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Li L, Atkinson N, Crews KR, Molinelli AR. Determination of Thiopurine S-Methyltransferase (TPMT) Activity in Human Erythrocytes by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). Methods Mol Biol 2024; 2737:465-472. [PMID: 38036847 DOI: 10.1007/978-1-0716-3541-4_43] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
Thiopurine methyltransferase (TPMT) is a cytosolic enzyme involved in the metabolism of thiopurine medications that are used in the treatment of multiple malignant and nonmalignant immunologic conditions. Polymorphisms in the TPMT gene associated with low enzyme activity can produce pronounced pharmacologic effects during therapy. The determination of TPMT erythrocyte activity is a valuable adjunct test to genotyping for the assignment of TPMT phenotype, especially in the presence of indeterminate genotypes. We present a method for the determination TPMT activity in human erythrocytes whereby we utilize LC-MS/MS to measure the amount of 6-methylmercaptopurine formed in red blood cell (RBC) lysates using 6-mercaptopurine as substrate and S-adenosylmethionine (SAM) as methyl donor. This method has been successfully implemented and proven to be reliable for use in human specimens.
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Affiliation(s)
- Lie Li
- Department of Pharmacy and Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Natalya Atkinson
- Department of Pharmacy and Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Kristine R Crews
- Department of Pharmacy and Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Alejandro R Molinelli
- Department of Pharmacy and Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, TN, USA.
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2
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Rieger H, Schmidt P, Schaeffeler E, Abe M, Schiffhauer M, Schwab M, von Ahsen N, Zurek G, Kirchherr H, Shipkova M, Wieland E. Validation of a high-performance liquid chromatography method for thiopurine S-methyltransferase activity in whole blood using 6-mercaptopurine as substrate. Clin Chem Lab Med 2019; 56:803-809. [PMID: 29194039 DOI: 10.1515/cclm-2017-0670] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 10/31/2017] [Indexed: 12/12/2022]
Abstract
BACKGROUND Variation in metabolism, toxicity and therapeutic efficacy of thiopurine drugs is largely influenced by genetic polymorphisms in the thiopurine S-methyltransferase (TPMT) gene. Determination of TPMT activity is routinely performed in patients to adjust drug therapy. METHODS We further optimized a previously established high-performance liquid chromatography (HPLC) method by measuring TPMT activity in whole blood instead of isolated erythrocytes, which is based on conversion of 6-mercaptopurine to 6-methylmercaptopurine using S-adenosyl-methionine as methyl donor. RESULTS The simplified TPMT whole-blood method showed similar or better analytical and diagnostic performance compared with the former erythrocyte assay. The whole-blood method was linear for TPMT activities between 0 and 40 nmol/(mL·h) with a quantification limit of 0.1 nmol/(mL·h). Within-day imprecision and between-day imprecision were ≤5.1% and ≤8.5%, respectively. The optimized method determining TPMT activity in whole blood (y) showed agreement with the former method determining TPMT activity in erythrocytes (x) (n=45, y=1.218+0.882x; p>0.05). Phenotype-genotype concordance (n=300) of the whole-blood method was better when TPMT activity was expressed per volume of whole blood (specificity 92.2%), whereas correction for hematocrit resulted in lower genotype concordance (specificity 86.9%). A new cutoff for the whole-blood method to distinguish normal from reduced TPMT activity was determined at ≤6.7 nmol/(mL·h). CONCLUSIONS This optimized TPMT phenotyping assay from whole blood using 6-MP as substrate is suitable for research and routine clinical analysis.
