novo purine synthesis (DNPS). The toxicity of DNPS inhibitors is influenced by methylthioadenosine phosphorylase (MTAP), a gene frequently deleted in cancers. Because the growth of MTAP-deleted tumor cells is dependent on DNPS or hypoxanthine salvage, we would predict such cells to show differential sensitivity to 6-MP and 6-TG. To test this hypothesis, sensitivity to 6-MP and 6-TG was compared in relation to MTAP status using cytotoxicity assays in two MTAP-deficient cell lines transfected to express MTAP: the T-cell acute lymphoblastic leukemic cell line, Jurkat, transfected with MTAP cDNA under the control of a tetracycline-inducible promoter, and a lung cancer cell line (A549-MTAP(-)) transfected to express MTAP constitutively (A549-MTAP(+)). Sensitivity to 6-MP or methyl mercaptopurine riboside, which is converted intracellularly to MeTIMP, was markedly higher in both cell lines under MTAP(-) conditions. Measurement of thiopurine metabolites support the hypothesis that DNPS inhibition is a major cause of cell death with 6-MP, whereas dG(s) incorporation is the main cause of cytotoxicity with 6-TG. These data suggest that thiopurines, particularly 6-MP, may be more effective in patients with deleted MTAP.

  • 2.
    Coulthard, Sally
    et al.
    Newcastle University, UK.
    Redfern, Christopher
    Newcastle University, UK.
    Vikingsson, Svante
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Lindqvist Appell, Malin
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Skoglund, Karin
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Jakobsen Falk, Ingrid
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Hall, Andrew
    Newcastle University, UK.
    Taylor, Gordon
    Newcastle University, UK.
    Hogarth, Linda
    Newcastle University, UK.
    Increased sensitivity to thiopurines in methylthioadenosine phosphorylase-deleted cancers in PURINERGIC SIGNALLING, vol 6, issue , pp 33-332010In: PURINERGIC SIGNALLING, Springer Science Business Media , 2010, Vol. 6, p. 33-33Conference paper (Refereed)
    Abstract [en]

    The thiopurines, 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG) are used in the treatment of leukaemia. Incorporation of deoxythioguanosine nucleotides (dGs) into the DNA of thiopurine-treated cells causes cell death but there is also evidence that thiopurine metabolites, particularly the 6-MP metabolite methylthioinosine monophosphate (MeTIMP), inhibit de novo purine synthesis (DNPS). The toxicity of DNPS inhibitors is influenced by methylthioadenosine phosphorylase (MTAP), a gene frequently deleted in cancers. Since the growth of MTAP-deleted tumour cells is dependent on DNPS or hypoxanthine salvage, we would predict such cells to show differential sensitivity to 6-MP and 6-TG. To test this hypothesis, sensitivity to 6-MP and 6-TG was compared in relation to MTAP status using cytotoxicity assays in two MTAP-deficient cell lines transfected to express MTAP: the T-cell acute lymphoblastic leukaemic cell line, Jurkat, transfected with MTAP cDNA under the control of a tetracycline-inducible promoter, and a lung cancer cell line (A549-MTAP-ve) transfected to express MTAP constitutively (A549-MTAP+ve). Sensitivity to 6-MP or methyl mercaptopurine riboside, which is converted intra-cellularly to MeTIMP, was markedly higher in both cell lines under MTAP-ve conditions. Measurement of thiopurine metabolites support the hypothesis that DNPS inhibition is a major cause of cell death with 6-MP, whereas dGs incorporation is the main cause of cytotoxicity with 6-TG. These data suggest that thiopurines, particularly 6-MP, may be more effective in patients with deleted MTAP.

  • 3.
    Fyrberg, Anna
    et al.
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Skoglund, Karin
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Wolk, M
    Israel Minist Health Central Labs, Israel .
    Lotfi, Kourosh
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Diagnostics, Department of Clinical Pharmacology.
    A potential role of fetal hemoglobin in the development of multidrug resistance2012In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 427, no 3, p. 456-460Article in journal (Refereed)
    Abstract [en]

    Our previous data from a human leukemic cell line made resistant to the nucleoside analog (NA) 9-beta-D-arabinofuranosylguanine (AraG) revealed a massive upregulation of fetal hemoglobin (HbF) genes and the ABCB1 gene coding for the multidrug resistance P-glycoprotein (P-gp). The expression of these genes is regulated through the same mechanisms, with activation of the p38-MAPK pathway and inhibition of methylation making transcription factors more accessible to activate these genes. We could show that AraG, as well as other NAs, and P-gp substrates could induce global DNA demethylation and induction of Hb gamma and P-gp both at the mRNA and protein expression level. We speculate that the expression of HbF prior to drug exposure or in drug-resistant cell lines is a strategy of the cancer to gain more oxygen, and thereby survival benefits. We also believe that P-gp may be induced in order to excrete Hb degradation products from the cells that would otherwise be toxic. By using Hb gamma siRNA and pharmacological inhibitors of HbF production we here present a possible relationship between HbF induction and multi-drug resistance in a human leukemia cell line model.

