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Maillard M, Nishii R, Yang W, Hoshitsuki K, Chepyala D, Lee SHR, Nguyen JQ, Relling MV, Crews KR, Leggas M, Singh M, Suang JLY, Yeoh AEJ, Jeha S, Inaba H, Pui CH, Karol SE, Trehan A, Bhatia P, Antillon Klussmann FG, Bhojwani D, Haidar CE, Yang JJ. Additive effects of TPMT and NUDT15 on thiopurine toxicity in children with acute lymphoblastic leukemia across multiethnic populations. J Natl Cancer Inst 2024; 116:702-710. [PMID: 38230823 PMCID: PMC11077315 DOI: 10.1093/jnci/djae004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Revised: 12/22/2023] [Accepted: 01/04/2024] [Indexed: 01/18/2024] Open
Abstract
BACKGROUND Thiopurines such as mercaptopurine (MP) are widely used to treat acute lymphoblastic leukemia (ALL). Thiopurine-S-methyltransferase (TPMT) and Nudix hydrolase 15 (NUDT15) inactivate thiopurines, and no-function variants are associated with drug-induced myelosuppression. Dose adjustment of MP is strongly recommended in patients with intermediate or complete loss of activity of TPMT and NUDT15. However, the extent of dosage reduction recommended for patients with intermediate activity in both enzymes is currently not clear. METHODS MP dosages during maintenance were collected from 1768 patients with ALL in Singapore, Guatemala, India, and North America. Patients were genotyped for TPMT and NUDT15, and actionable variants defined by the Clinical Pharmacogenetics Implementation Consortium were used to classify patients as TPMT and NUDT15 normal metabolizers (TPMT/NUDT15 NM), TPMT or NUDT15 intermediate metabolizers (TPMT IM or NUDT15 IM), or TPMT and NUDT15 compound intermediate metabolizers (TPMT/NUDT15 IM/IM). In parallel, we evaluated MP toxicity, metabolism, and dose adjustment using a Tpmt/Nudt15 combined heterozygous mouse model (Tpmt+/-/Nudt15+/-). RESULTS Twenty-two patients (1.2%) were TPMT/NUDT15 IM/IM in the cohort, with the majority self-reported as Hispanics (68.2%, 15/22). TPMT/NUDT15 IM/IM patients tolerated a median daily MP dose of 25.7 mg/m2 (interquartile range = 19.0-31.1 mg/m2), significantly lower than TPMT IM and NUDT15 IM dosage (P < .001). Similarly, Tpmt+/-/Nudt15+/- mice displayed excessive hematopoietic toxicity and accumulated more metabolite (DNA-TG) than wild-type or single heterozygous mice, which was effectively mitigated by a genotype-guided dose titration of MP. CONCLUSION We recommend more substantial dose reductions to individualize MP therapy and mitigate toxicity in TPMT/NUDT15 IM/IM patients.
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Affiliation(s)
- Maud Maillard
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Children’s Research Hospital, Memphis, TN, USA
| | - Rina Nishii
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Children’s Research Hospital, Memphis, TN, USA
| | - Wenjian Yang
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Children’s Research Hospital, Memphis, TN, USA
| | - Keito Hoshitsuki
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Children’s Research Hospital, Memphis, TN, USA
| | - Divyabharathi Chepyala
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Children’s Research Hospital, Memphis, TN, USA
| | - Shawn H R Lee
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Children’s Research Hospital, Memphis, TN, USA
- Khoo Teck Puat-National University Children’s Medical Institute, National University Hospital, National University Health System, Singapore, Singapore
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Jenny Q Nguyen
- Personalized Care Program, Children’s Hospital Los Angeles, Los Angeles, CA, USA
| | - Mary V Relling
- 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
| | - Mark Leggas
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Children’s Research Hospital, Memphis, TN, USA
| | - Meenu Singh
- Haematology-Oncology Unit, Department of Paediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Joshua L Y Suang
- Khoo Teck Puat-National University Children’s Medical Institute, National University Hospital, National University Health System, Singapore, Singapore
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Allen E J Yeoh
- Khoo Teck Puat-National University Children’s Medical Institute, National University Hospital, National University Health System, Singapore, Singapore
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Sima Jeha
- Department of Oncology, St Jude Children’s Research Hospital, Memphis, TN, USA
- Department of Global Pediatric Medicine, St Jude Children’s Research Hospital, Memphis, TN, USA
| | - Hiroto Inaba
- Department of Oncology, St Jude Children’s Research Hospital, Memphis, TN, USA
| | - Ching-Hon Pui
- Department of Oncology, St Jude Children’s Research Hospital, Memphis, TN, USA
- Department of Global Pediatric Medicine, St Jude Children’s Research Hospital, Memphis, TN, USA
| | - Seth E Karol
- Department of Oncology, St Jude Children’s Research Hospital, Memphis, TN, USA
| | - Amita Trehan
- Haematology-Oncology Unit, Department of Paediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Prateek Bhatia
- Haematology-Oncology Unit, Department of Paediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | | | - Deepa Bhojwani
- Cancer and Blood Disease Institute, Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Cyrine E Haidar
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Children’s Research Hospital, Memphis, TN, USA
| | - Jun J Yang
- Department of Pharmacy and Pharmaceutical Sciences, St Jude Children’s Research Hospital, Memphis, TN, USA
- Department of Oncology, St Jude Children’s Research Hospital, Memphis, TN, USA
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Pavelcova K, Hanova P, Ciferska H, Hasikova L, Stiburkova B. The Examination of a TPMT Gene Before Administration of Azathioprine in Rheumatology Practice and Identification of a Novel Variant p.W29R. J Clin Rheumatol 2022; 28:e363-e367. [PMID: 34870401 DOI: 10.1097/rhu.0000000000001727] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
METHODS Two-hundred patients were assessed for the presence of genetic allelic variants using PCR amplification and direct sequencing. RESULTS In 19 patients, we detected genetic allelic variants affecting TPMT activity; in 1 case, it was an unpublished heterozygous variant c.85T>C (p.W29R); of those, 15 patients were switched from AZA to a different medication, and 1 patient was prescribed a reduced dose of AZA. CONCLUSIONS Our findings show the importance of testing for variants of the TPMT gene before the administration of AZA in clinical rheumatology practice. Patients with documented episodes of leukopenia or elevated liver biochemical tests while on AZA should undergo TPMT genotype testing and/or TPMT enzyme activity testing.
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Franczyk B, Rysz J, Gluba-Brzózka A. Pharmacogenetics of Drugs Used in the Treatment of Cancers. Genes (Basel) 2022; 13:311. [PMID: 35205356 PMCID: PMC8871547 DOI: 10.3390/genes13020311] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/24/2022] [Accepted: 01/27/2022] [Indexed: 02/01/2023] Open
Abstract
Pharmacogenomics is based on the understanding of the individual differences in drug use, the response to drug therapy (efficacy and toxicity), and the mechanisms underlying variable drug responses. The identification of DNA variants which markedly contribute to inter-individual variations in drug responses would improve the efficacy of treatments and decrease the rate of the adverse side effects of drugs. This review focuses only on the impact of polymorphisms within drug-metabolizing enzymes on drug responses. Anticancer drugs usually have a very narrow therapeutic index; therefore, it is very important to use appropriate doses in order to achieve the maximum benefits without putting the patient at risk of life-threatening toxicities. However, the adjustment of the appropriate dose is not so easy, due to the inheritance of specific polymorphisms in the genes encoding the target proteins and drug-metabolizing enzymes. This review presents just a few examples of such polymorphisms and their impact on the response to therapy.
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Affiliation(s)
| | | | - Anna Gluba-Brzózka
- Department of Nephrology, Hypertension and Family Medicine, Medical University of Lodz, Zeromskiego 113, 90-549 Lodz, Poland; (B.F.); (J.R.)
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Garg K, Kramer J, Eswaran S. Common Gastrointestinal Medications Implicated in Drug-Induced Liver Injury. Clin Liver Dis (Hoboken) 2021; 18:184-188. [PMID: 34745575 PMCID: PMC8549715 DOI: 10.1002/cld.1110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 02/17/2021] [Accepted: 02/26/2021] [Indexed: 02/04/2023] Open
Abstract
Content available: Author Interview and Audio Recording.
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Affiliation(s)
- Kanika Garg
- Division of Gastroenterology, Hepatology and NutritionRush University Medical CenterChicagoIL
| | - Jason Kramer
- Division of Gastroenterology, Hepatology and NutritionRush University Medical CenterChicagoIL
| | - Sheila Eswaran
- Division of Gastroenterology, Hepatology and NutritionRush University Medical CenterChicagoIL
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Maldonato BJ, Russell DA, Totah RA. Human METTL7B is an alkyl thiol methyltransferase that metabolizes hydrogen sulfide and captopril. Sci Rep 2021; 11:4857. [PMID: 33649426 PMCID: PMC7921093 DOI: 10.1038/s41598-021-84218-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 02/12/2021] [Indexed: 11/15/2022] Open
Abstract
Methylation of alkyl thiols is a biotransformation pathway designed to reduce thiol reactivity and potential toxicity, yet the gene and protein responsible for human alkyl thiol methyltransferase (TMT) activity remain unknown. Here we demonstrate with a range of experimental approaches using cell lines, in vitro systems, and recombinantly expressed enzyme, that human methyltransferase-like protein 7B (METTL7B) catalyzes the transfer of a methyl group from S-adenosyl-L-methionine (AdoMet) to hydrogen sulfide (H2S) and other exogenous thiol small molecules. METTL7B gene modulation experiments, including knockdown in HepG2 cells and overexpression in HeLa cells, directly alter the methylation of the drug captopril, a historic probe substrate for TMT activity. Furthermore, recombinantly expressed and purified wild-type METTL7B methylates several thiol compounds, including H2S, 7α-thiospironolactone, L-penicillamine, and captopril, in a time- and concentration-dependent manner. Typical for AdoMet-dependent small molecule methyltransferases, S-adenosyl-L-homocysteine (AdoHcy) inhibited METTL7B activity in a competitive fashion. Similarly, mutating a conserved aspartate residue, proposed to anchor AdoMet into the active site, to an alanine (D98A) abolished methylation activity. Endogenous thiols such as glutathione and cysteine, or classic substrates for other known small molecule S-, N-, and O-methyltransferases, were not substrates for METTL7B. Our results confirm, for the first time, that METTL7B, a gene implicated in multiple disease states including rheumatoid arthritis and breast cancer, encodes a protein that methylates small molecule alkyl thiols. Identifying the catalytic function of METTL7B will enable future pharmacological research in disease pathophysiology where altered METTL7B expression and, potentially H2S levels, can disrupt cell growth and redox state.