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Affiliation(s)
- Hannah Rieger
- Central Institute for Clinical Chemistry and Laboratory Medicine, Klinikum Stuttgart, Stuttgart, Germany
| | - Patrik Schmidt
- Central Institute for Clinical Chemistry and Laboratory Medicine, Klinikum Stuttgart, Stuttgart, Germany
| | - Elke Schaeffeler
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, University of Tübingen, Stuttgart, Germany
| | - Manabu Abe
- Central Institute for Clinical Chemistry and Laboratory Medicine, Klinikum Stuttgart, Stuttgart, Germany
| | - Mira Schiffhauer
- Central Institute for Clinical Chemistry and Laboratory Medicine, Klinikum Stuttgart, Stuttgart, Germany
| | - Matthias Schwab
- Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, University of Tübingen, Stuttgart, Germany.,Department of Clinical Pharmacology, University Hospital Tübingen, Tübingen, Germany.,Department of Pharmacy and Biochemistry, University of Tübingen, Tübingen, Germany
| | | | | | | | - Maria Shipkova
- Central Institute for Clinical Chemistry and Laboratory Medicine, Klinikum Stuttgart, Stuttgart, Germany
| | - Eberhard Wieland
- Central Institute for Clinical Chemistry and Laboratory Medicine, Klinikum Stuttgart, Stuttgart, Germany
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Pecher D, Dokupilová S, Zelinková Z, Peppelenbosch M, Mikušová V, Mikuš P. Determination of thiopurine S-methyltransferase activity by hydrophilic interaction liquid chromatography hyphenated with mass spectrometry. J Pharm Biomed Anal 2017; 142:244-251. [PMID: 28525791 DOI: 10.1016/j.jpba.2017.05.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 05/05/2017] [Accepted: 05/08/2017] [Indexed: 12/18/2022]
Abstract
Thiopurine S-methyltransferase (TPMT) plays an important role in the metabolism of thiopurines used in the therapy of inflammatory bowel diseases (IBD). In this work a new progressive method for the determination of TPMT activity in red blood cells lysates was developed. Analysis was carried out by means of hydrophilic interaction liquid chromatography (HILIC) hyphenated with mass spectrometry (MS). In comparison with reversed-phase high-performance liquid chromatography (RP-HPLC), that has been typically applied in determination of TPMT activity, the HILIC significantly improved the analytical signal provided by MS, shortened analysis time, and improved chromatographic resolution. The HILIC-HPLC-MS method was optimized and validated, providing favorable parameters of detection and quantitation limits (5.5 and 16.5pmol/mL, respectively), linearity (coefficient of determination 0.9999 in the range of 0.01-1.0nmol/mL), recovery and precision (93.25-100.37% with RSD 1.06-1.32% in the whole concentration range of QC samples). Moreover, in contrast to the conventional RP-HPLC-UV approach, the complex phenotype TPMT profiles can be reliably and without interferences monitored using the HILIC-HPLC-MS method. Such advanced monitoring can provide valuable detail information on the thiopurines (e.g. evaluating ratio of methylated and non-methylated 6-mercaptopurine) and, by that, TPMT action in biological systems before and during the therapy of IBD.
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Affiliation(s)
- Daniel Pecher
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic; Toxicological and Antidoping center, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic
| | - Svetlana Dokupilová
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic; Toxicological and Antidoping center, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic
| | - Zuzana Zelinková
- Department of Gastroenterology, St Michael's Hospital, Bratislava, Slovak Republic
| | | | - Veronika Mikušová
- Toxicological and Antidoping center, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic; Department of Cell and Molecular Biology of Drugs, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic
| | - Peter Mikuš
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic; Toxicological and Antidoping center, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic.
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4
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Mei S, Li X, Gong X, Zhang X, Li X, Yang L, Zhu L, Zhou H, Liu Y, Zhou A, Zhang X, Zhao Z. Comparison of 6-mercaptopurine with 6-thioguanine for the analysis of thiopurine S-methyltransferase activity in human erythrocyte by LC-MS/MS. Biomed Chromatogr 2017; 31. [PMID: 28212467 DOI: 10.1002/bmc.3959] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Revised: 01/25/2017] [Accepted: 02/11/2017] [Indexed: 11/05/2022]
Abstract
Thiopurines (TPDs) are first-line drugs in treating neuromyelitis optica spectrum disorders (NMOSD). Evaluation of thiopurine S-methyltransferase activity (TPMT), a major determinant of TPD toxicity, before TPD treatment using 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG) as substrate was suggested. However, the equivalent of the two substrates in TPMT activity evaluation was unknown, and an alternative substrate was required in TPMT activity evaluation in patients who were already taking 6-MP or 6-TG. Before evaluating the agreement of 6-MP and 6-TG in TPMT activity measurement in patients with NMOSD, the affinity of the two substrates for the active center of TPMT should be established. A computer-based simulation indicated that 6-MP and 6-TG had similar affinities for the two active sites of TPMT. According to the guidelines, an LC-MS/MS method was developed and validated to evaluate the TPMT activity in human erythrocyte hemolysate using 6-MP or 6-TG as substrates via 1 h incubation at 37°C. The method was applied in 81 patients with NMOSD. Evaluated by Bland-Altman plot, 6-methylmercaptopurine and 6-methylthioguanine represented TPMT activities were in agreement with each other. Further studies are warranted to confirm the results.