  • 4.
    Gacic, Jelena
    et al.
    Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology.
    Vorkapic, Emina
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Slind Olsen, Renate
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. County Hospital Ryhov, Sweden.
    Söderberg, Daniel
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Gustafsson, Therese
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Geffers, Robert
    Helmholtz Centre Infect Research, Germany.
    Skoglund, Karin
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Matussek, Andreas
    County Hospital Ryhov, Sweden.
    Wågsäter, Dick
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Imatinib reduces cholesterol uptake and matrix metalloproteinase activity in human THP-1 macrophages2016In: Pharmacological Reports, ISSN 1734-1140, E-ISSN 2299-5684, Vol. 68, no 1, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Background: Imatinib mesylate (Glivec, formerly STI-571) is a selective tyrosine kinase inhibitor used for the treatment of chronic myeloid leukemia and gastrointestinal stromal tumors. However, there are reports suggesting that imatinib could be atheroprotective by lowering plasma low-density lipoprotein (LDL). Aim: To investigate the potential inhibitory effect of imatinib on cholesterol uptake in human macrophages as well as its effect on matrix metalloproteinase (MMP) activity. Methods and results: Uptake of fluorescence-labeled LDL was analyzed using flow cytometry. Macrophages treated with imatinib showed a 23.5%, 27%, and 15% decrease in uptake of native LDL (p < 0.05), acetylated LDL (p < 0.01), and copper-modified oxidized LDL (p < 0.01), respectively. Gel based zymography showed that secretion and activity of MMP-2 and MMP-9 were inhibited by imatinib. Using GeneChip Whole Transcript Expression array analysis, no obvious gene candidates involved in the mechanisms of cholesterol metabolism or MMP regulation were found to be affected by imatinib. Instead, we found that imatinib up-regulated microRNA 155 (miR155) by 43.8% and down-regulated ADAM metallopeptidase domain 28 (ADAM28) by 41.4%. Both genes could potentially play an atheroprotective role and would be interesting targets in future studies. Conclusion: Our results indicate that imatinib causes post-translational inhibition with respect to cholesterol uptake and regulation of MMP-2 and MMP-9. More research is needed to further evaluate the role of imatinib in the regulation of other genes and processes. (c) 2015 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Sp. z o.o. All rights reserved.

  • 5.
    Green, Henrik
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology.
    Skoglund, Karin
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology.
    Rommel, Franz
    Bertilsson, Leif
    KI, Stockholm.
    Lotfi, Kourosh
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pharmacology.
    Influence of CYP3A4 activity on imatinib response in paitents with chronic myeloid leukemia2006In: 11th congress of the European Heamtology Association,2006, 2006, p. 63-63Conference paper (Refereed)
    Abstract [en]

       

  • 6.
    Green, Henrik
    et al.
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Skoglund, Karin
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Rommel, Franz
    Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Haematology UHL.
    Mirghani, Rajaa A
    Karolinska University Hospital.
    Lotfi, Kourosh
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pharmacology.
    CYP3A activity influences imatinib response in patients with chronic myeloid leukemia: a pilot study on in vivo CYP3A activity2010In: EUROPEAN JOURNAL OF CLINICAL PHARMACOLOGY, ISSN 0031-6970, Vol. 66, no 4, p. 383-386Article in journal (Refereed)
    Abstract [en]

    Imatinib is currently used for the treatment of chronic myeloid leukemia (CML). The main metabolite CGP74588 has similar potency to that of imatinib and is a product of CYP3A4 and CYP3A5 metabolism. However, the clinical significance of the metabolism on therapeutic response and pharmacokinetics is still unclear. We designed this study to investigate the role of the CYP3A activity in the response to imatinib therapy. Fourteen CML patients were phenotyped for in vivo CYP3A activity using quinine as a probe drug. The plasma concentration ratio of quinine and its CYP3A metabolite was used for assessing CYP3A activity. The patients were divided into complete molecular responders with undetectable levels of BCR-ABL transcripts after 12 months of therapy and into partial molecular responders who had failed to achieve a complete molecular response. Patients that achieved complete molecular response showed significantly (Mann-Whitney U-test, p = 0.013) higher in vivo CYP3A activity (median quinine metabolic ratio = 10.1) than patients achieving partial molecular response (median = 15.9). These results indicate a clinical significance of the CYP3A activity and its metabolic products in CML patients treated with imatinib.

  • 7.
    Lindqvist Appell, Malin
    et al.
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Skoglund, Karin
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Hertervig, Erik
    Gastroenterologi, Lunds universitetssjukhus.
    Söderkvist, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Peterson, Curt
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Oncology UHL.
    Explaining TPMT genotype/phenotype discrepancy by identification of a novel sequence variant, TPMT*262008Conference paper (Refereed)
  • 8.
    Lindqvist Appell, Malin
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology.
    Skoglund, Karin
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology.
    Karlgren, Anna
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology.
    Peterson, Curt
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Söderkvist, Peter
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of cell biology.
    Kidhall, Irene
    Danderyds sjukhus.
    Almer, Sven
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Molecular and Clinical Medicine, Gastroenterology and Hepatology. Östergötlands Läns Landsting, Centre for Medicine, Department of Endocrinology and Gastroenterology UHL.
    Explaining TPMT genotype/phenotype discrepancy by haplotyping of TPMT*3A and identification of a novel sequence variant, TPMT*232007In: Pharmacogenetics and Genomics, ISSN 1744-6872, Vol. 17, no 10, p. 891-895Article in journal (Refereed)
    Abstract [en]

    Thiopurine methyltransferase (TPMT) is a polymorphic enzyme involved in the metabolism of thiopurine drugs. Owing to polymorphisms in the TPMT gene (TPMT*2-*22), the enzyme activity varies interindividually. Patients with reduced TPMT activity may develop adverse reactions when treated with standard doses of thiopurines. This work focuses on a TPMT genotype/phenotype discrepancy found in a patient during routine testing. The patient displayed very low TPMT enzyme activity and she was genotyped by pyrosequencing as being heterozygous for the 460G>A and 719A>G polymorphisms (TPMT*3A). Complete sequencing in combination with haplotyping of the TPMT gene revealed a novel sequence variant, 500C>G, on one allele and TPMT*3A on the other allele, giving rise to the novel genotype TPMT*3A/*23. When investigating the patient's relatives, they too had the TPMT*3A/*23 genotype in combination with low enzyme activity. We conclude that this novel variant allele affects enzyme activity, as the individuals carrying it had almost undetectable TPMT activity. © 2007 Lippincott Williams & Wilkins, Inc.

