| 1. |
- Bengtson, Curt, et al.
(författare)
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Deposition and Uptake of Nitrogen Oxides in Scots Pine needles (Pinus Sylvestris L.)
- 1982
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The deposition and uptake of nitrogen oxides in Scots pine needles were studied in exposure systems in the field and at the laboratory. For NO2 the deposition and uptake is a first order process determined by the stomatal conductance. The deposition velocities per needle area unit were during summer conditions determined to 0.65-1.67 mm x s-1 for daytime and 0.28 -0.78 m x s-1 for night time condition. Long term exposure of current needles to a concentration of 200 ug /m3 led to a decrease in transpration (stomatal conductance) after about 10 days exposure. One year old needles did not show any physiological effects at these concentrations. Short term studies of the deposition of NO showed that this was substantially lower than that for NO2
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| 2. |
- Nayeri, Fariba, et al.
(författare)
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An in vitro model for assessment of the biological activity of hepatocyte growth factor
- 2007
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Ingår i: Growth Factors. - : Informa UK Limited. - 0897-7194 .- 1029-2292. ; 25:1, s. 33-40
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Tidskriftsartikel (refereegranskat)abstract
- Hepatocyte growth factor (HGF) is a multifunctional growth factor with potent wound-healing properties that functions in the healing of chronic injuries. However, there may be a loss of HGF activity in certain chronic cases; this might be indicated by the presence of high amounts of HGF in body fluids and by the elevated expression of the HGF receptor in tissue biopsies. In such cases, a reliable means of assessing the activity of endogenous HGF would be valuable in allowing clinicians to decide if treatment with HGF would be useful. In this study, we developed an in vitro wound assay that used a mouse skin epithelial cell line to evaluate the biological activity of HGF. We showed that HGF accelerated the motility of the epithelial cells in a dose-dependent fashion with high sensitivity and specificity. This in vitro assay might be used to determine the activity of both endogenous and recombinant HGF.
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| 3. |
- Békássy, Albert, et al.
(författare)
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Pharmacokinetics of cytosine arabinoside in cerebrospinal fluid and of its metabolite in leukemic cells
- 1990
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Ingår i: Medical and Pediatric Oncology. - : Wiley. - 1096-911X .- 0098-1532. ; 18:2, s. 136-142
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Tidskriftsartikel (refereegranskat)abstract
- Concentrations of ara-CTP in leukemic cells isolated from CSF and of ara-C in lumbar CSF were measured following intraventricular ara-C administration in two girls with refractory meningeal leukemia. CSF samples were collected with a permanent intrathecal-lumbar catheter. In contrast to the comparatively short retention of ara-C in the CSF (t1/2 1.8 to 2.9 hours), there was a high accumulation and an extremely long retention of ara-CTP in the leukemic cells (t1/2 8.1 to 36 hours). The patients included in this study had an ara-C-resistant disease. No obvious relationship was seen between concentrations of ara-C in the CSF and of ara-CTP in the leukemic cells. Similar studies were performed after simultaneous intraventricular administration of hydrocortison and ara-C. Hydrocortison did not increase ara-CTP retention in the leukemic cells, nor did it effect CSF pleocytosis.
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| 4. |
- Bergmann, Troels K., et al.
(författare)
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Impact of ABCB1 Variants on Neutrophil Depression : A Pharmacogenomic Study of Paclitaxel in 92 Women with Ovarian Cancer
- 2012
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Ingår i: Basic & Clinical Pharmacology & Toxicology. - : Wiley. - 1742-7835 .- 1742-7843. ; 110:2, s. 199-204
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Tidskriftsartikel (refereegranskat)abstract
- The standard treatment for ovarian cancer in advanced stages is post-surgery treatment with taxane-platin chemotherapy. Despite an initial high response rate, most patients eventually relapse. The dose-limiting toxicities of paclitaxel are neutropenia and neuropathy, but the inter-individual variability is large. The aim of this prospective study was to investigate the impact of genetic variants in key drug metabolizing/transporter genes on toxicity and compliance. CYP2C8*3 and three ABCB1 polymorphisms were chosen for primary analysis, and a host of other candidate genes was explored in 92 prospectively recruited Scandinavian Caucasian women with primary ovarian cancer who were treated with paclitaxel and carboplatin. A single investigator assessed the clinical toxicity in 97% of the patients. Patients carrying variant alleles of ABCB1 C3435T experienced more pronounced neutrophil decrease (63%, 72% and 80% for 3435CC, CT and TT, respectively; p-value 0.03). A similar association was found for G2677T /A, p-value 0.02. For C1236T, there was a trend with p-value 0.06. No statistically significant correlations were found for paclitaxel compliance and sensory neuropathy in the primary analysis. Variants in the drug transporter ABCB1 gene are possibly associated with the neutrophil suppressing effect of paclitaxel in patients with ovarian cancer. This finding has implications for the understanding of bone marrow suppression and future tailored chemotherapy.
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| 5. |
- Bergmann, T K, et al.
(författare)
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Impact of CYP2C8*3 on paclitaxel clearance: a population pharmacokinetic and pharmacogenomic study in 93 patients with ovarian cancer
- 2011
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Ingår i: PHARMACOGENOMICS JOURNAL. - : Nature Publishing Group. - 1470-269X .- 1473-1150. ; 11:2, s. 113-120
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Tidskriftsartikel (refereegranskat)abstract
- The primary purpose of this study was to evaluate the effect of CYP2C8*3 and three genetic ABCB1 variants on the elimination of paclitaxel. We studied 93 Caucasian women with ovarian cancer treated with paclitaxel and carboplatin. Using sparse sampling and nonlinear mixed effects modeling, the individual clearance of unbound paclitaxel was estimated from total plasma paclitaxel and Cremophor EL. The geometric mean of clearance was 385 l h(-1) (range 176-726 l h(-1)). Carriers of CYP2C8*3 had 11% lower clearance than non-carriers, P = 0.03. This has not been shown before in similar studies; the explanation is probably the advantage of using both unbound paclitaxel clearance and a population of patients of same gender. No significant association was found for the ABCB1 variants C1236T, G2677T/A and C3435T. Secondarily, other candidate single-nucleotide polymorphisms were explored with possible associations found for CYP2C8*4 (P = 0.04) and ABCC1 g.7356253C andgt; G (P = 0.04).
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| 6. |
- Bergmann, Troels K., et al.
(författare)
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Retrospective study of the impact of pharmacogenetic variants on paclitaxel toxicity and survival in patients with ovarian cancer
- 2011
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Ingår i: European Journal of Clinical Pharmacology. - : Springer Science Business Media. - 0031-6970 .- 1432-1041. ; 67:7, s. 693-700
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Tidskriftsartikel (refereegranskat)abstract
- Paclitaxel has a broad spectrum of anti-tumor activity and is useful in the treatment of ovarian, breast, and lung cancer. Paclitaxel is metabolized in the liver by CYP2C8 and CYP3A4 and transported by P-glycoprotein. The dose-limiting toxicities are neuropathy and neutropenia, but the interindividual variability in toxicity and also survival is large. The main purpose of this study was to investigate the impact of genetic variants in CYP2C8 and ABCB1 on toxicity and survival. The 182 patients previously treated for ovarian cancer with carboplatin and paclitaxel in either the AGO-OVAR-9 or the NSGO-OC9804 trial in Denmark or Sweden were eligible for this study. Genotyping was carried out on formalin-fixed tissue. The patients toxicity profiles and survival data were derived from retrospective data. CYP2C8*3, ABCB1 C1236T, G2677T/A, and C3435T were chosen a priori for primary analysis; a host of other variants were entered into an exploratory analysis. Clinical data and tissue were available from a total of 119 patients. Twenty-two single nucleotide polymorphisms (SNPs) in 10 genes were determined. Toxicity registration was available from 710 treatment cycles. In the primary analysis, no statistically significant correlation was found between CYP2C8*3, ABCB1 C1236T, G2677T/A, and C3435T and neutropenia, sensoric neuropathy, and overall survival. CYP2C8*3 and the ABCB1 SNPs C1236T, G2677T/A, and C3435T were not statistically significantly correlated to overall survival, sensoric neuropathy, and neutropenia in 119 patients treated for ovarian cancer with paclitaxel/carboplatin.