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Affiliation(s)
- Shenghui Mei
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,Department of Clinical Pharmacology, College of Pharmaceutical Sciences, Capital Medical University, Beijing, People's Republic of China
| | - Xindi Li
- Neuroinfection and Neuroimmunology Center, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Xiaoqing Gong
- Neuroinfection and Neuroimmunology Center, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Xiaoyi Zhang
- College of Pharmaceutical Sciences, Capital Medical University, Beijing, People's Republic of China
| | - Xingang Li
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,Department of Clinical Pharmacology, College of Pharmaceutical Sciences, Capital Medical University, Beijing, People's Republic of China
| | - Li Yang
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,Department of Clinical Pharmacology, College of Pharmaceutical Sciences, Capital Medical University, Beijing, People's Republic of China
| | - Leting Zhu
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Heng Zhou
- Neuroinfection and Neuroimmunology Center, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Yonghong Liu
- Neuroinfection and Neuroimmunology Center, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Anna Zhou
- Neuroinfection and Neuroimmunology Center, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Xinghu Zhang
- Neuroinfection and Neuroimmunology Center, Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China.,China National Clinical Research Center for Neurological Diseases, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
| | - Zhigang Zhao
- Department of Pharmacy, Beijing Tiantan Hospital, Capital Medical University, Beijing, People's Republic of China
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5
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Zur RM, Roy LM, Ito S, Beyene J, Carew C, Ungar WJ. Thiopurine S-methyltransferase testing for averting drug toxicity: a meta-analysis of diagnostic test accuracy. THE PHARMACOGENOMICS JOURNAL 2016; 16:305-11. [PMID: 27217052 PMCID: PMC4957983 DOI: 10.1038/tpj.2016.37] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 04/15/2016] [Indexed: 01/12/2023]
Abstract
Thiopurine S-methyltransferase (TPMT) deficiency increases the risk of serious adverse events in persons receiving thiopurines. The objective was to synthesize reported sensitivity and specificity of TPMT phenotyping and genotyping using a latent class hierarchical summary receiver operating characteristic meta-analysis. In 27 studies, pooled sensitivity and specificity of phenotyping for deficient individuals was 75.9% (95% credible interval (CrI), 58.3-87.0%) and 98.9% (96.3-100%), respectively. For genotype tests evaluating TPMT*2 and TPMT*3, sensitivity and specificity was 90.4% (79.1-99.4%) and 100.0% (99.9-100%), respectively. For individuals with deficient or intermediate activity, phenotype sensitivity and specificity was 91.3% (86.4-95.5%) and 92.6% (86.5-96.6%), respectively. For genotype tests evaluating TPMT*2 and TPMT*3, sensitivity and specificity was 88.9% (81.6-97.5%) and 99.2% (98.4-99.9%), respectively. Genotyping has higher sensitivity as long as TPMT*2 and TPMT*3 are tested. Both approaches display high specificity. Latent class meta-analysis is a useful method for synthesizing diagnostic test performance data for clinical practice guidelines.The Pharmacogenomics Journal advance online publication, 24 May 2016; doi:10.1038/tpj.2016.37.
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Affiliation(s)
- RM Zur
- Child Health Evaluative Sciences, The Hospital for Sick Children Research Institute, Peter Gilgan Centre for Research and Learning, Toronto, Canada
| | - LM Roy
- Child Health Evaluative Sciences, The Hospital for Sick Children Research Institute, Peter Gilgan Centre for Research and Learning, Toronto, Canada
| | - S Ito
- Division of Clinical Pharmacology and Toxicology, The Hospital for Sick Children, Toronto, Canada
- Departments of Pharmacology & Pharmacy, Faculty of Medicine, Department of Paediatrics, University of Toronto, Toronto, Canada
| | - J Beyene
- Department of Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Canada
| | - C Carew
- Centre for Genetic Medicine, The Hospital for Sick Children, Toronto, Canada
| | - WJ Ungar
- Child Health Evaluative Sciences, The Hospital for Sick Children Research Institute, Peter Gilgan Centre for Research and Learning, Toronto, Canada
- Institute for Health Policy, Management & Evaluation, University of Toronto, Toronto, Canada
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6
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Roy LM, Zur RM, Uleryk E, Carew C, Ito S, Ungar WJ. Thiopurine S-methyltransferase testing for averting drug toxicity in patients receiving thiopurines: a systematic review. Pharmacogenomics 2016; 17:633-56. [PMID: 27020704 PMCID: PMC4931919 DOI: 10.2217/pgs.16.12] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
AIM Thiopurine S-methyltransferase (TPMT) testing is used in patients receiving thiopurines to identify enzyme deficiencies and risk for adverse drug reactions. It is uncertain whether genotyping is superior to phenotyping. The objectives were to conduct a systematic review of TPMT-test performance studies. MATERIALS & METHODS Electronic and grey literature sources were searched for studies reporting test performance compared with a reference standard. Sixty-six eligible studies were appraised for quality. RESULTS Thirty phenotype-genotype and six phenotype-phenotype comparisons were of high quality. The calculated sensitivity and specificity for genotyping to identify a homozygous mutation ranged from 0.0-100.0% and from 97.8-100.0%, respectively. CONCLUSION Clinical decision-makers require high-quality evidence of clinical validity and clinical utility of TPMT genotyping to ensure appropriate use in patients.