  • 9.
    Lindqvist Appell, Malin
    et al.
    Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Linköping University, Faculty of Health Sciences.
    Wennerstrand, Patricia
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Skoglund, Karin
    Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Linköping University, Faculty of Health Sciences.
    Lars-Göran, Mårtensson
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hertervig, Erik
    Lund University Hospital, Sweden.
    Peterson, Curt
    Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Oncology UHL.
    Explaining TPMT genotype/phenotype discrepancy by identification of a novel sequence variant, TPMT*272009In: 13th International Symposium on Purine and Pyrimidine metabolism in man, 2009Conference paper (Refereed)
    Abstract [en]

    Thiopurine methyltransferase (TPMT) is a polymorphic enzyme involved in the metabolism of thiopurine drugs. Owing to polymorphisms in the TPMT gene (TPMT*2-*22), the enzyme activity varies interindividually. Patients with reduced TPMT activity may develop adverse reactions when treated with standard doses of thiopurines. This work focuses on a TPMT genotype/phenotype discrepancy found in a patient during routine testing. The patient displayed very low TPMT enzyme activity and she was genotyped by pyrosequencing as being heterozygous for the 460G>A and 719A>G polymorphisms (TPMT*3A). Complete sequencing in combination with haplotyping of the TPMT gene revealed a novel sequence variant, 500C>G, on one allele and TPMT*3A on the other allele, giving rise to the novel genotype TPMT*3A/*23. When investigating the patient's relatives, they too had the TPMT*3A/*23 genotype in combination with low enzyme activity. We conclude that this novel variant allele affects enzyme activity, as the individuals carrying it had almost undetectable TPMT activity.

  • 10.
    Skoglund, Karin
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Influence of CYP3A enzymes and ABC transporters on the activity of tyrosine kinase inhibitors in chronic myeloid leukemia2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The introduction of imatinib, a tyrosine kinase inhibitor (TKI), in the treatment of chronic myeloid leukemia (CML) was a major break-through and the first drug that was successfully designed to target the specific mechanism of a malignant disease. Imatinib still remains as the standard treatment of newly diagnosed CML patients although a second generation of TKIs has also been approved for first-line CML treatment.

    Most patients achieve a good therapeutic effect with imatinib, but some patients are resistant to the drug and are at greater risk of disease progression. In order to further improve CML treatment, a better understanding of the underlying reasons for variable responses to imatinib and the second generation TKIs is important.

    A number of potential determinants of imatinib response have been suggested, including interindividual variability in pharmacokinetics. Variations in drug metabolism and cellular transport might contribute to the large variations observed in imatinib plasma concentrations and might, therefore, affect the amount of drug that reaches target CML cells. Imatinib is primarily metabolized by the CYP3A hepatic enzymes that are known to be highly variable in activity between different individuals. Imatinib is also a substrate of the ABCB1 and ABCG2 efflux pumps that potentially regulate the elimination of imatinib from the plasma. The ABCB1 and ABCG2 genes are polymorphic and contain single nucleotide polymorphisms (SNPs) that might influence the transport capacity of these proteins. The primary aim of the present thesis was to investigate the influence of CYP3A metabolic activity and cellular transport mediated by genetic variants of ABCB1 and ABCG2 on the response to imatinib and the second generation TKIs used for CML therapy.

    In vivo CYP3A activity and plasma concentrations of imatinib and its pharmacologically active metabolite CGP74588 were analyzed in CML patients treated with imatinib. CYP3A phenotypes were correlated to plasma concentrations and imatinib outcome 12 months after initiation of treatment. The influence of ABC transport on TKI efficacy was evaluated in vitro by the transduction of genetic variants of ABCB1 and ABCG2 into the CML cell line K562. Functionality of the transport proteins was evaluated by measuring protein expression levels on the cell surface, the intracellular accumulation of TKIs, and the ability of ABCB1 and ABCG2 variants to protect cells from TKI cytotoxicity.

    We found that CYP3A metabolic activity does not influence the drug plasma concentrations or the therapeutic outcome of imatinib in CML patients. These findings indicate that even though imatinib is primarily metabolized by CYP3A this metabolic activity is not the rate-limiting step in imatinib elimination. CYP3A activity, therefore, is not a suitable predictive marker of imatinib outcome. The in vitro studies revealed that the ABCB1 variants investigated here do not alter the transport of imatinib, CGP74588, dasatinib, or nilotinib. In contrast, the ABCG2 SNPs 421C>A, 623T>C, 886G>C, and 1574T>G significantly impaired the cellular efflux of imatinib, CGP74588, dasatinib, and nilotinib and could possibly influence transport of these TKIs in vivo. It was also found that CGP74588 is by far a better substrate than imatinib for both ABCB1 and ABCG2, and this might have implications in patients with high levels of CYP3A activity. In conclusion, our studies show that ABCG2 SNPs might be important for prediction of imatinib outcome in vivo. On the other hand, CYP3A activity and the ABCB1 SNPs investigated in this study are not likely to be useful as predictors of imatinib outcome.

