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Gallardo-Cóndor J, Naranjo P, Atarihuana S, Coello D, Guevara-Ramírez P, Flores-Espinoza R, Burgos G, López-Cortés A, Cabrera-Andrade A. Population-Specific Distribution of TPMT Deficiency Variants and Ancestry Proportions in Ecuadorian Ethnic Groups: Towards Personalized Medicine. Ther Clin Risk Manag 2023; 19:1005-1018. [PMID: 38050617 PMCID: PMC10693761 DOI: 10.2147/tcrm.s432856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Accepted: 11/06/2023] [Indexed: 12/06/2023] Open
Abstract
Purpose Thiopurine S-methyltransferase (TPMT) is an enzyme that metabolizes purine analogs, agents used in the treatment of acute lymphoblastic leukemia. Improper drug metabolism leads to toxicity in chemotherapy patients and reduces treatment effectiveness. TPMT variants associated with reduced enzymatic activity vary across populations. Therefore, studying these variants in heterogeneous populations, such as Ecuadorians, can help identify molecular causes of deficiency for this enzyme. Methods We sequenced the entire TPMT coding region in 550 Ecuadorian individuals from Afro-Ecuadorian, Indigenous, Mestizo, and Montubio ethnicities. Moreover, we conducted an ancestry analysis using 46 informative ancestry markers. Results We identified 8 single nucleotide variants in the coding region of TPMT. The most prevalent alleles were TPMT*3A, TPMT*3B, and TPMT*3C, with frequencies of 0.055, 0.012, and 0.015, respectively. Additionally, we found rare alleles TPMT*4 and TPMT*8 with frequencies of 0.005 and 0.003. Correlating the ancestry proportions with TPMT-deficient genotypes, we observed that the Native American ancestry proportion influenced the distribution of the TPMT*1/TPMT*3A genotype (OR = 5.977, p = 0.002), while the contribution of African ancestral populations was associated with the TPMT*1/TPMT*3C genotype (OR = 9.769, p = 0.003). The rates of TPMT-deficient genotypes observed in Mestizo (f = 0.121) and Indigenous (f = 0.273) groups provide evidence for the influence of Native American ancestry and the prevalence of the TPMT*3A allele. In contrast, although Afro-Ecuadorian groups demonstrate similar deficiency rates (f = 0.160), the genetic factors involved are associated with contributions from African ancestral populations, specifically the prevalent TPMT*3C allele. Conclusion The distribution of TPMT-deficient variants offers valuable insights into the populations under study, underscoring the necessity for genetic screening strategies to prevent thiopurine toxicity events among Latin American minority groups.
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Affiliation(s)
| | - Pablo Naranjo
- Facultad de Ingeniería y Ciencias Aplicadas, Universidad de Las Américas, Quito, Ecuador
| | - Sebastián Atarihuana
- Facultad de Ingeniería y Ciencias Aplicadas, Universidad de Las Américas, Quito, Ecuador
| | - Dayana Coello
- Laboratorios de Investigación, Universidad de Las Américas, Quito, Ecuador
| | - Patricia Guevara-Ramírez
- Centro de Investigación Genética y Genómica, Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
| | - Rodrigo Flores-Espinoza
- Laboratório de Diagnóstico por DNA (LDD), Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Germán Burgos
- One Health Research Group, Facultad de Medicina, Universidad de Las Américas, Quito, Ecuador
- Grupo de Medicina Xenomica, Instituto de Ciencias Forenses, Universidad de Santiago de Compostela, Satiago de Compostela, Spain
| | - Andrés López-Cortés
- Cancer Research Group (CRG), Faculty of Medicine, Universidad de Las Américas, Quito, Ecuador
- Latin American Network for the Implementation and Validation of Clinical Pharmacogenomics Guidelines (RELIVAF-CYTED), Madrid, Spain
| | - Alejandro Cabrera-Andrade
- Escuela de Enfermería, Facultad de Ciencias de la Salud, Universidad de Las Américas, Quito, Ecuador
- Grupo de Bio-Quimioinformática, Universidad de Las Américas, Quito, Ecuador
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Zeng D, Huang X, Lin S, Lin R, Weng X, Huang P. Cost-effectiveness analysis of genotype screening and therapeutic drug monitoring in patients with inflammatory bowel disease treated with azathioprine therapy: a Chinese healthcare perspective using real-world data. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:1138. [PMID: 34430579 PMCID: PMC8350671 DOI: 10.21037/atm-21-1980] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 07/07/2021] [Indexed: 11/15/2022]
Abstract