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Affiliation(s)
- Benjamin J Maldonato
- Department of Medicinal Chemistry, University of Washington, 1959 NE Pacific Ave, Box 357610, Seattle, WA, 98195, USA
| | - Drake A Russell
- Department of Medicinal Chemistry, University of Washington, 1959 NE Pacific Ave, Box 357610, Seattle, WA, 98195, USA
| | - Rheem A Totah
- Department of Medicinal Chemistry, University of Washington, 1959 NE Pacific Ave, Box 357610, Seattle, WA, 98195, USA.
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Maamari D, El-Khoury H, Saifi O, Muwakkit SA, Zgheib NK. Implementation of Pharmacogenetics to Individualize Treatment Regimens for Children with Acute Lymphoblastic Leukemia. Pharmgenomics Pers Med 2020; 13:295-317. [PMID: 32848445 PMCID: PMC7429230 DOI: 10.2147/pgpm.s239602] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/20/2020] [Indexed: 12/28/2022] Open
Abstract
Despite major advances in the management and high cure rates of childhood acute lymphoblastic leukemia (ALL), patients still suffer from many drug-induced toxicities, sometimes necessitating dose reduction, or halting of cytotoxic drugs with a secondary risk of disease relapse. In addition, investigators have noted significant inter-individual variability in drug toxicities and disease outcomes, hence the role of pharmacogenetics (PGx) in elucidating genetic polymorphisms in candidate genes for the optimization of disease management. In this review, we present the PGx data in association with main toxicities seen in children treated for ALL in addition to efficacy, with a focus on the most plausible germline PGx variants. We then follow with a summary of the highest evidence drug-gene annotations with suggestions to move forward in implementing preemptive PGx for the individualization of treatment regimens for children with ALL.
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Affiliation(s)
- Dimitri Maamari
- Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Habib El-Khoury
- Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Omran Saifi
- Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Samar A Muwakkit
- Department of Pediatrics and Adolescent Medicine, American University of Beirut Medical Center, Beirut, Lebanon
| | - Nathalie K Zgheib
- Department of Pharmacology and Toxicology, American University of Beirut, Faculty of Medicine, Beirut, Lebanon
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When Multiple Objective Measures of Medication Adherence Indicate Incongruent Adherence Results: An Example with Pediatric Cancer. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17061956. [PMID: 32192028 PMCID: PMC7142654 DOI: 10.3390/ijerph17061956] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 03/02/2020] [Accepted: 03/14/2020] [Indexed: 12/18/2022]
Abstract
Previous research suggests that children and adolescents with acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma (LBL) often have difficulty adhering to complex treatment regimens during the maintenance phase of therapy. Measurement of treatment adherence can be done via objective (e.g., electronic monitoring (EM), pharmacological assays) or subjective methods (patient, parent, or physician reports). This paper provides an illustration of recommended strategies for comparing discrepancies between two objective measures of medication adherence (e.g., behavioral adherence using electronic monitoring versus pharmacological adherence using 6-mercaptopurine (6MP) metabolite data) within a relatively large cohort of pediatric patients with ALL or LBL (N = 139) who had longitudinal data for both measures of medication adherence over a 15-month period. Additionally, individual- and family-level factors such as gender, socioeconomic status, household environment, and dose intensity will be examined to identify possible sources of discrepancies between adherence measures. This information will provide practical advice for physicians, healthcare providers, and psychologists in identifying nonadherence and the caveats therein so patients achieve the best possible health outcomes.
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9
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Lee SHR, Yang JJ. Pharmacogenomics in acute lymphoblastic leukemia. Best Pract Res Clin Haematol 2017; 30:229-236. [PMID: 29050696 DOI: 10.1016/j.beha.2017.07.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 07/17/2017] [Accepted: 07/24/2017] [Indexed: 10/19/2022]
Abstract
Pharmacogenomics is a fast-growing field of personalized medicine using a patient's genomic profile to determine drug disposition or response to drug therapy, in order to develop safer and more effective pharmacotherapy. Childhood acute lymphoblastic leukemia (ALL), being the most common malignancy in childhood, which is treated with uniform and standardized clinical trials, is remarkably poised for pharmacogenomic studies. In the last decade, unbiased genome-wide association studies have identified multiple germline risk factors that strongly modify host response to drug therapy. Some of these genomic associations (e.g. TPMT, NUDT15 and mercaptopurine dosing) have accumulated a significant level of evidence on their clinical utility such that they are warranted as routine clinical tests to guide modification of treatment. Most of these germline associations however, have not yet reached such actionability. Insights have also been gathered on germline factors that affect host susceptibility to adverse effects of antileukemic agents (eg, vincristine, asparaginase, methotrexate). Further large-scale studies are required, along with the assimilation of both germline and somatic variants, to precisely predict host drug response and drug toxicities, with the eventual aim of executing genomic-based precision-pharmacotherapy in the treatment of ALL.
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Affiliation(s)
- Shawn H R Lee
- KTP-University Children's Medical Institute, National University Hospital, Singapore.
| | - Jun J Yang
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, TN, USA.
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Abaji R, Krajinovic M. Thiopurine S-methyltransferase polymorphisms in acute lymphoblastic leukemia, inflammatory bowel disease and autoimmune disorders: influence on treatment response. PHARMACOGENOMICS & PERSONALIZED MEDICINE 2017; 10:143-156. [PMID: 28507448 PMCID: PMC5428801 DOI: 10.2147/pgpm.s108123] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The thiopurine S-methyltransferase (TPMT) gene encodes for the TPMT enzyme that plays a crucial role in the metabolism of thiopurine drugs. Genetic polymorphisms in this gene can affect the activity of the TPMT enzyme and have been correlated with variability in response to treatment with thiopurines. Advances in the pharmacogenetics of TPMT allowed the development of dosing recommendations and treatment strategies to optimize and individualize prescribing thiopurine in an attempt to enhance treatment efficacy while minimizing toxicity. The influence of genetic polymorphisms in the TPMT gene on clinical outcome has been well-documented and replicated in many studies. In this review, we provide an overview of the evolution, results, conclusions and recommendations of selected studies that investigated the influence of TPMT pharmacogenetics on thiopurine treatment in acute lymphoblastic leukemia, inflammatory bowel disease and autoimmune disorders. We focus mainly on prospective studies that explored the impact of individualized TPMT-based dosing of thiopurines on clinical response. Together, these studies demonstrate the importance of preemptive TPMT genetic screening and subsequent dose adjustment in mitigating the toxicity associated with thiopurine treatment while maintaining treatment efficacy and favorable long-term outcomes. In addition, we briefly address the cost-effectiveness of this pharmacogenetics approach and its impact on clinical practice as well as the importance of recent breakthrough advances in sequencing and genotyping techniques in refining the TPMT genetic screening process.
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Affiliation(s)
| | - Maja Krajinovic
- Departments of Pediatrics and Pharmacology, CHU Sainte-Justine Research Center, University of Montreal, Montreal, QC, Canada
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Regueiro MD, Greer JB, Hanauer SB. Established Management Paradigms in IBD: Treatment Targets and Therapeutic Tools. ACTA ACUST UNITED AC 2016. [DOI: 10.1038/ajgsup.2016.16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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12
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Mlakar V, Huezo-Diaz Curtis P, Satyanarayana Uppugunduri CR, Krajinovic M, Ansari M. Pharmacogenomics in Pediatric Oncology: Review of Gene-Drug Associations for Clinical Use. Int J Mol Sci 2016; 17:ijms17091502. [PMID: 27618021 PMCID: PMC5037779 DOI: 10.3390/ijms17091502] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 08/02/2016] [Accepted: 08/15/2016] [Indexed: 02/07/2023] Open
Abstract
During the 3rd congress of the European Society of Pharmacogenomics and Personalised Therapy (ESPT) in Budapest in 2015, a preliminary meeting was held aimed at establishing a pediatric individualized treatment in oncology and hematology committees. The main purpose was to facilitate the transfer and harmonization of pharmacogenetic testing from research into clinics, to bring together basic and translational research and to educate health professionals throughout Europe. The objective of this review was to provide the attendees of the meeting as well as the larger scientific community an insight into the compiled evidence regarding current pharmacogenomics knowledge in pediatric oncology. This preliminary evaluation will help steer the committee’s work and should give the reader an idea at which stage researchers and clinicians are, in terms of personalizing medicine for children with cancer. From the evidence presented here, future recommendations to achieve this goal will also be suggested.
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Affiliation(s)
- Vid Mlakar
- Cansearch Research Laboratory, Geneva University Medical School, Avenue de la Roseraie 64, 1205 Geneva, Switzerland.
| | - Patricia Huezo-Diaz Curtis
- Cansearch Research Laboratory, Geneva University Medical School, Avenue de la Roseraie 64, 1205 Geneva, Switzerland.
| | | | - Maja Krajinovic
- Charles-Bruneau Cancer Center, Centre hospitalier universitaire Sainte-Justine, 4515 Rue de Rouen, Montreal, QC H1V 1H1, Canada.