    List of papers
    1. ABCB1 haplotypes do not influence transport or efficacy of tyrosine kinase inhibitors in vitro
    Open this publication in new window or tab >>ABCB1 haplotypes do not influence transport or efficacy of tyrosine kinase inhibitors in vitro
    Show others...
    2013 (English)In: Pharmacogenomics and Personalized Medicine, ISSN 1178-7066, Vol. 6, p. 63-72Article in journal (Refereed) Published
    Abstract [en]

    Single-nucleotide polymorphisms (SNPs) in the gene coding for the efflux-transport protein ABCB1 (P-glycoprotein) are commonly inherited as haplotypes. ABCB1 SNPs and haplotypes have been suggested to influence the pharmacokinetics and therapeutic outcome of the tyrosine kinase inhibitor (TKI) imatinib, used for treatment of chronic myeloid leukemia (CML). However, no consensus has yet been reached with respect to the significance of variant ABCB1 in CML treatment. Functional studies of variant ABCB1 transport of imatinib as well as other TKIs might aid the interpretation of results from in vivo association studies, but are currently lacking. The aim of this study was to investigate the consequences of ABCB1 variant haplotypes for transport and efficacy of TKIs (imatinib, its major metabolite N-desmethyl imatinib [CGP74588], dasatinib, nilotinib, and bosutinib) in CML cells. Variant haplotypes - including the 61A>G, 1199G>A, 1236C>T, 1795G>A, 2677G>T/A, and 3435T>C SNPs - were constructed in ABCB1 complementary DNA and transduced to K562 cells using retroviral gene transfer. The ability of variant cells to express ABCB1 protein and protect against TKI cytotoxicity was investigated. It was found that dasatinib and the imatinib metabolite CGP74588 are effectively transported by ABCB1, while imatinib, nilotinib, and bosutinib are comparatively weaker ABCB1 substrates. None of the investigated haplotypes altered the protective effect of ABCB1 expression against TKI cytotoxicity. These findings imply that the ABCB1 haplotypes investigated here are not likely to influence TKI pharmacokinetics or therapeutic efficacy in vivo.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-97421 (URN)10.2147/PGPM.S45522 (DOI)24019750 (PubMedID)
    Available from: 2013-09-12 Created: 2013-09-12 Last updated: 2017-12-06Bibliographically approved
    2. Influence of variant ABCG2 on tyrosine kinase inhibitor transport and efficacy in the K562 chronic myeloid leukemia cell line
    Open this publication in new window or tab >>Influence of variant ABCG2 on tyrosine kinase inhibitor transport and efficacy in the K562 chronic myeloid leukemia cell line
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Objective: The tyrosine kinase inhibitors (TKIs) used in the treatment of chronic myeloid leukemia are substrates for the efflux transport protein ABCG2. Variations in ABCG2 activity might influence pharmacokinetics and therapeutic outcome of TKIs. The role of ABCG2 single nucleotide polymorphisms (SNPs) in TKI treatment is not clear and functional in vitro studies are lacking. The aim of this study was to investigate the consequences of ABCG2 SNPs for transport and efficacy of TKIs (imatinib, N-desmethyl imatinib (CGP74588), dasatinib, nilotinib and bosutinib). Methods: ABCG2 SNPs 34G>A, 421C>A, 623T>C, 886G>C, 1574T>G and 1582G>A were constructed from ABCG2 wild type cDNA and transduced to K562 cells by retroviral gene transfer. The ability of variant cells to express ABCG2 in the cell membrane and protect against TKI cytotoxicity was investigated. Results: Wild type ABCG2 had a protective effect against the cytotoxicity of all investigated compounds except bosutinib. It was found that ABCG2 expression provided a better protection against CGP74588 than its parent compound, imatinib. ABCG2 421C>A, 623T>C, 886G>C and 1574T>G reduced cell membrane expression of ABCG2 and the protective effect of ABCG2 against imatinib, CGP74588, dasatinib and nilotinib cytotoxicity. The most prominent effect was found for the 623T>C SNP which resulted in undetectable ABCG2 expression and low protection against TKI cytotoxicity. Conclusion: These findings show that the ABCG2 SNPs 421C>A, 623T>C, 886G>C and 1574T>G impair ABCG2 transport function and might influence TKI pharmacokinetics in vivo. Furthermore, the active imatinib metabolite CGP74588 is to a greater extent than the parent compound transported by ABCG2.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-97423 (URN)
    Available from: 2013-09-12 Created: 2013-09-12 Last updated: 2014-04-22Bibliographically approved
    3. CYP3A activity influences imatinib response in patients with chronic myeloid leukemia: a pilot study on in vivo CYP3A activity
    Open this publication in new window or tab >>CYP3A activity influences imatinib response in patients with chronic myeloid leukemia: a pilot study on in vivo CYP3A activity
    Show others...
    2010 (English)In: EUROPEAN JOURNAL OF CLINICAL PHARMACOLOGY, ISSN 0031-6970, Vol. 66, no 4, p. 383-386Article in journal (Refereed) Published
    Abstract [en]

    Imatinib is currently used for the treatment of chronic myeloid leukemia (CML). The main metabolite CGP74588 has similar potency to that of imatinib and is a product of CYP3A4 and CYP3A5 metabolism. However, the clinical significance of the metabolism on therapeutic response and pharmacokinetics is still unclear. We designed this study to investigate the role of the CYP3A activity in the response to imatinib therapy. Fourteen CML patients were phenotyped for in vivo CYP3A activity using quinine as a probe drug. The plasma concentration ratio of quinine and its CYP3A metabolite was used for assessing CYP3A activity. The patients were divided into complete molecular responders with undetectable levels of BCR-ABL transcripts after 12 months of therapy and into partial molecular responders who had failed to achieve a complete molecular response. Patients that achieved complete molecular response showed significantly (Mann-Whitney U-test, p = 0.013) higher in vivo CYP3A activity (median quinine metabolic ratio = 10.1) than patients achieving partial molecular response (median = 15.9). These results indicate a clinical significance of the CYP3A activity and its metabolic products in CML patients treated with imatinib.