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Affiliation(s)
- Lilla M Roy
- Child Health Evaluative Sciences, The Hospital for Sick Children Research Institute, Toronto, Canada
| | - Richard M Zur
- Child Health Evaluative Sciences, The Hospital for Sick Children Research Institute, Toronto, Canada
| | - Elizabeth Uleryk
- Library Services, The Hospital for Sick Children, Toronto, Canada
| | - Chris Carew
- Centre for Genetic Medicine, The Hospital for Sick Children, Toronto, Canada
| | - Shinya Ito
- Division of Clinical Pharmacology & Toxicology, The Hospital for Sick Children, Toronto, Canada
- Departments of Pharmacology & Pharmacy, Faculty of Medicine Department of Paediatrics, University of Toronto, Canada
| | - Wendy J Ungar
- Child Health Evaluative Sciences, The Hospital for Sick Children Research Institute, Toronto, Canada
- Institute for Health Policy, Management & Evaluation, University of Toronto, Canada
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7
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Karim H, Appell ML, Fotoohi A. Comparison of three methods for measuring thiopurine methyltransferase activity in red blood cells and human leukemia cells. J Chromatogr B Analyt Technol Biomed Life Sci 2013; 939:80-5. [PMID: 24113235 DOI: 10.1016/j.jchromb.2013.08.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 08/23/2013] [Accepted: 08/29/2013] [Indexed: 10/26/2022]
Abstract
Thiopurine efficacy is partly reflected by the genetic polymorphism of the thiopurine methyltransferase (TPMT) enzyme, which is responsible for variation in the metabolism, toxicity and therapeutic efficacy of the thiopurines azathioprine (AZA), 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG). Determination of TPMT activity before administration of thiopurines is thus crucial for individualized dosing in order to prevent toxicity in TPMT deficient individuals. These individuals must be treated with markedly lower (eg, 5-10% of the standard) doses of the prescribed medications. This paper describes a comparison of three different methods for the quantification of TPMT activity in red blood cells (RBC) and cultured human cell lines. We succeeded to perform the measurement of TPMT activity in a minimum amount of 1×10(6) cultured cells with an HPLC-UV system modified and optimized in our laboratory. The TPMT activity was linearly correlated with the cell concentration of the cultured cell line in a range of 1-10×10(6) cells. A significant correlation of determination of TPMT activity in RBC between radiometric detection by HPLC, classic radiochemical detection and UV detection by HPLC, was observed, correlation coefficient (r) were 0.72 and 0.73, respectively. The within-day and day-to-day coefficients of variation of the HPLC-UV-based method were 8% and 16%, respectively. The evaluation of the methods was demonstrated by studying the TPMT activity in RBC isolated from 198 patients, as well as in MOLT4 leukemic cell line and its sub-cell lines with acquired resistance to 6-MP and 6-TG.
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Affiliation(s)
- Hazhar Karim
- Department of Medicine, Clinical Pharmacology Unit, Karolinska Institutet, Karolinska University Hospital, SE-171 76 Stockholm, Sweden.
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8
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Establishment of thiopurine S-methyltransferase gene knockdown in jurkat T-lymphocytes: an in vitro model of TPMT polymorphism. Ther Drug Monit 2013; 34:584-92. [PMID: 22972540 DOI: 10.1097/ftd.0b013e31826ec4b4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Thiopurine S-methyltransferase (TPMT) is an excellent example of an enzyme whose pharmacogenetic polymorphisms affect efficacy and toxicity of a drug. The association between TPMT activity and thiopurine-related myelosuppression is well recognized. To study the significance of TPMT deficiency in thiopurine metabolism and immunosuppressive activity in vitro, we established RNA interference-based TPMT knockdown (kd) in a Jurkat cell line. RESULTS In Jurkat TPMT kd cells, TPMT expression was reduced to 73% at the RNA level and 83% at the protein level. TPMT kd cells were more sensitive to 6-mercaptopurine (6-MP) (10 μmol/L) and 6-thioguanine (6-TG) (8 μmol/L) than wild-type (wt) cells, (32% versus 20%) and (18% versus 9%), respectively. Both Jurkat wt and kd cells were more sensitive to 6-TG-induced apoptosis than to 6-MP. 6-TG activity was also more affected by TPMT levels than was 6-MP as reflected by IC60, concentrations that is, 6-MP [4.6 μmol/L (wt) and 4.7 μmol/L (kd)], 6-TG [2.7 μmol/L (wt) and 0.8 μmol/L (kd)]. IC60 concentrations induced significant apoptosis in both Jurkat wt and kd cells (257%, versus 314%) with 6-MP and (323% versus 306%) with 6-TG, respectively. At IC60 (6-MP) 6-thioguanine nucleotides (6-TGN) accumulation in cells was 518 versus 447 pmol/million cells in wt and kd cells, respectively. On the other hand 6-TGN accumulation at IC60 (6-TG) was 477 versus 570 pmol/million cells in wt and kd cells, respectively. 6-Methylated mercaptopurine (6-MeMP) concentrations were more affected than 6-TGN by TPMT kd (194 versus 10 pmol/million cells) in wt and kd cells, respectively. CONCLUSION We conclude that TPMT kd cells are an appropriate in vitro model to investigate the significance of TPMT deficiency with thiopurine therapy and could be helpful in understanding possible clinical consequences of TPMT polymorphism.