- Department of Pediatrics, University of Montreal, 2900 Boulevard Edouard-Montpetit, Montreal, QC H3T 1J4, Canada.
- Department of Pharmacology, Faculty of Medicine, University of Montreal, 2900 Boulevard Edouard-Montpetit, Montreal, QC H3T 1J4, Canada.
| | - Marc Ansari
- Cansearch Research Laboratory, Geneva University Medical School, Avenue de la Roseraie 64, 1205 Geneva, Switzerland.
- Pediatric Department, Onco-Hematology Unit, Geneva University Hospital, Rue Willy-Donzé 6, 1205 Geneva, Switzerland.
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Hoang PTV, Ambroise J, Dekairelle AF, Durant JF, Butoescu V, Chi VLD, Huynh N, Nguyen TB, Robert A, Vermylen C, Gala JL. Comparative pharmacogenetic analysis of risk polymorphisms in Caucasian and Vietnamese children with acute lymphoblastic leukemia: prediction of therapeutic outcome? Br J Clin Pharmacol 2015; 79:429-40. [PMID: 25099492 DOI: 10.1111/bcp.12481] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 08/04/2014] [Indexed: 01/10/2023] Open
Abstract
AIMS Acute lymphoblastic leukemia (ALL) is the most common of all paediatric cancers. Aside from predisposing to ALL, polymorphisms could also be associated with poor outcome. Indeed, genetic variations involved in drug metabolism could, at least partially, be responsible for heterogeneous responses to standardized leukemia treatments, hence requiring more personalized therapy. The aims of this study were to (a) to determine the prevalence of seven common genetic polymorphisms including those that affect the folate and/or thiopurine metabolic pathways, i.e. cyclin D1 (CCND1-G870A), γ-glutamyl hydrolase (GGH-C452T), methylenetetrahydrofolate reductase (MTHFR-C677T and MTHFR-A1298C), thymidylate synthase promoter (TYMS-TSER), thiopurine methyltransferase (TPMT*3A and TPMT*3C) and inosine triphosphate pyrophosphatase (ITPA-C94A), in Caucasian (n = 94, age < 20) and Vietnamese (n = 141, age < 16 years) childhood ALL and (b) to assess the impact of a multilocus genetic risk score (MGRS) on relapse-free survival (RFS) using a Cox proportional-hazards regression model. RESULTS The prevalence of MTHFR-677TT genotype was significantly higher in Caucasians (P = 0.008), in contrast to the prevalence of TYMS-TSER*3R/3R and ITPA-94AA/AC genotypes which were significantly higher in Vietnamese (P < 0.001 and P = 0.02, respectively). Compared with children with a low MGRS (≤ 3), those with a high MGRS (≥ 4) were 2.06 (95% CI = 1.01, 4.22; P = 0.04) times more likely to relapse. Adding MGRS into a multivariate Cox regression model with race/ethnicity and four clinical variables improved the predictive accuracy of the model (AUC from 0.682 to 0.709 at 24 months). CONCLUSION Including MGRS into a clinical model improved the predictive accuracy of short and medium term prognosis, hence confirming the association between well determined pharmacogenotypes and outcome of paediatric ALL. Whether variants on other genes associated with folate metabolism can substantially improve the predictive value of current MGRS is not known but deserves further evaluation.
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Affiliation(s)
- Phuong Thu Vu Hoang
- Centre de Technologies Moléculaires Appliquées (CTMA), Institut de Recherche Expérimentale et Clinique (IREC), Université catholique de Louvain (UCL), Brussels, Belgium; Service d'hématologie et oncologie pédiatrique, Cliniques universitaires Saint-Luc, Université catholique de Louvain (UCL), Brussels, Belgium; Pham Ngoc Thach University of Medecin, Ho Chi Minh city, Vietnam; Blood Transfusion and Hematology Hospital, Ho Chi Minh city, Vietnam
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Inherited genetic variation in childhood acute lymphoblastic leukemia. Blood 2015; 125:3988-95. [PMID: 25999454 DOI: 10.1182/blood-2014-12-580001] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 01/30/2015] [Indexed: 02/06/2023] Open
Abstract
Although somatically acquired genomic alterations have long been recognized as the hallmarks of acute lymphoblastic leukemia (ALL), the last decade has shown that inherited genetic variations (germline) are important determinants of interpatient variability in ALL susceptibility, drug response, and toxicities of ALL therapy. In particular, unbiased genome-wide association studies have identified germline variants strongly associated with the predisposition to ALL in children, providing novel insight into the mechanisms of leukemogenesis and evidence for complex interactions between inherited and acquired genetic variations in ALL. Similar genome-wide approaches have also discovered novel germline genetic risk factors that independently influence ALL prognosis and those that strongly modify host susceptibility to adverse effects of antileukemic agents (eg, vincristine, asparaginase, glucocorticoids). There are examples of germline genomic associations that warrant routine clinical use in the treatment of childhood ALL (eg, TPMT and mercaptopurine dosing), but most have not reached this level of actionability. Future studies are needed to integrate both somatic and germline variants to predict risk of relapse and host toxicities, with the eventual goal of implementing genetics-driven precision-medicine approaches in ALL treatment.
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Host thiopurine methyltransferase status affects mercaptopurine antileukemic effectiveness in a murine model. Pharmacogenet Genomics 2014; 24:263-71. [PMID: 24710003 DOI: 10.1097/fpc.0000000000000044] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Thiopurines are used for many cancers, including acute lymphoblastic leukemia (ALL). Patients with an inherited host defect in thiopurine methyltransferase (TPMT) are at high risk for life-threatening toxicity if treated with conventional dosages, but the impact on antileukemic efficacy is less clear. MATERIALS AND METHODS We treated thiopurine-sensitive BCR-ABL+Arf-null Tpmt+/+ ALL in Tpmt+/+, +/-, or -/- recipient mice to test the impact of the host polymorphism on antileukemic efficacy. RESULTS Median survival was similar in untreated mice of different Tpmt genotypes (16-18 days). However, in mice treated with low-dose mercaptopurine (such as tolerated by TPMT-/- patients), the difference in 30-day leukemia-free survival by Tpmt genotype was profound: 5% (±9%) for Tpmt+/+ mice, 47% (±26%) for Tpmt+/- mice, and 85% (±14%) for Tpmt-/- mice (P=5×10), indicating a substantial impact of host Tpmt status on thiopurine effectiveness. Among Tpmt+/+ recipient mice, leukemia-free survival improved with higher doses of mercaptopurine (similar to doses tolerated by wild-type patients) compared with lower doses, and at higher doses was comparable (P=0.6) to the survival of Tpmt-/- mice treated with the lower dose. CONCLUSIONS These findings support the notion that germline polymorphisms in Tpmt affect not only host tissue toxicity but also antitumor effectiveness.
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Belen BF, Gürsel T, Akyürek N, Albayrak M, Kaya Z, Koçak Ü. Severe Myelotoxicity Associated with Thiopurine S-Methyltransferase*3A/*3C Polymorphisms in a Patient with Pediatric Leukemia and the Effect of Steroid Therapy. Turk J Haematol 2014; 31:276-85. [PMID: 25541649 PMCID: PMC4454056 DOI: 10.4274/tjh.2013.0082] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Myelosuppression is a serious complication during treatment of acute lymphoblastic leukemia and the duration of myelosuppression is affected by underlying bone marrow failure syndromes and drug pharmacogenetics caused by genetic polymorphisms. Mutations in the thiopurine S-methyltransferase (TPMT) gene causing excessive myelosuppression during 6-mercaptopurine (MP) therapy may cause excessive bone marrow toxicity. We report the case of a 15-year-old girl with T-ALL who developed severe pancytopenia during consolidation and maintenance therapy despite reduction of the dose of MP to 5% of the standard dose. Prednisolone therapy produced a remarkable but transient bone marrow recovery. Analysis of common TPMT polymorphisms revealed TPMT *3A/*3C.
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Affiliation(s)
- Burcu Fatma Belen
- Gazi University Faculty of Medicine, Department of Pediatric Hematology, Ankara, Turkey. E-ma-il:
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Levinsen M, Rosthøj S, Nygaard U, Heldrup J, Harila-Saari A, Jonsson OG, Bechensteen AG, Abrahamsson J, Lausen B, Frandsen TL, Weinshilboum RM, Schmiegelow K. Myelotoxicity after high-dose methotrexate in childhood acute leukemia is influenced by 6-mercaptopurine dosing but not by intermediate thiopurine methyltransferase activity. Cancer Chemother Pharmacol 2014; 75:59-66. [PMID: 25347948 DOI: 10.1007/s00280-014-2613-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 10/14/2014] [Indexed: 11/29/2022]
Abstract
PURPOSE Through enhancement of 6-mercaptopurine (6MP) bioavailability and inhibition of purine de novo synthesis, high-dose methotrexate (HD-MTX) may increase incorporation into DNA of 6-thioguanine nucleotides, the cytotoxic metabolites of 6MP. Patients with intermediate activity of thiopurine methyltransferase (TPMT(IA)) have higher cytosol 6-thioguanine nucleotide levels. We investigated toxicity following HD-MTX during MTX/6MP maintenance therapy in relation to 6MP and TPMT. METHODS Using linear mixed models, we explored myelo- and hepatotoxicity in relation to 6MP dosage and TPMT phenotype following 1,749 HD-MTX courses to 411 children with acute lymphoblastic leukemia on maintenance therapy. RESULTS The degree of myelosuppression following HD-MTX was similar for patients with TPMT(IA) and patients with high TPMT activity (TPMT(HA)), when HD-MTX started with same blood counts and 6MP doses. However, since TPMT(IA) had lower blood counts at initiation of HD-MTX compared with TPMT(HA) patients (median WBC 2.8 vs. 3.3 × 10⁹/L, P = 0.01; median ANC 1.4 vs. 1.7 × 10⁹/L, P = 0.02), TPMT(IA) continued to have lower WBC and ANC levels compared with TPMT(HA) during all 28 days after HD-MTX [relative difference 9 % (95 % CI 2-17), P = 0.02 and 21 % (95 % CI 6-39), P = 0.005]. Still, the fractional decrease in WBC and ANC levels after HD-MTX did not differ between TPMT(IA) and TPMT(HA) patients (P = 0.47; P = 0.38). The degree of leukopenia, neutropenia, thrombocytopenia and rise in aminotransferases were all significantly related to 6MP dose (P < 0.001 for all analyses). CONCLUSION For both TPMT(IA) and TPMT(HA) patients, dose of 6MP prior to HD-MTX should be guided by pre-HD-MTX blood counts, but not by TPMT activity.