    Keywords
    Chronic myeloid leukemia, Imatinib, CYP3A4, CYP3A5, CGP74588, Complete molecular response
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-54710 (URN)10.1007/s00228-009-0772-y (DOI)000275710200008 ()
    Note

    The original publication is available at www.springerlink.com: Henrik Green, Karin Skoglund, Franz Rommel, Rajaa A Mirghani and Kourosh Lotfi, CYP3A activity influences imatinib response in patients with chronic myeloid leukemia: a pilot study on in vivo CYP3A activity, 2010, EUROPEAN JOURNAL OF CLINICAL PHARMACOLOGY, (66), 4, 383-386. http://dx.doi.org/10.1007/s00228-009-0772-y Copyright: Springer Science Business Media http://www.springerlink.com/

    Available from: 2010-04-06 Created: 2010-04-06 Last updated: 2014-01-09Bibliographically approved
    4. In vivo CYP3A activity and pharmacokinetics of imatinib in relation to therapeutic outcome in chronic myeloid leukemia patients
    Open this publication in new window or tab >>In vivo CYP3A activity and pharmacokinetics of imatinib in relation to therapeutic outcome in chronic myeloid leukemia patients
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Introduction: The hepatic enzymes CYP3A4 and CYP3A5 metabolize the tyrosine kinase inhibitor imatinib into a large number of metabolites including the pharmacologically active N-desmethyl imatinib (CGP74588). Because the metabolic activity of CYP3A varies considerably between individuals and a previous pilot study suggested an inverse association between in vivo CYP3A metabolic activity and therapeutic outcome of imatinib, the primary aim of this study was to investigate the influence of CYP3A metabolic activity on the outcome of imatinib therapy in chronic myeloid leukemia patients.

    Methods: Fifty-five patients were included and CYP3A activity was estimated in vivo using quinine as a probe drug. Imatinib and CGP74588 trough concentrations in the plasma were determined at steady state in 34 patients. Cytogenetic and molecular responses after 12 months of first-line imatinib were retrospectively collected from patients’ medical records.

    Results: Patients with optimal response to imatinib (complete cytogenetic response (CCgR) or molecular response of BCR-ABL <1%) did not have different levels of CYP3A activity compared to non-optimal responders. Similar results were found when analyzing the molecular response and CCgR separately. Neither the imatinib trough concentration nor the CGP74588/imatinib ratio were significantly associated with CYP3A activity.

    Conclusion: CYP3A enzyme activity, as measured by quinine metabolic ratio, does not correlate with the plasma concentrations of imatinib or CGP74588 and is not predictive of imatinib therapeutic outcome. These results indicate that even though imatinib is metabolized by CYP3A enzymes, this activity is not the   ratelimiting step in imatinib metabolism and excretion. Future studies should focus on other pharmacokinetic processes such as plasma protein binding or transport protein activity to look for the major contributor to patient variability in imatinib plasma concentration.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-97425 (URN)
    Available from: 2013-09-12 Created: 2013-09-12 Last updated: 2013-09-12Bibliographically approved
  • 11.
    Skoglund, Karin
    et al.
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Boiso Moreno, Samuel
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Jönsson, Jan-Ingvar
    Linköping University, Department of Clinical and Experimental Medicine, Experimental Hematology. Linköping University, Faculty of Health Sciences.
    Green, Henrik
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Functional Characterization of ABCG2 Polymorphisms and Their Influence on Tyrosine Kinase Inhibitor Effects in Chronic Myeloid Leukemia Cells in BLOOD, vol 118, issue 21, pp 1491-14912011In: BLOOD, American Society of Hematology , 2011, Vol. 118, no 21, p. 1491-1491Conference paper (Refereed)
    Abstract [en]

    n/a

  • 12.
    Skoglund, Karin
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Boiso, Samuel
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Jönsson, Jan-Ingvar
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Vikingsson, Svante
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Carlsson, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Pharmacology.
    Green, Henrik
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Single-nucleotide polymorphisms of ABCG2 increase the efficacy of tyrosine kinase inhibitors in the K562 chronic myeloid leukemia cell line2014In: Pharmacogenetics & Genomics, ISSN 1744-6872, E-ISSN 1744-6880, Vol. 24, no 1, p. 52-61Article in journal (Refereed)
    Abstract [en]