Background This study aimed to analyze the cost-effectiveness of combining screening for thiopurine methyl transferase (TPMT) and nucleotide triphosphate diphosphatase (NUDT15) defective alleles with therapeutic drug monitoring (TDM) in Chinese patients with inflammatory bowel disease (IBD) treated with azathioprine (AZA). Methods We evaluated the cost-effectiveness of combining screening for NUDT15 and TPMT deficiency with TDM in patients receiving AZA treatment over a 1-year horizon by developing a decision tree model. Real-world data and published literature were used to derive model inputs. The model’s primary outcomes included quality-adjusted life-years (QALYs) and incremental cost-effectiveness ratios (ICERs). One-way and probabilistic sensitivity analyses were used to address uncertainty. Results Compared to NUDT15 genotyping, the combined TPMT/NUDT15 genotyping strategy cost an additional $13.83, yielding an ICER of $3,929.54/QALY, which was under the willingness-to-pay level of $30,425 per QALY in China. Compared to strategies with singular TPMT genotyping or no genotyping, the combined TPMT/NUDT15 genotyping strategy gained 0.00406 and 0.00782 QALYs and reduced the cost by $25.15 and $99.06, respectively. Additionally, incorporating TDM of AZA was more effective and less expensive than strategies without TDM. One-way sensitivity analysis revealed the expense attached to severe myelotoxicity to be the factor with the greatest influence in the present research. The application of the combined genotype screening strategy with TDM of AZA treatment was found to have a 91.7% chance of being cost-effective. Conclusions For Chinese patients with IBD who receive an AZA regimen, a strategy involving combined NUDT15/TPMT genotype screening prior to treatment initiation and incorporating TDM for treatment management is cost-effective compared to strategies involving genotyping of NUDT15 or TPMT alone or genotyping without TDM.
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Affiliation(s)
- Dayong Zeng
- Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Xiaoting Huang
- Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Shen Lin
- Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Rongfang Lin
- Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Xiuhua Weng
- Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Pinfang Huang
- Department of Pharmacy, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China
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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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Devasia AJ, Illangeswaran RSS, Raj IX, George B, Balasubramanian P. NUDT15 polymorphism explains serious toxicity to azathioprine in Indian patients with chronic immune thrombocytopenia and autoimmune hemolytic anemia: a case series. Drug Metab Pers Ther 2020; 35:/j/dmdi.ahead-of-print/dmdi-2020-0128/dmdi-2020-0128.xml. [PMID: 32827393 DOI: 10.1515/dmpt-2020-0128] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 07/06/2020] [Indexed: 11/15/2022]
Abstract
OBJECTIVES Azathioprine (AZA) is a commonly used immunosuppressant in patients with autoimmune diseases. The toxic side effect to AZA (myelosuppression, hair loss, and oral ulcers) are highly unpredictable which can be life threatening if not identified earlier and dose adjustments made or the drug is withdrawn. CASE PRESENTATION Here we report a case series of five patients with severe toxicity while on treatment with AZA for autoimmune hemolytic anemia (n=1) and Immune thrombocytopenia (n=4). The common thiopurine methyltransferase (TPMT) variants (TPMT*2, *3A, *3B) were not present in these patients. However, all these patients had the NUDT15 415C>T variant that has been reported to explain serious toxicity to thioguanine in Asian patients. CONCLUSIONS Our report suggests pre-emptive genotype-based dosing of AZA could reduce adverse toxicity and hence better outcome.
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Affiliation(s)
- Anup J Devasia
- Department of Haematology, Christian Medical College, Vellore, India
| | | | | | - Biju George
- Department of Haematology, Christian Medical College, Vellore, India
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SLCO1B1 Polymorphisms are Associated With Drug Intolerance in Childhood Leukemia Maintenance Therapy. J Pediatr Hematol Oncol 2018; 40:e289-e294. [PMID: 29683944 DOI: 10.1097/mph.0000000000001153] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND Therapy discontinuations and toxicities occur because of significant interindividual variations in 6-mercaptopurine (6-MP) and methotrexate (MTX) response during maintenance therapy of childhood acute lymphoblastic leukemia (ALL). 6-MP/MTX intolerance in some of the patients cannot be explained by thiopurine S-methyl transferase (TPMT) gene variants. In this study, we aimed to investigate candidate pharmacogenetic determinants of 6-MP and MTX intolerance in Turkish ALL children. METHODS In total, 48 children with ALL who had completed or were receiving maintenance therapy according to Children's Oncology Group (COG) protocols were enrolled. Fifteen single-nucleotide polymorphisms in 8 candidate genes that were related to drug toxicity or had a role in the 6-MP/MTX metabolism (TPMT, ITPA, MTHFR, IMPDH2, PACSIN2, SLCO1B1, ABCC4, and PYGL) were genotyped by competitive allele-specific PCR (KASP). Drug doses during maintenance therapy were modified according to the protocol. RESULTS The median drug dose intensity was 50% (28% to 92%) for 6-MP and 58% (27% to 99%) for MTX in the first year of maintenance therapy, which were lower than that scheduled in all patients. Among the analyzed polymorphisms, variant alleles in SLCO1B1 rs4149056 and rs11045879 were found to be associated with lower 6-MP/MTX tolerance. CONCLUSIONS SLCO1B1 rs4149056 and rs11045879 polymorphisms may be important genetic markers to individualize 6-MP/MTX doses.
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Alsous M, Yousef AM, Abdel Jalil M, Zawiah M, Yacoub S, Momani D, Gharabli A, Omar S, Rihani R. Genetic Polymorphism of Thiopurine S-methyltransferase in Children with Acute Lymphoblastic Leukemia in Jordan. Asian Pac J Cancer Prev 2018; 19:199-205. [PMID: 29373914 PMCID: PMC5844618 DOI: 10.22034/apjcp.2018.19.1.199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Background and Aims: It has been demonstrated that homozygote and heterozygote mutant allele carriers for thiopurine S-methyltransferase (TPMT) are at high risk of developing myelosuppression after receiving standard doses of 6-mercaptopurine (6-MP). The aim of this study was to determine the frequency of TPMT deficient alleles in children with acute lymphoblastic leukemia (ALL) in Jordan and to compare it with other ethnic groups. Methods: We included 52 ALL childhood cases from King Hussein Cancer Research Center in Jordan. Genotyping of the rs1800460, rs1800462, and rs1142345 SNPs was performed by polymerase chain reaction (PCR) followed by sequencing. Comparisons were made with historical data for controls and for both volunteers and cases from other middle-eastern countries. Results: Mutant TPMT alleles were present in 3.8% (2/52) of patients. Allelic frequencies were 1.0% for both TPMT*B and TPMT*C. None of the patients were heterozygous or homozygous for TPMT*3A or TPMT *2. We did not find statistically significant differences in the distribution of mutant alleles between Jordan and other middle-eastern countries for both healthy volunteers or ALL patients. Conclusions: The overall frequency of TPMT mutant alleles was low and did not exhibit differences compared to other middle-eastern countries, including Jordanian studies assessing TPMT mutant alleles in healthy volunteers. The current results question the value of TPMT genotyping in the Jordanian population.
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Affiliation(s)
- Mervat Alsous
- Department of Clinical Pharmacy and Therapeutics, Faculty of Pharmacy, Applied Science Private University, Amman, Jordan.
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Jiménez-Morales S, Ramírez-Florencio M, Mejía-Aranguré JM, Núñez-Enríquez JC, Bekker-Mendez C, Torres-Escalante JL, Flores-Lujano J, Jiménez-Hernández E, Del Carmen Rodríguez-Zepeda M, Leal YA, González-Montalvo PM, Pantoja-Guillen F, Peñaloza-Gonzalez JG, Gutiérrez-Juárez EI, Núñez-Villegas NN, Pérez-Saldivar ML, Guerra-Castillo FX, Flores-Villegas LV, Ramos-Cervantes MT, Fragoso JM, García-Escalante MG, Del Carmen Pinto-Escalante D, Ramírez-Bello J, Hidalgo-Miranda A. Analysis of Thiopurine S-Methyltransferase Deficient Alleles in Acute Lymphoblastic Leukemia Patients in Mexican Patients. Arch Med Res 2017; 47:615-622. [PMID: 28476189 DOI: 10.1016/j.arcmed.2016.11.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 11/23/2016] [Indexed: 11/27/2022]
Abstract
BACKGROUND AND AIMS It has been demonstrated that heterozygote and homozygote thiopurine S-methyltransferase (TPMT) mutant allele carriers are at high risk to develop severe and potentially fatal hematopoietic toxicity after treatment with standard doses of 6-mercaptopurine (6-MP) and methotrexate (MX). Those drugs are the backbone of acute lymphoblastic leukemia (ALL) and several autoimmune disease treatments. We undertook this study to determine the frequency of the TPMT deficient alleles in children with ALL and non-ALL subjects from Mexico City and Yucatan, Mexico. METHODS We included 849 unrelated subjects, of which 368 ALL children and 342 non-ALL subjects were from Mexico City, and 60 ALL cases and 79 non-ALL individuals were from Yucatan. Genotyping of the rs1800462, rs1800460 and rs1142345 SNPs was performed by 5'exonuclease technique using TaqMan probes (Life Technologies Foster City, CA). RESULTS The mutant TPMT alleles were present in 4.8% (81/1698 chromosomes) and only 0.2% were homozygote TPMT*3A/TPMT*3A. We did not find statistically significant differences in the distribution of the mutant alleles between patients from Mexico City and Yucatan in either ALL cases or non-ALL. Nonetheless, the TPMT*3C frequency in ALL patients was higher than non-ALL subjects (p = 0.03). To note, the null homozygous TPMT*3A/TPMT*3A genotype was found in 2.5% of the non-ALL subjects. CONCLUSIONS TPMT mutant alleles did not exhibit differential distribution between both evaluated populations; however, TPMT*3C is overrepresented in ALL cases in comparison with non-ALL group. Assessing the TPMT mutant alleles could benefit the ALL children and those undergoing 6-MP and MX treatment.
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Affiliation(s)
- Silvia Jiménez-Morales
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Mexico City, México.
| | - Mireya Ramírez-Florencio
- Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, Mexico City, México
| | - Juan Manuel Mejía-Aranguré
- Unidad de Investigación Médica en Epidemiología Clínica, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, México; Coordinación de Investigación en Salud, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, México
| | - Juan Carlos Núñez-Enríquez
- Unidad de Investigación Médica en Epidemiología Clínica, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, México
| | - Carolina Bekker-Mendez
- Unidad de Investigación en Inmunología e Infectología Hospital de Infectologia, Centro Médico Nacional La Raza, Instituto Mexicano del Seguro Social, Mexico City, México
| | - José Luis Torres-Escalante
- Servicio de Pediatría de la UMAE, IMSS, Yucatán, Mexico; Facultad de Medicina, Universidad Autónoma de Yucatán, Yucatán, Mexico
| | - Janet Flores-Lujano
- Unidad de Investigación Médica en Epidemiología Clínica, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, México
| | - Elva Jiménez-Hernández
- Servicio de Hematología Pediátrica, Hospital General "Gaudencio González Garza", CMN "La Raza", IMSS, Ciudad de México, México
| | | | - Yelda A Leal
- Unidad de Investigación Médica Yucatán (UIMY), Registro de Cáncer Unidad Médica de Alta Especialidad UMAE-IMSS, Yucatán, México
| | - Pablo Miguel González-Montalvo
- Facultad de Medicina, Universidad Autónoma de Yucatán, Yucatán, Mexico; Servicio de Oncología Pediátrica del Hospital ÓHorán, SS, Yucatán, Mexico
| | - Francisco Pantoja-Guillen
- Facultad de Medicina, Universidad Autónoma de Yucatán, Yucatán, Mexico; Servicio de Oncología Pediátrica del Hospital ÓHorán, SS, Yucatán, Mexico
| | | | | | - Nora Nancy Núñez-Villegas
- Servicio de Hematología Pediátrica, Hospital General "Gaudencio González Garza", CMN "La Raza", IMSS, Ciudad de México, México
| | - Maria Luisa Pérez-Saldivar
- Unidad de Investigación Médica en Epidemiología Clínica, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, México
| | - Francisco Xavier Guerra-Castillo
- Unidad de Investigación en Inmunología e Infectología Hospital de Infectologia, Centro Médico Nacional La Raza, Instituto Mexicano del Seguro Social, Mexico City, México
| | - Luz Victoria Flores-Villegas
- Servicio de Hematología Pediátrica, CMN "20 de Noviembre", Instituto de Seguridad Social al Servicio de los Trabajadores del Estado (ISSSTE), Ciudad de México, México
| | - María Teresa Ramos-Cervantes
- Unidad de Investigación en Inmunología e Infectología Hospital de Infectologia, Centro Médico Nacional La Raza, Instituto Mexicano del Seguro Social, Mexico City, México
| | - José Manuel Fragoso
- Departamento de Biología Molecular, Instituto Nacional de Cardiología, Ignacio Chávez, Ciudad de México, Mexico
| | - María Guadalupe García-Escalante
- Laboratorio de Genética, Centro de Investigaciones Regionales Dr. Hideyo Noguchi, Universidad Autónoma de Yucatán, Yucatán, México
| | - Doris Del Carmen Pinto-Escalante
- Laboratorio de Genética, Centro de Investigaciones Regionales Dr. Hideyo Noguchi, Universidad Autónoma de Yucatán, Yucatán, México
| | - Julián Ramírez-Bello
- Laboratorio de la Unidad de Investigación en Enfermedades Metabólicas y Endócrinas del Hospital Juárez de México, Ciudad de México, Mexico
| | - Alfredo Hidalgo-Miranda
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Mexico City, México.
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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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Abdelaziz DH, Elhosseiny NM, Khaleel SA, Sabry NA, Attia AS, El-Sayed MH. Association Between Combined Presence of Hepatitis C Virus and Polymorphisms in Different Genes With Toxicities of Methotrexate and 6-Mercaptopurine in Children With Acute Lymphoblastic Leukemia. Pediatr Blood Cancer 2016; 63:1539-45. [PMID: 27163515 DOI: 10.1002/pbc.26045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 04/06/2016] [Indexed: 01/26/2023]
Abstract
BACKGROUND The aim of the present study is to determine the correlation of hepatitis C virus (HCV) infection and polymorphisms in different genes with toxicity of either methotrexate (MTX) or 6-mercaptopurine (6-MP) administered to children with acute lymphoblastic leukemia (ALL). PROCEDURE One hundred children with low-risk ALL, who were treated according to the St. Jude Total therapy XV, were recruited. The recruited children were receiving MTX and 6-MP during maintenance phase. Patients were excluded from the study if they had other types of leukemia. Genotyping analyses for the thiopurine methyltransferase (TPMT), methylenetetrahydrofolate reductase (MTHFR), and glutathione S-transferase (GST) genes were performed using a combination of polymerase chain reaction (PCR) and PCR-RFLP (where RFLP is restriction fragment length polymorphism) protocols. Relevant clinical data on adverse drug reactions were collected objectively (blinded to genotypes) from the patient medical records. RESULTS There was a significant correlation between the combined presence of HCV and TPMT*3B G460A gene polymorphisms and grades 2-4 hepatotoxicity as aspartate aminotransferase (AST) elevation (P < 0.04). The same observation was seen when comparing either the presence of HCV alone or the presence of the gene polymorphism alone. A significant association between the combined presence of HCV and MTHFR C677T polymorphism and grades 2-4 hepatotoxicity as alanine aminotransferase (ALT), AST, and alkaline phosphatase (ALP) elevation was observed (P values <0.001, 0.02, and 0.001, respectively). The presence of HCV infection had a significant negative effect on hepatic transaminases. CONCLUSIONS The present data support a role for combining analysis of genetic variation in drug-metabolizing enzymes and the presence of HCV in the assessment of specific drugs toxicities in multiagent chemotherapeutic treatment regimens.
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Affiliation(s)
- Doaa H Abdelaziz
- Department of Clinical Pharmacy, National Hepatology and Tropical Medicine Research Institute, Cairo, Egypt
| | - Noha M Elhosseiny
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Sahar A Khaleel
- Department of Pediatric Oncology, National Cancer Institute, Cairo University, Cairo, Egypt
| | - Nirmeen A Sabry
- Department of Clinical Pharmacy, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Ahmed S Attia
- Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Manal H El-Sayed
- Department of Pediatrics, Hematology-Oncology Division, Faculty of Medicine, Ain-Shams University, Cairo, Egypt
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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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Ayesh BM, Harb WM, Abed AA. Thiopurine methyltransferase genotyping in Palestinian childhood acute lymphoblastic leukemia patients. BMC HEMATOLOGY 2013; 13:3. [PMID: 24499706 PMCID: PMC3816621 DOI: 10.1186/2052-1839-13-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 01/30/2013] [Indexed: 11/10/2022]
Abstract
BACKGROUND The genetic polymorphism of thiopurine methyltransferase (TPMT) is well characterized in most populations. Four common polymorphic alleles are associated with impaired activity of the enzyme. These are TPMT*2 (238G>C), TPMT*3B (c.460G>A), TPMT*3A (c.460G>A and c.719A>G) and TPMT*3C (c.719A>G). The aim of the present study was to determine the frequency of TPMT polymorphisms and their association with the occurrence of adverse events, during 6-mercaptopurine therapy in pediatric acute lymphoblastic leukemic (ALL) patients in Gaza Strip. METHODS A total of 56 DNA samples from all pediatric ALL patients admitted to the pediatric hematology departments of Gaza strip hospitals were analyzed. Genomic DNA from peripheral blood leukocytes was isolated and the TPMT*2, TPMT*3B TPMT*3A and TPMT*3C allelic polymorphism was determined by PCR-RFLP and allele specific PCR technique. RESULTS No TPMT*2, *3B or *3C alleles were detected. Only one, out of 56 patients, was found heterozygous for the TPMT*3A allele. Thus, the frequency of TPMT*3A allele was calculated to be 0.89%. Fourteen patients of ALL were suffering from myelotoxicity during 6-MP therapy. From our results, no significant association could be established between clinical and laboratory data and/or the presence of the mutation in TPMT gene. CONCLUSION TPMT*3A was the only deficiency allele detected in our population with an allelic frequency of 0.89%. Other polymorphic alleles in TPMT gene, or factors other than TPMT polymorphisms may be responsible for the development of myelosuppression in cases that don't carry the investigated TPMT alleles (*2, *3A, *3B and *3C). Therefore, more studies are recommended to study such factors.
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Affiliation(s)
| | | | - Abdalla Assaf Abed
- Biology Department, Islamic University of Gaza, Gaza, Palestinian authority
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Ben Salah L, Belkhiria el Haj Amor M, Chbili C, Khlifi S, Fathallah N, Bougmiza I, Ben Jazia E, Houdret N, Ben Salem C, Saguem S. Analysis of thiopurine S-methyltransferase phenotype-genotype in a Tunisian population with Crohn's disease. Eur J Drug Metab Pharmacokinet 2013; 38:241-4. [PMID: 23553048 DOI: 10.1007/s13318-013-0127-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 03/20/2013] [Indexed: 10/27/2022]
Abstract
This study was conducted to investigate the thiopurine S-methyltransferase TPMT activity distribution and gene mutations in Tunisian population with positive diagnostic for Crohn's disease. TPMT activity was measured in Tunisian population (n = 88) by a high performance liquid chromatography assay. Polymerase chain reaction-based methods were used to determine the frequency of TPMT mutant alleles TPMT*2, TPMT*3A, TPMT*3B and TPMT*3C. TPMT activity was normally distributed, ranging from 4.58 to 35.27 nmol/(h ml) RBC with a mean of 18.67 ± 7.10 nmol/(h ml) RBC. Seven TPMT*3A heterozygotes and one TPMT*3C homozygote were found in 88 patients, with allele frequencies of 0.039 and 1.13, respectively. TPMT*3A and the TPMT*3C, which cause the largest decrease in enzyme activity, were both variant alleles detected in the Tunisian population.
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Affiliation(s)
- Lynda Ben Salah
- Metabolic Biophysics and Applied Toxicology Laboratory, Department of Biophysics, Faculty of Medicine of Sousse, Sousse University, Avenue Mohamed Karoui, 4002, Sousse, Tunisia,
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Elawi AM, Irshaid YM, Ismail SI, Mustafa KN. Thiopurine S-methytransferase gene polymorphism in rheumatoid arthritis. Arch Med Res 2013; 44:105-9. [PMID: 23398787 DOI: 10.1016/j.arcmed.2013.01.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 01/17/2013] [Indexed: 11/26/2022]
Abstract
BACKGROUND AND AIMS Thiopurine S-methyltransferase (TPMT) is responsible for inactivation of thiopurine drugs which are commonly used in leukemia, organ transplantation and autoimmune diseases. The gene encoding TPMT is polymorphic, and both phenotyping and genotyping studies have shown ethnic variations in gene sequence and enzyme activity worldwide. The aim of this study is to identify the most common genetic polymorphisms of TPMT in healthy Jordanian volunteers and patients with rheumatoid arthritis (RA). METHODS A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay was used to identify the frequency of TPMT (*2, *3A, *3B, and *3C) polymorphisms in 250 healthy Jordanian volunteers and 110 RA patients. RESULTS Only four healthy subjects (1.6%) and one RA patient (0.9%) with variant alleles were identified in this study. Two healthy subjects had the TPMT*3A allele and the other two had the TPMT*3B allele, whereas the one RA patient had the TPMT*3A allele. No homozygous polymorphisms were detected and all genotypes detected were heterozygous (*1/*3A) (*1/*3B). None of the subjects had TPMT*2 or TPMT*3C variant alleles. CONCLUSIONS Mutant alleles identified in this study have a low frequency. TPMT (*3A and *3B) were the only detected heterozygous alleles. No homozygous variant allele was detected. Further studies are necessary to identify other variant alleles that might uniquely occur in Jordanians.
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Affiliation(s)
- Asma M Elawi
- Department of Pharmacology, Faculty of Medicine, The University of Jordan, Amman, Jordan
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Outcome of modified St Jude total therapy 13A for childhood acute lymphoblastic leukemia in the southeast region of Turkey. J Pediatr Hematol Oncol 2013; 35:36-41. [PMID: 23138117 DOI: 10.1097/mph.0b013e318271f43f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To fill the gap in the current data on childhood acute lymphoblastic leukemia (ALL) in low-income and middle-income countries. METHODS This study included 106 children between the ages of 1 and 17 years with newly diagnosed ALL monitored between 1999 and 2010. All the patients were treated with the modified St Jude Total 13A treatment plan at the Pediatric Hematology Clinic at Harran University. RESULTS Sixty-eight (64.2%) patients were boys and 38 (35.8%) were girls. The median age at diagnosis was 5.9 ± 3.7 years. Thirty-eight (35.8%) children were classified as standard risk, 53 (39.3%) were intermediate risk, and 15 (14.2%) were high risk. Thirteen (12.3%) children died in induction before the remission date (43 d of remission induction). Of all the 93 (100%) patients who completed remission induction therapy and whose bone marrow were in remission, 5 (4.7%) had a bone marrow relapse, 1 (0.9%) had a retinal relapse, and 5 (4.7%) had secondary acute myeloid leukemia. At a median follow-up of 44 months (range, 0.36 to 135.5 mo), the estimated 5-year overall survival and event-free survival were 77.4 ± 5% and 68.9 ± 6.5%, respectively. The estimated 5-year overall survival for boys and girls was 76.5 ± 6% and 65.8 ± 8%, respectively (P = 0.182). CONCLUSIONS St Jude Total 13A treatment protocols to treat childhood ALL can be successfully adapted, which suggests that such an approach may be useful in low socioeconomic regions; however, it should be noted that secondary leukemia can occur at a high rate.
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Román M, Cabaleiro T, Ochoa D, Novalbos J, Chaparro M, Gisbert JP, Abad-Santos F. Validation of a genotyping method for analysis of TPMT polymorphisms. Clin Ther 2012; 34:878-84. [PMID: 22421577 DOI: 10.1016/j.clinthera.2012.02.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/14/2012] [Indexed: 01/26/2023]
Abstract
BACKGROUND Thiopurine methyltransferase (TPMT) catalyzes the methylation of thiopurine drugs such as azathioprine and 6-mercaptopurine. Several mutations in the TPMT gene correlate with low enzyme activity and adverse effects such as myelotoxicity. Hence, genotyping TPMT makes it possible to identify patients at high risk for drug toxicity. OBJECTIVE The aim of this study was to validate a TPMT genotyping method by comparing it with a conventional polymerase chain reaction (PCR) approach. METHODS LightSNiP is a real-time PCR method for the detection of TPMT*2, *3B, and *3C without a sequencing step. We evaluated the frequencies of 3 TPMT alleles in 111 white adult patients by comparing genotyping by LightSNiP with conventional PCR (sequencing). RESULTS No differences were observed between conventional genotyping with sequencing and LightSNiP for *2, *3B, and *3C, suggesting the validity of this method. CONCLUSIONS Compared with the conventional PCR sequencing method, the data suggest that LightSNiP correctly detected the TPMT *2, *3B, and *3C in this select population.
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Affiliation(s)
- Manuel Román
- Clinical Pharmacology Service, Hospital Universitario de la Princesa, Instituto Teófilo Hernando, UAM, Instituto de Investigación Sanitaria Princesa (IP), Madrid, Spain
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Abstract
Genetic variation influences the absorption and efflux of drugs in the intestine, the metabolism of drugs in the liver and the effects of these drugs on their target proteins. Indeed, variations in genes whose products have a role in the pathophysiology of nonmalignant gastrointestinal diseases, such as IBD, have been shown to affect the response of patients to therapy. This Review provides an overview of pharmacogenetics in the management of nonmalignant gastrointestinal diseases on the basis of data from clinical trials. Genetic variants that have the greatest effect on the management of patients with IBD involve the metabolism of thiopurines. Variation in drug metabolism by cytochrome P450 enzymes also requires attention so as to avoid drug interactions in patients receiving tricyclic antidepressants and PPIs. Few genotyping tests are currently used in the clinical management of patients with nonmalignant gastrointestinal diseases, owing to a lack of data from clinical trials showing their effectiveness in predicting nonresponse or adverse outcomes. However, pharmacogenetics could have a beneficial role in enabling pharmacotherapy for nonmalignant gastrointestinal diseases to be targeted to the individual patient.
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Affiliation(s)
- Michael Camilleri
- College of Medicine, Mayo Clinic, Charlton, 8–110, 200 First Street, South West, Rochester, MN 55905, USA
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Ben Salah L, Ben Salem C, B’Chir F, Bouraoui K, Broly F, Saguem S. Thiopurine S-methyltransferase genetic polymorphism in the Tunisian population. EGYPTIAN JOURNAL OF MEDICAL HUMAN GENETICS 2011. [DOI: 10.1016/j.ejmhg.2011.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Association between polymorphisms of EPHX1 and XRCC1 genes and the risk of childhood acute lymphoblastic leukemia. Arch Toxicol 2011; 86:431-9. [DOI: 10.1007/s00204-011-0760-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 09/20/2011] [Indexed: 12/20/2022]
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Moini M, Ghaderi F, Sagheb MM, Tavasolli AR, Azarpira N, Darai M, Geramizadeh B. The frequency and distribution of thiopurine S-methyltransferase alleles in south Iranian population. Mol Biol Rep 2011; 39:4581-7. [PMID: 21938428 DOI: 10.1007/s11033-011-1248-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Accepted: 09/14/2011] [Indexed: 01/29/2023]
Abstract
Thiopurine methyltransferase (TPMT) catalyzes the S-methylation of thiopurine drugs such as 6-mercaptopurine, 6-thioguanine, and azathiopurine. Variability in TPMT activity is mainly due to genetic polymorphism. The frequency of the four allelic variants of the TPMT gene, TPMT*2 (G238C), TPMT*3A (G460A and A719G), TPMT*3B (G460A) and TPMT*3C (A719G) were determined in an Iranian population from south of Iran (n = 500), using polymerase chain reaction (PCR)-RFLP and allele-specific PCR-based assays. Four hundred seventy four persons (94.8%) were homozygous for the wild type allele (TPMT*1/*1) and twenty five people were TPMT*1/*3C (5%). One patient was found to be heterozygous in terms TPMT*1 and *2 alleles with genotype of TPMT*1/*2 (0.2%). None of the participants had both defective alleles. The TPMT*3C and *2 were the only variant alleles observed in this population. The total frequency of variant alleles was 2.6% and the wild type allele frequency was 97.4%. The TPMT*3B and *3A alleles were not detected. Distributions of TPMT genotype and allele frequency in Iranian populations are different from the genetic profile found among Caucasian or Asian populations. Our findings also revealed inter-ethnic differences in TPMT frequencies between different parts of Iran. This view may help clinicians to choose an appropriate strategy for thiopurine drugs and reduce adverse drug reactions such as bone marrow suppression.
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Affiliation(s)
- Maryam Moini
- Department of Internal Medicine, Gastroenterology and Hepatology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
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Thiopurine methyltransferase polymorphisms and mercaptopurine tolerance in Turkish children with acute lymphoblastic leukemia. Cancer Chemother Pharmacol 2011; 68:1155-9. [DOI: 10.1007/s00280-011-1599-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Accepted: 02/28/2011] [Indexed: 12/22/2022]
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Tumer TB, Yilmaz D, Tanrikut C, Sahin G, Ulusoy G, Arinç E. DNA repair XRCC1 Arg399Gln polymorphism alone, and in combination with CYP2E1 polymorphisms significantly contribute to the risk of development of childhood acute lymphoblastic leukemia. Leuk Res 2010; 34:1275-81. [DOI: 10.1016/j.leukres.2010.02.035] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 02/19/2010] [Accepted: 02/27/2010] [Indexed: 12/08/2022]
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The role of polymorphic cytochrome P450 enzymes in drug design, development and drug interactions with a special emphasis on phenotyping. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/j.molcatb.2009.03.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
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Hakooz N, Arafat T, Payne D, Ollier W, Pushpakom S, Andrews J, Newman W. Genetic analysis of thiopurine methyltransferase polymorphism in the Jordanian population. Eur J Clin Pharmacol 2010; 66:999-1003. [PMID: 20521035 DOI: 10.1007/s00228-010-0826-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Accepted: 03/31/2010] [Indexed: 01/26/2023]
Abstract
UNLABELLED This study provides the first analysis of the TPMT mutant allele frequency in a sample of the Jordanian population and indicates that TPMT*3A is the most common allele in Jordanian subjects. PURPOSE thiopurine methyltransferase TPMT catalyses the S-methylation of thiopurine drugs such as 6-mercaptopurine, 6-thioguanine, and azathiopurine. Thiopurine methyltransferase (TPMT) polymorphisms are the major determinants of interindividual differences in the severe haematological toxicity of 6-mercaptopurine. Several variants in the TPMT gene have been identified that correlate with a low activity phenotype. Four variant alleles, TPMT*2, TPMT*3A, TPMT*3B and TPMT*3C, are responsible for over 80% of the low or undetectable enzyme activity. The allelic frequency of TPMT variants has been established in many populations. METHODS In this study, the frequencies of four (TPMT*2, TPMT*3A, TPMT*3B and TPMT*3C) variants were investigated in 169 healthy Jordanian men (18-45 years of age). Single nucleotide polymorphisms (SNPs) were genotyped using the Sequenom MassARRAY technology (Sequenom; San Diego, CA, USA). RESULTS TPMT*3A and TPMT*3C were the only deficiency alleles detected in the Jordanian population with an allele frequency of 0.59% and 0.30% respectively. The TPMT*3A allele frequency is found to be lower than in the European Caucasian population. CONCLUSION TPMT*3A and TPMT*3C were the only deficiency alleles detected in the Jordanian population with an allele frequency of 0.59% and 0.30% respectively. The TPMT*3A allele frequency is found to be lower than in the European Caucasian population.
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Affiliation(s)
- Nancy Hakooz
- Faculty of Pharmacy, University of Jordan, Amman 11942, Jordan,
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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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