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| 7. |
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| 8. |
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| 9. |
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| 10. |
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| 11. |
- Börjeson, Sussanne, et al.
(författare)
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Treatment of nausea and emesis during cancer chemotherapy : Discrepancies between antiemetic effect and well-being
- 2002
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Ingår i: Journal of Pain and Symptom Management. - 0885-3924 .- 1873-6513. ; 24:3, s. 345-358
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to describe the relationship between antiemetic effect and well-being in patients receiving four different antiemetic treatment strategies, representing developments in the field during the past 15 years. A total of 162 women with ovarian cancer receiving cisplatin-based chemotherapy and participating in two comparative antiemetic trials were enrolled and studied for up to four cycles. In study I, a combined antiemetic strategy including a nursing intervention program (increased access to support and increased information) and antiemetics based on high-dose metoclopramide and dexamethasone was compared with the standard antiemetic treatment during the 1980s. In study II, ondansetron plus dexamethasone/placebo was evaluated. The assessment methods used were similar for all patients. Questionnaires were used to assess frequency, intensity, and duration of nausea, emesis, anxiety, pain, and well-being at baseline, and for acute (24 hours after chemotherapy) and delayed (up to 2 weeks after chemotherapy) symptoms. The mean intensity of acute nausea during the first cycle was higher in the groups in study I, as compared to the groups in study II. The group receiving a nursing intervention reported better well-being than the other groups. Duration of nausea was an important predictor of well-being, even when nausea intensity was controlled. Apart from nausea intensity, nausea duration and nursing interventions may be important determinants for well-being during chemotherapy. © U.S. Cancer Pain Relief Committee, 2002.
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| 12. |
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| 13. |
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| 14. |
- Djerf, Emelie, 1980-
(författare)
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Studies on the effect of ErbB tyrosine kinase inhibitors on malignant melanoma growth and survival in vitro
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Malignant melanoma has one of the fastest increasing incidences among the different types of cancerin the Western world. This raise can partly be ascribed to the change in sun habits that has takenplace during the last decades, since the major external risk factor for melanoma is exposure toultraviolet radiation. Patients with early stages of melanoma can often be cured by surgery, howeverfor patients suffering from metastatic melanoma there are only a few treatment options available.Unfortunately malignant melanoma is often resistant to radio-, bio- and chemotherapy and treatmentwith the currently most frequently used agent, dacarbazine, is characterized by a very low clinicalresponse rate. Therefore, there is an urgent need for new treatment strategies which can increase theoverall survival and cause less severe side effects.The aim of this thesis was to investigate the anti-tumor effect of two different tyrosine kinaseinhibitors (TKIs), gefitinib and canertinib, on two different human malignant melanoma (RaH3 andRaH5) cell lines. We investigate the effect of these two drugs on cell proliferation and survival andstudied the effect of gefitinib and canertinib on ErbB1-4 receptor phosphorylation, as well as Akt,Erk1/2 and Stat3 activity.Our results showed that phosphorylation of ErbB1, ErbB2 and ErbB3 decreased followingtreatment with both gefitinib and canertinib and that the subsequent downstream signaling via Akt,Erk1/2 and Stat3 was inhibited after TKI treatment. However, it was noted that the gefitinibinducedinhibition of Akt, and particularly Erk1/2, was transient and only a weak inhibition of Stat3phosphorylation was seen. Gefitinib treatment of the RaH3 and RaH5 cells resulted in anaccumulation of the cells in the G1 phase of the cell cycle without any induction of apoptosis.Canertinib caused a more pronounced inhibition of Akt, Erk1/2, and Stat3 phosphorylation thangefitinib. This might be one explanation to why canertinib induced apoptosis in RaH3 and RaH5cells whereas gefitinib only caused cell cycle arrest. In conclusion, gefitinib and canertinib displaypromising anti-tumor effects on ErbB expressing malignant melanoma and might be used in futurestudies in combination with conventional chemotherapy or other targeted therapies in the treatmentof malignant melanoma.
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| 15. |
- Fotoohi, Alan Kambiz, et al.
(författare)
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Impaired transport as a mechanism of resistance to thiopurines in human T-lymphoblastic leukemia cells
- 2006
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Ingår i: Nucleosides, Nucleotides & Nucleic Acids. - : Informa UK Limited. - 1525-7770 .- 1532-2335. ; 25:9-11, s. 1039-1044
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Tidskriftsartikel (refereegranskat)abstract
- In order to better understand the mechanisms of resistance to thiopurines, we studied two sublines of the MOLT4 T-lymphoblastic leukemia cell line, resistant to 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG). We found that the underlying mechanism of resistance in both resistant cell lines was a markedly reduction in initial transport of 6-MP (3- and 5-fold, respectively, in 6-MP- and 6-TG-resistant cells). No significant alteration of activities of hypoxanthine-guanine phosphoribosyl transferase, thiopurine methyltransferase or inosine monophosphate dehydrogenase, the key enzymes involved in the metabolism of thiopurines was detected. We conclude that defected initial transport of thiopurines by cells may very well explain their resistance to these drugs. Copyright © Taylor & Francis Group, LLC.
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| 16. |
- Fotoohi, Alan Kambiz, et al.
(författare)
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Involvement of the concentrative nucleoside transporter 3 and equilibrative nucleoside transporter 2 in the resistance of T-lymphoblastic cell lines to thiopurines
- 2006
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 343:1, s. 208-215
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Tidskriftsartikel (refereegranskat)abstract
- Mechanisms of resistance to thiopurines, 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG) were investigated in human leukemia cell lines. We developed two 6-MP- and 6-TG-resistant cell lines from the human T-lymphoblastic cell line (MOLT-4) by prolonged exposure to these drugs. The resistant cells were highly cross resistant to 6-MP and 6-TG, and exhibited marked reduction in cellular uptake of 6-MP (70% and 80%, respectively). No significant modification of the activities of hypoxanthine-guanine phosphoribosyl transferase, thiopurine methyltransferase or inosine monophosphate dehydrogenase was observed. Real-time PCR of concentrative nucleoside transporter 3 (CNT3) and equilibrative nucleoside transporter 2 (ENT2) of resistant cells showed substantial reductions in expression of messenger RNAs. Small interfering RNA designed to silence the CNT3 and ENT2 genes down-regulated the expression of these genes in leukemia cells. These decreases were accompanied by reduction of transport of 6-MP (47% and 21%, respectively) as well as its cytocidal effect (30% and 21%, respectively). Taken together these results show that CNT3 and ENT2 play a key role in the transport of 6-MP and 6-TG by leukemia cells. From a clinical point of view determination of CNT3 and ENT2 levels in leukemia cells may be useful in predicting the efficacy of thiopurine treatment. © 2006 Elsevier Inc. All rights reserved.
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| 17. |
- Fotoohi, A K, et al.
(författare)
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Molecular mechanisms underlying the enhanced sensitivity of thiopurine-resistant T-lymphoblastic cell lines to methyl mercaptopurineriboside
- 2006
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Ingår i: Biochemical Pharmacology. - : Elsevier BV. - 0006-2952 .- 1356-1839. ; 72:7, s. 816-823
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Tidskriftsartikel (refereegranskat)abstract
- Methylmercaptopurine riboside (meMPR), a cellular metabolite of 6-mercaptopurine (6-MP), is a potent inhibitor of de novo purine synthesis (DNPS). Human MOLT4 T-lymphoblastic leukaemia cells that have acquired resistance to 6-MP or 6-thioguanine (6-TG) as a consequence of defective transport exhibit enhanced sensitivity to meMPR. HPLC-based analysis of the transport of meMPR revealed normal uptake of this compound by our thiopurine-resistant cell sublines, suggesting a route of transport distinct from that for 6-MP and 6-TG. Studies on the wild-type parental leukemic cells showed that adenosine, dipyridamole and nitrobenzylthioinosine inhibit uptake of meMPR to a significant extent, whereas Na+ ions have no influence on this process. Transfection of these leukemic cells with small interference RNA molecules targeting the gene encoding the first member of the family of equiliberative nucleoside transporters (ENT1) strongly reduced the initial rate of meMPR transport. Our resistant cell lines exhibited 30-52% reductions (p < 0.005) in their levels of mRNA encoding several proteins involved in de novo purine synthesis, i.e., aminoimidazole carboxamide ribonucleotide formyltransferase, glycinamide ribonucleotide transformylase and guanine monophosphate synthetase. Consequently, the rate of de novo purine synthesis in these resistant sublines was decreased by 50%. Furthermore, the levels of ribonucleoside triphosphates in these cells were significantly lower than in the non-resistant parental cells. In combination, a reduced rate of de novo purine synthesis together with low levels of ribonucleoside triphosphates can explain the enhanced sensitivity of our thiopurine-resistant cell lines to meMPR. In this manner, meMPR bypasses the mechanisms of resistance to thiopurines and is even more cytotoxic towards resistant than towards wild-type cells. © 2006.