    ObjectiveThe tyrosine kinase inhibitors (TKIs) used in the treatment of chronic myeloid leukemia are substrates for the efflux transport protein ATP-binding cassette subfamily G member 2 (ABCG2). Variations in ABCG2 activity might influence pharmacokinetics and therapeutic outcome of TKIs. The role of ABCG2 single-nucleotide polymorphisms (SNPs) in TKI treatment is not clear and functional in-vitro studies are lacking. The aim of this study was to investigate the consequences of ABCG2 SNPs for transport and efficacy of TKIs [imatinib, N-desmethyl imatinib (CGP74588), dasatinib, nilotinib, and bosutinib].Materials and methodsABCG2 SNPs 34Ggreater thanA, 421Cgreater thanA, 623Tgreater thanC, 886Ggreater thanC, 1574Tgreater thanG, and 1582Ggreater thanA were constructed from ABCG2 wild-type cDNA and transduced to K562 cells by retroviral gene transfer. Variant ABCG2 expression in cell membranes was evaluated and the effects of ABCG2 SNPs on transport and efficacy of TKIs were measured as the ability of ABCG2 variants to protect against TKI cytotoxicity.ResultsWild-type ABCG2 had a protective effect against the cytotoxicity of all investigated compounds except bosutinib. It was found that ABCG2 expression provided better protection against CGP74588 than its parent compound, imatinib. ABCG2 421Cgreater thanA, 623Tgreater thanC, 886Ggreater thanC, and 1574Tgreater thanG reduced cell membrane expression of ABCG2 and the protective effect of ABCG2 against imatinib, CGP74588, dasatinib, and nilotinib cytotoxicity.ConclusionThese findings show that the ABCG2 SNPs 421Cgreater thanA, 623Tgreater thanC, 886Ggreater thanC, and 1574Tgreater thanG increase the efficacy of investigated TKIs, indicating a reduced transport function that might influence TKI pharmacokinetics in vivo. Furthermore, the active imatinib metabolite CGP74588 is influenced by ABCG2 expression to a greater extent than the parent compound.

  • 13.
    Skoglund, Karin
    et al.
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Lindqvist Appell, Malin
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Almér, Sven
    Linköping University, Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Endocrinology and Gastroenterology UHL.
    Peterson, Curt
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Oncology UHL.
    Söderkvist, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Low expression of TPMT wild type alleles in a patient with absent TPMT activity2008Conference paper (Other academic)
  • 14.
    Skoglund, Karin
    et al.
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Lindqvist Appell, Malin
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Almér, Sven
    Linköping University, Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Endocrinology and Gastroenterology UHL.
    Peterson, Curt
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Oncology UHL.
    Söderkvist, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Low Expression of TPMT wild type alleles in a patient with absent TPMT activity2008Conference paper (Other academic)
  • 15.
    Skoglund, Karin
    et al.
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Lindqvist Appell, Malin
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Karlgren, Anna
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Söderkvist, Peter
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Peterson, Curt
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Oncology UHL.
    Kidhall, Irene
    Div of Gastroenterology and Hepatology, Danderyd Hospital.
    Almér, Sven
    Linköping University, Department of Clinical and Experimental Medicine, Gastroenterology and Hepatology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Centre, Department of Endocrinology and Gastroenterology UHL.
    Explaining TPMT Genotype/Phenotype Discrepancy by Identification of a Novel Sequence Variant, TPMT*232007Conference paper (Other academic)
  • 16.
    Skoglund, Karin
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Moreno, Samuel Boiso
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medical and Health Sciences, Division of Drug Research.
    Baytar, Maria
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Health Sciences.
    Jönsson, Jan-Ingvar
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Gréen, Henrik
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    ABCB1 haplotypes do not influence transport or efficacy of tyrosine kinase inhibitors in vitro2013In: Pharmacogenomics and Personalized Medicine, ISSN 1178-7066, Vol. 6, p. 63-72Article in journal (Refereed)
    Abstract [en]

    Single-nucleotide polymorphisms (SNPs) in the gene coding for the efflux-transport protein ABCB1 (P-glycoprotein) are commonly inherited as haplotypes. ABCB1 SNPs and haplotypes have been suggested to influence the pharmacokinetics and therapeutic outcome of the tyrosine kinase inhibitor (TKI) imatinib, used for treatment of chronic myeloid leukemia (CML). However, no consensus has yet been reached with respect to the significance of variant ABCB1 in CML treatment. Functional studies of variant ABCB1 transport of imatinib as well as other TKIs might aid the interpretation of results from in vivo association studies, but are currently lacking. The aim of this study was to investigate the consequences of ABCB1 variant haplotypes for transport and efficacy of TKIs (imatinib, its major metabolite N-desmethyl imatinib [CGP74588], dasatinib, nilotinib, and bosutinib) in CML cells. Variant haplotypes - including the 61A>G, 1199G>A, 1236C>T, 1795G>A, 2677G>T/A, and 3435T>C SNPs - were constructed in ABCB1 complementary DNA and transduced to K562 cells using retroviral gene transfer. The ability of variant cells to express ABCB1 protein and protect against TKI cytotoxicity was investigated. It was found that dasatinib and the imatinib metabolite CGP74588 are effectively transported by ABCB1, while imatinib, nilotinib, and bosutinib are comparatively weaker ABCB1 substrates. None of the investigated haplotypes altered the protective effect of ABCB1 expression against TKI cytotoxicity. These findings imply that the ABCB1 haplotypes investigated here are not likely to influence TKI pharmacokinetics or therapeutic efficacy in vivo.