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Affiliation(s)
- Mette Levinsen
- Department of Paediatrics and Adolescent Medicine, The University Hospital Rigshospitalet, Copenhagen, Denmark
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Constable S, Johnson MR, Pirmohamed M. Pharmacogenetics in clinical practice: considerations for testing. Expert Rev Mol Diagn 2014; 6:193-205. [PMID: 16512779 DOI: 10.1586/14737159.6.2.193] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Pharmacogenetics is a rapidly evolving field that will undoubtedly lead to the development of pharmacogenetic tests. Such tests will need to be assimilated into healthcare systems, but represent a further call on scarce healthcare resources. Therefore, in order for a pharmacogenetic test to fulfill its potential beyond the laboratory and into the clinical environment, it must prove itself on a wide range of multifaceted criteria. The test must have proven and reproducible analytical and clinical validity, and stand up to critical appraisal of clinical utility and cost-effectiveness. Pharmacogenetic testing can be considered to be a form of screening, and the experience that has been gained to date in evaluating other forms of screening tests may prove beneficial in evaluating pharmacogenetic technology. It is essential that the goals of pharmacogenetic testing are defined as early as possible to ensure that appropriate studies can be designed to provide the evidence base, and thereby enable appropriate evaluation of the technology by clinicians and healthcare administrators for incorporation into clinical practice. This review focuses on issues that will need to be considered in the scientific assessment of pharmacogenetic testing.
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Affiliation(s)
- Simon Constable
- Department of Pharmacology & Therapeutics, Ashton Street Medical School, University of Liverpool, Ashton Street, Liverpool, L69 3GE, UK.
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19
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Abstract
The drug-metabolizing enzyme thiopurine methyltransferase (TPMT) has become one of the best examples of pharmacogenomics to be translated into routine clinical practice. TPMT metabolizes the thiopurines 6-mercaptopurine, 6-thioguanine, and azathioprine, drugs that are widely used for treatment of acute leukemias, inflammatory bowel diseases, and other disorders of immune regulation. Since the discovery of genetic polymorphisms in the TPMT gene, many sequence variants that cause a decreased enzyme activity have been identified and characterized. Increasingly, to optimize dose, pretreatment determination of TPMT status before commencing thiopurine therapy is now routine in many countries. Novel TPMT sequence variants are currently numbered sequentially using PubMed as a source of information; however, this has caused some problems as exemplified by two instances in which authors' articles appeared on PubMed at the same time, resulting in the same allele numbers given to different polymorphisms. Hence, there is an urgent need to establish an order and consensus to the numbering of known and novel TPMT sequence variants. To address this problem, a TPMT nomenclature committee was formed in 2010, to define the nomenclature and numbering of novel variants for the TPMT gene. A website (http://www.imh.liu.se/tpmtalleles) serves as a platform for this work. Researchers are encouraged to submit novel TPMT alleles to the committee for designation and reservation of unique allele numbers. The committee has decided to renumber two alleles: nucleotide position 106 (G>A) from TPMT*24 to TPMT*30 and position 611 (T>C, rs79901429) from TPMT*28 to TPMT*31. Nomenclature for all other known alleles remains unchanged.
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Polymorphism of genes involved in purine metabolism (XDH, AOX1, MOCOS) in kidney transplant recipients receiving azathioprine. Ther Drug Monit 2013; 34:266-74. [PMID: 22495427 DOI: 10.1097/ftd.0b013e31824aa681] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Xanthine dehydrogenase (XDH), aldehyde oxidase1 (AOX1), and molybdenum cofactor sulfurase (MOCOS) are enzymes involved in purine metabolism. The aim of this study was to investigate single nucleotide polymorphisms (SNPs) in XDH, AOX1, and MOCOS genes in relation to clinical parameters and risk of drug side effects in a cohort of kidney transplant recipients treated with azathioprine (AZA) as a part of standard immunosuppressive regimen. METHODS One hundred fifty-six patients receiving AZA for the first year from the surgery were genotyped for the presence of common SNPs in the coding regions of XDH, AOX1, and MOCOS genes using TaqMan assays. RESULTS AOX1 rs55754655 variant allele carriers received a higher mean AZA dose 3, 6, and 12 months after transplantation (P < 0.05). The patients inheriting rs594445 MOCOS minor allele required significantly lower doses of AZA for efficient treatment compared with wild-type heterozygotes at 3, 6, and 12 months from the transplantation (mean values: 1.39 versus 1.59, 1.38 versus 1.58, and 1.33 versus 1.53 mg·kg·24 h) and displayed lower mean RBC count at the time points evaluated. Multivariate analysis has shown that the effect of MOCOS rs594445 polymorphism is independent of other investigated gene variations and might influence AZA dosage, similarly to TPMT heterozygosity. The authors have not observed an association between any of the studied XDH SNPs and clinical parameters of AZA-treated patients. CONCLUSIONS The results of this study should be regarded as preliminary. However, if the observed association between SNPs: AOX1 rs55754655, MOCOS rs594445, and AZA dose requirements would be positively confirmed in further independent studies, it could be introduced into clinical practice to individualize thiopurine treatment.
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O'Connor A, Qasim A, O'Moráin CA. The long-term risk of continuous immunosuppression using thioguanides in inflammatory bowel disease. Ther Adv Chronic Dis 2012; 1:7-16. [PMID: 23251725 DOI: 10.1177/2040622310368736] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The efficacy of thiopurine treatment in the induction, and especially maintenance, of remission in inflammatory bowel disease is well proven; however, it is associated with side effects in both medium and long-term use. The potential harmful effects may be anticipated and minimised by due diligence prior to commencing these drugs followed by close monitoring of haematological and biochemical parameters once started. Careful clinical examination and history taking are also essential. Affected patients are expected to lead lives that include travel, employment and pregnancy - the implications of continued thiopurine therapy in such patients are discussed.
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Affiliation(s)
- Anthony O'Connor
- Dr Asghar Qasim Prof. Colm A. O'Moráin Department of Gastroenterology, Adelaide and Meath Hospital incorporating the National Children's Hospital/Trinity College Dublin, Belgard Road, Tallaght, Dublin 24, Ireland
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Abstract
Oncology chemotherapeutics frequently exhibit a narrow therapeutic index, further complicated by the serious nature of dosing either too high (dangerous toxicities) or too low (loss of antitumor benefits). This underscores the need for optimal individualized drug selection and dosing, especially with agents that have wide interpatient variability. Pharmacogenomic assessment of drug metabolizing enzymes can improve the ability to optimally dose patients being treated with certain agents such as 6-mercaptopurine, irinotecan, tamoxifen, and flurouracil. Two of these agents (6-mercaptopurine and irinotecan) already have mention of pharmacogenomic testing in their FDA approved package inserts. Ongoing retrospective and prospective trials will help to further optimize the place in clinical practice for not only performing these pharmacogenomic assessments but, more importantly, how the results should be incorporated into therapy dosing decisions for patients.
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Affiliation(s)
- Christine M Walko
- UNC School of Pharmacy, Division of Pharmacotherapy and Experimental Therapeutics, Chapel Hill, NC 27599-7569, USA.
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Du J, Wang Y, Zhang W. Label‐Free, Non‐Derivatization CRET Detection Platform for 6‐Mercaptopurine Based on the Distance‐Dependent Optical Properties of Gold Nanoparticles. Chemistry 2012; 18:8540-6. [DOI: 10.1002/chem.201200013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Revised: 03/25/2012] [Indexed: 12/19/2022]
Affiliation(s)
- Jianxiu Du
- Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062 (P. R. China), Fax: (+86) 29‐8153‐0727
| | - Yadi Wang
- Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062 (P. R. China), Fax: (+86) 29‐8153‐0727
| | - Weimin Zhang
- Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062 (P. R. China), Fax: (+86) 29‐8153‐0727
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Peregud-Pogorzelski J, Tetera-Rudnicka E, Kurzawski M, Brodkiewicz A, Adrianowska N, Mlynarski W, Januszkiewicz D, Drozdzik M. Thiopurine S-methyltransferase (TPMT) polymorphisms in children with acute lymphoblastic leukemia, and the need for reduction or cessation of 6-mercaptopurine doses during maintenance therapy: the Polish multicenter analysis. Pediatr Blood Cancer 2011; 57:578-82. [PMID: 21319286 DOI: 10.1002/pbc.23013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 12/09/2010] [Indexed: 01/07/2023]
Abstract
BACKGROUND 6-Mercaptopurine (6-MP) is used for the treatment of pediatric acute lymphoblastic leukemia (ALL). Mutations in the TPMT gene may influence the efficacy and safety of 6-MP treatment. This multicenter study investigated the association between TPMT genotype, 6-MP dose adjustments, and the incidence of adverse effects in patients. PROCEDURE A total of 203 ALL children were genotyped using PCR/allele-specific amplification and PCR/RFLP. The control group consisted of 394 healthy volunteers. RESULTS The TPMT*3A variant allele was found in 16 patients (15 TPMT*1/*3A, 1 TPMT*3A/*3A) and the TPMT*3C (A719G) allele in 1 patient. No TPMT*2 (G238C) or TPMT*3B (G460A) alleles were detected in the study group. TPMT*3A, TPMT*1 (wild-type), and TPMT*3C alleles were detected at frequencies of 3.94%, 95.81%, and 0.25%, respectively. The genotype and allele distributions were similar in the ALL and control groups. The 6-MP dose was reduced more frequently in patients with TPMT*3A and TPMT*3C alleles, compared with wild-type alleles (P = 0.042). Reductions because of leucopenia with respiratory tract infection, or because of leucopenia, anemia and/or thrombocytopenia were four (P = 0.007) and five (P = 0.03) times more common, respectively. The groups differed with regard to the rates of 6-MP dose reduction (P = 0.028). 6-MP was discontinued more often in patients with TPMT*3A and TPMT*3C alleles (14-fold) as a result of leucopenia, anemia, and/or thrombocytopenia (P = 0.004). CONCLUSIONS The results indicate that TPMT genotype influences the safety and efficacy of ALL treatment and genotype information may therefore be useful for optimizing 6-MP therapy.