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| 18. |
- Fotoohi, K, et al.
(författare)
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Interference of 7-hydroxymethotrexate with the determination of methotrexate in plasma samples from children with acute lymphoblastic leukemia employing routine clinical assays
- 2005
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Ingår i: Journal of Chromatography. B. - : Elsevier BV. - 1873-376X .- 1570-0232. ; 817:2, s. 139-144
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Tidskriftsartikel (refereegranskat)abstract
- The accuracy of two clinical assays, the enzyme-multiplied immunoassay (EMIT) and fluorescence polarization immunoassay (FPIA2), universally employed for measurement of plasma levels of methotrexate (MTX) in children administered a high dose of this drug for treatment of acute lymphoblastic leukemia was evaluated here. Because of its superior specificity, sensitivity, and precision, high performance liquid chromatography (HPLC) was selected as the reference method with which the other two procedures were compared using approximately 420 different plasma samples for method comparison. 7-Hydroxymethotrexate (7-OHMTX), the major plasma metabolite of MTX, that can be detected in plasma at relatively high concentrations for long periods following infusion of a high dose of MTX, was also quantitated by HPLC. Forty-two and 66 h after infusion, the plasma level of MTX was overestimated in 2% and 3% of the samples by the FPIA2 procedure in 5% and 31% by the EMIT assay. The overall correlation coefficients (r(2)) for the values obtained by FPIA2 or EMIT versus those based on HPLC were 0.989 and 0.663, respectively. The presence of 7-OHMTX exerted a highly significant influence (p = 0.0007 as determined by the unpaired t-test) on MTX measurement by the EMIT assay. We conclude that the rapid automated procedures routinely used at present and in particular EMIT, suffer from cross-reactivity with metabolites of MTX. Thus, the relatively high percentage of samples in which the level of MTX is overestimated at check-points by EMIT may result in longer periods of hospitalization, higher costs and prolonged administration of elevated doses of "rescue" leucovorin with an increased risk for relapse.
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| 19. |
- Fransson, Martin, 1978-, et al.
(författare)
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A preliminary study of modeling and simulation in individualized drug dosage – azathioprine on inflammatory bowel disease
- 2007
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Ingår i: SIMS 2006: Proceedings of the 47th Conference on Simulation and Modelling, Helsinki, Finland. - Helsinki : Kopio Niini Oy. - 9525183300 ; , s. 216-220
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Konferensbidrag (refereegranskat)abstract
- Individualized drug dosage based on population pharmacokinetic/dynamic models is an important future technology used to reduce or eliminate side effects of certain drugs, e.g. cancer drugs. In this paper we report preliminary results from work-in-progress: a simplified linear model of the metabolism of a cancer treatment drug was estimated from experimental data. The model was then validated against the same data as a test of the adequacy of the model structure. From this investigation it became apparent that the model structure could not be used due to its inability to recreate the dynamic properties of the system.
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| 20. |
- Fyrberg, Anna, et al.
(författare)
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Induction of fetal hemoglobin and ABCB1 gene expression in 9-β-D-arabinofuranosylguanine-resistant MOLT-4 cells
- 2011
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Ingår i: Cancer Chemotherapy and Pharmacology. - : Springer. - 0344-5704 .- 1432-0843. ; 68:3, s. 583-591
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To characterize resistance mechanisms to the nucleoside analog 9-β-D-arabinofuranosylguanine (AraG) in the T-cell acute lymphoblastic leukemia cell line MOLT-4 and its AraG-resistant variant. METHODS: A gene expression microarray analysis was performed, as well as gene expression and enzyme activity measurements of key enzymes in the activation of AraG. Cytotoxicity of AraG and cross-resistance to other compounds were evaluated using a standard cytotoxicity assay. RESULTS: Gene expression microarray analysis revealed that fetal hemoglobin genes and the multidrug resistance ABCB1 gene, encoding the drug efflux pump P-gp, were the most highly upregulated genes in the resistant cells, while genes traditionally associated with nucleoside analog resistance were not. Fetal hemoglobin and ABCB1 induction can be due to global DNA hypomethylation. This phenomenon was studied using AraG during a period of 4 weeks in MOLT-4 cells and the lung adenocarcinoma cell line A549, leading to up-regulation of hemoglobin gamma and ABCB1 as well as DNA hypomethylation. Inhibiting P-gp in the AraG-resistant MOLT-4 cells led to decreased proliferation, reduced hemoglobin expression, and highly induced ABCB1 expression. CONCLUSIONS: We show that AraG can cause hypomethylation of DNA and induce the expression of the fetal hemoglobin gamma gene and the ABCB1 gene. We speculate that the induction of ABCB1/P-gp may occur in order to help with excretion of hemoglobin degradation products that would otherwise be toxic to the cells, and we present data supporting our theory that P-gp may be linked to the induction of hemoglobin.
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| 21. |
- Fyrberg, Anna, 1981-
(författare)
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Nucleoside analoge cytotoxicity-focus on enzyme regulation, metabolism, and mechanisms of resistance
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis was to determine the role of nucleoside analog activating and deactivating enzymes in nucleoside analog metabolism and resistance development. Nucleoside analogs are anti-cancer drogs and are often used to treat different leukemias, attributably to presence of high levels of nucleoside analog activating enzymes in hematopoietic cells. More recently some of the newer analogs have been used successfully to treat solid tumors as well.We have used human leukemic cell lines, and isolated cells from patients with leukemia, to investigate the nucleoside analog activating enzymes deoxycytidine kinase (dCK) and deoxyguanosine kinase (dGK) and some of the deactivating enzymes called 5'nucleotidases (5'-NTs). We have measured mRNA expressions and enzymatic activities and correlated them with the cytotoxic response to nuc1eoside analogs and changes in cell cycle progression. We optimized and evaluated a siRNA-transfection method and decreased the activities of dCK and dGK in two different cell lines in order to find out more about their respective contribution to activation of these drogs. An expression microarray analysis of a nucleoside analog resistant cell line was also performed in order to clarify which genes are involved in development of resistance.We found that expressions and activities of dCK and dGK were not correlated. The enzyme activities of activating and deactivating enzymes changed during cell cycle progression, giving actively proliferating cells a more favorable enzymatic profile with regard to nucleoside analog cytotoxicity.The activities of dCK and dGK could be reduced transiently in leukemic and solid tumor cell lines, thereby confer either resistance or increased sensitivity to nucleoside analogs to variable degrees. Expression microarray analysis was used to evaluate the effect of the transfection method and the specificity of siRNA. We concluded that cells tolerated the transfection weIl without major effects on gene expression, and considered the siRNA used to be specific to its target.An expression microarray experiment on a nucleoside analog-induced resistant cell line revealed a hypomethylating capacity of the drog and induction of fetal hemoglobin and a multidrog resistance efflux pump as a result of the hypomethylation. This pump should not be affected by nucleoside analoges since they are not a substrate of it, and upregulation of the pump unfortunately renders the cells highly cross-resistant to different types of drogs. Our preliminary data supports our theory that it may be upregulated in order to help excrete hemoglobin that otherwise would be toxic to the cells.
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| 22. |
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| 23. |
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| 24. |
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| 25. |
- Green, Henrik, et al.