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Loit E, Tricco AC, Tsouros S, Sears M, Ansari MT, Booth RA. Pre-analytic and analytic sources of variations in thiopurine methyltransferase activity measurement in patients prescribed thiopurine-based drugs: A systematic review. Clin Biochem 2011; 44:751-7. [PMID: 21402061 DOI: 10.1016/j.clinbiochem.2011.03.022] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 02/16/2011] [Accepted: 03/04/2011] [Indexed: 12/13/2022]
Abstract
OBJECTIVES Low thiopurine S-methyltransferase (TPMT) enzyme activity is associated with increased thiopurine drug toxicity, particularly myelotoxicity. Pre-analytic and analytic variables for TPMT genotype and phenotype (enzyme activity) testing were reviewed. DESIGN AND METHODS A systematic literature review was performed, and diagnostic laboratories were surveyed. RESULTS Thirty-five studies reported relevant data for pre-analytic variables (patient age, gender, race, hematocrit, co-morbidity, co-administered drugs and specimen stability) and thirty-three for analytic variables (accuracy, reproducibility). TPMT is stable in blood when stored for up to 7 days at room temperature, and 3 months at -30°C. Pre-analytic patient variables do not affect TPMT activity. Fifteen drugs studied to date exerted no clinically significant effects in vivo. Enzymatic assay is the preferred technique. Radiochemical and HPLC techniques had intra- and inter-assay coefficients of variation (CVs) below 10%. CONCLUSION TPMT is a stable enzyme, and its assay is not affected by age, gender, race or co-morbidity.
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Affiliation(s)
- Evelin Loit
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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10
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Association Between Adverse Effects Under Azathioprine Therapy and Inosine Triphosphate Pyrophosphatase Activity in Patients With Chronic Inflammatory Bowel Disease. Ther Drug Monit 2011; 33:321-8. [DOI: 10.1097/ftd.0b013e31821a7c34] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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11
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Xiong H, Xin HW, Wu XC, Li Q, Xiong L, Yu AR. Association between inosine triphosphate pyrophosphohydrolase deficiency and azathioprine-related adverse drug reactions in the Chinese kidney transplant recipients. Fundam Clin Pharmacol 2010; 24:393-400. [PMID: 19682085 DOI: 10.1111/j.1472-8206.2009.00770.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Azathioprine (AZA) is a thiopurine prodrug commonly used in patients with kidney transplantation. The aim of this study is to explore in patients with kidney transplantation whether AZA-related side effects can be explained by the inosine triphophate pyrophosphatase (ITPA) or thiopurine S-methyltransferase (TPMT) polymorphisms using both pheno-and genotyping. Erythrocyte ITPA and TPMT activity of 155 patients with kidney transplantation and AZA therapy was determined by HPLC. The frequencies of ITPA and TPMT polymorphisms were detected. Among 155 patients, three cases with zero activity were homozygote for 94C>A. The allele frequency of the 94C>A polymorphism was 0.12. Allele for the IVS2+21A>C mutation in the patients of this study was not found. Thirty-five cases had stopped azathioprine medication or were on reduced dose due to AZA-related side effects, including hematotoxicity (n = 12), hepatotoxicity (n = 18), gastrointestinal toxicity (n = 5, one patient developed hepatotoxicity simultaneously) and flu-like symptoms (n = 1). No statistical significant associations between ITPA 94C>A phenotype or genotype and AZA-related hematotoxicity or hepatotoxicity could be detected. However, five patients who developed gastrointestinal disturbance, two patients were homozygote for 94C>A and other three patients had 94C>A heterozygous allele. The patient who experienced flu-like symptoms were the remaining homozygote for 94C>A. This study demonstrates that ITPA activity reduced in patients with 94C>A mutation (P < 0.01). Patients with ITPA 94C>A homozygous allele are at high risk to develop AZA-related gastrointestinal toxicity and flu-like symptoms (P < 0.01). TPMT wild-type/ITPA variant (homozygote) is closely related to the AZA-induced side effects (P < 0.01).