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Budhiraja P, Popovtzer M. Azathioprine-related myelosuppression in a patient homozygous for TPMT*3A. Nat Rev Nephrol 2011; 7:478-84. [PMID: 21712851 DOI: 10.1038/nrneph.2011.74] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND A 50-year-old man who had received a simultaneous pancreas and kidney transplant 9 years earlier developed pancytopenia 3 weeks after starting azathioprine therapy to treat worsening proteinuria suspected to be caused by sirolimus. INVESTIGATIONS Laboratory tests, including complete blood counts, measurement of serum levels of vitamin B(12) and folate, liver function tests, virological assays, and thiopurine S-methyltransferase (TPMT) genotyping. DIAGNOSIS Severe myelosuppression as a consequence of azathioprine therapy in a patient homozygous for the TPMT*3A allele. MANAGEMENT Discontinuation of azathioprine, treatment with an erythropoiesis-stimulating agent, red blood cell transfusions, filgrastim (a granulocyte colony-stimulating factor analogue) and folic acid.
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Affiliation(s)
- Pooja Budhiraja
- Southern Arizona Veterans Affairs Health Care System, 3601 South 6th Avenue, Tucson, AZ 85723, USA.
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26
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Kverka M, Rossmann P, Tlaskalova-Hogenova H, Klimesova K, Jharap B, de Boer NK, Vos RM, van Bodegraven AA, Lukas M, Mulder CJ. Safety and efficacy of the immunosuppressive agent 6-tioguanine in murine model of acute and chronic colitis. BMC Gastroenterol 2011; 11:47. [PMID: 21545711 PMCID: PMC3097145 DOI: 10.1186/1471-230x-11-47] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Accepted: 05/05/2011] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Oral thiopurines are effective and widely used in treatment of inflammatory bowel disease (IBD) in humans, although their use is limited due the development of adverse events. Here, we examine the efficacy and toxicity of oral treatment with 6-tioguanine (6-TG) and azathioprine (AZA) in a murine model of IBD. METHODS We induced acute or chronic colitis in BALB/c mice by one or four cycles of 3% dextran sulphate sodium (DSS), respectively. Mice were treated by daily gavages of various dosages of 6-tioguanine, azathioprine, or by phosphate buffered saline (PBS) starting the first day of DSS or after two cycles of DSS, respectively. We monitored the efficacy and toxicity by measuring the weight change and serum alanine aminotransferase (ALT) activity and by disease severity and histology, at the end of the experiment. Moreover, we measured cytokine production after colon fragment cultivation by enzyme-linked immunoabsorbent assay and numbers of apoptotic cells in the spleen by flow cytometry. RESULTS 6-TG is effective in the treatment of acute DSS-induced colitis in a dose-dependent manner and 40 μg of 6-TG is significantly more effective in the treatment of acute colitis than both AZA and PBS. This effect is accompanied by decrease of IL-6 and IFN-γ production in colon. We did not observe histological abnormalities in liver samples from control (PBS) or 6-TG treated mice. However, liver samples from most mice treated with AZA showed mild, yet distinct signs of hepatotoxicity. In chronic colitis, all thiopurine derivatives improved colitis, 20 μg of 6-TG per dose was superior. High doses of 6-TG led to significant weight loss at the end of the therapy, but none of the thiopurine derivatives increased levels of serum ALT. Both thiopurine derivatives reduced the proportion of apoptotic T helper cells, but a high production of both IL-6 and TGF-β was observed only in colon of AZA-treated mice. CONCLUSIONS Use of 6-TG in the treatment of experimental colitis in mice appears superior to AZA administration and placebo. In contrast to 6-TG, the use of AZA resulted in histological liver abnormalities.
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Affiliation(s)
- Miloslav Kverka
- Department of Immunology and Gnotobiology, Institute of Microbiology, Academy of Sciences of Czech Republic, Videnska 1083, 14220 Prague 4, Czech Republic.
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Abstract
Interindividual variability in the disposition and action associated with similar doses of a given medication is an inherent characteristic of both adult and pediatric populations. Genotype-phenotype relationships in infants and children must take into account the role that ontogeny plays in producing variability in both pharmacokinetics and pharmacodynamics. This review explores pharmacogenomics in the context of ontogeny and relates these to the expression of drug-metabolizing enzymes and transporters and the consequent effect on the exposure-response relationship in the early years of life.
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Affiliation(s)
- Kathleen A Neville
- Department of Pediatrics, University of Missouri - Kansas City, Kansas City, MO, USA.
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Bahari A, Hashemi M, Bari Z, Moazeni-Roodi A, Kaykhaei MA, Narouie B. Frequency of thiopurine S-methyltransferase (TPMT) alleles in southeast Iranian population. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2010; 29:237-44. [PMID: 20408054 DOI: 10.1080/15257771003720418] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Thiopurine S-methyltransferase (TPMT, EC 2.1.1.67) plays a key role in the metabolism of thioprine drugs. Subjects with intermediate or no TPMT activity are at risk of azathioprines toxicity treated with conventional dosages of thiopurine drugs. While TPMT polymorphisms have been extensively studied in many countries, there is insufficient data in Iranian populations. In the present study, we aimed to identify the common functional TPMT alleles in southeast Iranian population. The TPMT allele frequencies were determined by multiplexed allele-specific polymerase chain reaction. Among 832 samples of Iranian population, the frequency for the TPMT*2, TPMT*3A, TPMT*3B and TPMT*3C, were 2.16%, 1.68%, 1.62%, and 0.54%, respectively. The distribution of the TPMT genotypes were 87.98% for TPMT*1/*1, 4.33% for TPMT*1/*2, 3.36% for TPMT*1/*3A, 3.24% for TPMT*1/*3B, and 1.08% for TPMT*1/*3C. This functional analysis of common TPMT alleles in an Iranian population could provide useful information for thioprine drugs therapy.
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Affiliation(s)
- Ali Bahari
- Department of Internal Medicine, School of Medicine, Zahedan University of Medical Sciences, Zahedan, I.R. Iran
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Byrn SR, Zografi G, Chen X(S. Accelerating Proof of Concept for Small Molecule Drugs Using Solid-State Chemistry. J Pharm Sci 2010; 99:3665-75. [DOI: 10.1002/jps.22215] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Higgs JE, Payne K, Roberts C, Newman WG. Are patients with intermediate TPMT activity at increased risk of myelosuppression when taking thiopurine medications? Pharmacogenomics 2010; 11:177-88. [PMID: 20136357 DOI: 10.2217/pgs.09.155] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
UNLABELLED Thiopurine S-methyltransferase (TPMT) metabolizes thiopurine medications, including azathioprine and 6-mercaptopurine. Absent TPMT activity (i.e., in individuals homozygous for a variant TPMT allele) is associated with an increased risk of myelosuppression in patients taking thiopurine drugs. However, it is not clear if there is also an increased risk for patients with intermediate TPMT activity (i.e., in individuals heterozygous for a variant TPMT allele). AIMS To quantify the increased risk of myelosuppression for patients with intermediate TPMT activity. MATERIALS & METHODS A systematic review identified published studies, up to 29 September 2008, that explored the relationship between TMPT and hematological adverse drug reactions to thiopurines. Following a critical appraisal of the quality of published studies, a meta-analysis calculated the odds ratio of myelosuppression for patients with intermediate TPMT activity compared with wild-type. RESULTS A total of 67 studies were identified, the majority retrospective cohort in design. Patients with two TPMT variant alleles who are TPMT deficient have a substantial increase in their risk of myelotoxicity (86% of deficient patients developed myelosuppression). The increase in odds ratio of developing leukopenia for patients with intermediate TPMT activity or one TPMT variant allele compared with wild-type was 4.19 (95% CI: 3.20-5.48). CONCLUSION This meta-analysis suggests that individuals with both intermediate and absent TPMT activity have an increased risk of developing thiopurine-induced myelosuppression, compared with individuals with normal activity. However, there is significant variability in the quality of the reported studies and large prospective studies to clarify the size of the effect of TPMT variant alleles on the risk of myelosuppression should be conducted. Accurate risk assessments will provide important data to inform clinical guidelines.