(författare)
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Impact of CYP3A5(*)3 and CYP2C8-HapC on Paclitaxel/Carboplatin-Induced Myelosuppression in Patients with Ovarian Cancer
- 2011
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Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier. - 0022-3549 .- 1520-6017. ; 100:10, s. 4205-4209
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Tidskriftsartikel (refereegranskat)abstract
- The influence of genetic variants on paclitaxel-induced toxicity is of considerable interest for reducing adverse drug reactions. Recently, the genetic variants CYP2C8(*)3, CYP2C8-HapC, and CYP3A5(*)3 were associated with paclitaxel-induced neurotoxicity. We, therefore, investigated the impact of CYP2C8-HapC and CYP3A5(*)3 on paclitaxel/carboplatin-induced myelosuppression and neurotoxicity. Thirty-three patients from a prospective pharmacokinetics study were genotyped using pyrosequencing. Patients with variant alleles of CYP2C8-HapC were found to have significantly lower nadir values of both leukocytes and neutrophils (p andlt; 0.05) than patients with the wild-type genotype. CYP3A5(*)3/(*)1 patients were shown to have borderline, significantly lower nadir values of leukocytes (p = 0.07) than (*)3/(*)3 patients. Combining the two genotypes resulted in a significant correlation with both leukopenia and neutropenia (p = 0.01). No effect of these genetic variants on neurotoxicity could be shown in this rather small study, but their importance for paclitaxel-induced toxicity could be confirmed.
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| 26. |
- Green, Henrik, et al.
(författare)
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In response [2]
- 2006
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Ingår i: Clinical Cancer Research. - 1078-0432 .- 1557-3265. ; 12:13
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Annan publikation (övrigt vetenskapligt/konstnärligt)
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| 27. |
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| 28. |
- Green, Henrik, et al.
(författare)
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mdr-1 single nucleotide polymorphisms in ovarian cancer tissue – G2677T/A correlates with response to paclitaxel chemotherapy
- 2006
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Ingår i: Clinical Cancer Research. - 1078-0432. ; 12:3 pt 1, s. 854-859
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: P-glycoprotein, encoded by the mdr-1 gene, confers multidrug resistance to a variety of antineoplastic agents, e.g., paclitaxel. Recently, different polymorphisms in the mdr-1 gene have been identified and their consequences for the function of P-glycoprotein, as well as for the treatment response to P-glycoprotein substrates, are being clarified. We analyzed the allelic frequencies at polymorphic sites G2677T/A and C3435T in ovarian cancer patients with good or poor response to treatment with paclitaxel in combination with carboplatin in order to evaluate their predictive values. Experimental Design: Fifty-three patients were included in the study; 28 of them had been relapse-free for at least 1 year and 25 had progressive disease or relapsed within 12 months. A reference material consisting of 200 individuals was also analyzed. The genotypes of each single nucleotide polymorphism (SNP) were determined using Pyrosequencing. Results: The G2677T/A SNP was found to significantly correlate with treatment outcome. The probability of responding to paclitaxel treatment was higher in homozygously mutated patients (T/T or T/A; Fisher's exact test; P < 0.05). The frequency of the T or A alleles was also higher in the group of patients who had a good response (P < 0.05). There was also a dose-dependent influence of the number of mutated alleles on the response to paclitaxel treatment (Χ2 test for linear-by-linear association; P = 0.03). However, the C3435T SNP was not found to correlate to treatment outcome. Conclusions: The mdr-1 polymorphism G2677T/A in exon 21 correlates with the paclitaxel response in ovarian cancer and may be important for the function of P-glycoprotein and resistance to paclitaxel and provide useful information for individualized therapy.
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| 29. |
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| 30. |
- Green, Henrik, et al.
(författare)
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Measurement of paclitaxel and its metabolites in human plasma using liquid chromatography/ion trap mass spectrometry with a sonic spray ionization interface
- 2006
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Ingår i: Rapid Communications in Mass Spectrometry. - : Wiley. - 1097-0231 .- 0951-4198. ; 20:14, s. 2183-2189
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Tidskriftsartikel (refereegranskat)abstract
- A quantitative liquid chromatography/ion trap mass spectrometry method for the simultaneous determination of paclitaxel, 6α-hydroxypaclitaxel and p-3'-hydroxypaclitaxel in human plasma has been developed and validated. 6α-,p-3'-Dihydroxypaclitaxel was also quantified using paclitaxel as a reference and docetaxel as an internal standard. The substances were extracted from 0.500 mL plasma using solid-phase extraction. The elution was performed with acetonitrile and the samples were reconstituted in the mobile phase. Isocratic high-performance liquid chromatography analysis was performed by injecting 50 µL of reconstituted material onto a 100 × 3.00 mm C12 column with a methanol:1% trifluoroacetic acid/ammonium trifluoroacetate in H2O 70:30 mobile phase at 350 µL/min. The [M+H]+ ions generated in the sonic spray ionization interface were isolated and fragmented using two serial mass spectrometric methods: one for paclitaxel (transition 854 → 569 & 551) and the dihydroxymetabolite (transition 886 → 585 & 567) and one for the hydroxy metabolites (transition 870 → 585 & 567; transition 870 → 569 & 551) and docetaxel ([M+Na]+, transition 830 → 550). Calibration curves were created ranging between 0.5 and 7500 ng/mL for paclitaxel, 0.5 and 750 ng/mL for 6α-hydroxypaclitaxel, and 0.5 and 400 ng/mL for p-3'-hydroxypaclitaxel. Adduct ion formation was noted and investigated during method development and controlled by mobile phase optimization. In conclusion, a sensitive method for simultaneous quantification of paclitaxel and its metabolites suitable for analysis in clinical studies was obtained.
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| 31. |
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| 32. |
- Green, Henrik, 1975-
(författare)
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Pharmacogenetic Studies of Paclitaxel in Ovarian Cancer : focus on interindividual differences in pharmacodynamics and pharmacokinetics
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ovarian cancer is one of the most common female cancer diseases in the world today and in Sweden more than 800 new cases are diagnosed every year. The standard treatment consists of chemotherapy with paclitaxel in combination with carboplatin after initial cytoreductive surgery. The response to treatment and the severity of adverse drug reactions after chemotherapy varies greatly among individuals, and one of the most important factors responsible for these differences is now recognized to be the genetic variability. One of the major obstacles to successful treatment is drug resistance. Several potential mechanisms have been suggested for the resistance to paclitaxel, such as mutations in the target protein β-tubulin, single nucleotide polymorphisms (SNPs) in the gene ABCB1, which encodes the transport protein P-glycoprotein. P-glycoprotein can mediate efflux of various drugs from cancer cells as well as from the circulation into the intestinal lumen, and overexpression and/or high activity leads to drug resistance and/or increased elimination. Another reason might be the high interindividual variability of paclitaxel plasma concentrations, which has been suggested to be influenced by variability in metabolic enzymes, such as CYP2C8 and CYP3A4, and transport proteins e.g. P-glycoprotein.In the studies constituting this thesis we have investigated the possibilities of predicting the pharmacokinetics of paclitaxel as well as the tumor response and adverse drug reactions after chemotherapy in the preparation of personalized chemotherapy. We studied the correlation between the response and the presence of mutations in the dominant β-tubulin gene and SNPs in ABCB1. DNA from 40 ovarian tumors was screened for sequence variations in the β-tubulin gene without finding any, showing that β-tubulin mutations are rare and unlikely to be a clinically relevant resistance mechanism for paclitaxel. The SNPs G2677T/A and C3435T in the ABCB1 gene were determined in 53 ovarian cancer tumors from patients with poor (progressive disease or relapse within one year) or good (disease-free survival of more than one year) response to paclitaxel-carboplatin chemotherapy. Patients homozygously mutated for G2677T/A had a higher probability of responding to chemotherapy. There was also a dose-dependent influence of the number of mutated alleles on the response to paclitaxel treatment. No correlation was found for the C3435T variant.By using a newly developed quantitative LC/MS method for the simultaneous determination of paclitaxel and its hydroxymetabolites in human plasma we assessed the individual elimination of paclitaxel in 33 ovarian cancer patients. The patients were genotyped for SNPs in the ABCB1, CYP2C8 and CYP3A4 genes and their in vivo CYP3A4 enzyme activity, tumor response and toxicity, especially the neurotoxicity, were determined. Patients heterozygous for G/A in position 2677 in ABCB1 had a significantly higher clearance of paclitaxel than patients with the wild type or homozygously mutated, but not compared to patients carrying the G/T alleles. A lower clearance of paclitaxel was also found for patients heterozygous for CYP2C8*3 when stratified according to the ABCB1 G2677T/A genotype. The CYP3A4 enzyme activity in vivo affected the relative influence of CYP2C8 and CYP3A4 on the metabolism, but not the total clearance of paclitaxel. The exposure to paclitaxel was correlated to the neurotoxicity, but not to the treatment response. In conclusion, our findings suggest that the SNP G2677T/A in the ABCB1 gene, but not β-tubulin mutations, might be a predictor for paclitaxel response and that the interindividual variability in paclitaxel pharmacokinetics might be predicted by ABCB1 and CYP2C8 genotypes and provide useful information for individualized chemotherapy.