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Affiliation(s)
- Hui Xiong
- Department of Clinical Pharmacology, Wuhan General Hospital of Guangzhou Command, Wuhan 430070, China
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12
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Atanasova S, Shipkova M, Svinarov D, Mladenova A, Genova M, Wieland E, Oellerich M, von Ahsen N. Analysis of ITPA phenotype-genotype correlation in the Bulgarian population revealed a novel gene variant in exon 6. Ther Drug Monit 2007; 29:6-10. [PMID: 17304144 DOI: 10.1097/ftd.0b013e3180308554] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Mutations in the inosine triphosphate pyrophosphohydrolase (ITPA) gene causing enzyme deficiency were shown to have pharmacogenetic implications in azathioprine-induced adverse drug reactions. The distribution of ITPA activity as well as the types and the frequencies of gene variants associated with a lower enzyme activity were determined in healthy volunteers from a Bulgarian population. The ITPA activity was measured in 185 erythrocyte samples by an established high-performance liquid chromatography procedure. All samples were genotyped for 94C > A, IVS2 + 21A > C, and IVS2 + 68T > C/G by real-time polymerase chain reaction with hybridization probes. The ITPA activity ranged from 7.5 to 587.8 micromoL IMP/(g Hb x h) with a median value of 162.9 micromoL IMP/(g Hb x h). The enzyme activity showed significant differences between females and males (P = 0.006) with 17% higher values in men than women. Mutant allele frequencies were 0.038 (94C > A) and 0.130 (IVS2 + 21A > C). Mutations at IVS2 + 68 were not identified. Using a cutoff at 75 micromoL IMP/(g Hb x h) phenotyping detected all heterozygous carriers of 94C > A, two compound heterozygotes, all IVS2 + 21A > C homozygotes and 12.5% of IVS2 + 21A > C heterozygous cases. A novel frameshift mutation 359_366dupTCAGCACC in exon 6 was found in a subject with reduced enzyme activity of 61.2 micromoL IMP/(g Hb x h). The interindividual variability in ITPA activity among the Bulgarian population resembles the distribution of enzyme activity in other whites, although the observed median activity was approximately 25% lower in the Bulgarians [163 vs 219 micromoL IMP/(g Hb x h)]. The most common mutant allele IVS2 + 21A > C showed a similar frequency like in other white populations, whereas the 94C > A mutation was less frequently observed compared with other whites. Heterozygosity for the novel gene variant 359_366dupTCAGCACC was associated with 30% enzyme activity of the wild-type median value. The role of this rare variant for the thiopurine intolerance is not explored. These data further extend the knowledge for ITPA heterogeneity in whites.
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Affiliation(s)
- Srebrena Atanasova
- Department of Clinical Chemistry, Georg-August University Goettingen, Goettingen, Germany.
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Abstract
BACKGROUND In the past 10-20 years, knowledge of both thiopurine pharmacology and -pharmacogenetics has been extended dramatically and used to develop new strategies to improve efficacy and reduce toxicity. AIM To review thiopurine efficacy, toxicity, pharmacology, pharmacogenetics, interactions in patients with inflammatory bowel disease. Special attention was paid to new strategies for optimization of pharmacotherapy. METHODS To collect relevant scientific articles, a Pubmed search was performed from 1966 through January 2006 with the following key words (MeSH terms preferentially) in multiple combinations: 'azathioprine', '6-mercaptopurine', '6-MP', '6-thioguanine', '6-TG', 'thiopurine(s)', 'metabolites', 'level(s)', 'TDM', 'TMPT', 'ITPA', 'genotype(s)', 'phenotype(s)', 'inflammatory bowel disease', 'Crohn('s) disease', 'ulcerative colitis'. RESULTS Strategies for optimization of pharmacotherapy include therapeutic drug monitoring of thiopurine metabolites, geno- or phenotyping crucial enzymes in thiopurine metabolism like thiopurine S-methyltransferase and inosine triphosphate pyrophosphatase, and the use of thioguanine as such. CONCLUSIONS Thiopurine S-methyltransferase genotyping and therapeutic drug monitoring are useful instruments for individualizing thiopurine pharmacotherapy of inflammatory bowel disease. Inosine triphosphate pyrophosphatase genotyping may be helpful in case of unexplainable myelotoxicity. In case of azathioprine- or mercaptopurine-intolerance, thioguanine seems a promising alternative. However, more knowledge needs to be gathered about its potential hepatotoxicity.
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Affiliation(s)
- L J J Derijks
- Department of Clinical Pharmacy, Máxima Medical Center, Veldhoven, The Netherlands.