  • 17.
    Skoglund, Karin
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Moreno, Samuel Boiso
    Linköping University, Department of Medical and Health Sciences, Division of Radiological Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Jönsson, Jan-Ingvar
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Vikingsson, Svante
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Carlsson, Björn
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Pharmacology.
    Gréen, Henrik
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Influence of variant ABCG2 on tyrosine kinase inhibitor transport and efficacy in the K562 chronic myeloid leukemia cell lineManuscript (preprint) (Other academic)
    Abstract [en]

    Objective: The tyrosine kinase inhibitors (TKIs) used in the treatment of chronic myeloid leukemia are substrates for the efflux transport protein ABCG2. Variations in ABCG2 activity might influence pharmacokinetics and therapeutic outcome of TKIs. The role of ABCG2 single nucleotide polymorphisms (SNPs) in TKI treatment is not clear and functional in vitro studies are lacking. The aim of this study was to investigate the consequences of ABCG2 SNPs for transport and efficacy of TKIs (imatinib, N-desmethyl imatinib (CGP74588), dasatinib, nilotinib and bosutinib). Methods: ABCG2 SNPs 34G>A, 421C>A, 623T>C, 886G>C, 1574T>G and 1582G>A were constructed from ABCG2 wild type cDNA and transduced to K562 cells by retroviral gene transfer. The ability of variant cells to express ABCG2 in the cell membrane and protect against TKI cytotoxicity was investigated. Results: Wild type ABCG2 had a protective effect against the cytotoxicity of all investigated compounds except bosutinib. It was found that ABCG2 expression provided a better protection against CGP74588 than its parent compound, imatinib. ABCG2 421C>A, 623T>C, 886G>C and 1574T>G reduced cell membrane expression of ABCG2 and the protective effect of ABCG2 against imatinib, CGP74588, dasatinib and nilotinib cytotoxicity. The most prominent effect was found for the 623T>C SNP which resulted in undetectable ABCG2 expression and low protection against TKI cytotoxicity. Conclusion: These findings show that the ABCG2 SNPs 421C>A, 623T>C, 886G>C and 1574T>G impair ABCG2 transport function and might influence TKI pharmacokinetics in vivo. Furthermore, the active imatinib metabolite CGP74588 is to a greater extent than the parent compound transported by ABCG2.

  • 18.
    Skoglund, Karin
    et al.
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Health Sciences.
    Richter, J.
    Department of Hematology and Coagulation, Skåne University Hospital, Lund, Sweden.
    Olsson-Strömberg, U.
    Department of Medical Sciences, Uppsala University and Department of Hematology, University Hospital, Uppsala, Sweden.
    Bergquist, J.
    Analytical Chemistry, Department of Chemistry – Biomedical Center and Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
    Aluthgedara, W.
    Analytical Chemistry, Department of Chemistry – Biomedical Center and Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
    Ubhayasekera, K.
    Analytical Chemistry, Department of Chemistry – Biomedical Center and Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
    Vikingsson, Svante
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Svedberg, A.
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Söderlund, S.
    Department of Medical Sciences, Uppsala University and Department of Hematology, University Hospital, Uppsala, Sweden.
    Sandstedt, Anna
    Linköping University, Department of Social and Welfare Studies. Linköping University, Faculty of Health Sciences.
    Johnsson, A.
    Department of Internal Medicine, Motala Hospital, Motala, Sweden.
    Aagesen, J.
    Department of Medicine, Ryhov County Hospital, Jönköping, Sweden.
    Alsenhed, J.
    Department of Internal Medicine, Västervik Hospital, Västervik, Sweden.
    Hägg, Staffan
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Peterson, Curt
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Oncology.
    Lotfi, Kourosh
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pharmacology.
    Green, Henrik
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    In vivo CYP3A activity and pharmacokinetics of imatinib in relation to therapeutic outcome in chronic myeloid leukemia patientsManuscript (preprint) (Other academic)
    Abstract [en]

    Introduction: The hepatic enzymes CYP3A4 and CYP3A5 metabolize the tyrosine kinase inhibitor imatinib into a large number of metabolites including the pharmacologically active N-desmethyl imatinib (CGP74588). Because the metabolic activity of CYP3A varies considerably between individuals and a previous pilot study suggested an inverse association between in vivo CYP3A metabolic activity and therapeutic outcome of imatinib, the primary aim of this study was to investigate the influence of CYP3A metabolic activity on the outcome of imatinib therapy in chronic myeloid leukemia patients.

    Methods: Fifty-five patients were included and CYP3A activity was estimated in vivo using quinine as a probe drug. Imatinib and CGP74588 trough concentrations in the plasma were determined at steady state in 34 patients. Cytogenetic and molecular responses after 12 months of first-line imatinib were retrospectively collected from patients’ medical records.

    Results: Patients with optimal response to imatinib (complete cytogenetic response (CCgR) or molecular response of BCR-ABL <1%) did not have different levels of CYP3A activity compared to non-optimal responders. Similar results were found when analyzing the molecular response and CCgR separately. Neither the imatinib trough concentration nor the CGP74588/imatinib ratio were significantly associated with CYP3A activity.

    Conclusion: CYP3A enzyme activity, as measured by quinine metabolic ratio, does not correlate with the plasma concentrations of imatinib or CGP74588 and is not predictive of imatinib therapeutic outcome. These results indicate that even though imatinib is metabolized by CYP3A enzymes, this activity is not the   ratelimiting step in imatinib metabolism and excretion. Future studies should focus on other pharmacokinetic processes such as plasma protein binding or transport protein activity to look for the major contributor to patient variability in imatinib plasma concentration.