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| 33. |
- Green, Henrik, et al.
(författare)
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Pharmacogenetic Studies of Paclitaxel in the Treatment of Ovarian Cancer
- 2009
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Ingår i: Basic & Clinical Pharmacology & Toxicology. - : Wiley-Blackwell Publishing Inc.. - 1742-7835 .- 1742-7843. ; 104:2, s. 130-137
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to evaluate the role of sequence variants in the CYP2C8, ABCB1 and CYP3A4 genes and the CYP3A4 phenotype for the pharmacokinetics and toxicity of paclitaxel in ovarian cancer patients. Thirty-eight patients were treated with paclitaxel and carboplatin. The genotypes of CYP2C8*1B, *1C, *2, *3, *4, *5, *6, *7, *8 and P404A, ABCB1 G2677T/A and C3435T, as well as CYP3A4*1B, were determined by pyrosequencing. Phenotyping of CYP3A4 was performed in vivo with quinine as a probe. The patients were monitored for toxicity and 23 patients underwent a more extensive neurotoxicity evaluation. Patients heterozygous for G/A in position 2677 in ABCB1 had a significantly higher clearance of paclitaxel than most other ABCB1 variants. A lower clearance of paclitaxel was found for patients heterozygous for CYP2C8*3 when stratified according to the ABCB1 G2677T/A genotype. In addition, the CYP3A4 enzyme activity in vivo affected which metabolic pathway was dominant in each patient, but not the total clearance of paclitaxel. The exposure to paclitaxel correlated to the degree of neurotoxicity. Our findings suggest that interindividual variability in paclitaxel pharmacokinetics might be predicted by ABCB1 and CYP2C8 genotypes and provide useful information for individualized chemotherapy.
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| 34. |
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| 35. |
- Green, Henrik, et al.
(författare)
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Spontaneous Reversal of P-Glycoprotein Expression in Multidrug Resistant Cell Lines
- 2003
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Ingår i: Pharmacology and Toxicology. - : Wiley. - 0901-9928 .- 1600-0773. ; 93:6, s. 297-304
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Tidskriftsartikel (refereegranskat)abstract
- Increased expression of P-glycoprotein encoded by the mdr-1 gene is a well-characterised mechanism for resistance to cancer chemotherapeutic drugs in cell lines. However, the P-glycoprotein expression after removal of the selection pressure has not fully been elucidated. The stability of P-glycoprotein expression in the presence (+) and absence (-) of vincristine (30 or 150 nM) was studied in multidrug resistant K562 cell lines (VCR30+, VCR150+, VCR30- and VCR150-) for 11 months. The P-glycoprotein protein and mdr-1 mRNA levels were determined at regular intervals using flow cytometry and real-time PCR, respectively. Chemosensitivity to a panel of antineoplastic drugs was measured using an MTT assay. The presence of vincristine (VCR30+ and VCR150+) resulted in high and stable levels of P-glycoprotein and mdr-1 mRNA during the whole period compared to wild type. As for the VCR30- and VCR150- subcultures, the expressions of P-glycoprotein and mdr-1 mRNA were stable for five months, and then the levels decreased rapidly. Concomitantly, the sensitivity to drugs known as P-glycoprotein substrates was restored. In conclusion, resistant cells growing in the presence of the inducing drug have a stable P-glycoprotein expression and resistance level, but removing the inducing drug may result in a sudden and rapid lowering of P-glycoprotein and mdr-1 mRNA levels as long as five months after drug withdrawal.
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| 36. |
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| 37. |
- Green, Henrik, et al.
(författare)
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Using Whole-Exome Sequencing to Identify Genetic Markers for Carboplatin and Gemcitabine-Induced Toxicities
- 2016
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Ingår i: Clinical Cancer Research. - : AMER ASSOC CANCER RESEARCH. - 1078-0432 .- 1557-3265. ; 22:2, s. 366-373
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Chemotherapies are associated with significant interindividual variability in therapeutic effect and adverse drug reactions. In lung cancer, the use of gemcitabine and carboplatin induces grade 3 or 4 myelosuppression in about a quarter of the patients, while an equal fraction of patients is basically unaffected in terms of myelosuppressive side effects. We therefore set out to identify genetic markers for gemcitabine/carboplatin-induced myelosuppression. Experimental Design: We exome sequenced 32 patients that suffered extremely high neutropenia and thrombocytopenia (grade 3 or 4 after first chemotherapy cycle) or were virtually unaffected (grade 0 or 1). The genetic differences/polymorphism between the groups were compared using six different bioinformatics strategies: (i) whole-exome nonsynonymous single-nucleotide variants association analysis, (ii) deviation from Hardy-Weinberg equilibrium, (iii) analysis of genes selected by a priori biologic knowledge, (iv) analysis of genes selected from gene expression meta-analysis of toxicity datasets, (v) Ingenuity Pathway Analysis, and (vi) FunCoup network enrichment analysis. Results: A total of 53 genetic variants that differed among these groups were validated in an additional 291 patients and were correlated to the patients myelosuppression. In the validation, we identified rs1453542 in OR4D6 (P = 0.0008; OR, 5.2; 95% CI, 1.8-18) as a marker for gemcitabine/carboplatin-induced neutropenia and rs5925720 in DDX53 (P = 0.0015; OR, 0.36; 95% CI, 0.17-0.71) as a marker for thrombocytopenia. Patients homozygous for the minor allele of rs1453542 had a higher risk of neutropenia, and for rs5925720 the minor allele was associated with a lower risk for thrombocytopenia. Conclusions: We have identified two new genetic markers with the potential to predict myelosuppression induced by gemcitabine/ carboplatin chemotherapy. (C)2015 AACR.
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| 38. |
- Gregers, Jannie, et al.
(författare)
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Pharmacogenetic polymorphisms in folate metabolism affect toxicity after high dose methotrexate in childhood acute lymphoblastic leukemia
- 2012
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We hypothesized that polymorphisms in folate metabolism would affect treatment effects of the folate antagonist methotrexate (MTX). We studied whether ATIC347C>T, MTHFR677C>T, MTHFR1298C>A and SHMT1-1420C>T polymorphisms influence risk of disease or efficacy and toxicity of MTX in a large population of children with acute lymphoblastic leukaemia (ALL). The children were treated after standardized Nordic protocols with 5-8 g/m2 high-dose MTX courses and long term oral maintenance therapy with weekly MTX. Ninety-four percent (n=533) of the children diagnosed during a 16 year time period were included. The study showed that the polymorphisms had no effect on risk of ALL, MTX pharmacokinetics or outcome. However after high-dose MTX treatment, patients with MTHFR677TT/MTHFR677CT had more liver toxicity than patients with MTHFR677CC (alanine transferase: 174/154 versus 115U/L, p=0.049). Patients with MTHFR1298AA had more liver toxicity than patients with MTHFR1298CC (alanine transferase: 144 versus 108 U/L, p=0.04). More bone marrow toxicity was found in patients with MTHFR1298CC compared to MTHFR1298CT / MTHFR1298AA (Nadir means: Platelets 72 versus 109/93*109/L, p=0.0001). In conclusion this study supports that MTHFR1298C>A and MTHFR677C>T are associated with toxicity in MTX treatment and the MTHFR variants should be considered as markers for individualization of treatment in childhood ALL in combination with other pharmacogenetic markers.