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Shipkova M, Lorenz K, Oellerich M, Wieland E, von Ahsen N. Measurement of erythrocyte inosine triphosphate pyrophosphohydrolase (ITPA) activity by HPLC and correlation of ITPA genotype-phenotype in a Caucasian population. Clin Chem 2006; 52:240-7. [PMID: 16384889 DOI: 10.1373/clinchem.2005.059501] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Inosine triphosphate (ITP) pyrophosphohydrolase (ITPA) catalyzes the pyrophosphohydrolysis of ITP/dITP and xanthosine triphosphate to prevent incorporation of unusual nucleotides into RNA and DNA. Important mutations leading to enzyme deficiency are 94C>A and IVS2 + 21A>C. An association between ITPA 94C>A and adverse reactions during azathioprine treatment has been shown. To investigate the ITPA phenotype, an HPLC procedure was developed and phenotype-genotype correlations were assessed. METHODS The enzymatic conversion of ITP to inosine monophosphate (IMP) was terminated by perchloric acid and saturated dipotassium hydrogen phosphate. We quantified the IMP at 262 nm after separation on an Aqua perfect C18 column using 20 mmol/L phosphate buffer, pH 2.5. We also genotyped samples for ITPA 94C>A and IVS2 + 21A>C by real-time fluorescence PCR. RESULTS The assay was linear to 3 mmol/L IMP [approximately 500 micromol/(g Hb x h)] with a lower limit of quantification of 4 micromol/L [approximately 0.5 micromol/(g Hb x h)]. With IMP-enriched samples, within- and between-day imprecision was < or = 3.6% and < or = 4.9%, respectively, and the inaccuracy was < or = 5.2%. With pooled erythrocytes, within- and between-day imprecision was 3.8% and 7.5%, respectively. ITPA activity in 130 healthy controls was between < 0.5 and 408 micromol IMP/(g Hb x h). Mutant allele frequencies were 0.062 (94C>A) and 0.131 (IVS2 + 21A>C). When we used a cutoff of 125 micromol IMP/(g Hb x h), phenotyping detected all 94C>A mutant cases, all 94C>A and IVS2 + 21A>C compound heterozygotes, all IVS2 + 21A>C homozygotes, and 6 of 24 IVS2 + 21A>C heterozygote-only cases. A novel IVS2 + 68T>C mutation was also found. CONCLUSIONS The HPLC procedure provides an excellent ITPA phenotype-genotype correlation and led to the discovery of a novel IVS2 + 68T>C mutation. The method could facilitate investigation of the role of ITPA activity for drug toxicity during thiopurine therapy.
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Affiliation(s)
- Maria Shipkova
- Central Institute of Clinical Chemistry and Laboratory Medicine, Klinikum Stuttgart, Stuttgart, Germany.
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von Ahsen N, Armstrong VW, Behrens C, von Tirpitz C, Stallmach A, Herfarth H, Stein J, Bias P, Adler G, Shipkova M, Oellerich M, Kruis W, Reinshagen M, Schütz E. Association of inosine triphosphatase 94C>A and thiopurine S-methyltransferase deficiency with adverse events and study drop-outs under azathioprine therapy in a prospective Crohn disease study. Clin Chem 2005; 51:2282-8. [PMID: 16214825 DOI: 10.1373/clinchem.2005.057158] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Azathioprine (aza) therapy is beneficial in the treatment of inflammatory bowel disease, but 10%-30% of patients cannot tolerate aza therapy because of adverse drug reactions. Thiopurine S-methyltransferase (TPMT) deficiency predisposes to myelotoxicity, but its association with other side effects is less clear. Inosine triphosphatase (ITPA) mutations are other pharmacogenetic polymorphisms possibly involved in thiopurine metabolism and tolerance. METHODS We analyzed data from a 6-month prospective study including 71 patients with Crohn disease undergoing first-time aza treatment with respect to aza intolerance. Patients were genotyped for common TPMT and ITPA mutations and had pretherapy TPMT activity measured. RESULTS Early drop-out (within 2 weeks) from aza therapy was associated with ITPA 94C > A [P = 0.020; odds ratio (OR), 4.6; 95% confidence interval (95% CI), 1.2-17.4] and low TPMT activity [<10 nmol/(mL erythrocytes . h); P = 0.007; OR = 5.5; 95% CI, 1.6-19.2]. A high-risk group defined by ITPA 94C > A or TPMT <10 nmol/(mL erythrocytes . h) showed significant association with early drop-out (P = 0.001; OR = 11.3; 95% CI, 2.5-50.0) and all drop-outs (P = 0.002; OR = 4.8; 95% CI, 1.8-13.3). For only drop-outs attributable to aza-related side effects (n = 16), there was a significant association with ITPA 94C > A (P = 0.002; OR = 7.8; 95% CI, 2.1-29.1). Time-to-event analysis over the 24-week study period revealed a significant association (P = 0.031) between the time to drop-out and ITPA 94C > A mutant allele carrier status. CONCLUSIONS Patients with ITPA 94C > A mutations or low TPMT activity constitute a pharmacogenetic high-risk group for drop-out from aza therapy. ITPA 94C>A appears to be a promising marker indicating predisposition to aza intolerance.