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Affiliation(s)
- Jenny E Higgs
- Central Manchester & Manchester Children's University Hospitals NHS Trust, Manchester Royal Infirmary, Manchester, UK
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Guidelines for the management of inflammatory bowel disease in children in the United Kingdom. J Pediatr Gastroenterol Nutr 2010; 50 Suppl 1:S1-13. [PMID: 20081543 DOI: 10.1097/mpg.0b013e3181c92c53] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Hawwa AF, Millership JS, Collier PS, McCarthy A, Dempsey S, Cairns C, McElnay JC. The development of an objective methodology to measure medication adherence to oral thiopurines in paediatric patients with acute lymphoblastic leukaemia—an exploratory study. Eur J Clin Pharmacol 2009; 65:1105-12. [DOI: 10.1007/s00228-009-0700-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2009] [Accepted: 07/03/2009] [Indexed: 10/20/2022]
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Kurzawski M, Dziewanowski K, Lener A, Drozdzik M. TPMT but not ITPA gene polymorphism influences the risk of azathioprine intolerance in renal transplant recipients. Eur J Clin Pharmacol 2009; 65:533-40. [PMID: 19229528 DOI: 10.1007/s00228-009-0630-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Accepted: 01/28/2009] [Indexed: 01/29/2023]
Abstract
PURPOSE Thiopurine drugs have to be withdrawn in 10-30% of cases due to side effects, and it has been presented that genetic factors may be responsible for some of reported toxicity cases. Among polymorphic enzymes of thiopurines' metabolic pathway, thiopurine S-methyltransferase (TPMT) has been studied most extensively, and some recent studies point to inosine triphosphate pyrophosphohydrolase (ITPA) polymorphism as an additional toxicity risk factor. METHODS The aim of the current study was to evaluate an association between TPMT and ITPA gene polymorphisms and drug intolerance in a cohort of 157 renal transplant recipients treated with azathioprine (AZA). Each subject was genotyped for the presence of variant TPMT (*2, *3A, *3B, and *3C) and ITPA (94C>A and IVS2+21A>C) alleles. RESULTS Mean AZA dose, mean white-blood-cell count, and platelet count in the course of treatment were lower in carriers of variant TPMT alleles compared to patients with TPMT wild-type genotype. Leukocyte numbers fell below 4.0 x 10(9)/L in 41.2% of TPMT heterozygous renal transplant recipients, compared to only 18.0% of wild-type patients (P < 0.01). In contrast, ITPA genotype did not influence AZA dose, hematological parameters, or leucopenia risk. CONCLUSIONS Our results suggest that routine genotyping of renal transplant recipients for TPMT variants may be useful in reducing the risk of AZA-related myelotoxicity, but there is not enough evidence to introduce ITPA testing into clinical practice.
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Affiliation(s)
- Mateusz Kurzawski
- Department of Pharmacology, Pomeranian Medical University, Powstancow Wlkp. 72, Szczecin 70-111, Poland.
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Gardiner SJ, Gearry RB, Burt MJ, Ding SL, Barclay ML. Severe hepatotoxicity with high 6-methylmercaptopurine nucleotide concentrations after thiopurine dose escalation due to low 6-thioguanine nucleotides. Eur J Gastroenterol Hepatol 2008; 20:1238-42. [PMID: 18989148 DOI: 10.1097/meg.0b013e3282ffda37] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Azathioprine and its initial metabolite, 6-mercaptopurine (6-MP), are associated with high rates of treatment cessation due to toxicity or inadequate response. Individualization of thiopurine dose based on concentrations of the active 6-thioguanine nucleotide (6-TGN) metabolites can help improve outcomes with this class. Some individuals, however, preferentially metabolize thiopurine drugs to the potentially hepatotoxic 6-methylmercaptopurine nucleotide (6-MMPN) metabolites rather than the 6-TGNs. For these patients, escalation in thiopurine dose is not likely to increase 6-TGN concentrations sufficiently but may lead to a disproportionate increase in exposure to the 6-MMPNs. We present three cases in whom thiopurine dose escalation based on clinical status and low 6-TGN concentrations (100-262 pmol/8 x 10 RBC) resulted in severe hepatotoxicity (liver failure in two cases) associated with unrecognized extremely high 6-MMPN concentrations of 26,000-40,000 pmol/8 x 10 RBC. These cases illustrate a risk with thiopurine dose adjustment based on monitoring of 6-TGN metabolites without also monitoring 6-MMPN.
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Affiliation(s)
- Sharon J Gardiner
- Department of Clinical Pharmacology, Christchurch Hospital, University of Otago, Christchurch, New Zealand
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Shai RM, Reichardt JKV, Chen TC. Pharmacogenomics of brain cancer and personalized medicine in malignant gliomas. Future Oncol 2008; 4:525-34. [PMID: 18684063 DOI: 10.2217/14796694.4.4.525] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The pharmacogenetics of cancer treatment has been aimed at identifying genetic components of interindividual variability in patients' response to cancer chemotherapy and toxicity. This, in turn, will establish an individually based treatment, and also elucidate the molecular basis of the treatment regimen for further improvements. Brain cancer is an instructive example for the potential contributions of pharmacogenomics to improved treatment in the 21st century. Patients with oligodendrogliomas have benefited from phamacogenomics, as there is a clear relationship between response to chemotherapy and chromosomal profile. Drug efficacy, safety and response could be improved by using pharmacogenomics to identify genetic markers that differentiate responder from nonresponder patient groups, as well as identifying patients likely to develop adverse drug reactions. This review will focus on how pharmacogenomics by microarray studies may lead to much more accurate tumor classification, drug and biomarker discovery, and drug efficacy testing. We will discuss relevant scientific advances in pharmacogenetics for more personalized chemotherapy.
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Affiliation(s)
- Ruty Mehrian Shai
- USC Keck School of Medicine, Department of Biochemistry and Molecular Biology, Institute for Genetic Medicine, Los Angeles, CA 90089, USA.
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Ansari A, Arenas M, Greenfield SM, Morris D, Lindsay J, Gilshenan K, Smith M, Lewis C, Marinaki A, Duley J, Sanderson J. Prospective evaluation of the pharmacogenetics of azathioprine in the treatment of inflammatory bowel disease. Aliment Pharmacol Ther 2008; 28:973-83. [PMID: 18616518 DOI: 10.1111/j.1365-2036.2008.03788.x] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
AIM To investigate whether pharmacogenetic loci or metabolite concentrations explain clinical response or side effects to AZA. METHODS Patients with IBD were given 2 mg/kg of AZA without dose escalation or adjustment. Serial clinical response, thiopurine methyl transferase (TPMT) activity and thioguanine nucleotide (TGN) concentrations were measured over 6 months. All patients were genotyped for inosine triphosphatase (ITPase) and TPMT. Clinical response and side effects were compared to these variables. RESULTS Two hundred and seven patients were analysed. Thirty-nine per cent withdrew due to adverse effects. Heterozygous TPMT genotype strongly predicted adverse effects (79% heterozygous vs. 35% wild-type TPMT, P < 0.001). The ITPA 94C>A mutation was associated with withdrawal due to flu-like symptoms (P = 0.014). A baseline TPMT activity below 35 pmol/h/mg/Hb was associated with a greater chance of clinical response compared with a TPMT above 35 pmo/h/mg/Hb (81% vs. 43% respectively, P < 0.001). Patients achieving a mean TGN level above 100 were significantly more likely to respond (P = 0.0017). CONCLUSIONS TPMT testing predicts adverse effects and reduced chance of clinical response (TPMT >35 pmol/h/mg/Hb). ITPase deficiency is a predictor of adverse effects and TGN concentrations above 100 correlate with clinical response.
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Affiliation(s)
- A Ansari
- Department of Gastroenterology, St Thomas' Hospitals Foundation, NHS Trust, London, UK
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Chowbay B, Zhou S, Lee EJD. An Interethnic Comparison of Polymorphisms of the Genes Encoding Drug-Metabolizing Enzymes and Drug Transporters: Experience in Singapore. Drug Metab Rev 2008; 37:327-78. [PMID: 15931768 DOI: 10.1081/dmr-28805] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Much of the interindividual variability in drug response is attributable to the presence of single nucleotide polymorphisms (SNPs) in genes encoding drug-metabolizing enzymes and drug transporters. In recent years, we have investigated the polymorphisms in a number of genes encoding phase I and II drug-metabolizing enzymes including CYPIA1, CYP3A4, CYP3A5, GSTM1, NAT2, UGT1A1, and TPMT and drug transporter (MDR1) in three distinct Asian populations in Singapore, namely the Chinese, Malays, and Indians. Significant differences in the frequencies of common alleles encoding these proteins have been observed among these three ethnic groups. For example, the frequency of the variant A2455G polymorphism of CYP1A1 was 28% in Chinese and 31% in Malays, but only 18% in Indians. CYP3A4*4 was detected in two of 110 Chinese subjects, but absent in Indians and Malays. Many Chinese and Malays (61-63%) were homozygous for the GSTM1*0 null genotype compared with 33% of Indians. The frequency of the UGTIA1*28 allele was highest in the Indian population (35%) compared to similar frequencies that were found in the Chinese (16%) and Malay (19%) populations. More importantly, our experience over the years has shown that the pharmacogenetics of these drug-metabolizing enzymes and MDR1 in the Asian populations are different from these in the Caucasian and African populations. For example, the CYP3A4*1B allele, which contains an A-290G substitution in the promoter region of CYP3A4, is absent in all three Asian populations of Singapore studied, but occurs in more than 54% of Africans and 5% of Caucasians. There were no difference in genotype and allelic variant frequencies in exon 12 of MDR1 between the Chinese, Malay, and Indian populations. When compared with other ethnic groups, the distribution of the wild-type C allele in exon 12 in the Malays (34.2%) and Indians (32.8%) was relatively high and similar to the Japanese (38.55%) and Caucasians (41%) but different from African-Americans (15%). The frequency of wild-type TT genotype in Asians (43.5% to 52.1%) and Japanese (61.5%) was much higher than those found in Caucasians (13.3%). All the proteins we studied represent the primary hepatic or extrahepatic enzymes, and their polymorphic expression may be implicated in disease risk and the disposition of drugs or endogenous substances. As such, dose requirements of certain drugs may not be optimal for Asian populations, and a second look at the factors responsible for this difference is necessary.