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| 39. |
- Gregers, Jannie, 1964-
(författare)
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Pharmacogenetic studies in childhood acute lymphoblastic leukaemia with primary focus on methotrexate
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Childhood acute lymphoblastic leukaemia is the most common type of cancer in children. Improvement in treatment has increased survival to approximately 85 per cent. Pharmacogenetics can influence the disposition of anticancer agents and can ideally be used as tool to further improve treatment based on the individual child’s pharmacogenetic profile.The hypothesis in this thesis was that polymorphisms in genes responsible for MTX influx (SLC19A1), efflux (ABCB1, studies with MTX monotherapy have demonstrated effect of variations in this gene) or other MTX pathways (ATIC, MTHFR and SHMT) could have impact on efficacy in childhood acute lymphoblastic leukaemia.The uptake of MTX and impact of SLC19A1 80G>A was investigated in vitro and showed that SLC19A1 80GG had decreased uptake in CD+ T cells and B cells caused by reduced capacity on receptor-to-receptor basis.In more than 500 patients the clinical effect of SLC19A1 80G>A genotype was evaluated and showed that patients with the SLC19A1 80AA had better survival, more bone marrow toxicity, but less liver toxicity than patients with SLC19A1 80GG or 80GA variants. Furthermore, it was demonstrated that SLC19A1 80G>A interacts with chromosome 21 copy number in the leukemic clone.The clinical impact of ABCB1 1199G>A, 1236C>T, 2677GT on the treatment was evaluated. Patients with either the 1199GA or the 3435CC variant had increased risk of relapse compared to patients with the 1199GG or 3435CT/TT variants, respectively. Toxicity was also affected by the ABCB1 polymorphisms.No association between polymorphisms in the ATIC, MTHFR and SHMT genes and outcome was seen. However the 677C>T and 1298 C>A in the MTHFR gene were associated with toxicity.The genotype frequencies between healthy donors and patients were compared, but no association to risk of developing cancer was seen in the investigated polymorphisms.The results in this thesis emphasise the importance of including pharmacogenetic markers in attempts to improve outcome and reduced side effects in childhood ALL.
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| 40. |
- Gregers, Jannie, et al.
(författare)
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Polymorphisms in the ABCB1 gene affect outcome and toxicity in Childhood Acute Lymphoblastic Leukemia
- 2012
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The membrane transporter P-glycoprotein, encoded by the ABCB1 gene, influences pharmacokinetics in several anti-cancer drugs. We hypothesized that 1199G>A, 1236C>T, 2677G>A/T and 3435C>T variants of ABCB1 could affect outcome and toxicity in childhood acute lymphoblastic leukemia (ALL), since treatment includes known P-glycoprotein substrates and 3435C/T may affect methotrexate therapy. We studied 522 Danish children with ALL treated according to NOPHO ALL92 and ALL2000 protocols, 93% of all those eligible during 1992-2007. Risk of relapse was 2.9-fold increased for 41 patients with the 1199GA variant compared to 477 with 1199GG (p=0.001), and reduced by 61% and 40%, respectively for 421 patients with the 3435CT or 3435TT variants compared to 96 with 3435CC (overall p=0.02). Degree of bone marrow toxicity during doxorubicin, vincristine and prednisolone induction therapy was higher in 71 patients with 3435TT variant (median nadirs: hemoglobin 3% and platelets 34/37% lower in3435CT/3435CC) compared to 160 patients with 3435CT/3435CC (Hemoglobin p=0.01 and platelets p<0.0001). We observed more liver toxicity after high-dose methotrexate in 109 patients with 3435CC variant versus 3435CT/TT (Median max alanineaminotransferase: 280 versus 142/111 U/L, p=0.03). In conclusion, there is a statistically significant association between ABCB1 polymorphisms and efficacy and toxicity in childhood ALL.
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| 41. |
- Gregers, Jannie, et al.
(författare)
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Polymorphisms in the ABCB1 gene and effect on outcome and toxicity in childhood acute lymphoblastic leukemia
- 2015
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Ingår i: The Pharmacogenomics Journal. - : Nature Publishing Group: Open Access Hybrid Model Option B. - 1470-269X .- 1473-1150. ; 15:4, s. 372-379
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Tidskriftsartikel (refereegranskat)abstract
- The membrane transporter P-glycoprotein, encoded by the ABCB1 gene, influences the pharmacokinetics of anti-cancer drugs. We hypothesized that variants of ABCB1 affect outcome and toxicity in childhood acute lymphoblastic leukemia (ALL). We studied 522 Danish children with ALL, 93% of all those eligible. Risk of relapse was increased 2.9-fold for patients with the 1199GA variant versus 1199GG (P = 0.001), and reduced 61% and 40%, respectively, for patients with the 3435CT or 3435TT variants versus 3435CC (overall P = 0.02). The degree of bone marrow toxicity during doxorubicin, vincristine and prednisolone induction therapy was more prominent in patients with 3435TT variant versus 3435CT/3435CC (P = 0.01/P less than 0.0001). We observed more liver toxicity after high-dose methotrexate in patients with 3435CC variant versus 3435CT/TT ( P = 0.03). In conclusion, there is a statistically significant association between ABCB1 polymorphisms, efficacy and toxicity in the treatment of ALL, and ABCB1 1199G greater than A may be a new possible predictive marker for outcome in childhood ALL.
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| 42. |
- Gregers, Jannie, et al.
(författare)
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The association of reduced folate carrier 80G greater than A polymorphism to outcome in childhood acute lymphoblastic leukemia interacts with chromosome 21 copy number
- 2010
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 115:23, s. 4671-4677
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Tidskriftsartikel (refereegranskat)abstract
- The reduced folate carrier (RFC) is involved in the transport of methotrexate (MTX) across the cell membrane. The RFC gene (SLC19A1) is located on chromosome 21, and we hypothesized that the RFC80 G greater than A polymorphism would affect outcome and toxicity in childhood leukemia and that this could interact with chromosome 21 copy number in the leukemic clone. A total of 500 children with acute lymphoblastic leukemia treated according to the common Nordic treatment protocols were included, and we found that the RFC AA variant was associated with a 50% better chance of staying in remission compared with GG or GA variants (P = .046). Increased copy numbers of chromosome 21 appear to improve outcome also in children with GA or GG variant. In a subset of 182 children receiving 608 high-dose MTX courses, we observed higher degree of bone marrow toxicity in patients with the RFC AA variant compared with GA/GG variants (platelet 73 vs 99/105 x 10(9)/L, P = .004, hemoglobin 5.6 vs 5.9/6.0 mmol/L, P = .004) and a higher degree of liver toxicity in patients with RFC GG variant (alanine aminotransferase 167 vs 127/124 U/L, P = .05). In conclusion, the RFC 80G greater than A polymorphism interacts with chromosome 21 copy numbers and affects both efficacy and toxicity of MTX.
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| 43. |
- Haglund, Sofie, et al.
(författare)
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Gene Expression and Thiopurine Metabolite Profiling in Inflammatory Bowel Disease : Novel Clues to Drug Targets and Disease Mechanisms?
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- Background and AimsThiopurines are effective to induce and maintain remission in inflammatory bowel disease (IBD). The methyl thioinosine monophosphate (meTIMP)/6-thioguanine nucleotide (6-TGN) concentration ratio has been associated with drug efficacy. Here we explored the molecular basis of differences in metabolite profiles and in relation to disease activity.MethodsTranscriptional profiles in blood samples from an exploratory IBD-patient cohort (n = 21) with a normal thiopurine S-methyltransferase phenotype and meTIMP/6-TGN ratios >20, 10.0–14.0 and ≤4, respectively, were assessed by hybridization to microarrays. Results were further evaluated with RT qPCR in an expanded patient cohort (n = 54). Additionally, 30 purine/thiopurine related genes were analysed separately.ResultsAmong 17 genes identified by microarray-screening, there were none with a known relationship to pathways of purines/thiopurines. For nine of them a correlation between expression level and the concentration of meTIMP, 6-TGN and/or the meTIMP/6-TGN ratio was confirmed in the expanded cohort. Nine of the purine/thiopurine related genes were identified in the expanded cohort to correlate with meTIMP, 6-TGN and/or the meTIMP/6-TGN ratio. However, only small differences in gene expression levels were noticed over the three different metabolite profiles. The expression levels of four genes identified by microarray screening (PLCB2, HVCN1, CTSS, and DEF8) and one purine/thiopurine related gene (NME6) correlated significantly with the clinical activity of Crohn’s disease. Additionally, 16 of the genes from the expanded patient cohort interacted in networks with candidate IBD susceptibility genes.ConclusionsSeventeen of the 18 genes which correlated with thiopurine metabolite levels also correlated with disease activity or participated in networks with candidate IBD susceptibility genes involved in processes such as purine metabolism, cytokine signaling, and functioning of invariant natural killer T cells, T cells and B cells. Therefore, we conclude that the identified genes to a large extent are related to drug targets and disease mechanisms of IBD.
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| 44. |
- Haglund, Sofie, 1975-, et al.
(författare)
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IMPDH activity in thiopurine-treated patients with inflammatory bowel disease - Relation to TPMT activity and metabolite concentrations
- 2008
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Ingår i: British Journal of Clinical Pharmacology. - : Wiley. - 0306-5251 .- 1365-2125. ; 65:1, s. 69-77
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Azathioprine and 6-mercaptopurine are steroid-sparing drugs used in inflammatory bowel disease (IBD). The polymorphic enzyme thiopurine S-methyltransferase (TPMT) is of importance for thiopurine metabolism and occurrence of adverse events. The role of other thiopurine-metabolizing enzymes is less well known. This study investigated the role of inosine-5′- monophosphate dehydrogenase (IMPDH), which is a key enzyme in the de novo synthesis of guanine nucleotides and also strategically positioned in the metabolic pathway of thiopurines. METHODS: IMPDH was measured in 100 healthy blood donors. IMPDH, TPMT and metabolite concentrations were studied in 50 patients with IBD on stable thiopurine therapy. IMPDH activity was measured in peripheral blood mononuclear cells. TPMT activity, 6-methylthioinosine 5′-monophosphate (meTIMP) and 6-thioguanine nucleotide (6-TGN) concentrations were measured in red blod cells, which is the current practice in clinical monitoring of thiopurines. Enzyme activities were related to metabolite concentrations and clinical characteristics. RESULTS: A wide range of IMPDH activity was observed both in healthy blood donors (median 13.1, range 4.7-24.2 nmol mg-1 protein h-1) and IBD patients (median 14.0, range 7.0-21.7). There was a negative correlation between IMPDH activity and dose-normalized meTIMP concentrations (rs = -0.31, P = 0.03), but no evident correlation to 6-TGN concentration or the meTIMP/6-TGN ratio. There were no significant correlations between TPMT activity and metabolite concentrations. CONCLUSION: Even though the meTIMP concentrations correlated inversely to the IMPDH activity, the role of IMPDH in balancing the formation of methylated and phosphorylated metabolites was not evident. Taken together, the results give cause to question established opinions about thiopurine metabolism. © 2007 The Authors.
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| 45. |
- Haglund, Sofie
(författare)
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Interindividual differences in thiopurine metabolism : studies with focus on inflammatory bowel disease
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thiopurines, 6-mercaptopurine and its prodrug azathioprine, are used in the treatment of inflammatory bowel disease, ulcerative colitis and Crohn´s disease. The main active metabolites are the phosphorylated thioguanine nucleotides (6-TGNs) and methylated thioinosine monophosphate (meTIMP). Both groups contribute to the immunomodulatory effects. About 30-40% of patients fail to benefit from thiopurine treatment. A well-known cause of adverse reactions is decreased or absent thiopurine S-methyltransferase (TPMT) activity. Low TPMT activity is inherited as an autosomal codominant recessive trait and is present in approximately 10% of the population. Although several clinical issues can be solved from determination of TPMT activity, there are cases where it is not possible. In Sweden approximately 25% of IBD-patients display suboptimal 6-TGN concentrations and unexpectedly high concentrations of meTIMP despite a normal TPMT activity. A high meTIMP/6-TGN concentration ratio has been associated with both unresponsiveness to therapy and emergence of adverse reactions. Inosine 5’-monophosphate dehydrogenase (IMPDH) may constitute a candidate gene to explain this metabolite profile, as it is strategically positioned in the metabolic pathway of thiopurines where it competes with TPMT for their common substrate 6-TIMP.In paper I a pyrosequencing method was developed for genotyping of at that time all known genetic variants of TPMT. The concordance between genotype and phenotype in 30 individuals was 93%. The allele frequencies of TPMT*3A, *3B, *3C and *2 in a Swedish background population (n=800) were in agreement with those in other Caucasian or European populations. In Paper II-IV we explored the molecular basis of different metabolite profiles, i.e. low, normal and high meTIMP/6-TGN concentration ratios. The activity of IMPDH was measured in mononuclear cells (MNC). Patients with high metabolite ratios had lower IMPDH activity than patients with normal or low ratios, explained by an inverse correlation to red blood cells concentration of meTIMP. No correlation to 6-TGN was observed. Downregulation of IMPDH activity in HEK293 cells with genetically engineered TPMT activity was associated with an increase in meTIMP, but unexpectedly also of 6-TGN, irrespective of the TPMT status. These results suggest effects of pharmacogenes other than TPMT and IMPDH. A whole genome expression analysis was performed, (1) to identify new candidate genes that could explain differences in metabolite profiles, and (2) to study genes with known associations to the metabolic pathway of (thio)purines. The whole genome expression analysis did not identify any significant group differences. In analysis of the thiopurine related genes, three clusters of co-regulated genes were defined. A co-operation between expression levels of SLC29A1 and NT5E in explaining the meTIMP/6-TGN concentration ratio was observed, and individually SLC29A1 and NT5E correlated to 6-TGN and meTIMP, respectively.Pysosequencing is a convenient and flexible method which is now run in parallel to phenotyping in our laboratory. Our results also illustrate the complexity of the thiopurine metabolism and suggest that differences between metabolite profiles are explained either by interactions between several genes, each with a small contribution, or at the post-transcriptional level. Search for more precise tools to explain differences in metabolite profiles is needed. Furthermore, in order to investigate small effects it is necessary to analyse metabolite concentrations and gene expression levels, as well as enzyme activities in the target cells of therapy (MNC).
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| 46. |
- Haglund, Sofie, 1975-, et al.
(författare)
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Pharmacotranscriptomics in thiopurine treated IBD patients with different metabolite profiles
- 2008
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Thiopurine drugs are used to induce and maintain remission in inflammatory bowel disease. The methyl thioinosine monophosphate (meTIMP)/6-thioguanine nucleotide (6-TGN) concentration ratio has been related to drug response and adverse reactions. Here we investigated for differences in gene expression levels between patients with different metabolite profiles. Methods: Transcriptional profiles in blood samples from an exploratory patient cohort (n=21) comprising three groups; patients with normal thiopurine S-methyltransferase phenotype and meTIMP/6-TGN concentration ratio >20, ratio 10.0-14.0 and ratio ≤4, respectively, were assessed by hybridization to microarrays. Results were further evaluated with reverse transcription qPCR [exploratory and a validation cohort of patients (n=33)]. Additionally, known genes of the thiopurine metabolic pathway were analysed separately. Results: The whole genome expression analysis did not identify any significant differences between metabolite profiles. Analysis of thiopurine related genes revealed a large interindividual variation in gene expression, but only small differences between metabolite profiles. Three clusters of co-regulated genes were defined based on correlations between gene expression levels. The concentration of meTIMP correlated to the expression of NT5E (rs = 0.33, P = 0.02) and TPMT (rs = - 0.37, P = 0.007). The concentration of 6-TGN correlated to the expression of HPRT1 (rs = - 0.31, P = 0.03) and SLC29A1 (rs = 0.33, P = 0.02). With the exception of SLC29A1, these genes belonged to the same cluster of genes. Conclusions: Our results illustrates the complexity of the thiopurine metabolism and suggest that differences between metabolite profiles are explained either by interactions between several genes, each with a small contribution, or at the post-transcriptional level. Search for more precise tools in order to explain differences in metabolite profiles is needed.
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| 47. |
- Haglund, Sofie, et al.
(författare)
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Pyrosequencing of TPMT Alleles in a General Swedish Population and in Patients with Inflammatory Bowel Disease
- 2004
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Ingår i: Clinical Chemistry. - : Oxford University Press (OUP). - 0009-9147 .- 1530-8561. ; 50:2, s. 288-295
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Tidskriftsartikel (refereegranskat)abstract
- Background: Interindividual differences in therapeutic efficacy in patients treated with thiopurines might be explained by the presence of thiopurine S-methyltransferase (TPMT) alleles that encode for reduced TPMT enzymatic activity. It is therefore of value to know an individual's inherent capacity to express TPMT. Method: We developed a pyrosequencing method to detect 10 single-nucleotide polymorphisms (SNPs) in TPMT. A Swedish population (n = 800) was examined for TPMT*3A, TPMT*3B, TPMT*3C, and TPMT*2. Patients with inflammatory bowel disease (n = 24) and healthy volunteers (n = 6), selected on the basis of TPMT enzymatic activity, were investigated for all 10 SNPs to determine the relationship between TPMT genotype and phenotype. Results: In the general population we identified the following genotypes with nonfunctional alleles: TPMT*1/*3A (*3A allelic frequency, 3.75%), TPMT*1/*3C (*3C allelic frequency, 0.44%), TPMT*1/*3B (*3B allelic frequency, 0.13%), and TPMT*1/*2 (*2 allelic frequency, 0.06%). All nine individuals with normal enzymatic activity were wild-type TPMT*1/*1. Thirteen individuals with intermediate activity were either TPMT*1/*3A (n = 12) or TPMT*1/*2 (n = 1). Eight individuals with low enzymatic activity were TPMT*3A/*3A (n = 4), TPMT*3A/*3C (n = 2), or TPMT*1/*3A (n = 2). Conclusion: Next to wild type, the most frequent alleles in Sweden are TPMT*3A and TPMT*3C. A previously established phenotypic cutoff for distinguishing normal from intermediate metabolizers was confirmed. To identify the majority of cases (90%) with low or intermediate TPMT activity, it was sufficient to analyze individuals for only 3 of the 10 SNPs investigated. Nevertheless, this investigation indicates that other mutations might be of relevance for decreased enzymatic activity. © 2004 American Association for Clinical Chemistry.
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| 48. |
- Haglund, Sofie, et al.
(författare)
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The Role of Inosine-5'-Monophosphate Dehydrogenase in Thiopurine Metabolism in Patients With Inflammatory Bowel Disease.
- 2011
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Ingår i: Therapeutic Drug Monitoring. - : Lippincott Williams & Wilkins. - 0163-4356 .- 1536-3694. ; 33:2, s. 200-208
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:: There is a large interindividual variability in thiopurine metabolism. High concentrations of methylthioinosine-5'-monophosphate (meTIMP) and low concentrations of 6-thioguanine nucleotides (6-TGNs) have been associated with a lower response rate and an increased risk of adverse events. In this study, the role of inosine-5'-monophosphate dehydrogenase (IMPDH) for differences in metabolite patterns of thiopurines was investigated. METHODS:: IMPDH activity and thiopurine metabolite concentrations were determined in patients with inflammatory bowel disease and a normal thiopurine methyltransferase (TPMT) phenotype and meTIMP/6-TGN concentration ratio > 20 (n = 26), in patients with a metabolite ratio ≤20 (n = 21), in a subgroup with a metabolite ratio <4 (n = 6), and in 10 patients with reduced TPMT activity. In vitro studies were conducted on human embryonic kidney cells (HEK293) with genetically engineered IMPDH and TPMT activities. RESULTS:: Patients with metabolite ratios >20 had lower IMPDH activity than those with ratios ≤20 (P < 0.001). Metabolic ratios >20 were only observed in patients with normal TPMT activity. Downregulation of IMPDH activity in HEK293 cells was associated with an increase in the concentration of meTIMP (fold change: 17 up to 93, P < 0.001) but, unexpectedly, also of 6-thioguanosine monophosphate (fold change: 2.6 up to 5.0, P < 0.001). CONCLUSIONS:: These data question the general view of IMPDH as the rate-limiting enzyme in the phosphorylation of thiopurines. Investigations of other mechanisms are needed to more fully explain the various metabolite patterns and outcomes in patients under treatment.
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| 49. |
- Hasmats, Johanna, et al.
(författare)
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Using whole exome sequencing to identify genetic candidates for carboplatin and gemcitabine induced toxicities
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Chemotherapies are associated with significant inter-individual variability in therapeutic effect and adverse drug reactions. In lung cancer the use of gemcitabine and carboplatin induces grade 3-4 myelosuppression in about ¼ of the patients while an equal fraction of patients are basically unaffected in terms of myelosuppressive side effects. We therefore set out to try to identify genetic markers for gemcitabine / carboplatin induced myelosuppression. We selected 32 patients that suffered extremely high neutropenia and thrombocytopenia (grade 3 or 4 after first chemotherapy cycle) or were virtually unaffected (grade 0-1 after the first chemotherapy cycle) by the chemotherapy out of 243 lung cancer patients treated with gemcitabine / carboplatin. These patients were exome sequenced and their genetic differences compared using six different bioinformatic strategies; whole exome non-synonymous SNV association analysis, deviation from Hardy-Weinberg equilibrium, analysis of genes selected by a priori biological knowledge, analysis of genes selected from gene expression meta-analysis of toxicity data sets, Ingenuity pathway analysis and FunCoup network enrichment analysis. All patients were successfully sequenced and 5000-7000 non-synonymous single nucleotide variants were identified in each patient. PI3 (elastase specific inhibitor in neutrophils) showed the strongest association in the single SNV analysis (nominal p=0.0005). Further, variants within IL37, an inhibitor of the innate immune system, and CSAG1, a tumor antigen, differed among the two patient groups and appeared among the top hits in several of the performed analysis, indicating that the approach identifies genetic variants associated with the immune system and tumor differentiation, which might be important for the sensitivity to chemotherapeutic agents. However, the associations reported here are in a need of replication before clinical interpretations can be made.
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| 50. |
- Hindorf, U., et al.
(författare)
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Assessment of thiopurine methyltransferase and metabolite formation during thiopurine therapy : Results from a large swedish patient population
- 2004
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Ingår i: Therapeutic Drug Monitoring. - : Ovid Technologies (Wolters Kluwer Health). - 0163-4356 .- 1536-3694. ; 26:6, s. 673-678
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Tidskriftsartikel (refereegranskat)abstract
- This study examined thiopurine methyltransferase (TPMT) and the relationship to thioguanine nucleotides (TGN) and methylthioinosine monophosphate (meTIMP) in a large Swedish patient population. The current hypothesis is that the cytotoxic effects of thiopurine drugs are mediated by the incorporation of TGN into DNA. The authors assayed the TPMT activity in red blood cells from 1151 subjects and the concentrations of TGN (n = 602) and meTIMP (n = 593) from patients treated with thiopurine drugs. The TPMT frequency distribution in both adults and children showed some differences from what had been found in unselected general populations. Children had lower median TPMT activity than adults (12.0 versus 12.9 U/mL RBC, P < 0.001). Relative differences in both TGN formation [medians: normal TPMT, 1.3, intermediate TPMT, 3.3, low TPMT, 47.9 pmol/8 × 108 RBC per mg azathioprine (AZA), P < 0.001] and meTIMP formation (medians: normal TPMT, 13, intermediate TPMT, 7.3, low TPMT, 0 pmol/8 × 108 RBC per mg AZA, P = 0.001) per 1 mg administered drug were noted among the 3 TPMT activity groups. Women formed higher concentrations of both TGN (1.5 versus 1.3 pmol/8 × 108 RBC per mg AZA, P = 0.01) and meTIMP (14.4 versus 10.7 pmol/8 × 108 RBC per mg AZA, P = 0.01) than men did. There was a significant correlation between the AZA dose and the meTIMP concentrations (r = 0.45, P < 0.001). Furthermore, dose alterations made in subjects with normal TPMT (n = 84) and intermediate TPMT (n = 22) activity resulted in more pronounced increases in TGN concentrations (170 versus 30 pmol/8 × 10 8 RBC, P < 0.001) in intermediate TPMT activity, whereas in normal TPMT activity changes in meTIMP concentrations were more pronounced (1.3 versus 0 nmol/8 × 108 RBC, P < 0.001). In normal TPMT activity both metabolites increased in a dose-dependent fashion, whereas in intermediate TPMT activity only TGN concentrations increased. The results of this study demonstrate the dynamic nature of thiopurine metabolism and its importance for thiopurine dosing.
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