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Affiliation(s)
- Nicolas von Ahsen
- Department of Clinical Chemistry, University of Göttingen, Göttingen, Germany
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Kontorinis N, Agarwal K, Gondolesi G, Fiel MI, O'Rourke M, Schiano TD. Diagnosis of 6 mercaptopurine hepatotoxicity post liver transplantation utilizing metabolite assays. Am J Transplant 2004; 4:1539-42. [PMID: 15307844 DOI: 10.1111/j.1600-6143.2004.00543.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Azathioprine and 6-mercaptopurine (6 MP) are commonly used as immunosuppression postsolid organ transplantation. Recently, a better understanding of the metabolism of these drugs has developed. 6 Mercaptopurine is metabolized by thiopurine methyl transferase (TPMT) which is under the control of a common genetic polymorphism. Genetic testing and measurement of levels of 6 MP metabolites allow identification of patients at risk of toxicity. We report two cases of cholestatic hepatocellular injury associated with 6 MP toxicity occurring after orthotopic liver transplantation. Cholestasis developed after the introduction of 6 MP. Patients underwent extensive investigation and 6 MP toxicity was considered only after all other causes had been excluded. Thiopurine methyl transferase alleles identified on genetic testing were normal as were the 6 thioguanine levels. However, 6-methyl mercaptopurine levels were significantly elevated into the toxic range. Cholestasis resolved within a few weeks of drug withdrawal. 6 Mercaptopurine hepatotoxicity can present with a variety of clinical, biochemical and histological manifestations post OLT and should be considered as a cause of liver enzyme elevation. Monitoring of 6 MP metabolite levels in addition to TPMT allele testing is useful to prevent 6 MP toxicity and to help guide therapy.
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Affiliation(s)
- Nickolas Kontorinis
- Recanati-Miller Transplantation Institute, Mount Sinai Medical Center, New York, NY, USA.
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Armstrong VW, Shipkova M, von Ahsen N, Oellerich M. Analytic aspects of monitoring therapy with thiopurine medications. Ther Drug Monit 2004; 26:220-6. [PMID: 15228169 DOI: 10.1097/00007691-200404000-00024] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The thiopurine medications 6-mercaptopurine (6-MP), 6-thioguanine (6-TG), and azathioprine are used in treatment of childhood acute lymphoblastic leukemia, autoimmune diseases, and, in the case of azathioprine, in solid organ transplantation. They are converted in vivo to the active 6-thioguanine nucleotides (6-TGN). One person in 300 in white populations has low or undetectable TPMT activity and is at risk for accumulating 6-TGN with the consequence of severe, life-threatening myelosuppression. A rational therapeutic strategy for thiopurine drug use is to first determine TPMT phenotype/genotype and then to adjust the dosage on an individual basis. Determination of erythrocyte 6-TGN levels can further help to optimize therapy. TPMT activity (phenotype) is determined in erythrocytes using radiochemical or HPLC procedures. Recent HPLC procedures show good agreement with the original radiochemical method, while offering simplified sample pretreatment and improved precision. To date, 12 mutant alleles responsible for TPMT deficiency have been published. Restriction fragment length polymorphism PCR and allele-specific PCR have been used for detection of TPMT mutations. Genotyping methods that allow a higher throughput include real-time PCR (LightCycler) and denaturing HPLC. Numerous HPLC methods have been reported for quantification of 6-TGN. The majority involve acid hydrolysis to 6-TG at high temperature. There are substantial differences in the hydrolysis step, extraction procedure, chromatographic conditions and method of detection. Erythrocyte 6-TGN concentrations can vary up to 2.6-fold depending on the HPLC method. The method that has found the greatest application in clinical studies is that of Lennard. This has served as the basis for the establishment of treatment-related therapeutic ranges for thiopurine therapy. These ranges will not necessarily be applicable when other methodology is used. There is an urgent need to harmonize the analytic procedures for 6-TGN.
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Affiliation(s)
- Victor W Armstrong
- Department of Clinical Chemistry, George-August University, D-37075 Goettingen, Germany.
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Shipkova M, Niedmann PD, Armstrong VW, Oellerich M, Wieland E. Determination of Thiopurine Methyltransferase Activity in Isolated Human Erythrocytes Does Not Reflect Putative in Vivo Enzyme Inhibition by Sulfasalazine. Clin Chem 2004; 50:438-41. [PMID: 14752016 DOI: 10.1373/clinchem.2003.026096] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Maria Shipkova
- Central Institute for Clinical Chemistry and Laboratory Medicine, Klinikum Stuttgart, Germany.
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