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Smith LS, Wang X, Shi J, He B, Zhu HJ. Genome-Wide Association Study for the Genetic Determinants of Thiopurine Methyltransferase Protein Expression in Human Livers and Racial Differences. Pharm Res 2023; 40:2525-2531. [PMID: 37430149 DOI: 10.1007/s11095-023-03558-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 06/26/2023] [Indexed: 07/12/2023]
Abstract
INTRODUCTION Polymorphisms in the Thiopurine S-Methyltransferase (TPMT) gene are associated with decreased TPMT activity, but little is known about their impact on TPMT protein expression in the liver. This project is to conduct a genome-wide association study (GWAS) to identify single nucleotide polymorphisms (SNPs) associated with altered TPMT protein expression in human livers and to determine if demographics affect hepatic TPMT protein expression. METHODS Human liver samples (n = 287) were genotyped using a whole genome genotyping panel and quantified for TPMT protein expression using a Data-Independent Acquisition proteomics approach. RESULTS AND DISCUSSION Thirty-one SNPs were found to be associated with differential expression of TPMT protein in the human livers. Subsequent analysis, conditioning on rs1142345, a SNP associated with the TPMT*3A and TPMT*3C alleles, showed no additional independent signals. Mean TPMT expression is significantly higher in wildtype donors compared to those carrying the known TPMT alleles, including TPMT*3A, TPMT*3C, and TPMT*24 (0.107 ± 0.028 vs. 0.052 ± 0.014 pmol/mg total protein, P = 2.2 × 10-16). After removing samples carrying the known TPMT variants, European ancestry donors exhibited significantly higher expression than African ancestry donors (0.109 ± 0.026 vs. 0.090 ± 0.041 pmol/mg total protein, P = 0.020). CONCLUSION The GWAS identified 31 SNPs associated with TPMT protein expression in human livers. Hepatic TPMT protein expression was significantly lower in subjects carrying the TPMT*3A, TPMT*3C, and TPMT*24 alleles compared to non-carriers. European ancestry was associated with significantly higher hepatic TPMT protein expression than African ancestry, independent of known TPMT variants.
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Affiliation(s)
- Logan S Smith
- Department of Clinical Pharmacy, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Xinwen Wang
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, OH, 44272, USA
| | - Jian Shi
- Bristol Myers Squibb, 3401 Princeton Pike, Lawrence Township, NJ, 08648, USA
| | - Bing He
- Department of Computational Medicine and Bioinformatics, Medical School, University of Michigan, Ann Arbor, MI, USA
| | - Hao-Jie Zhu
- Department of Clinical Pharmacy, University of Michigan, Ann Arbor, MI, 48109, USA.
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2
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Pharmacogenetics of Drugs Used in the Treatment of Cancers. Genes (Basel) 2022; 13:genes13020311. [PMID: 35205356 PMCID: PMC8871547 DOI: 10.3390/genes13020311] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [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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Mitchell KN, Tay YK, Heath CR, Silverberg NB. Review article: Emerging issues in pediatric skin of color, Part 2. Pediatr Dermatol 2021; 38 Suppl 2:30-36. [PMID: 34708446 DOI: 10.1111/pde.14774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Dermatology for pediatric skin of color is the application of dermatology to the genetically diverse and distinctive segment of the pediatric population that includes children of non-White racial and ethnic groups with increased pigmentation including individuals of Asian, Hispanic/LatinX, African, Native American, Pacific Island descent, indigenous people among others with overlap in particular individuals, and mixtures thereof. The discipline of pediatric skin of color can be challenging with difficulty in diagnosis of common conditions due to underlying pigmentation, variations in common hair styling practices, and differences in demographics of cutaneous disease. Whereas some conditions are more common in children of color, other conditions have nuances in clinical appearance and therapeutics with regard to skin color. This article, the second of the series, focuses on inflammatory skin disease nuances, melanocytic disorders, and hypopigmented mycosis fungoides.
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Affiliation(s)
- Krystal N Mitchell
- Department of Dermatology, Icahn School of Medicine at Mt Sinai, New York, NY, USA
| | - Yong Kwang Tay
- Department of Dermatology, Changi General Hospital, Singapore, Singapore
| | - Candrice R Heath
- Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Nanette B Silverberg
- Department of Dermatology, Icahn School of Medicine at Mt Sinai, New York, NY, USA.,Department of Pediatrics, Icahn School of Medicine at Mt Sinai, New York, NY, USA
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Insights into S-adenosyl-l-methionine (SAM)-dependent methyltransferase related diseases and genetic polymorphisms. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2021; 788:108396. [PMID: 34893161 DOI: 10.1016/j.mrrev.2021.108396] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 10/03/2021] [Accepted: 10/05/2021] [Indexed: 12/11/2022]
Abstract
Enzymatic methylation catalyzed by methyltransferases has a significant impact on many human biochemical reactions. As the second most ubiquitous cofactor in humans, S-adenosyl-l-methionine (SAM or AdoMet) serves as a methyl donor for SAM-dependent methyltransferases (MTases), which transfer a methyl group to a nucleophilic acceptor such as O, As, N, S, or C as the byproduct. SAM-dependent methyltransferases can be grouped into different types based on the substrates. Here we systematically reviewed eight types of methyltransferases associated with human diseases. Catechol O-methyltransferase (COMT), As(III) S-adenosylmethionine methyltransferase (AS3MT), indolethylamine N-methyltransferase (INMT), phenylethanolamine N-methyltransferase (PNMT), histamine N-methyltransferase (HNMT), nicotinamide N-methyltransferase (NNMT), thiopurine S-methyltransferase (TPMT) and DNA methyltansferase (DNMT) are classic SAM-dependent MTases. Correlations between genotypes and disease susceptibility can be partially explained by genetic polymorphisms. The physiological function, substrate specificity, genetic variants and disease susceptibility associated with these eight SAM-dependent methyltransferases are discussed in this review.
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Brown P, Inaba H, Annesley C, Beck J, Colace S, Dallas M, DeSantes K, Kelly K, Kitko C, Lacayo N, Larrier N, Maese L, Mahadeo K, Nanda R, Nardi V, Rodriguez V, Rossoff J, Schuettpelz L, Silverman L, Sun J, Sun W, Teachey D, Wong V, Yanik G, Johnson-Chilla A, Ogba N. Pediatric Acute Lymphoblastic Leukemia, Version 2.2020, NCCN Clinical Practice Guidelines in Oncology. J Natl Compr Canc Netw 2021; 18:81-112. [PMID: 31910389 DOI: 10.6004/jnccn.2020.0001] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Advancements in technology that enhance our understanding of the biology of the disease, risk-adapted therapy, and enhanced supportive care have contributed to improved survival rates. However, additional clinical management is needed to improve outcomes for patients classified as high risk at presentation (eg, T-ALL, infant ALL) and who experience relapse. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for pediatric ALL provide recommendations on the workup, diagnostic evaluation, and treatment of the disease, including guidance on supportive care, hematopoietic stem cell transplantation, and pharmacogenomics. This portion of the NCCN Guidelines focuses on the frontline and relapsed/refractory management of pediatric ALL.
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Affiliation(s)
- Patrick Brown
- The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins
| | - Hiroto Inaba
- St. Jude Children's Research Hospital/The University of Tennessee Health Science Center
| | - Colleen Annesley
- Fred Hutchinson Cancer Research Center/Seattle Cancer Care Alliance
| | | | - Susan Colace
- The Ohio State University Comprehensive Cancer Center - James Cancer Hospital and Solove Research Institute
| | - Mari Dallas
- Case Comprehensive Cancer Center/University Hospitals Seidman Cancer Center and Cleveland Clinic Taussig Cancer Institute
| | | | - Kara Kelly
- Roswell Park Comprehensive Cancer Center
| | | | | | | | - Luke Maese
- Huntsman Cancer Institute at the University of Utah
| | - Kris Mahadeo
- The University of Texas MD Anderson Cancer Center
| | | | | | | | - Jenna Rossoff
- Ann & Robert H. Lurie Children's Hospital of Chicago
| | - Laura Schuettpelz
- Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine
| | | | | | - Weili Sun
- City of Hope National Medical Center
| | - David Teachey
- Abramson Cancer Center at the University of Pennsylvania
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Nakase H, Uchino M, Shinzaki S, Matsuura M, Matsuoka K, Kobayashi T, Saruta M, Hirai F, Hata K, Hiraoka S, Esaki M, Sugimoto K, Fuji T, Watanabe K, Nakamura S, Inoue N, Itoh T, Naganuma M, Hisamatsu T, Watanabe M, Miwa H, Enomoto N, Shimosegawa T, Koike K. Evidence-based clinical practice guidelines for inflammatory bowel disease 2020. J Gastroenterol 2021; 56:489-526. [PMID: 33885977 PMCID: PMC8137635 DOI: 10.1007/s00535-021-01784-1] [Citation(s) in RCA: 189] [Impact Index Per Article: 63.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 03/25/2021] [Indexed: 02/07/2023]
Abstract
Inflammatory bowel disease (IBD) is a general term for chronic or remitting/relapsing inflammatory diseases of the intestinal tract and generally refers to ulcerative colitis (UC) and Crohn's disease (CD). Since 1950, the number of patients with IBD in Japan has been increasing. The etiology of IBD remains unclear; however, recent research data indicate that the pathophysiology of IBD involves abnormalities in disease susceptibility genes, environmental factors and intestinal bacteria. The elucidation of the mechanism of IBD has facilitated therapeutic development. UC and CD display heterogeneity in inflammatory and symptomatic burden between patients and within individuals over time. Optimal management depends on the understanding and tailoring of evidence-based interventions by physicians. In 2020, seventeen IBD experts of the Japanese Society of Gastroenterology revised the previous guidelines for IBD management published in 2016. This English version was produced and modified based on the existing updated guidelines in Japanese. The Clinical Questions (CQs) of the previous guidelines were completely revised and categorized as follows: Background Questions (BQs), CQs, and Future Research Questions (FRQs). The guideline was composed of a total of 69 questions: 39 BQs, 15 CQs, and 15 FRQs. The overall quality of the evidence for each CQ was determined by assessing it with reference to the Grading of Recommendations Assessment, Development and Evaluation approach, and the strength of the recommendation was determined by the Delphi consensus process. Comprehensive up-to-date guidance for on-site physicians is provided regarding indications for proceeding with the diagnosis and treatment.
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Affiliation(s)
- Hiroshi Nakase
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan ,grid.263171.00000 0001 0691 0855Department of Gastroenterology and Hepatology, Sapporo Medical University School of Medicine, S-1, W-16, Chuoku, Sapporo, Hokkaido 060-8543 Japan
| | - Motoi Uchino
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Shinichiro Shinzaki
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Minoru Matsuura
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Katsuyoshi Matsuoka
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Taku Kobayashi
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Masayuki Saruta
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Fumihito Hirai
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Keisuke Hata
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Sakiko Hiraoka
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Motohiro Esaki
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Ken Sugimoto
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Toshimitsu Fuji
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Kenji Watanabe
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Shiro Nakamura
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Nagamu Inoue
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Toshiyuki Itoh
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Makoto Naganuma
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Tadakazu Hisamatsu
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Mamoru Watanabe
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Hiroto Miwa
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Nobuyuki Enomoto
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Tooru Shimosegawa
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
| | - Kazuhiko Koike
- Guidelines Committee for Creating and Evaluating the “Evidence-Based Clinical Practice Guidelines for Inflammatory Bowel Disease”, The Japanese Society of Gastroenterology, 6F Shimbashi i-MARK Building, 2-6-2 Shimbashi, Minato-ku, Tokyo, 105-0004 Japan
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Nakase H, Matsumoto T, Watanabe K, Hisamatsu T. The shining DIAMOND for evidence-based treatment strategies for Crohn's disease. J Gastroenterol 2020; 55:824-832. [PMID: 32661927 DOI: 10.1007/s00535-020-01702-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 06/18/2020] [Indexed: 02/04/2023]
Abstract
Anti-tumor necrosis factor (TNF)-α antibodies are effective therapeutic agents to treat inflammatory bowel disease (IBD). In the biologic era, the development of immunogenicity has been a critical issue for secondary loss of response. The superiority of anti-TNF therapy in combination with immunomodulators (IMs) is well-established for infliximab (IFX) but less evident for adalimumab (ADA). To clarify the contribution of thiopurines to ADA-treated patients with Crohn's disease (CD), the deep remission of immunomodulator and adalimumab combination therapy for Crohn's disease (DIAMOND) studies provided the first randomized comparison of efficacy between ADA monotherapy and ADA with thiopurine. The results of the DIAMOND and DIAMOND2 studies revealed the appropriate ADA therapeutic strategy for immunosuppressant-naïve patients with active CD based on therapeutic drug monitoring, endoscopic findings and clinical issues regarding the use of thiopurines.
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Affiliation(s)
- Hiroshi Nakase
- Department of Gastroenterology and Hepatology, Sapporo Medical University School of Medicine, S-1, W-16, Chuoku, Sapporo, Hokkaido, 060-8543, Japan.
| | - Takayuki Matsumoto
- Division of Gastroenterology, Department of Medicine, Iwate Medical University, Morioka, Iwate, Japan
| | - Kenji Watanabe
- Division of Internal Medicine, Center for Inflammatory Bowel Disease, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan
| | - Tadakazu Hisamatsu
- Department of Gastroenterology and Hepatology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
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Daniel LL, Dickson AL, Chung CP. Precision medicine for rheumatologists: lessons from the pharmacogenomics of azathioprine. Clin Rheumatol 2020; 40:65-73. [PMID: 32617765 DOI: 10.1007/s10067-020-05258-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/16/2020] [Accepted: 06/22/2020] [Indexed: 12/13/2022]
Abstract
Precision medicine aims to personalize treatment for both effectiveness and safety. As a critical component of this emerging initiative, pharmacogenomics seeks to guide drug treatment based on genetics. In this review article, we give an overview of pharmacogenomics in the setting of an immunosuppressant frequently prescribed by rheumatologists, azathioprine. Azathioprine has a narrow therapeutic index and a high risk of adverse events. By applying candidate gene analysis and unbiased approaches, researchers have identified multiple variants associated with an increased risk for adverse events associated with azathioprine, particularly bone marrow suppression. Variants in two genes, TPMT and NUDT15, are widely recognized, leading drug regulatory agencies and professional organizations to adopt recommendations for testing before initiation of azathioprine therapy. As more gene-drug interactions are discovered, our field will continue to face the challenge of balancing benefits and costs associated with genetic testing. However, novel approaches in genomics and the integration of clinical and genetic factors into risk scores offer unprecedented opportunities for the application of pharmacogenomics in routine practice. Key Points • Pharmacogenomics can help us understand how individuals' genetics may impact their response to medications. • Azathioprine is a success story for the clinical implementation of pharmacogenomics, particularly the effects of TPMT and NUDT15 variants on myelosuppression. • As our knowledge advances, testing and dosing recommendations will continue to evolve, with our field striving to balance costs and benefits to patients. • As we aim toward the goals of precision medicine, future research may integrate increasingly individualized traits-including clinical and genetic characteristics-to predict the safety and efficacy of particular medications for individual patients.
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Affiliation(s)
- Laura L Daniel
- Department of Medicine, Division of Rheumatology, Vanderbilt University Medical Center (LLD, ALD, CPC), Nashville, TN, 37232, USA
| | - Alyson L Dickson
- Department of Medicine, Division of Rheumatology, Vanderbilt University Medical Center (LLD, ALD, CPC), Nashville, TN, 37232, USA
| | - Cecilia P Chung
- Department of Medicine, Division of Rheumatology, Vanderbilt University Medical Center (LLD, ALD, CPC), Nashville, TN, 37232, USA. .,Tennessee Valley Healthcare System-Nashville Campus (CPC), Nashville, TN, USA. .,Vanderbilt Genetics Institute, Vanderbilt University School of Medicine (CPC), Nashville, TN, USA.
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Czaja AJ. Review article: opportunities to improve and expand thiopurine therapy for autoimmune hepatitis. Aliment Pharmacol Ther 2020; 51:1286-1304. [PMID: 32363674 DOI: 10.1111/apt.15743] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 03/07/2020] [Accepted: 03/31/2020] [Indexed: 12/14/2022]
Abstract
BACKGROUND Thiopurines in combination with glucocorticoids are used as first-line, second-line and maintenance therapies in autoimmune hepatitis and opportunities exist to improve and expand their use. AIMS To describe the metabolic pathways and key factors implicated in the efficacy and toxicity of the thiopurine drugs and to indicate the opportunities to improve outcomes by monitoring and manipulating metabolic pathways, individualising dosage and strengthening the response. METHODS English abstracts were identified in PubMed by multiple search terms. Full-length articles were selected for review, and secondary and tertiary bibliographies were developed. RESULTS Thiopurine methyltransferase activity and 6-tioguanine (6-thioguanine) nucleotide levels influence drug efficacy and safety, and they can be manipulated to improve treatment response and prevent myelosuppression. Methylated thiopurine metabolites are associated with hepatotoxicity, drug intolerance and nonresponse and their production can be reduced or bypassed. Universal pre-treatment assessment of thiopurine methyltransferase activity and individualisation of dosage to manipulate metabolite thresholds could improve outcomes. Early detection of thiopurine resistance by metabolite testing, accurate estimations of drug onset and strength by surrogate markers and adjunctive use of allopurinol could improve the management of refractory disease. Dose-restricted tioguanine (thioguanine) could expand treatment options by reducing methylated metabolites, increasing the bioavailability of 6-tioguanine nucleotides and ameliorating thiopurine intolerance or resistance. CONCLUSIONS The efficacy and safety of thiopurines in autoimmune hepatitis can be improved by investigational efforts that establish monitoring strategies that allow individualisation of dosage and prediction of outcome, increase bioavailability of the active metabolites and demonstrate superiority to alternative agents.
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Affiliation(s)
- Albert J Czaja
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
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Tatsumi G, Kawahara M, Imai T, Nishishita-Asai A, Nishida A, Inatomi O, Yokoyama A, Kakuta Y, Kito K, Andoh A. Thiopurine-mediated impairment of hematopoietic stem and leukemia cells in Nudt15 R138C knock-in mice. Leukemia 2019; 34:882-894. [PMID: 31645647 DOI: 10.1038/s41375-019-0583-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 07/09/2019] [Accepted: 08/05/2019] [Indexed: 01/05/2023]
Abstract
Thiopurines are widely used as antileukemia agents and immunosuppressants. Recent large-scale clinical studies revealed a strong association between the NUDT15 p.Arg139Cys (NUDT15R139C) polymorphism and severe thiopurine-induced leukocytopenia. We established knock-in mice harboring p.Arg138Cys (Nudt15R138C), which corresponds to the human polymorphism. A clinically relevant dose of mercaptopurine (MP) induced lethal cytopenia in Nudt15R138C-harboring mice. MP dose reduction attenuated the hematopoietic toxicity, phenocopying clinical observations and providing Nudt15 genotype-based tolerable doses of MP. High-dose MP induced acute damage to hematopoietic stem and progenitor cells (HSPCs) in Nudt15R138C/R138C mice. A competitive transplantation assay revealed that not only Nudt15R138C/R138C HSPCs, but also Nudt15+/R138C HSPCs suffered stronger damage than Nudt15+/+ HSPCs, even by lower-dose MP, after long-term administration. In a Nudt15 genotype-based posttransplantation leukemia recurrence model generated by bone marrow replacement with congenic wild-type cells and a small number of leukemia stem cells, MP prolonged the survival of mice with posttransplantation Nudt15R138C/R138C leukemia recurrence. In conclusion, our model will facilitate NUDT15 genotype-based precision medicine by providing safer estimates for MP dosing, and our findings highlighted the high susceptibility of hematopoietic stem cells to MP and suggested that exploiting thiopurine toxicity might be a novel treatment approach for leukemia in NUDT15R139C-harboring patients.
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Affiliation(s)
- Goichi Tatsumi
- Division of Gastroenterology and Hematology, Department of Medicine, Shiga University of Medical Science, Shiga, Japan.,Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Masahiro Kawahara
- Division of Gastroenterology and Hematology, Department of Medicine, Shiga University of Medical Science, Shiga, Japan.
| | - Takayuki Imai
- Division of Gastroenterology and Hematology, Department of Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Ai Nishishita-Asai
- Division of Gastroenterology and Hematology, Department of Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Atsushi Nishida
- Division of Gastroenterology and Hematology, Department of Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Osamu Inatomi
- Division of Gastroenterology and Hematology, Department of Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Akihiko Yokoyama
- Tsuruoka Metabolomics Laboratory, National Cancer Center, Yamagata, Japan
| | - Yoichi Kakuta
- Division of Gastroenterology, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Katsuyuki Kito
- Division of Gastroenterology and Hematology, Department of Medicine, Shiga University of Medical Science, Shiga, Japan
| | - Akira Andoh
- Division of Gastroenterology and Hematology, Department of Medicine, Shiga University of Medical Science, Shiga, Japan
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Johnson D, Hughes D, Pirmohamed M, Jorgensen A. Evidence to Support Inclusion of Pharmacogenetic Biomarkers in Randomised Controlled Trials. J Pers Med 2019; 9:jpm9030042. [PMID: 31480618 PMCID: PMC6789450 DOI: 10.3390/jpm9030042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 08/15/2019] [Accepted: 08/19/2019] [Indexed: 01/01/2023] Open
Abstract
Pharmacogenetics and biomarkers are becoming normalised as important technologies to improve drug efficacy rates, reduce the incidence of adverse drug reactions, and make informed choices for targeted therapies. However, their wider clinical implementation has been limited by a lack of robust evidence. Suitable evidence is required before a biomarker’s clinical use, and also before its use in a clinical trial. We have undertaken a review of five pharmacogenetic biomarker-guided randomised controlled trials (RCTs) and evaluated the evidence used by these trials to justify biomarker inclusion. We assessed and quantified the evidence cited in published rationale papers, or where these were not available, obtained protocols from trial authors. Very different levels of evidence were provided by the trials. We used these observations to write recommendations for future justifications of biomarker use in RCTs and encourage regulatory authorities to write clear guidelines.
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Affiliation(s)
- Danielle Johnson
- Institute of Translational Medicine, Department of Biostatistics, University of Liverpool, Waterhouse Building, 1-5 Brownlow Street, Liverpool L69 3GL, UK.
| | - Dyfrig Hughes
- Centre for Health Economics and Medicines Evaluation, Bangor University, Ardudwy, Normal Site, Bangor LL57 2PZ, UK
| | - Munir Pirmohamed
- MRC Centre for Drug Safety Science and Wolfson Centre for Personalised Medicine, Institute of Translational Medicine, Waterhouse Building, 1-5 Brownlow Street, Liverpool L69 3GL, UK
| | - Andrea Jorgensen
- Institute of Translational Medicine, Department of Biostatistics, University of Liverpool, Waterhouse Building, 1-5 Brownlow Street, Liverpool L69 3GL, UK
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12
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Influence of thiopurine methyltransferase gene polymorphism on Egyptian children with acute lymphoblastic leukaemia. J Genet 2018; 96:905-910. [PMID: 29321348 DOI: 10.1007/s12041-017-0853-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Thiopurine methyltransferase (TPMT) gene polymorphism regulates thiopurine therapeutic efficacy and toxicity. The aim of this study was to determine the influence of TPMT gene polymorphism in Egyptian children with acute lymphoblastic leukaemia (ALL). Sixty-four patients with ALL, T lineage (27%) and pre-B phenotype (73%), who were treated with BFM 90 or CCG 1991 standard risk protocol, and who also experiencedmyleosuppresion toxicity and required interruption and/ormodification of thiopurine chemotherapy were recruited over a year period. Thirty-two patients were on maintenance and another 32 completed their chemotherapy. Seventy healthy age-matched and sex-matched children served as controls. They were subjected to clinical assessment, haematological panel investigations and TPMT gene polymorphism for G238C, G460A and A719G alleles assessment using PCRfollowed byRFLP analysis.Although none of the studied patients had themutantTPMTvariant alleles,myelosuppression toxicity in the form of different degree of neutropenia was detected in all patients. As a result of myelosuppression toxicity, most of the patients needed 6-MP dose modification either once (53.1%), twice (15.6%), or ≥ thrice (25.1%) during their maintenance course and 96.9% of the patients required to stop 6-MP for less than a week (62.5%), up to 2 weeks (28.1%), or > 2 weeks (6.3%). Patients also developed infection who mostly (71%) needed hospitalization. None of the studied G238C, G460A and A719G TPMT variant alleles were detected. Infections and febrile neutropenia were common causes of 6-PM dose modification and interruption.
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Wall GC, Muktar H, Effken C, Mahajan PB. Addition of Allopurinol for Altering Thiopurine Metabolism to Optimize Therapy in Patients with Inflammatory Bowel Disease. Pharmacotherapy 2018; 38:259-270. [PMID: 29197117 DOI: 10.1002/phar.2067] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Thiopurine drugs, including azathioprine and 6-mercaptopurine, are used commonly in patients with inflammatory bowel disease for maintenance of remission. Although generally well tolerated, adverse effects lead to discontinuation in a significant minority of patients. Pharmacogenomic studies have suggested that metabolic breakdown of azathioprine in an individual is genetically determined. Coupled with the fact that certain thiopurine metabolites, notably 6-thioguanine nucleotide and 6-methylmercaptopurine, are associated with antiinflammatory effects and adverse effects, respectively, some investigators have examined intentionally shunting the metabolism of azathioprine toward increasing 6-thioguanine nucleotide levels by using low doses of the xanthine oxidoreductase inhibitor allopurinol to improve efficacy and decrease toxicity of azathioprine in patients with inflammatory bowel disease. We performed a search of the MEDLINE and Embase databases for basic and clinical research reports of this modality. Pertinent articles were retrieved, reviewed, and assessed by the authors. Case series, cohort studies, and one randomized trial have investigated adding allopurinol to azathioprine therapy in patients with inflammatory bowel disease. Most reports primarily examined metabolite levels in these patients. In general, the literature suggests that this modality was successful at significantly increasing 6-thioguanine nucleotide levels while decreasing 6-methylmercaptopurine levels. Several small reports have suggested that patients with increased 6-thioguanine nucleotide levels had improved symptoms or symptom remission. Adverse effects and discontinuation rates remained similar or were improved in patients who were taking a thiopurine and started allopurinol. In conclusion, the addition of allopurinol may be an option for optimizing thiopurine metabolite production in select patients with low 6-thioguanine nucleotide levels. Appropriate care and monitoring of these patients are mandatory to prevent neutropenia or other adverse effects.
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Affiliation(s)
- Geoffrey C Wall
- Drake University College of Pharmacy and Health Sciences, Des Moines, Iowa.,Iowa Methodist Medical Center-University of Iowa Medical Residency Program, Des Moines, Iowa
| | - Hamid Muktar
- Iowa Methodist Medical Center-University of Iowa Medical Residency Program, Des Moines, Iowa
| | - Cassandra Effken
- Drake University College of Pharmacy and Health Sciences, Des Moines, Iowa
| | - Pramod B Mahajan
- Drake University College of Pharmacy and Health Sciences, Des Moines, Iowa
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14
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Patel JN, Villadolid J. Cancer Drug Delivery. PHARMACEUTICAL SCIENCES 2017. [DOI: 10.4018/978-1-5225-1762-7.ch008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Advancements in cancer drug delivery have led to the development of personalized oncology care through molecularly-driven targeted therapies. Understanding molecular and cellular mechanisms which drive tumor progression and resistance is critical in managing new treatment strategies which have shifted from empiric to biomarker-directed therapy selection. Biomarker-directed therapies have improved clinical outcomes in multiple malignancies as monotherapy and in combination with other treatment modalities, however the changing scope of treatment options presents new opportunities and challenges for research. Furthermore, pharmacogenetics may provide a rationale method of personalizing anticancer drug dosing and supportive care management for oncology patients. This chapter reviews biomarker classifications and pharmacogenetics in anticancer therapy and supportive care. Examples of biomarker-directed therapies and clinical assays, in addition to future directions of molecular profiling in oncology therapy management are discussed.
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15
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Lee DK, Chang VY, Kee T, Ho CM, Ho D. Optimizing Combination Therapy for Acute Lymphoblastic Leukemia Using a Phenotypic Personalized Medicine Digital Health Platform: Retrospective Optimization Individualizes Patient Regimens to Maximize Efficacy and Safety. SLAS Technol 2016; 22:276-288. [PMID: 27920397 DOI: 10.1177/2211068216681979] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Acute lymphoblastic leukemia (ALL) is a blood cancer that is characterized by the overproduction of lymphoblasts in the bone marrow. Treatment for pediatric ALL typically uses combination chemotherapy in phases, including a prolonged maintenance phase with oral methotrexate and 6-mercaptopurine, which often requires dose adjustment to balance side effects and efficacy. However, a major challenge confronting combination therapy for virtually every disease indication is the inability to pinpoint drug doses that are optimized for each patient, and the ability to adaptively and continuously optimize these doses to address comorbidities and other patient-specific physiological changes. To address this challenge, we developed a powerful digital health technology platform based on phenotypic personalized medicine (PPM). PPM identifies patient-specific maps that parabolically correlate drug inputs with phenotypic outputs. In a disease mechanism-independent fashion, we individualized drug ratios/dosages for two pediatric patients with standard-risk ALL in this study via PPM-mediated retrospective optimization. PPM optimization demonstrated that dynamically adjusted dosing of combination chemotherapy could enhance treatment outcomes while also substantially reducing the amount of chemotherapy administered. This may lead to more effective maintenance therapy, with the potential for shortening duration and reducing the risk of serious side effects.
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Affiliation(s)
- Dong-Keun Lee
- 1 Division of Oral Biology and Medicine, School of Dentistry, UCLA, Los Angeles, CA, USA
| | - Vivian Y Chang
- 2 Division of Pediatric Hematology and Oncology, David Geffen School of Medicine, UCLA, Los Angeles, CA, USA.,3 Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, CA, USA
| | - Theodore Kee
- 4 Department of Bioengineering, Henry Samueli School of Engineering and Applied Science, UCLA, Los Angeles, CA, USA
| | - Chih-Ming Ho
- 3 Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, CA, USA.,4 Department of Bioengineering, Henry Samueli School of Engineering and Applied Science, UCLA, Los Angeles, CA, USA.,5 Department of Mechanical and Aerospace Engineering, Henry Samueli School of Engineering and Applied Science, UCLA, Los Angeles, CA, USA
| | - Dean Ho
- 1 Division of Oral Biology and Medicine, School of Dentistry, UCLA, Los Angeles, CA, USA.,3 Jonsson Comprehensive Cancer Center, UCLA, Los Angeles, CA, USA.,4 Department of Bioengineering, Henry Samueli School of Engineering and Applied Science, UCLA, Los Angeles, CA, USA.,6 Jane and Jerry Weintraub Center for Reconstructive Biotechnology, UCLA, Los Angeles, CA, USA.,7 California NanoSystems Institute, UCLA, Los Angeles, CA, USA
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16
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Liu C, Yang W, Pei D, Cheng C, Smith C, Landier W, Hageman L, Chen Y, Yang JJ, Crews KR, Kornegay N, Karol SE, Wong FL, Jeha S, Sandlund JT, Ribeiro RC, Rubnitz JE, Metzger ML, Pui CH, Evans WE, Bhatia S, Relling MV. Genomewide Approach Validates Thiopurine Methyltransferase Activity Is a Monogenic Pharmacogenomic Trait. Clin Pharmacol Ther 2016; 101:373-381. [PMID: 27564568 DOI: 10.1002/cpt.463] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 07/26/2016] [Accepted: 08/23/2016] [Indexed: 12/11/2022]
Abstract
We performed a genomewide association study (GWAS) of primary erythrocyte thiopurine S-methyltransferase (TPMT) activity in children with leukemia (n = 1,026). Adjusting for age and ancestry, TPMT was the only gene that reached genomewide significance (top hit rs1142345 or 719A>G; P = 8.6 × 10-61 ). Additional genetic variants (in addition to the three single-nucleotide polymorphisms [SNPs], rs1800462, rs1800460, and rs1142345, defining TPMT clinical genotype) did not significantly improve classification accuracy for TPMT phenotype. Clinical mercaptopurine tolerability in 839 patients was related to TPMT clinical genotype (P = 2.4 × 10-11 ). Using 177 lymphoblastoid cell lines (LCLs), there were 251 SNPs ranked higher than the top TPMT SNP (rs1142345; P = 6.8 × 10-5 ), revealing a limitation of LCLs for pharmacogenomic discovery. In a GWAS, TPMT activity in patients behaves as a monogenic trait, further bolstering the utility of TPMT genetic testing in the clinic.
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Affiliation(s)
- C Liu
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - W Yang
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - D Pei
- Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - C Cheng
- Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - C Smith
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - W Landier
- School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - L Hageman
- School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Y Chen
- School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - J J Yang
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - K R Crews
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - N Kornegay
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - S E Karol
- Department of Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - F L Wong
- Department of Population Sciences, City of Hope, Duarte, California, USA
| | - S Jeha
- Department of Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - J T Sandlund
- Department of Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - R C Ribeiro
- Department of Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - J E Rubnitz
- Department of Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - M L Metzger
- Department of Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - C-H Pui
- Department of Oncology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - W E Evans
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - S Bhatia
- School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - M V Relling
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
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17
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Abstract
The goal of pharmacogenomic research is to discover and validate genetic variants that are predictive of drug response, for eventual implementation into clinical practice. Cancer pharmacogenomics provides the opportunity to analyze two sets of DNA, that of the tumor (somatic) and that of the host (germline). Germline variants are inherited variations and are often associated with the pharmacokinetic behavior of a drug, including drug disposition and ultimately drug efficacy and/or toxicity, whereas somatic mutations are often useful in predicting the pharmacodynamic response to drugs. Pharmacoethnicity, or ethnic diversity in drug response or toxicity, is an increasingly recognized factor accounting for interindividual variations in anticancer drug response. Pharmacoethnicity is often determined by germline pharmacogenomic factors and the distribution of single nucleotide polymorphisms across various populations, but it may also be influenced by nongenetic factors, such as environmental factors. This review aims to elucidate the importance of pharmacoethnicity in cancer pharmacogenomic research and implementation, focusing solely on germline variants.
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18
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Fong SCM, Blaker PA, Arenas-Hernandez M, Marinaki AM, Sanderson JD. Getting the best out of thiopurine therapy: thiopurine S-methyltransferase and beyond. Biomark Med 2015; 9:51-65. [PMID: 25605455 DOI: 10.2217/bmm.14.97] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Thiopurines are the cornerstone of treatment for a wide variety of medical disorders, ranging from pediatric leukemia to inflammatory bowel disease. Because of their complex metabolism and potential toxicities, the use of biomarkers to predict risk and response is paramount. Thiopurine S-methyltransferase and thiopurine metabolite levels have emerged as companion diagnostics with crucial roles in facilitating safe and effective treatment. This review serves to update the reader on how these tools are being developed and implemented in clinical practice. A useful paradigm in thiopurine therapeutic strategy is presented, along with fresh insights into the mechanisms underlying these approaches. We elaborate on potential future developments in the optimization of thiopurine therapy.
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19
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Odahara S, Uchiyama K, Kubota T, Ito Z, Takami S, Kobayashi H, Saito K, Koido S, Ohkusa T. A Prospective Study Evaluating Metabolic Capacity of Thiopurine and Associated Adverse Reactions in Japanese Patients with Inflammatory Bowel Disease (IBD). PLoS One 2015; 10:e0137798. [PMID: 26360046 PMCID: PMC4567281 DOI: 10.1371/journal.pone.0137798] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 08/20/2015] [Indexed: 12/26/2022] Open
Abstract
Azathioprine (AZA) is frequently used in patients with inflammatory bowel disease (IBD). However, toxic adverse reactions frequently develop and limit the clinical benefits. Currently, the precise mechanisms underlying thiopurine-related toxicity are not well understood. To investigate the relationship between the extent of thiopurine metabolism and adverse reactions in Japanese IBD patients, we prospectively observed 48 IBD patients who received AZA. We analyzed the thiopurine S-methyltransferase (TPMT) and inosine triphosphate pyrophosphatase (ITPA) gene mutations and measured the concentrations of 6-thioguanine nucleotide (6-TGN) continuously for 52 weeks. All patients possessed wild-type TPMT gene sequences. The ITPA 94C>A mutation was detected in 19 patients (39.6%). Adverse reactions developed in 14 of the 48 patients (29.2%), including leukopenia in 10 patients (20.8%). In the leukopenia group, the percentages of patients with 94C>A were higher than those in the without-leukopenia group (70.0% vs. 31.6%, P < 0.05). The average concentrations of 6-TGN in the patients with 94C>A were generally higher than those in the patients without 94C>A, however, there were no significant differences. Only 3 out of 10 patients with leukopenia exhibited high 6-TGN levels (30.0%). No negative correlations between white blood cell (WBC) counts and 6-TGN concentrations were observed. The cumulative incidence of leukopenia were higher for patients with 94C>A. Seven out of 19 patients (36.8%) with the ITPA 94C>A mutation developed leukopenia; however, this mutation may not unequivocally increase the risk of developing leukopenia. In addition, there are factors other than increased 6-TGN levels that are involved in the onset of leukopenia.
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Affiliation(s)
- Shunichi Odahara
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, The Jikei University School of Medicine (Kashiwa Hospital), Chiba, Japan
| | - Kan Uchiyama
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, The Jikei University School of Medicine (Kashiwa Hospital), Chiba, Japan
- * E-mail:
| | - Takahiro Kubota
- Department of Biopharmaceutics, Faculty of Pharmaceutical Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata, Japan
| | - Zensho Ito
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, The Jikei University School of Medicine (Kashiwa Hospital), Chiba, Japan
| | - Shinichiro Takami
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, The Jikei University School of Medicine (Kashiwa Hospital), Chiba, Japan
| | - Hiroko Kobayashi
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, The Jikei University School of Medicine (Kashiwa Hospital), Chiba, Japan
| | - Keisuke Saito
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, The Jikei University School of Medicine (Kashiwa Hospital), Chiba, Japan
| | - Shigeo Koido
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, The Jikei University School of Medicine (Kashiwa Hospital), Chiba, Japan
| | - Toshifumi Ohkusa
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, The Jikei University School of Medicine (Kashiwa Hospital), Chiba, Japan
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20
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Patel JN, Papachristos A. Personalizing chemotherapy dosing using pharmacological methods. Cancer Chemother Pharmacol 2015; 76:879-96. [PMID: 26298089 DOI: 10.1007/s00280-015-2849-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 08/13/2015] [Indexed: 01/01/2023]
Abstract
PURPOSE Given the toxic nature and narrow therapeutic index of traditional chemotherapeutics, better methods of dose and therapy selection are critical. Pharmacological methods, including pharmacogenomics and pharmacokinetics, offer a practical method to enrich drug exposure, reduce toxicity, and improve quality of life for patients. METHODS PubMed and key abstracts from the American Society of Clinical Oncology (ASCO) and American Association for Cancer Research (AACR) were searched until July 2015 for clinical data relating to pharmacogenomic- and/or pharmacokinetic-guided dosing of anticancer drugs. RESULTS Based on the results returned from a thorough search of the literature and the plausibility of utilizing pharmacogenomic and/or pharmacokinetic methods to personalize chemotherapy dosing, we identified several chemotherapeutic agents with the potential for therapy individualization. We highlight the available data, clinical validity, and utility of using pharmacogenomics to personalize therapy for tamoxifen, 5-fluorouracil, mercaptopurine, and irinotecan, in addition to using pharmacokinetics to personalize dosing for 5-fluorouracil, busulfan, methotrexate, taxanes, and topotecan. CONCLUSION A concerted effort should be made by researchers to further elucidate the role of pharmacological methods in personalizing chemotherapy dosing to optimize the risk-benefit profile. Clinicians should be aware of the clinical validity, utility, and availability of pharmacogenomic- and pharmacokinetic-guided therapies in clinical practice, to ultimately allow optimal dosing for each and every cancer patient.
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Affiliation(s)
- Jai N Patel
- Department of Cancer Pharmacology, Levine Cancer Institute, Carolinas HealthCare System, 1021 Morehead Medical Drive, Charlotte, NC, 28204, USA.
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21
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Immune Pathways in Atopic Dermatitis, and Definition of Biomarkers through Broad and Targeted Therapeutics. J Clin Med 2015; 4:858-73. [PMID: 26239452 PMCID: PMC4470203 DOI: 10.3390/jcm4050858] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 04/20/2015] [Accepted: 04/21/2015] [Indexed: 12/22/2022] Open
Abstract
Atopic dermatitis (AD) is the most common inflammatory skin disease. Recent research findings have provided an insight into the complex pathogenic mechanisms involved in this disease. Despite a rising prevalence, effective and safe therapeutics for patients with moderate-to-severe AD are still lacking. Biomarkers of lesional, nonlesional skin, and blood have been developed for baseline as well as after treatment with broad and specific treatments (i.e., cyclosporine A and dupilumab). These biomarkers will help with the development of novel targeted therapeutics and assessment of disease reversal, with the promise of a more personalized treatment approach. Since AD involves more than one subtype (i.e., intrinsic/extrinsic, pediatric/adult, etc.), these molecular fingerprints needs to be validated in all subpopulations with AD.
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22
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Zeglam HB, Benhamer A, Aboud A, Rtemi H, Mattardi M, Saleh SS, Bashein A, Enattah N. Polymorphisms of the thiopurine S-methyltransferase gene among the Libyan population. Libyan J Med 2015; 10:27053. [PMID: 25819542 PMCID: PMC4376936 DOI: 10.3402/ljm.v10.27053] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 03/02/2015] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Thiopurine S-methyltransferase (TPMT) is a cytosolic enzyme that catalyses the S-methylation of 6-mercaptopurine and azathioprine. Low activity phenotypes are correlated with polymorphism in the TPMT gene. Patients with low or undetectable TMPT activity could develop severe myelosuppression when they are treated with standard doses of thiopurine drugs. Since ethnic differences in the TPMT gene polymorphism have been demonstrated worldwide, assessing it in the Libyan population is worthwhile. METHODS We investigated TPMT gene polymorphism in a total of 246 Libyan healthy adult blood donors from three different Libyan regions (Tripoli, Yefren, and Tawargha) and 50 children with acute lymphoblastic leukaemia (ALL). We used polymerase chain reaction restriction length polymorphism (PCR-RFLP) and allele-specific PCR-based assays to analyse the TPMT gene for the variants *2 c.238 G>C, *3A (c.460 G>A and c.719 A>G), *3B (c.460 G>A), and *3C (c.719 A>G). RESULTS Our results show that the TPMT variants associated with low enzymatic activity were detected in 3.25% (8 in 246) of adult Libyan individuals and the frequency of total mutant alleles was 1.63%. Heterozygous genotypes were TPMT*3A in three subjects (0.61%) and TPMT*3C in five subjects (1.02%). No TPMT*2 and TPMT*3B allelic variants and no homozygous or compound heterozygous mutant alleles were detected. The normal allele (wild-type) was found in 98.4% of the adult individuals studied. No mutant alleles were detected among the 50 children who had ALL. CONCLUSIONS We report on the presence of the TPMT*3C and *3A mutant alleles in the Libyan population. Therefore, monitoring the patients to be treated with doses of thiopurine drugs for TPMT variants is worthwhile to avoid the development of severe myelosuppression.
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Affiliation(s)
- Hamza Ben Zeglam
- Department of Genetic Engineering, Biotechnology Research Center (BTRC), Twisha, Tripoli, Libya
| | - Abdrazak Benhamer
- Department of Genetic Engineering, Biotechnology Research Center (BTRC), Twisha, Tripoli, Libya
| | - Adel Aboud
- Department of Genetic Engineering, Biotechnology Research Center (BTRC), Twisha, Tripoli, Libya
| | - Haitem Rtemi
- Department of Genetic Engineering, Biotechnology Research Center (BTRC), Twisha, Tripoli, Libya
| | - Meftah Mattardi
- Department of Genetic Engineering, Biotechnology Research Center (BTRC), Twisha, Tripoli, Libya
| | - Saleh Suleiman Saleh
- Department of Genetic Engineering, Biotechnology Research Center (BTRC), Twisha, Tripoli, Libya
| | - Abdullah Bashein
- Department of Biochemistry, Faculty of Medicine, University of Tripoli, Tripoli, Libya
| | - Nabil Enattah
- Department of Genetic Engineering, Biotechnology Research Center (BTRC), Twisha, Tripoli, Libya; ;
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23
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Exome sequencing and array-based comparative genomic hybridisation analysis of preferential 6-methylmercaptopurine producers. THE PHARMACOGENOMICS JOURNAL 2015; 15:414-21. [DOI: 10.1038/tpj.2015.9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 01/15/2014] [Accepted: 01/28/2015] [Indexed: 12/23/2022]
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24
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Lennard L. Implementation of TPMT testing. Br J Clin Pharmacol 2014; 77:704-14. [PMID: 23962279 DOI: 10.1111/bcp.12226] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 07/23/2013] [Indexed: 12/21/2022] Open
Abstract
The activity of the enzyme thiopurine methyltransferase (TPMT) is regulated by a common genetic polymorphism. One in 300 individuals lack enzyme activity and 11% are heterozygous for a variant low activity allele and have an intermediate activity. The thiopurine drugs azathioprine, mercaptopurine and thioguanine are substrates for TPMT; these drugs exhibit well documented myelosuppressive effects on haematopoietic cells and have a track record of idiosyncratic drug reactions. The development of severe bone marrow toxicity, in patients taking standard doses of thiopurine drugs, is associated with TPMT deficiency whilst the TPMT heterozygote is at an increased risk of developing myelosuppression. Factors influencing TPMT enzyme activity, as measured in the surrogate red blood cell, are discussed in this review to enable an appreciation of why concordance between TPMT genotype and phenotype is not 100%. This is particularly important for lower/intermediate TPMT activities to avoid misclassification of TPMT status. TPMT testing is now widely available in routine service laboratories. The British National Formulary suggests TPMT testing before starting thiopurine drugs. Dermatologists were quick to adopt routine TPMT testing whilst gastroenterologists do not specifically recommend TPMT screening. TPMT testing is mandatory prior to the use of mercaptopurine in childhood leukaemia. Thiopurine drug dose and other treatment related influences on cell counts explain some of the differing recommendations between clinical specialities. TPMT testing is cost-effective and the major role is in the identification of the TPMT deficient individual prior to the start of thiopurine drugs.
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Affiliation(s)
- Lynne Lennard
- Clinical Pharmacology Unit, Department of Human Metabolism, University of Sheffield, Sheffield, UK
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Farfan MJ, Salas C, Canales C, Silva F, Villarroel M, Kopp K, Torres JP, Santolaya ME, Morales J. Prevalence of TPMT and ITPA gene polymorphisms and effect on mercaptopurine dosage in Chilean children with acute lymphoblastic leukemia. BMC Cancer 2014; 14:299. [PMID: 24774509 PMCID: PMC4012712 DOI: 10.1186/1471-2407-14-299] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 04/23/2014] [Indexed: 10/26/2022] Open
Abstract
BACKGROUND Mercaptopurine (6-MP) plays a pivotal role in treatment of childhood acute lymphoblastic leukemia (ALL); however, interindividual variability in toxicity of this drug due to genetic polymorphism in 6-MP metabolizing enzymes has been described. We determined the prevalence of the major genetic polymorphisms in 6-MP metabolizing enzymes in Chilean children with ALL. METHODS 103 Chilean pediatric patients with a confirmed diagnosis of ALL were enrolled. DNA was isolated from whole blood and genetic polymorphism in thiopurine S-methyltransferase (TPMT) and inosine triphosphate pyrophosphatase (ITPA) coding genes were detected by polymorphism chain reaction-restriction fragment length (PCR-RFLP) assay. RESULTS The total frequency of variant TPMT alleles was 8%. TPMT*2, TPMT*3A and TPMT*3B alleles were found in 0%, 7%, and 1% of patients, respectively. For ITPA, the frequency of P32T allele was 3%. We did not observe any homozygous variant for TPMT and ITPA alleles. We also analyzed a subgroup of 40 patients who completed the maintenance phase of ALL treatment, and we found that patients carrying a TPMT gene variant allele required a significantly lower median cumulative dosage and median daily dosage of 6-MP than patients carrying wild type alleles. CONCLUSION TMPT genotyping appears an important tool to further optimize 6-MP treatment design in Chilean patients with ALL.
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Affiliation(s)
- Mauricio J Farfan
- Departamento de Pediatría, Centro de Estudios Moleculares, Facultad de Medicina, Universidad de Chile, Antonio Varas 360, Santiago, Chile.
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Zhang B, Xu XW, Zeng XJ, Li DK. Correlation of thiopurine methyltransferase activity and 6-thioguanine nucleotide concentration in Han Chinese patients treated with azathioprine 25 to 100 mg: A 1-year, single-center, prospective study. Curr Ther Res Clin Exp 2014; 67:270-82. [PMID: 24678102 DOI: 10.1016/j.curtheres.2006.07.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2006] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Of the enzymes involved in the metabolism of azathioprine, thiopurine methyltransferase (TPMT) is the one characterized by genetic polymorphisms and ethnic variations. There have been several studies of the ethnic variations in phenotype and genotype of TPMT, although few have assessed the possible correlation between TPMT activity and 6-thioguanine nucleotide (6-TGN) concentrations. OBJECTIVE The aim of this study was to examine the relationship between TPMT activity and the steady-state concentration (Css) of 6-TGN, the primary active metabolite of azathioprine, in red blood cells (RBCs) in Han Chinese patients treated with azathioprine. METHODS Han Chinese patients aged 18 to 60 years with immunosuppression and normal hepatic and renal function who had been receiving a stable dose (25-100 mg/d) of oral azathioprine as a part of their regular anti-immunosuppression regimen for at least 10 days were recruited for this 1-year, single-center, prospective study. Azathioprine was administered PO QD in the morning, in combination with a stable regimen of other immunosuppressive drugs, for 1 year. At 1 year, blood samples were drawn just before the ingestion of azathioprine. TPMT activity and 6-TGN Css in RBCs were determined in our laboratory using high-performance liquid chromatography. Adverse drug events were monitored by a patient questionnaire and laboratory testing. Out of the initial cohort, several patients were concurrently enrolled in a subanalysis in which the effect of TPMT polymorphism on the pharmacokinetic properties of 6-mercaptopurine, the intermediate metabolite of azathioprine, was examined. RESULTS Nineteen patients (14 women, 5 men; mean [SD] age, 41 [9.6] years [range, 22-59 years]; mean [SD] weight, 62 [12] kg) were included in the study; 7 were included in the subanalysis. A significant negative correlation was found between TPMT activity and 6-TGN Css in RBCs (r = -0.712; P = 0.001); when the outlier data were removed, no significant correlation was found. Mean (SD) TPMT activity was 12.95 (3.07) nmol/h · mL(-1) RBCs and the interindividual CV was 23.68%. Mean (SD) 6-TGN CSS was 42.95 (41.98) ng/8 × 108 RBCs and the interindividual CV was 97.74% (N = 19), while the intraindividual CV of 6-TGNs within 8 hours after azathioprine ingestion was between 4.23% and 7.37% (n = 7). No significant correlation was found between 6-TGN Css in RBCs and the dose of azathioprine used. One patient's treatment was discontinued because her white blood cell count decreased to < 4 × 109 cells/L, indicating myelotoxicity; the t/12 of 6-TGNs in this patient was 5.85 days. Treatment was well tolerated by all other patients. CONCLUSION In this small study, a significant negative correlation was found between TPMT activity and 6-TGN concentration in the RBCs of these Han Chinese patients. However, the correlation was not significant when data from 1 patient with low TPMT activity were excluded.
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Affiliation(s)
- Bo Zhang
- Department of Pharmacy, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences-Peking Union Medical College, Beijing, China
| | - Xiao-Wei Xu
- Department of Pharmacy, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences-Peking Union Medical College, Beijing, China
| | - Xue-Jun Zeng
- Department of Rheumatology and Immunology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences-Peking Union Medical College, Beijing, China
| | - Da-Kui Li
- Department of Pharmacy, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences-Peking Union Medical College, Beijing, China
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Correlation of thiopurine methyltransferase and inosine triphosphate pyrophosphatase polymorphisms and adverse effects induced by azathioprine treatment in Taiwanese dermatology patients. DERMATOL SIN 2014. [DOI: 10.1016/j.dsi.2013.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Abstract
The efficacy, safety, and tolerability of drugs are dependent on numerous factors that influence their disposition. A dose that is efficacious and safe for one individual may result in sub-therapeutic or toxic blood concentrations in other individuals. A major source of this variability in drug response is drug metabolism, where differences in pre-systemic and systemic biotransformation efficiency result in variable degrees of systemic exposure (e.g., AUC, C max, and/or C min) following administration of a fixed dose.Interindividual differences in drug biotransformation have been studied extensively. It is well recognized that both intrinsic (such as genetics, age, sex, and disease states) and extrinsic (such as diet, chemical exposures from the environment, and even sunlight) factors play a significant role. For the family of cytochrome P450 enzymes, the most critical of the drug metabolizing enzymes, genetic variation can result in the complete absence or enhanced expression of a functional enzyme. In addition, up- and down-regulation of gene expression, in response to an altered cellular environment, can achieve the same range of metabolic function (phenotype), but often in a less reliably predictable and time-dependent manner. Understanding the mechanistic basis for drug disposition and response variability is essential if we are to move beyond the era of empirical, trial-and-error dose selection and into an age of personalized medicine that brings with it true improvements in health outcomes in the therapeutic treatment of disease.
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Affiliation(s)
- Kenneth E Thummel
- Department of Pharmaceutics, University of Washington, Seattle, WA, USA
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Abstract
In the past several years, human genetics studies have progressed from monogenic to complex and common diseases because of the advancement in technologies. There is increased knowledge of the pharmacokinetics and pharmacogenomics of the drugs in adults as well as in children. These technological developments provided new diagnostic, prognostic, and therapeutic opportunities. We are now in a position to address many additional ambitious questions. For instance, in clinical medicine, interindividual variation in drug response is a major problem. Some of the heterogeneity of drug safety and efficacy among individuals can be explained by pharmacogenomics. It has also the potential to improve the treatment in both adults and children. In pediatrics however, there is ontogeny and metabolic capacity in children is different compared to adults. Several specific developmental changes may underlie some of the variability in drug response seen in children. They may also be responsible for adverse drug reactions (ADRs). Therefore, much of the diversity in drug effects cannot be explained by studying the genomic diversity alone. It is necessary to include the effect of growth (involves variations in gene expression) along with genetic differences when explaining the variability in treatment response. In this respect epigenomics may expand the scope of pharmacogenomics towards optimization of drug therapy. Future studies must focus on periods of maturation of the drug-metabolizing enzymes and polymorphisms in their genes by using candidate gene approach, gene expression analysis, genome-wide haplotype mapping, and proteomics. The integration of genetic data and clinical phenotypes along with the role of other factors is necessary to evaluate both efficacy and ADRs of any drug. It may require extensive genetic epidemiological studies spanning over many years.
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Yang JJ, Bhojwani D. Thiopurine S-methyltransferase pharmacogenetics in childhood acute lymphoblastic leukemia. Methods Mol Biol 2014; 999:273-84. [PMID: 23666706 DOI: 10.1007/978-1-62703-357-2_20] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Pharmacogenetics is the growing field of study of genetic variations underlying interindividual differences in drug response. Inherited polymorphisms in genes coding for drug-metabolizing enzymes, transporters, and targets influence toxicity as well as efficacy associated with the medication. Thiopurines are agents widely used in hematologic malignancies, transplantation, and chronic inflammatory conditions. Myelosuppression is the commonly encountered dose-limiting toxicity. Polymorphisms in the thiopurine S-methyltransferase gene (TPMT), the predominant inactivating enzyme for thiopurines in hematopoietic tissue, are correlated with enzymatic activity of TPMT, thiopurine metabolism, and risk of clinical toxicity. In this chapter, we present TPMT genotype assessment that allows for prescribing pharmacogenetically guided doses to enhance patient safety and drug efficacy.
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Affiliation(s)
- Jun J Yang
- Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, TN, USA
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Czaja AJ. Review article: the management of autoimmune hepatitis beyond consensus guidelines. Aliment Pharmacol Ther 2013; 38:343-64. [PMID: 23808490 DOI: 10.1111/apt.12381] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2013] [Revised: 05/30/2013] [Accepted: 06/03/2013] [Indexed: 12/17/2022]
Abstract
BACKGROUND Consensus guidelines aid in the diagnosis and management of autoimmune hepatitis, but they are frequently based on low-quality clinical evidence, conflicting experiences and divergent opinions. Recommendations may be weak, discrepant or non-existent at critical decision points. AIMS To identify the decision points where guidelines are weak or non-existent and review the evidence essential in the decision process. METHODS Full-text articles published in English using the keyword 'autoimmune hepatitis' were identified by PubMed from 1972 to 2013. Personal experience and investigations in autoimmune hepatitis also identified important contributions. RESULTS Seventy per cent of the guidelines developed by the American Association for the Study of Liver Diseases and 48% of those proposed by the British Society of Gastroenterology are based on low-quality evidence, conflicting experiences or divergent opinions. The key uncertainties in diagnosis relate to the timing of liver biopsy, recognising acute severe (fulminant) disease, interpreting coincidental nonclassical histological changes, accommodating atypical or deficient features in non-White patients, differentiating drug-induced from classical disease and identifying overlap syndromes. The key uncertainties in management relate to pre-treatment testing for thiopurine methyltransferase activity, treating asymptomatic mild disease, determining treatment end points, managing suboptimal responses, incorporating nonstandard medications as front-line and salvage agents, using azathioprine in pregnancy and instituting surveillance for hepatocellular carcinoma. CONCLUSIONS Consensus guidelines are fraught with uncertainties in the diagnosis and management of autoimmune hepatitis. Each decision point must counterbalance the current available evidence and tailor the application of this evidence to the individual patient.
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Affiliation(s)
- A J Czaja
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
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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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Rassekh SR, Ross CJD, Carleton BC, Hayden MR. Cancer pharmacogenomics in children: research initiatives and progress to date. Paediatr Drugs 2013; 15:71-81. [PMID: 23529868 DOI: 10.1007/s40272-013-0021-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Over the last few decades, cure rates for pediatric cancer have increased dramatically, and now over 80 % of children with cancer are cured of their disease. This improvement in cure has come with a significant cost, with many children suffering irreversible, life-threatening, or long-lasting toxicities due to the medications required during their treatment. In the last 2 decades, major technological advances in genomics and the mapping of the human genome have made it possible to identify genetic differences between children in order to investigate differing responses to cancer therapy and to help explain why children treated with the same medications can have different outcomes. The emerging field of pharmacogenomics has had many important findings in pediatric cancer. The focus of this review is drug toxicity in pediatric cancer and the use of pharmacogenomics to reduce these adverse drug reactions, with a specific focus on thiopurines, methotrexate, cisplatin, vincristine and anthracyclines. Future areas of research and the need for international collaboration are discussed.
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Affiliation(s)
- Shahrad Rod Rassekh
- Department of Pediatrics, Division of Pediatric Hematology/Oncology/BMT, University of British Columbia, Vancouver, BC, Canada.
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Nutritional therapy versus 6-mercaptopurine as maintenance therapy in patients with Crohn's disease. Dig Liver Dis 2012; 44:649-54. [PMID: 22542605 DOI: 10.1016/j.dld.2012.03.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 03/01/2012] [Accepted: 03/04/2012] [Indexed: 02/08/2023]
Abstract
BACKGROUND 6-Mercaptopurine is often used as maintenance therapy in patients with Crohn's disease. However, toxicities like myelosuppression limit its clinical benefit. AIMS To evaluate the efficacy of elemental diet versus 6-mercaptopurine as maintenance therapy in Crohn's disease. METHODS Ninety-five eligible patients with Crohn's disease activity index ≤150 were randomly assigned to: 6-mercaptopurine (0.5-1.5mg/kg/day, n=30); Elental as an elemental diet (≥900 kcal/day, n=32); none (control, n=33). In the three groups, patients were and remained on 5-aminosalicylic acid (2250-3000 mg/day). Patients were observed for 2 years and the rate of relapse (Crohn's disease activity index ≥200) was monitored. RESULTS At 24 months, the fractions of patients who had maintained remission were 60%, 46.9% and 27.2% for 6-mercaptopurine, Elental and the control groups, respectively. Log-rank test showed better efficacy for 6-mercaptopurine (P=0.0041) and Elental (P=0.0348) versus control. No significant difference was found between 6-mercaptopurine and Elental. Further, in the 6-mercaptopurine group, 2 patients experienced liver injury and one developed alopecia. CONCLUSIONS This 24 months comparison study showed that Elental as maintenance therapy in Crohn's disease patients was as effective as 6-mercaptopurine. Elental should be useful for long-term maintenance therapy in Crohn's disease. This is the first comparison study evaluating nutritional therapy versus 6-mercaptopurine.
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Stocco G, Yang W, Crews KR, Thierfelder WE, Decorti G, Londero M, Franca R, Rabusin M, Valsecchi MG, Pei D, Cheng C, Paugh SW, Ramsey LB, Diouf B, McCorkle JR, Jones TS, Pui CH, Relling MV, Evans WE. PACSIN2 polymorphism influences TPMT activity and mercaptopurine-related gastrointestinal toxicity. Hum Mol Genet 2012; 21:4793-804. [PMID: 22846425 DOI: 10.1093/hmg/dds302] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Treatment-related toxicity can be life-threatening and is the primary cause of interruption or discontinuation of chemotherapy for acute lymphoblastic leukemia (ALL), leading to an increased risk of relapse. Mercaptopurine is an essential component of continuation therapy in all ALL treatment protocols worldwide. Genetic polymorphisms in thiopurine S-methyltransferase (TPMT) are known to have a marked effect on mercaptopurine metabolism and toxicity; however, some patients with wild-type TPMT develop toxicity during mercaptopurine treatment for reasons that are not well understood. To identify additional genetic determinants of mercaptopurine toxicity, a genome-wide analysis was performed in a panel of human HapMap cell lines to identify trans-acting genes whose expression and/or single-nucleotide polymorphisms (SNPs) are related to TPMT activity, then validated in patients with ALL. The highest ranking gene with both mRNA expression and SNPs associated with TPMT activity in HapMap cell lines was protein kinase C and casein kinase substrate in neurons 2 (PACSIN2). The association of a PACSIN2 SNP (rs2413739) with TPMT activity was confirmed in patients and knock-down of PACSIN2 mRNA in human leukemia cells (NALM6) resulted in significantly lower TPMT activity. Moreover, this PACSIN2 SNP was significantly associated with the incidence of severe gastrointestinal (GI) toxicity during consolidation therapy containing mercaptopurine, and remained significant in a multivariate analysis including TPMT and SLCO1B1 as covariates, consistent with its influence on TPMT activity. The association with GI toxicity was also validated in a separate cohort of pediatric patients with ALL. These data indicate that polymorphism in PACSIN2 significantly modulates TPMT activity and influences the risk of GI toxicity associated with mercaptopurine therapy.
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Affiliation(s)
- Gabriele Stocco
- Department of Pharmaceutical Sciences, St Jude Children's Research Hospital, Memphis, TN 38105, USA
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Vachiramon V, Tey HL, Thompson AE, Yosipovitch G. Atopic dermatitis in African American children: addressing unmet needs of a common disease. Pediatr Dermatol 2012; 29:395-402. [PMID: 22471955 DOI: 10.1111/j.1525-1470.2012.01740.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Recent published data suggest that the prevalence of atopic dermatitis (AD) in African American children is significantly higher than in Caucasians. There are certain characteristics in the presentation of AD in African Americans that seem to differ from those in other racial groups, but there is a paucity of information on this topic. In this review, we highlight the differences in pathophysiology, clinical presentation, and treatment of AD between African Americans and Caucasians. It is important for dermatologists to understand these differences in order to provide better care for African American children with AD.
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Affiliation(s)
- Vasanop Vachiramon
- Department of Dermatology, School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27157, USA
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Bhatia S, Landier W, Shangguan M, Hageman L, Schaible AN, Carter AR, Hanby CL, Leisenring W, Yasui Y, Kornegay NM, Mascarenhas L, Ritchey AK, Casillas JN, Dickens DS, Meza J, Carroll WL, Relling MV, Wong FL. Nonadherence to oral mercaptopurine and risk of relapse in Hispanic and non-Hispanic white children with acute lymphoblastic leukemia: a report from the children's oncology group. J Clin Oncol 2012; 30:2094-101. [PMID: 22564992 PMCID: PMC3601449 DOI: 10.1200/jco.2011.38.9924] [Citation(s) in RCA: 229] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 02/28/2012] [Indexed: 12/21/2022] Open
Abstract
PURPOSE Systemic exposure to mercaptopurine (MP) is critical for durable remissions in children with acute lymphoblastic leukemia (ALL). Nonadherence to oral MP could increase relapse risk and also contribute to inferior outcome in Hispanics. This study identified determinants of adherence and described impact of adherence on relapse, both overall and by ethnicity. PATIENTS AND METHODS A total of 327 children with ALL (169 Hispanic; 158 non-Hispanic white) participated. Medication event-monitoring system caps recorded date and time of MP bottle openings. Adherence rate, calculated monthly, was defined as ratio of days of MP bottle opening to days when MP was prescribed. RESULTS After 53,394 person-days of monitoring, adherence declined from 94.7% (month 1) to 90.2% (month 6; P < .001). Mean adherence over 6 months was significantly lower among Hispanics (88.4% v 94.8%; P < .001), patients age ≥ 12 years (85.8% v 93.1%; P < .001), and patients from single-mother households (80.6% v 93.1%; P = .001). A progressive increase in relapse was observed with decreasing adherence (reference: adherence ≥ 95%; 94.9% to 90%: hazard ratio [HR], 4.1; 95% CI,1.2 to 13.5; P = .02; 89.9% to 85%: HR, 4.0; 95% CI, 1.0 to 15.5; P = .04; < 85%: HR. 5.7; 95% CI, 1.9 to 16.8; P = .002). Cumulative incidence of relapse (± standard deviation) was higher among Hispanics (16.5% ± 4.0% v 6.3% ± 2.2%; P = .02). Association between Hispanic ethnicity and relapse (HR, 2.6; 95% CI, 1.1 to 6.1; P = .02) became nonsignificant (HR, 1.8; 95% CI, 0.6 to 5.2; P = .26) after adjusting for adherence and socioeconomic status. At adherence rates ≥ 90%, Hispanics continued to demonstrate higher relapse, whereas at rates < 90%, relapse risk was comparable to that of non-Hispanic whites. CONCLUSION Lower adherence to oral MP increases relapse risk. Ethnic difference in relapse risk differs by level of adherence-an observation currently under investigation.
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Iyer SN, Tilak AV, Mukherjee MS, Singhal RS. Genotype Frequencies of Drug-Metabolizing Enzymes Responsible for Purine and Pyrimidine Antagonists in a Healthy Asian-Indian Population. Biochem Genet 2012; 50:684-93. [DOI: 10.1007/s10528-012-9511-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Accepted: 02/28/2012] [Indexed: 10/28/2022]
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Larussa T, Suraci E, Lentini M, Nazionale I, Gallo L, Abenavoli L, Imeneo M, Costanzo FS, Cuda G, Luzza F. High prevalence of polymorphism and low activity of thiopurine methyltransferase in patients with inflammatory bowel disease. Eur J Intern Med 2012; 23:273-7. [PMID: 22385887 DOI: 10.1016/j.ejim.2011.12.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 12/03/2011] [Accepted: 12/08/2011] [Indexed: 01/30/2023]
Abstract
BACKGROUND Gene polymorphism of thiopurine methyltransferase (TPMT) correlates with decreased enzyme activity which determines a significant risk of adverse effect reactions (ADR) in patients treated with thiopurines. The aim of this study was to investigate TPMT genotype and phenotype status in patients with inflammatory bowel diseases (IBD). METHODS Fifty-one consecutive out-patients with IBD were genotyped for the following allelic variants: rs1800462 (referred as TPMT 2 allele), rs1800460 (referred as TPMT 3B allele), and 1142345 (referred as TPMT 3C allele). Red blood cell TPMT activity was measured using a competitive micro-well immunoassay for the semi-quantitative determination of TPMT activity in red blood cells (RBC) by means of a 6-MP substrate. RESULTS Polymorphism of TPMT was found in 5 out of 51 patients (10%; 95% CI 2%-18%), three heterozygous and two homozygous carriers. Six patients (11.8%; 95% CI 2.4%-19.5%) displayed very low, 12 (23.5%; 95% CI 11.4%-34.5%) intermediate, and 33 (64.7%; 95% CI 52%-78%) normal/high TPMT activity. There were no differences between TPMT genotype and phenotype groups according to age, type of disease, smoking, and chronic medications. A 71% (95% CI 61%-81%; κ=0.45) concordance rate was found between genotype and phenotype status. Six out of 27 (22%) current or past users of azathioprine developed ADR, with three (50%) displaying TPMT genotype and/or phenotype alterations. CONCLUSION Compared to the general population, IBD patients may have significantly higher prevalence of TPMT polymorphism and, even more, low activity. Phenotypic more than genotypic TPMT analysis could be useful to better manage IBD therapy with thiopurines.
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Affiliation(s)
- Tiziana Larussa
- Department of Health Science, University of Catanzaro "Magna Graecia", Catanzaro, Italy
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Pharmacogenetic determinants of mercaptopurine disposition in children with acute lymphoblastic leukemia. Eur J Clin Pharmacol 2012; 68:1233-42. [PMID: 22421815 DOI: 10.1007/s00228-012-1251-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 02/14/2012] [Indexed: 12/15/2022]
Abstract
BACKGROUND The backbone of drug therapy used in acute lymphoblastic leukemia (ALL) in children includes 6-mercaptopurine (6-MP). Intracellular metabolism of this prodrug is a key component of the therapeutic response. Many metabolizing enzymes are involved in 6-MP disposition and active 6-MP metabolites are represented by 6-thioguanine nucleotides (6-TGN) and methylated metabolites primarily methylated by the thiopurine S-methyltransferase enzyme (TPMT). The genetic polymorphism affecting TPMT activity displays an important inter-subject variability in metabolites pharmacokinetics and influences the balance between 6-MP efficacy and toxicity: patients with high 6-TGN levels are at risk of myelosuppression while patients with high levels of methylated derivates are at hepatotoxic risk. However, the genetic TPMT polymorphism does not explain all 6-MP adverse events and some severe toxicities leading to life-threatening conditions remain unexplained. Additional single nucleotide polymorphisms (SNPs) in genes encoding enzymes involved in 6-MP metabolism and 6-MP transporters may also be responsible for this inter-individual 6-MP response variability. AIM This review presents the pharmacogenetic aspects of 6-MP metabolism in great detail. We have focused on published data on ALL treatment supporting the great potential of 6-MP pharmacogenetics to improve efficacy, tolerance, and event-free survival rates in children with ALL.
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Ferraldeschi R, Newman WG. Pharmacogenetics and pharmacogenomics: a clinical reality. Ann Clin Biochem 2011; 48:410-7. [DOI: 10.1258/acb.2011.011084] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Deenen MJ, Cats A, Beijnen JH, Schellens JHM. Part 3: Pharmacogenetic variability in phase II anticancer drug metabolism. Oncologist 2011; 16:992-1005. [PMID: 21659608 DOI: 10.1634/theoncologist.2010-0260] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Equivalent drug doses may lead to wide interpatient variability in drug response to anticancer therapy. Known determinants that may affect the pharmacological response to a drug are, among others, nongenetic factors, including age, gender, use of comedication, and liver and renal function. Nonetheless, these covariates do not explain all the observed interpatient variability. Differences in genetic constitution among patients have been identified to be important factors that contribute to differences in drug response. Because genetic polymorphism may affect the expression and activity of proteins encoded, it is a key covariate that is responsible for variability in drug metabolism, drug transport, and pharmacodynamic drug effects. We present a series of four reviews about pharmacogenetic variability. This third part in the series of reviews is focused on genetic variability in phase II drug-metabolizing enzymes (glutathione S-transferases, uridine diphosphoglucuronosyl transferases, methyltransferases, sulfotransferases, and N-acetyltransferases) and discusses the effects of genetic polymorphism within the genes encoding these enzymes on anticancer drug therapy outcome. Based on the literature reviewed, opportunities for patient-tailored anticancer therapy are proposed.
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Affiliation(s)
- Maarten J Deenen
- The Netherlands Cancer Institute, Department of Medical Oncology, Amsterdam, The Netherlands
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Bhatia S. Disparities in cancer outcomes: lessons learned from children with cancer. Pediatr Blood Cancer 2011; 56:994-1002. [PMID: 21328525 PMCID: PMC3369622 DOI: 10.1002/pbc.23078] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Accepted: 01/18/2011] [Indexed: 11/05/2022]
Abstract
Disparities in cancer burden by race/ethnicity have been reported, primarily in adults with cancer. However, there appear to be gaps in the pediatric oncology literature with regards to a comprehensive overview on this topic. Extant literature is used to highlight the results of studies focusing on racial and ethnic disparities in outcome observed in selected childhood cancers. A comprehensive approach is utilized to understand possible underlying causes of disparities in cancer outcomes, and to highlight the gaps that currently exist. This review helps define areas of future research that could help develop targeted, disease-specific approaches to eliminate the disparities.
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Affiliation(s)
- Smita Bhatia
- Department of Population Sciences, City of Hope, Duarte, CA 91010, USA.
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Newman WG, Payne K, Tricker K, Roberts SA, Fargher E, Pushpakom S, Alder JE, Sidgwick GP, Payne D, Elliott RA, Heise M, Elles R, Ramsden SC, Andrews J, Houston JB, Qasim F, Shaffer J, Griffiths CEM, Ray DW, Bruce I, Ollier WER. A pragmatic randomized controlled trial of thiopurine methyltransferase genotyping prior to azathioprine treatment: the TARGET study. Pharmacogenomics 2011; 12:815-26. [PMID: 21692613 DOI: 10.2217/pgs.11.32] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
AIM To conduct a pragmatic, randomized controlled trial to assess whether thiopurine methyltransferase (TPMT) genotyping prior to azathioprine reduces adverse drug reactions (ADRs). METHODS A total of 333 participants were randomized 1:1 to undergo TPMT genotyping prior to azathioprine or to commence treatment without genotyping. RESULTS There was no difference in the primary outcome of stopping azathioprine due to an adverse reaction (ADR, p = 0.59) between the two study arms. ADRs were more common in older patients (p = 0.01). There was no increase in stopping azathioprine due to ADRs in TPMT heterozygotes compared with wild-type individuals. The single individual with TPMT variant homozygosity experienced severe neutropenia. CONCLUSION Our work supports the strong evidence that individuals with TPMT variant homozygosity are at high risk of severe neutropenia, whereas TPMT heterozygotes are not at increased risk of ADRs at standard doses of azathioprine.
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Affiliation(s)
- William G Newman
- Genetic Medicine, Manchester Academic Health Science Centre (MAHSC), University of Manchester and Central Manchester NHS Foundation Trust, UK.
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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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Schmajuk G, Yazdany J. Drug monitoring in systemic lupus erythematosus: a systematic review. Semin Arthritis Rheum 2010; 40:559-75. [PMID: 21030066 DOI: 10.1016/j.semarthrit.2010.07.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 07/27/2010] [Accepted: 07/29/2010] [Indexed: 12/16/2022]
Abstract
OBJECTIVES To conduct an evidence-based review of the common medication toxicities and strategies and utility of drug toxicity monitoring among patients with systemic lupus erythematosus (SLE). METHODS PubMed and other databases were searched for articles published between the years 1960 and 2010 for keywords referring to medication toxicity or monitoring strategies for 7 drugs commonly used in SLE. All relevant English-language articles were reviewed. Most of the evidence we reviewed comprised studies that addressed the incidence of toxicity-randomized trials that compare different monitoring strategies for these drugs do not exist. RESULTS Data to describe the frequency of adverse events and appropriate strategies for screening for these events are scarce. Toxicities do not appear to be substantially more common among patients with SLE compared to other conditions for which these drugs are used. CONCLUSIONS Our review demonstrates that the scientific basis for many aspects of drug toxicity monitoring is weak and that most current recommendations are based largely on expert consensus. We present a future research agenda to address these gaps.
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Affiliation(s)
- Gabriela Schmajuk
- Department of Medicine, Division of Rheumatology, Stanford University, CA, USA.
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Hanai H, Iida T, Takeuchi K, Arai O, Watanabe F, Abe J, Maruyama Y, Oohata A, Ikeya K, Kageoka M, Miwa I, Yoshirou S, Hosoda Y, Kubota T. Thiopurine maintenance therapy for ulcerative colitis: the clinical significance of monitoring 6-thioguanine nucleotide. Inflamm Bowel Dis 2010; 16:1376-81. [PMID: 20049951 DOI: 10.1002/ibd.21190] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
BACKGROUND 6-Mercaptopurine (6-MP) is an effective maintenance medication in patients with ulcerative colitis (UC), but toxic effects like myelosuppression limit its clinical benefit. In the blood, 6-thioguanine (6-TGN) is formed from 6-MP and mediates the therapeutic efficacy and most of the toxicities of 6-MP. The level of 6-TGN depends on the activity of thiopurine methyltransferase (TPMT), inherited as 1 of its 3 polymorphic forms with low, moderate, or normal/high activity. Accordingly, the 6-MP dose needs to be pharmacogenetically guided. METHODS Patients with quiescent UC received 6-MP as maintenance therapy and 6-TGN was assayed as its concentrations in red blood cells (RBCs) done by high-performance liquid chromatography. In a preliminary investigation, 30 mg/day 6-MP (n = 50) was given orally over 12 weeks to determine the time course of blood 6-TGN level. Then 257 patients were given 6-MP at 15-80 mg/day in a stepwise manner based on RBC 6-TGN, white blood cell count, and body weight to monitor 6-MP efficacy and safety profiles. RESULTS At 30 mg/day 6-MP, RBC 6-TGN peaked over 4-8 weeks. In the main dosing study, the mean RBC 6-TGN level in patients who remained in remission during the 1-year observation time (n = 151) was 322.3 +/- 119.5 pmole/8 x 10(8) RBC versus 204.8 +/- 78.7 pmole/8 x 10(8) RBC in patients (n = 19) who relapsed (P < 0.001). Bone marrow suppression was seen almost exclusively at high 6-TGN concentration ranges. Further, a regression plot showed an inverse relationship between 6-TGN levels in RBC and TPMT enzyme activity. CONCLUSIONS By regularly measuring RBC 6-TGN in patients with quiescent UC receiving 6-MP as maintenance therapy, we could monitor bone marrow suppression as well as other toxic side effects. Potentially, this strategy should enable physicians to avoid thiopurine-related adverse effects and identify individuals who may benefit most from 6-MP maintenance therapy.
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Affiliation(s)
- Hiroyuki Hanai
- Centre for Gastroenterology and Inflammatory Bowel Disease Research, Hamamatsu South Hospital, Hamamatsu, Japan.
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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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Fotoohi AK, Coulthard SA, Albertioni F. Thiopurines: factors influencing toxicity and response. Biochem Pharmacol 2010; 79:1211-20. [PMID: 20096268 DOI: 10.1016/j.bcp.2010.01.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 12/22/2009] [Accepted: 01/12/2010] [Indexed: 11/17/2022]
Abstract
Thiopurines are the backbone of current anti-leukemia regimens and have also been effective immunosuppressive agents for the past half a century. Extensive research on their mechanism of action has been undertaken, yet many issues remain to be addressed to resolve unexplained cases of thiopurine toxicity or treatment failure. The aim of this review is to summarize current knowledge of the mechanism of thiopurine action in experimental models and put into context with clinical observations. Clear understanding of their metabolism will contribute to maximizing efficacy and minimizing toxicity by individually tailoring therapy according to the expression profile of relevant factors involved in thiopurine activation pathway.
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Affiliation(s)
- Alan Kambiz Fotoohi
- Department of Oncology and Pathology, Cancer Center Karolinska, Karolinska Institutet, SE-17176 Stockholm, Sweden
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Nasedkina TV, Guseva NA, Gra OA, Mityaeva ON, Chudinov AV, Zasedatelev AS. Diagnostic microarrays in hematologic oncology: applications of high- and low-density arrays. Mol Diagn Ther 2009; 13:91-102. [PMID: 19537844 DOI: 10.1007/bf03256318] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Microarrays have become important tools for high-throughput analysis of gene expression, chromosome aberrations, and gene mutations in cancer cells. In addition to high-density experimental microarrays, low-density, gel-based biochip technology represents a versatile platform for translation of research into clinical practice. Gel-based microarrays (biochips) consist of nanoliter gel drops on a hydrophobic surface with different immobilized biopolymers (primarily nucleic acids and proteins). Because of the high immobilization capacity of the gel, such biochips have a high probe concentration and high levels of fluorescence signals after hybridization, which allow the use of simple, portable detection systems. The notable accuracy of the analysis is reached as a result of the high level of discrimination between positive and negative gel-bound probes. Different applications of biochips in the field of hematologic oncology include analysis of chromosomal translocations in leukemias, diagnostics of T-cell lymphomas, and pharmacogenetics.
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Affiliation(s)
- Tatyana V Nasedkina
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia.
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