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Affiliation(s)
- Balram Chowbay
- Laboratory of Clinical Pharmacology, Division of Clinical Trials and Epidemiological Sciences, National Cancer Centre, Singapore
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Tamm R, Oselin K, Kallassalu K, Magi R, Anier K, Remm M, Metspalu A. Thiopurine S-methyltransferase (TPMT) pharmacogenetics: three new mutations and haplotype analysis in the Estonian population. Clin Chem Lab Med 2008; 46:974-9. [PMID: 18605963 DOI: 10.1515/cclm.2008.187] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Thiopurine methyltransferase (TPMT) is a cytoplasmic enzyme involved in the metabolism of thiopurine drugs. To date, at least 25 single nucleotide polymorphisms have been reported in the TPMT gene, 23 of these are associated with reduced enzyme activity. METHODS The aim of the present study was to sequence the whole coding region of TPMT (exons 3-10) to identify known and novel TPMT sequence variants amongst healthy Estonians. Erythrocyte TPMT activity was also measured to carry out a genotype-phenotype comparison. RESULTS A total of 21 subjects were heterozygous for known TPMT alleles (*2, *3A, *3C, *9, *12). Several other previously described intronic and exon polymorphisms were identified. Three novel mutations were detected -30T>A in exon 3, 10A>G in intron 3, and 145A>G in intron 10. Association analysis revealed four markers (114T>A, 94T>A, 460G>A, 719A>G) whose frequencies were significantly different in intermediate (enzyme activity <or=60 ng/mL/h) methylators compared to normal (enzyme activity 61-139 ng/mL/h) and high (enzyme activity >or=140 ng/mL/h) methylators (p<0.001). Haplotype analysis found one haplotype to be associated with intermediate TPMT activity. CONCLUSIONS Our results point to several markers that predict reduced enzyme activity. None of the identified markers were associated with high enzyme activity.
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Affiliation(s)
- Riin Tamm
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia.
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Gardiner SJ, Gearry RB, Begg EJ, Zhang M, Barclay ML. Thiopurine dose in intermediate and normal metabolizers of thiopurine methyltransferase may differ three-fold. Clin Gastroenterol Hepatol 2008; 6:654-60; quiz 604. [PMID: 18467186 DOI: 10.1016/j.cgh.2008.02.032] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Patients with inflammatory bowel disease (IBD) may have different thiopurine dose requirements in relation to thiopurine methyltransferase (TPMT) genotype and/or phenotype. The purpose of this study was to determine thiopurine dose requirements in intermediate versus normal TPMT metabolism status. METHODS Consecutive patients starting azathioprine or 6-mercaptopurine for IBD were followed up for 9 months. The thiopurine dose was individualized using 6-thioguanine nucleotide (6-TGN) concentrations (range, 235-450 pmol/8 x 10(8) red blood cells [RBCs]) and clinical status. Additional assessments undertaken every three months included measures of disease activity. RESULTS Eight (10%) of 77 participants were withdrawn because of protocol violation. Fifty-two (75%) of the remaining 69 subjects ( approximately 90% and 10% with the TPMT*1/*1 and *1/*3 genotypes, respectively) completed follow-up on azathioprine (n = 46) or 6-mercaptopurine (n = 6). The mean initial dose (as azathioprine equivalents) was similar ( approximately 1 mg/kg/d) for the 2 TPMT genotypes, but after 9 months the dose was 50% lower in the TPMT*1/*3 group (0.9 vs 1.8 mg/kg/d, P < .0001). Despite dose adjustment, median 6-TGN concentrations still were 2-fold higher in the TPMT*1/*3 group at the end of the follow-up period (505 vs 273 pmol/8 x 10(8) RBCs, P = .02). This difference was 3-fold when the concentration was adjusted for dose (578 vs 183 pmol/8 x 10(8) per mg/kg/d, P = .0007). Results were similar if TPMT phenotype was used instead of genotype. Clinical outcomes did not differ between groups. CONCLUSIONS Initial target doses to attain therapeutic 6-TGN concentrations (>235 pmol/8 x 10(8) RBCs) in patients with IBD might be 1 and 3 mg/kg/d in intermediate and normal metabolizers, respectively.
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Affiliation(s)
- Sharon J Gardiner
- Department of Medicine, Christchurch Hospital and Christchurch School of Medicine, Christchurch, New Zealand.
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Chowdhury J, Kaigala GV, Pushpakom S, Lauzon J, Makin A, Atrazhev A, Stickel A, Newman WG, Backhouse CJ, Pilarski LM. Microfluidic platform for single nucleotide polymorphism genotyping of the thiopurine S-methyltransferase gene to evaluate risk for adverse drug events. J Mol Diagn 2007; 9:521-9. [PMID: 17690215 PMCID: PMC1975104 DOI: 10.2353/jmoldx.2007.070014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Prospective clinical pharmacogenetic testing of the thiopurine S-methyltransferase gene remains to be realized despite the large body of evidence demonstrating clinical benefit for the patient and cost effectiveness for health care systems. We describe an entirely microchip-based method to genotype for common single nucleotide polymorphisms in the thiopurine S-methyltransferase gene that lead to serious adverse drug reactions for patients undergoing thiopurine therapy. Restriction fragment length polymorphism and allele-specific polymerase chain reaction have been adapted to a microfluidic chip-based polymerase chain reaction and capillary electrophoresis platform to genotype the common *2, *3A, and *3C functional alleles. In total, 80 patients being treated with thiopurines were genotyped, with 100% concordance between microchip and conventional methods. This is the first report of single nucleotide polymorphism detection using portable instrumentation and represents a significant step toward miniaturized for personalized treatment and automated point-of-care testing.
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Affiliation(s)
- Jeeshan Chowdhury
- Cross Cancer Institute, 11560 University Ave., Edmonton AB T6G1Z2, Canada
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Gardiner SJ, Gearry RB, Barclay ML, Begg EJ. Two cases of thiopurine methyltransferase (TPMT) deficiency--a lucky save and a near miss with azathioprine. Br J Clin Pharmacol 2007; 62:473-6. [PMID: 16995868 PMCID: PMC1885160 DOI: 10.1111/j.1365-2125.2005.02474.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND The association between thiopurine methyltransferase (TPMT) deficiency and myelosuppression with azathioprine is well recognized. Two cases are presented that illustrate the very different outcomes that may occur with azathioprine in patients with TPMT deficiency, which affects 0.3-0.6% of caucasians. CASE 1: The first patient's TPMT deficiency was identified following hospitalization for pancytopenia attributed to azathioprine. CASE 2: The second patient was identified as deficient early in treatment and myelosuppression was avoided by treating with a greatly decreased dose (25 mg per week). CONCLUSIONS Testing for TPMT ideally should be performed in every patient commencing a thiopurine drug.
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Affiliation(s)
- Sharon J Gardiner
- Department of Clinical Pharmacology, Christchurch Hospital and Christchurch School of Medicine, Private Bag, Christchurch, New Zealand.
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Abstract
Pharmacoeconomics and pharmacogenetics are two fields converging together as it is increasingly recognized that genetic markers predicting efficacy and toxicity to drugs can cost-effectively improve patient care. While pharmacogenetics aims at identifying genetic markers underlying the response to drugs, pharmacoeconomics aims at delivering healthcare cost-effectively. Several studies have investigated the potential cost-effectiveness of pharmacogenetic-based approaches. Recent evidences include screening for thiopurine methyltransferase gene polymorphisms to prevent azathioprine-induced myelosuppression, or screening for human leukocyte antigen (HLA)B5701 to prevent hypersensitivity reactions to abacavir therapy. Furthermore, examples suggesting a cost-effectiveness of markers predicting drug efficacy include screening the angiotensin-converting enzyme gene polymorphisms for statins therapy, the alpha-adducin gene variant for diuretic therapy and the assessment of human epidermal growth factor receptor (HER2) expression for trastuzumab therapy. However, thus far, all these pharmacoeconomic analyses are exploratory and validations in prospective randomized clinical trials are warranted.
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Affiliation(s)
- Thierry Dervieux
- Proprius Pharmaceuticals, 12264 El Camino Real, Suite 300, San Diego, CA 92130-3062, USA.
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Pharmacokinetics, dose adjustments, and 6-mercaptopurine/ methotrexate drug interactions in two patients with thiopurine methyltransferase deficiency. Acta Paediatr 2007. [DOI: 10.1111/j.1651-2227.1998.tb01399.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Song DK, Zhao J, Zhang LR. TPMT genotype and its clinical implication in renal transplant recipients with azathioprine treatment. J Clin Pharm Ther 2006; 31:627-35. [PMID: 17176368 DOI: 10.1111/j.1365-2710.2006.00775.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Thiopurine S-methyltransferase (TPMT) catalyses the S-methylation of thiopurine drugs. Patients with intermediate or deficient TPMT activity are at risk of toxicity after receiving standard doses of these drugs. OBJECTIVE This study determined the frequencies of TPMT alleles (TPMT*2, *3A, *3B and *3C) and explored the association between TPMT genetic polymorphism and the development of adverse drug reactions in Chinese renal transplant patients receiving azathioprine (AZA). METHODS TPMT genotypes were determined using polymerase chain reaction-based assays in 122 renal transplant patients and 210 healthy subjects. Biochemical and clinical data were retrospectively evaluated after renal transplantation. RESULTS Of 122 patients, eight (allele frequency 3.28%) were heterozygous for TPMT*3C and no TPMT*2, *3A or *3B or homozygous TPMT*3C subjects were identified. The pattern and frequency of the main mutant TPMT alleles were similar in patients and healthy subjects. Four of five patients (80%) with haematopoietic toxicity were heterozygotes. TPMT heterozygosity was associated with significant reductions in haematological indices and a significant decrease in cyclosporine plasma concentrations in the first year after renal transplantation. No association between TPMT genotype and renal rejection was identified. CONCLUSION Our results, together with those of others pointing in the same direction, suggest that genotyping the major TPMT variant alleles may be a valuable tool in preventing AZA toxicity and optimization of immunosuppressive therapy.
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Affiliation(s)
- D-K Song
- Department of Urology, The First Affiliated Hospital, Zhengzhou University, Zhengzhou, China
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Gardiner SJ, Begg EJ. Pharmacogenetics, drug-metabolizing enzymes, and clinical practice. Pharmacol Rev 2006; 58:521-90. [PMID: 16968950 DOI: 10.1124/pr.58.3.6] [Citation(s) in RCA: 235] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The application of pharmacogenetics holds great promise for individualized therapy. However, it has little clinical reality at present, despite many claims. The main problem is that the evidence base supporting genetic testing before therapy is weak. The pharmacology of the drugs subject to inherited variability in metabolism is often complex. Few have simple or single pathways of elimination. Some have active metabolites or enantiomers with different activities and pathways of elimination. Drug dosing is likely to be influenced only if the aggregate molar activity of all active moieties at the site of action is predictably affected by genotype or phenotype. Variation in drug concentration must be significant enough to provide "signal" over and above normal variation, and there must be a genuine concentration-effect relationship. The therapeutic index of the drug will also influence test utility. After considering all of these factors, the benefits of prospective testing need to be weighed against the costs and against other endpoints of effect. It is not surprising that few drugs satisfy these requirements. Drugs (and enzymes) for which there is a reasonable evidence base supporting genotyping or phenotyping include suxamethonium/mivacurium (butyrylcholinesterase), and azathioprine/6-mercaptopurine (thiopurine methyltransferase). Drugs for which there is a potential case for prospective testing include warfarin (CYP2C9), perhexiline (CYP2D6), and perhaps the proton pump inhibitors (CYP2C19). No other drugs have an evidence base that is sufficient to justify prospective testing at present, although some warrant further evaluation. In this review we summarize the current evidence base for pharmacogenetics in relation to drug-metabolizing enzymes.
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Affiliation(s)
- Sharon J Gardiner
- Department of Medicine, Christchurch School of Medicine, Private Bag 4345, Christchurch, New Zealand.
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van den Akker-van Marle ME, Gurwitz D, Detmar SB, Enzing CM, Hopkins MM, Gutierrez de Mesa E, Ibarreta D. Cost-effectiveness of pharmacogenomics in clinical practice: a case study of thiopurine methyltransferase genotyping in acute lymphoblastic leukemia in Europe. Pharmacogenomics 2006; 7:783-92. [PMID: 16886902 DOI: 10.2217/14622416.7.5.783] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Only a few studies have addressed the cost-effectiveness of pharmacogenetics interventions in healthcare. Lack of health economics data on aspects of pharmacogenetics is perceived as one of the barriers hindering its implementation for improving drug safety. Thus, a recent Institute for Prospective Technological Studies (IPTS) study, entitled 'Pharmacogenetics and pharmacogenomics: state-of-the-art and potential socio-economic impact in the EU' included an explorative cost-effectiveness review for a pharmacogenetic treatment strategy compared with traditional medical practice. The selected case study examined the cost-effectiveness of thiopurine methyltransferase (TMPT) genotyping prior to thiopurine treatment in children with acute lymphoblastic leukemia (ALL). Information for the cost-effectiveness model parameters was collected from literature surveys and interviews with experts from four European countries (Germany, Ireland, the Netherlands and the UK). The model has established that TPMT testing in ALL patients has a favorable cost-effectiveness ratio. This conclusion was based on parameters collected for TPMT genotyping costs, estimates for frequency of TMPT deficiency, rates of thiopurine-mediated myelosuppression in TPMT-deficient individuals, and myelosuppression-related hospitalization costs in each of the four countries studied. The mean calculated cost per life-year gained by TPMT genotyping in ALL patients in the four study countries was euro 2100 (or euro 4800 after 3% discount) based on genotyping costs of euro 150 per patient. Cost per life-year gained is expected to further improve following the introduction of the wider use of TMPT genotyping and the availability of lower cost genotyping methods. Our analysis indicates that TPMT genotyping should be seriously considered as an integral part of healthcare prior to the initiation of therapy with thiopurine drugs.
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Kurzawski M, Dziewanowski K, Gawrońska-Szklarz B, Domański L, Droździk M. The impact of thiopurine s-methyltransferase polymorphism on azathioprine-induced myelotoxicity in renal transplant recipients. Ther Drug Monit 2006; 27:435-41. [PMID: 16044099 DOI: 10.1097/01.ftd.0000164393.09402.c9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Thiopurine S-methyltransferase (TPMT) is an enzyme that catalyzes the S-methylation of thiopurine drugs such as 6-mercaptopurine, 6-thioguanine, and azathioprine. TPMT activity exhibits an interindividual variability, mainly as a result of genetic polymorphism. Patients with intermediate or deficient TMPT activity are at risk for toxicity after receiving standard doses of thiopurine drugs. It has previously been reported that 3 variant alleles: TPMT*2, *3A, and *3C are responsible for over 95% cases of low enzyme activity. The purpose of this study was to explore the association between these polymorphisms and the occurrence of azathioprine adverse effects in 112 renal transplant recipients undergoing triple immunosuppressive therapy including azathioprine, cyclosporine, and prednisone. TPMT genetic polymorphism was determined using PCR-RFLP and allele-specific PCR methods. Azathioprine dose, leukocyte, erythrocyte, and platelet counts, graft rejection episodes, as well as cyclosporine levels were analyzed throughout the first year after organ transplantation. We found the frequency of leukopenia episodes (WBC < 4.0 x 10(9)/L) significantly higher in heterozygous patients (53.8%) compared with those with TPMT wild-type genotype (23.5%). One patient, who was a compound homozygote (3A/*3C), experienced severe azathioprine-related myelotoxicity each time after receiving the standard drug dose. Our results suggest that polymorphisms in TPMT gene may be responsible for approximately 12.5% of all leukopenia episodes in renal transplant recipients treated with azathioprine. Genotyping for the major TPMT variant alleles may be a valuable tool in preventing AZA toxicity and optimization of immunosuppressive therapy.
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Affiliation(s)
- Mateusz Kurzawski
- Department of Pharmacology, Pomeranian Medical University, Szczecin, Poland.
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Abstract
The use of combination chemotherapy to cure acute lymphoblastic leukaemia (ALL) in children emerged in the 1980s as a paradigm for curing any disseminated cancer, and many of the therapeutic principles were subsequently applied to the treatment of other disseminated human cancers. Similarly, elucidation of the pharmacogenomics of ALL and its translation into new chemotherapeutic approaches might serve as a model for optimizing the treatment of other human cancers. Germline polymorphisms and gene-expression patterns in ALL cells have been linked to the toxicity and efficacy of chemotherapy for ALL and are beginning to emerge as useful clinical diagnostics.
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Affiliation(s)
- Meyling H Cheok
- St. Jude Children's Research Hospital, Department of Pharmaceutical Sciences, 332 North Lauderdale Street, Memphis, Tennessee 38105, USA
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Abstract
Over the past four decades, treatment of acute leukemia in children has made remarkable progress, from this disease being lethal to now achieving cure rates of 80% for acute lymphoblastic leukemia and 45% for acute myeloid leukemia. This progress is largely owed to the optimization of existing treatment modalities rather than the discovery of new agents. However, the annual number of patients with leukemia who experience relapse after initial therapy remains greater than that of new cases of most childhood cancers. The aim of pharmacogenetics is to develop strategies to personalize medications and tailor treatment regimens to individual patients, with the goal of enhancing efficacy and safety through better understanding of the person's genetic makeup. In this review, we summarize recent pharmacogenomic studies related to the treatment of pediatric acute leukemia. These include work using candidate-gene approaches, as well as genome-wide studies using haplotype mapping and gene expression profiling. These strategies illustrate the promise of pharmacogenomics to further advance the treatment of human cancers, with childhood leukemia serving as a paradigm.
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Affiliation(s)
- Meyling H Cheok
- St. Jude Children's Research Hospital, Department of Pharmaceutical Sciences, Memphis, TN 38105, USA.
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Duley JA, Florin THJ. Thiopurine therapies: problems, complexities, and progress with monitoring thioguanine nucleotides. Ther Drug Monit 2006; 27:647-54. [PMID: 16175140 DOI: 10.1097/01.ftd.0000169061.52715.3e] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Metabolism of thiopurine drugs--azathioprine, 6-mercaptopurine, and 6-thioguanine--has provided a powerful pharmacogenetic model incorporating polymorphism of the enzyme thiopurine methyltransferase (TPMT) and the primary active metabolite, thioguanine nucleotide (TGN). However, a sense of uncertainty about the usefulness of TGNs and other thiopurine metabolites has appeared. This review critically appraises the basis of thiopurine metabolism and reveals the problems and complexities in TGN research. Erythrocyte TGN is used in transplantation medicine and in chronic inflammatory conditions such as Crohn's disease, as a "surrogate" pharmacokinetic parameter for TGN in the target cells: leukocytes or bone marrow. It is not generally appreciated that erythrocytes do not express the enzyme IMP dehydrogenase and cannot convert mercaptopurine to TGN, which explains some of the confusion in interpretation of erythrocyte TGN measurements. TGN routinely measured in erythrocytes derives from hepatic metabolism. Another concern is that TGN are not generally assayed directly: most methods assay the thiopurine bases. Ion-exchange HPLC and enzymatic conversion of TGNs to nucleosides have been used to overcome this, and may reveal undisclosed roles for an unusual cytotoxic nucleotide, thio-inosine triphosphate, and methylated thiopurines. There appear to be additional interactions between xanthine oxidase and TPMT, and folate and TPMT, that could predict leukopenia. Difficult questions remain to be answered, which may be assisted by technological advances. Prospective TGN studies, long overdue, are at last revealing clearer results.
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Affiliation(s)
- John A Duley
- Chemical Pathology Department, Mater Health Services, Brisbane, Queensland, Australia
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