  • 19.
    Skoglund, Karin
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Richter, Johan
    Skåne University Hospital, Sweden.
    Olsson-Stromberg, Ulla
    Uppsala University, Sweden.
    Bergquist, Jonas
    Uppsala University, Sweden.
    Aluthgedara, Warunika
    Uppsala University, Sweden.
    Ubhayasekera, S. J. Kumari A.
    Uppsala University, Sweden.
    Vikingsson, Svante
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. Karolinska Institute, Sweden.
    Svedberg, Anna
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Söderlund, Stina
    Uppsala University, Sweden.
    Sandstedt, Anna
    Linköping University, Department of Social and Welfare Studies. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Haematology.
    Johnsson, Anders
    Region Östergötland, Local Health Care Services in West Östergötland, Department of Medical Specialist in Motala.
    Aagesen, Jesper
    Ryhov County Hospital, Sweden.
    Alsenhed, Jonas
    Vastervik Hosp, Dept Internal Med, Västervik, Sweden.
    Hägg, Staffan
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Pharmacology.
    Peterson, Curt
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Oncology.
    Lotfi, Kourosh
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Haematology.
    Green, Henrik
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. National Board Forens Med, Department Forens Genet and Forens Toxicol, Linkoping, Sweden.
    In Vivo Cytochrome P450 3A Isoenzyme Activity and Pharmacokinetics of Imatinib in Relation to Therapeutic Outcome in Patients With Chronic Myeloid Leukemia2016In: Therapeutic Drug Monitoring, ISSN 0163-4356, E-ISSN 1536-3694, Vol. 38, no 2, p. 230-238Article in journal (Refereed)
    Abstract [en]

    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.

  • 20.
    Wennerstrand, Patricia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Dametto, Paolo
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Hennig, Janosch
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology. Linköping University, The Institute of Technology.
    Klingstedt, Therése
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Skoglund, Karin
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Lindqvist Appell, Malin
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Mårtensson, Lars-Göran
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Structural Characteristics Determine the Cause of the Low Enzyme Activity of Two Thiopurine S-Methyltransferase Allelic Variants: A Biophysical Characterization of TPMT*2 and TPMT*52012In: Biochemistry, ISSN 0006-2960, E-ISSN 1520-4995, Vol. 51, no 30, p. 5912-5920Article in journal (Refereed)
    Abstract [en]

    The enzyme thiopurine S-methyltransferase (TPMT) is involved in the metabolism of thiopurine drugs used to treat acute lymphoblastic leukemia and inflammatory bowel disease. Thus far, at least 29 variants of the TPMT gene have been described, many of which encode proteins that have low enzyme activity and in some cases become more prone to aggregation and degradation. Here, the two naturally occurring variants, TPMT*2 (Ala80 → Pro) and TPMT*5 (Leu49 → Ser), were cloned and expressed in Escherichia coli. Far-UV circular dichroism spectroscopy showed that TPMT*2 was substantially destabilized whereas TPMT*5 showed much greater stability comparable to that of wild-type TPMT (TPMTwt). The extrinsic fluorescent molecule anilinonaphthalene sulfonate (ANS) was used to probe the tertiary structure during thermal denaturation. In contrast to TPMTwt, neither of the variants bound ANS to a large extent. To explore the morphology of the TPMT aggregates, we performed luminescent conjugated oligothiophene staining and showed fibril formation for TPMT*2 and TPMT*5. The differences in the flexibility of TPMTwt, TPMT*2, and TPMT*5 were evaluated in a limited proteolysis experiment to pinpoint stable regions. Even though there is only one amino acid difference between the analyzed TPMT variants, a clear disparity in the cleavage patterns was observed. TPMT*2 displays a protected region in the C-terminus, which differs from TPMTwt, whereas the protected regions in TPMT*5 are located mainly in the N-terminus close to the active site. In conclusion, this in vitro study, conducted to probe structural changes during unfolding of TPMT*2 and TPMT*5, demonstrates that the various causes of the low enzyme activity in vivo could be explained on a molecular level.

  • 21.
    Wennerstrand, Patricia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Mårtensson, Lars-Göran
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Dametto, P
    Linköping University, Department of Physics, Chemistry and Biology, Biochemistry. Linköping University, The Institute of Technology.
    Hennig, Janosch
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Biotechnology. Linköping University, The Institute of Technology.
    Skoglund, Karin
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Peterson, Curt
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Oncology UHL.
    Different mechanisms behind low enzyme activity in vivo of two different variants of Thiopurine S-methyltransferase, TPMT2010In: The FEBS Journal, ISSN 1742-464X, E-ISSN 1742-4658, Vol. 277, no Suppl. 1, p. 257-258Article in journal (Other academic)
    Abstract [en]

    In treatment of acute lymphoblastic leukemia and inflammatorybowel disease (IBD) thiopurines such as azathioprine and 6-mercaptopurineare used. All of these drugs are prodrugs and are, inthe cell, converted to 6-thioguanines (6-TGNs) and incorporatedinto DNA or inhibiting purine synthesis. A key enzyme for thisregulation is the cytosolic enzyme thiopurine S-methyltransferase(TPMT). This enzyme degrades azathioprine and 6-mercaptopurineto methylmercapto-purine and thereby reduces the bioavailabilityof the 6-TGNs incorporated into DNA. TPMT is apolymorphic enzyme with at least 29 different allelic variantsknown today and is one of the more classical examples of pharmacogeneticswhere the TPMT enzyme activity of the allelic variantsis directly correlated to the clinical dosages of the thiopurines, with a 10–15 fold dosage reduction for an allelic variantwith low TPMT enzyme activity. Even though TPMT is awell studied protein. Many studies have been performed in yeast‘‘suspensions’’ and not on pure protein solutions. It has beenspeculated and in a few cases shown that the reason for the lowactivity for most of the allelic variants is mainly due to the lowstability and/or tendency to aggregate. The mutations in thisstudy TPMT *2 (A80P) and TPMT * 5 (L49S) are both situatedat a distance far from the active site, however the enzyme activitiesare severely affected at 37°C. Preliminary results, using a repertoireof techniques such as CD, fluorescence and limitedproteolysis experiments suggest two different mechanisms for thelow enzyme activity at a temperature corresponding to in vivo conditions.

1 - 21 of 21
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf