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Spano D, Catara G. Targeting the Ubiquitin-Proteasome System and Recent Advances in Cancer Therapy. Cells 2023; 13:29. [PMID: 38201233 PMCID: PMC10778545 DOI: 10.3390/cells13010029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/12/2023] [Accepted: 12/20/2023] [Indexed: 01/12/2024] Open
Abstract
Ubiquitination is a reversible post-translational modification based on the chemical addition of ubiquitin to proteins with regulatory effects on various signaling pathways. Ubiquitination can alter the molecular functions of tagged substrates with respect to protein turnover, biological activity, subcellular localization or protein-protein interaction. As a result, a wide variety of cellular processes are under ubiquitination-mediated control, contributing to the maintenance of cellular homeostasis. It follows that the dysregulation of ubiquitination reactions plays a relevant role in the pathogenic states of human diseases such as neurodegenerative diseases, immune-related pathologies and cancer. In recent decades, the enzymes of the ubiquitin-proteasome system (UPS), including E3 ubiquitin ligases and deubiquitinases (DUBs), have attracted attention as novel druggable targets for the development of new anticancer therapeutic approaches. This perspective article summarizes the peculiarities shared by the enzymes involved in the ubiquitination reaction which, when deregulated, can lead to tumorigenesis. Accordingly, an overview of the main pharmacological interventions based on targeting the UPS that are in clinical use or still in clinical trials is provided, also highlighting the limitations of the therapeutic efficacy of these approaches. Therefore, various attempts to circumvent drug resistance and side effects as well as UPS-related emerging technologies in anticancer therapeutics are discussed.
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Affiliation(s)
- Daniela Spano
- Institute for Endocrinology and Experimental Oncology “G. Salvatore”, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
| | - Giuliana Catara
- Institute of Biochemistry and Cell Biology, National Research Council, Via Pietro Castellino 111, 80131 Naples, Italy
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2
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Shipman KE, Shipman AR, Marinaki AM. Genotyping before azathioprine administration in dermatology. Clin Exp Dermatol 2021; 47:503-504. [PMID: 34609021 DOI: 10.1111/ced.14915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/25/2021] [Indexed: 11/26/2022]
Affiliation(s)
- K E Shipman
- Department of Clinical Chemistry, University Hospitals Sussex, Worthing Hospital, Worthing, UK
| | - A R Shipman
- Department of Dermatology, St Mary's Hospital, Portsmouth, UK
| | - A M Marinaki
- Purine Research Laboratory, Viapath, St Thomas' Hospital, London, UK
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Maggiore U, Palmisano A, Buti S, Claire Giudice G, Cattaneo D, Giuliani N, Fiaccadori E, Gandolfini I, Cravedi P. Chemotherapy, targeted therapy and immunotherapy: Which drugs can be safely used in the solid organ transplant recipients? Transpl Int 2021; 34:2442-2458. [PMID: 34555228 PMCID: PMC9298293 DOI: 10.1111/tri.14115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 08/04/2021] [Accepted: 09/03/2021] [Indexed: 11/29/2022]
Abstract
In solid organ transplant recipients, cancer is associated with worse prognosis than in the general population. Among the causes of increased cancer‐associated mortality, are the limitations in selecting the optimal anticancer regimen in solid organ transplant recipients, because of the associated risks of graft toxicity and rejection, drug‐to‐drug interactions, reduced kidney or liver function, and patient frailty and comorbid conditions. The advent of immunotherapy has generated further challenges, mainly because checkpoint inhibitors increase the risk of rejection, which may have life‐threatening consequences in recipients of life‐saving organs. In general, there are no safe or unsafe anticancer drugs. Rather, the optimal choice of the anticancer regimen results from a careful risk/benefit assessment, from the awareness of potential pharmacokinetic and pharmacodynamic drug‐to‐drug interactions, and of the risk of drug overexposure in patients with kidney or liver dysfunction. In this review, we summarize general principles that may help the oncologists and transplant physicians in the multidisciplinary management of recipients of solid organ transplantation with cancer who are candidates for chemotherapy, targeted therapy, or immunotherapy.
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Affiliation(s)
- Umberto Maggiore
- Department of Medicine and Surgery, University of Parma, Parma, Italy.,Nephrology Unit, University Hospital of Parma, Parma, Italy
| | | | - Sebastiano Buti
- Medical Oncology Unit, University Hospital of Parma, Parma, Italy
| | | | - Dario Cattaneo
- Unit of Clinical Pharmacology, ASST Fatebenefratelli Sacco University Hospital, Milan, Italy
| | - Nicola Giuliani
- Department of Medicine and Surgery, University of Parma, Parma, Italy.,Hematology Unit, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
| | - Enrico Fiaccadori
- Department of Medicine and Surgery, University of Parma, Parma, Italy.,Nephrology Unit, University Hospital of Parma, Parma, Italy
| | - Ilaria Gandolfini
- Department of Medicine and Surgery, University of Parma, Parma, Italy.,Nephrology Unit, University Hospital of Parma, Parma, Italy
| | - Paolo Cravedi
- Renal Division, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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Jena A, Jha DK, Kumar-M P, Kasudhan KS, Kumar A, Sarwal D, Mishra S, Singh AK, Bhatia P, Patil A, Sharma V. Prevalence of polymorphisms in thiopurine metabolism and association with adverse outcomes: a South Asian region-specific systematic review and meta-analysis. Expert Rev Clin Pharmacol 2021; 14:491-501. [PMID: 33682590 DOI: 10.1080/17512433.2021.1900729] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Background: Prevalence and impact of thiopurine S-methyltransferase (TPMT) and Nudix hydrolase (NUDT15) minor allele frequencies in South Asian population is unclear.Methods: We searched PubMed and Embase with keywords-TPMT and NUDT15 combined with South Asian countries. We included studies reporting frequency of TPMT and NUDT15 polymorphisms. We estimated the pooled prevalence of TPMT and NUDT15 polymorphisms and their impact on pooled odds ratio of adverse events with thiopurines.Results: We included 26 studies in our analysis. The pooled prevalence of NUDT15 and TPMT polymorphisms was 16.5% (95% CI: 13.09-20.58) and 4.57% (95% CI: 3.66-5.68), respectively. In patients with adverse effects, the pooled prevalence of NUDT15 and TPMT polymorphism was 49.51% (95% C.I. 21.69-77.64) and 9.47% (95% C.I. 5.39-16.11), respectively. The odds ratio (OR) of adverse events with presence of TPMT polymorphisms was 3.65 (95% C.I., 1.43-9.28). The pooled OR for adverse events in presence of NUDT15 polymorphism was 12.63 (95% C.I., 3.68-43.26).Conclusion: NUDT15 were reported more frequently than the TPMT polymorphisms in South Asian population and were more frequently associated with adverse events. These findings may have implications for preemptive testing amongst South Asian population and immigrants prior to starting thiopurines.
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Affiliation(s)
- Anuraag Jena
- Department of Gastroenterology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Daya Krishna Jha
- Department of Gastroenterology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Praveen Kumar-M
- Department of Pharmacology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Kripa Shanker Kasudhan
- Department of Pharmacology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Ankit Kumar
- Department of Pharmacology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Dhruv Sarwal
- Government Medical College and hospital- Sector 32, Ex-intern, Chandigarh, India
| | - Shubhra Mishra
- Department of Gastroenterology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Anupam Kumar Singh
- Department of Gastroenterology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Prateek Bhatia
- Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Amol Patil
- Department of Pharmacology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Vishal Sharma
- Department of Gastroenterology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
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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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Severe pancytopenia and aspergillosis caused by thioguanine in a thiopurine S-methyltransferase deficient patient: a case report. Eur J Gastroenterol Hepatol 2019; 31:1592-1596. [PMID: 31464791 DOI: 10.1097/meg.0000000000001504] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Azathioprine and mercaptopurine are widely used in the treatment of inflammatory bowel disease. However, its use is limited by adverse drug event related to the relatively narrow therapeutic index of the active metabolites. Several patients discontinue treatment because of intolerable adverse events or toxicity such as leucopenia and hepatotoxicity. High 6-thioguanine nucleotides and 6-methylmercaptopurine ribonucleotides levels are associated with toxicity. Variations in the thiopurine S-methyltransferase (TPMT) gene can lead to diminished TPMT enzyme activity and to an increased incidence of myelotoxicity due to high 6-methylmercaptopurine ribonucleotides levels after treatment with azathioprine and mercaptopurine. Unlike azathioprine and mercaptopurine, thioguanine is more directly metabolized to the active metabolites without formation of the toxic 6-methylmercaptopurine ribonucleotides. Taking this into account, it seems likely that thioguanine is less associated with myelotoxicity due to TPMT deficiency. However, we report the case of a Crohn's disease patient with life-threatening complications on 6TG treatment due to TPMT deficiency. Our patient developed a severe pancytopenia on thioguanine therapy, with 6-thioguanine nucleotides levels more than 10 times higher than the upper limit of the therapeutic window and was found to be a TPMT poor metabolizer (TPMT *3A/*3A). This case strongly illustrates that knowledge of TPMT enzyme activity is very important in the use of all thiopurines, including thioguanine. In conclusion, clinicians should be aware of the impact of TPMT deficiency on the metabolism of thioguanine and should consider performing preemptive TPMT genotyping in combination with frequent blood test monitoring when using thiopurines in general.
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Derijks LJJ, Wong DR, Hommes DW, van Bodegraven AA. Clinical Pharmacokinetic and Pharmacodynamic Considerations in the Treatment of Inflammatory Bowel Disease. Clin Pharmacokinet 2019; 57:1075-1106. [PMID: 29512050 DOI: 10.1007/s40262-018-0639-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
According to recent clinical consensus, pharmacotherapy of inflammatory bowel disease (IBD) is, or should be, personalized medicine. IBD treatment is complex, with highly different treatment classes and relatively few data on treatment strategy. Although thorough evidence-based international IBD guidelines currently exist, appropriate drug and dose choice remains challenging as many disease (disease type, location of disease, disease activity and course, extraintestinal manifestations, complications) and patient characteristics [(pharmaco-)genetic predisposition, response to previous medications, side-effect profile, necessary onset of response, convenience, concurrent therapy, adherence to (maintenance) therapy] are involved. Detailed pharmacological knowledge of the IBD drug arsenal is essential for choosing the right drug, in the right dose, in the right administration form, at the right time, for each individual patient. In this in-depth review, clinical pharmacodynamic and pharmacokinetic considerations are provided for tailoring treatment with the most common IBD drugs. Development (with consequent prospective validation) of easy-to-use treatment algorithms based on these considerations and new pharmacological data may facilitate optimal and effective IBD treatment, preferably corroborated by effectiveness and safety registries.
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Affiliation(s)
- Luc J J Derijks
- Department of Clinical Pharmacy and Pharmacology, Máxima Medical Center, PO Box 7777, 5500 MB, Veldhoven, The Netherlands.
| | - Dennis R Wong
- Department of Clinical Pharmacy, Pharmacology and Toxicology, Zuyderland Medical Center, Sittard-Geleen, The Netherlands
| | - Daniel W Hommes
- Center for Inflammatory Bowel Diseases, UCLA, Los Angeles, CA, USA
| | - Adriaan A van Bodegraven
- Department of Gastroenterology, Zuyderland Medical Center, Sittard-Geleen, The Netherlands
- Department of Gastroenterology, VU University Medical Center, Amsterdam, The Netherlands
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Al-Eitan LN, Mohammad NN, Al-Maqableh HW, Hakooz NM, Dajani RB. Genetic Polymorphisms of Pharmacogenomic VIP Variants in the Circassian Subpopulation from Jordan. Curr Drug Metab 2019; 20:674-681. [PMID: 31362667 DOI: 10.2174/1389200220666190729124000] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 05/27/2019] [Accepted: 07/01/2019] [Indexed: 12/11/2022]
Abstract
BACKGROUND It has been suggested that genetic variation within candidate pharmacogenes contributes to the differences in drug safety and efficacy as well as risk of adverse drug reactions among different ethnic groups. Illustrating the polymorphic distribution of Very Important Pharmacogenes (VIPs) in various ethnic groups will contribute to the development of personalized medicine for those populations. OBJECTIVE The present study aimed to identify the polymorphic distribution of VIPs in the Circassian subpopulation of Jordan and compare their allele frequencies with those of other populations. METHODS A total of 130 healthy and unrelated Circassian adults from Jordan were randomly recruited and genotyped for eleven VIP variants within the thiopurine S-methyltransferase (TPMT), ATP-binding cassette, sub-family B, member 1 (ABCB1), and vitamin D receptor (VDR) genes via Sequenom's MassARRAY® genotyping platform (iPLEX GOLD). RESULTS Our data on the allelic frequencies of the investigated VIP variants were compared to those of 18 other populations, comprising 11 HapMap populations, 6 Exome Aggregation Consortium populations, and the Chechen- Jordanian population from Jordan. Circassian-Jordanians were found to most resemble the African, Chechen- Jordanian, European (Finnish), European (non-Finnish), and South-Asian populations. CONCLUSION Circassians from Jordan significantly differ from other populations in terms of the allelic frequencies of selected VIP variants. The present findings constitute the first set of pharmacogenetic data for Circassian population from Jordan, providing a basis for safe drug administration that may be useful in diagnosing and treating diseases in this ethnic group.
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Affiliation(s)
- Laith N Al-Eitan
- Department of Applied Biological Sciences, Jordan University of Science and Technology, Irbid 22110, Jordan.,Department of Biotechnology and Genetic Engineering, Jordan University of Science and Technology, Irbid 22110, Jordan
| | - Namarg N Mohammad
- Department of Applied Biological Sciences, Jordan University of Science and Technology, Irbid 22110, Jordan
| | - Haneen W Al-Maqableh
- Department of Biology and Biotechnology, Hashemite University, Zarqa 13133, Jordan
| | - Nancy M Hakooz
- Department of Biopharmaceutics and Clinical Pharmacy, School of Pharmacy, University of Jordan, Amman 11942, Jordan
| | - Rana B Dajani
- Department of Biology and Biotechnology, Hashemite University, Zarqa 13133, Jordan.,Radcliffe Institute for Advanced Studies, Harvard University, Cambridge, 02138 MA, United States
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Toksvang LN, Schmidt MS, Arup S, Larsen RH, Frandsen TL, Schmiegelow K, Rank CU. Hepatotoxicity during 6-thioguanine treatment in inflammatory bowel disease and childhood acute lymphoblastic leukaemia: A systematic review. PLoS One 2019; 14:e0212157. [PMID: 31125338 PMCID: PMC6534292 DOI: 10.1371/journal.pone.0212157] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 04/18/2019] [Indexed: 12/14/2022] Open
Abstract
Background The recently established association between higher levels of DNA-incorporated thioguanine nucleotides and lower relapse risk in childhood acute lymphoblastic leukaemia (ALL) calls for reassessment of prolonged 6-thioguanine (6TG) treatment, while avoiding the risk of hepatotoxicity. Objectives To assess the incidence of hepatotoxicity in patients treated with 6TG, and to explore if a safe dose of continuous 6TG can be established. Data sources Databases, conference proceedings, and reference lists of included studies were systematically searched for 6TG and synonyms from 1998–2018. Methods We included studies of patients with ALL or inflammatory bowel disorder (IBD) treated with 6TG, excluding studies with 6TG as part of an intensive chemotherapy regimen. We uploaded a protocol to PROSPERO (registration number CRD42018089424). Database and manual searches yielded 1823 unique records. Of these, 395 full-texts were screened for eligibility. Finally, 134 reports representing 42 studies were included. Results and conclusions We included data from 42 studies of ALL and IBD patients; four randomised controlled trials (RCTs) including 3,993 patients, 20 observational studies including 796 patients, and 18 case reports including 60 patients. Hepatotoxicity in the form of sinusoidal obstruction syndrome (SOS) occurred in 9–25% of the ALL patients in two of the four included RCTs using 6TG doses of 40–60 mg/m2/day, and long-term hepatotoxicity in the form of nodular regenerative hyperplasia (NRH) was reported in 2.5%. In IBD patients treated with 6TG doses of approximately 23 mg/m2/day, NRH occurred in 14% of patients. At a 6TG dose of approximately 12 mg/m2/day, NRH was reported in 6% of IBD patients, which is similar to the background incidence. According to this review, doses at or below 12 mg/m2/day are rarely associated with notable hepatotoxicity and can probably be considered safe.
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Affiliation(s)
- Linea Natalie Toksvang
- Department of Paediatrics and Adolescent Medicine, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Magnus Strøh Schmidt
- Department of Paediatrics and Adolescent Medicine, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Sofie Arup
- Department of Paediatrics and Adolescent Medicine, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Rikke Hebo Larsen
- Department of Paediatrics and Adolescent Medicine, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Leth Frandsen
- Department of Paediatrics and Adolescent Medicine, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Kjeld Schmiegelow
- Department of Paediatrics and Adolescent Medicine, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Institute of Clinical Medicine, The Faculty of Medicine, University of Copenhagen, Copenhagen, Denmark
- * E-mail:
| | - Cecilie Utke Rank
- Department of Haematology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Paediatric Oncology Research Laboratory, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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Rucci F, Cigoli MS, Marini V, Fucile C, Mattioli F, Robbiano L, Cavallari U, Scaglione F, Perno CF, Penco S, Marocchi A. Combined evaluation of genotype and phenotype of thiopurine S-methyltransferase (TPMT) in the clinical management of patients in chronic therapy with azathioprine. Drug Metab Pers Ther 2019; 34:dmpt-2018-0037. [PMID: 30840585 DOI: 10.1515/dmpt-2018-0037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 01/29/2019] [Indexed: 06/09/2023]
Abstract
Background The thiopurine S-methyltransferase (TPMT)/azathioprine (AZA) gene-drug pair is one of the most well-known pharmacogenetic markers. Despite this, few studies investigated the implementation of TPMT testing and the combined evaluation of genotype and phenotype in multidisciplinary clinical settings where patients are undergoing chronic therapy with AZA. Methods A total of 356 AZA-treated patients for chronic autoimmune diseases were enrolled. DNA was isolated from whole blood and the samples were analyzed for the c.460G>A and c.719A>G variants by the restriction fragment length polymorphism (RFLP) technique and sequenced for the c.238G>C variant. The TPMT enzyme activity was determined in erythrocytes by a high-performance liquid chromatography (HPLC) assay. Results All the patients enrolled were genotyped while the TPMT enzyme activity was assessed in 41 patients. Clinical information was available on 181 patients. We found no significant difference in the odds of having adverse drug reactions (ADRs) in wild-type patients and variant allele carriers, but the latter had an extra risk of experiencing hematologically adverse events. The enzyme activity was significantly associated to genotype. Conclusions TPMT variant allele carriers have an extra risk of experiencing hematologically adverse events compared to wild-type patients. Interestingly, only two out of 30 (6.6%) patients had discordant results between genotype, phenotype and onset of ADRs.
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Affiliation(s)
- Francesco Rucci
- Department of Laboratory Medicine, Medical Genetics, ASST Niguarda Hospital, Piazza Ospedale Maggiore, 3-20162 - Milan, Italy, Tel. +39 0264442803
- University of Milan, Department of Oncology and Onco-Hematology, Postgraduate School of Clinical Pharmacology and Toxicology, Milan, Italy
| | - Maria Sole Cigoli
- Department of Laboratory Medicine, Medical Genetics, ASST Niguarda Hospital, Milan, Italy
| | - Valeria Marini
- Department of Internal Medicine, University of Genova, Genova, Italy
| | - Carmen Fucile
- Department of Internal Medicine, University of Genova, Genova, Italy
| | | | - Luigi Robbiano
- Department of Internal Medicine, University of Genova, Genova, Italy
| | - Ugo Cavallari
- Department of Laboratory Medicine, Medical Genetics, ASST Niguarda Hospital, Milan, Italy
| | - Francesco Scaglione
- University of Milan, Department of Oncology and Onco-Hematology, Postgraduate School of Clinical Pharmacology and Toxicology, Milan, Italy
| | - Carlo F Perno
- Department of Laboratory Medicine, ASST Niguarda Hospital, Milan, Italy
| | - Silvana Penco
- Department of Laboratory Medicine, Medical Genetics, ASST Niguarda Hospital, Milan, Italy
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Saiz-Rodríguez M, Ochoa D, Belmonte C, Román M, Martínez-Ingelmo C, Ortega-Ruíz L, Sarmiento-Iglesias C, Herrador C, Abad-Santos F. Influence of thiopurine S-methyltransferase polymorphisms in mercaptopurine pharmacokinetics in healthy volunteers. Basic Clin Pharmacol Toxicol 2018; 124:449-455. [PMID: 30346660 DOI: 10.1111/bcpt.13153] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 10/14/2018] [Indexed: 12/29/2022]
Abstract
Mercaptopurine is a drug commonly used in the treatment of different types of cancer, especially acute lymphoblastic leukaemia, and autoimmune diseases such as ulcerative colitis or Crohn's disease and in patients receiving organ transplants. It is metabolized by three cytosolic enzymes. One of them, thiopurine S-methyltransferase (TPMT), is responsible for catalysing the methylation reaction of mercaptopurine to 6-methylmercaptopurine, thus inactivating the drug. Individuals with TPMT loss-of-function alleles (*2, *3A, *3B or *3C) can be extremely sensitive to the effect of mercaptopurine, since it can be accumulated, therefore producing haematological toxicity. The objective of this study was to evaluate the role of TPMT polymorphisms on the pharmacokinetics of mercaptopurine. For that purpose, we used collected pharmacokinetic data from 48 healthy volunteers (all males) who received a single oral dose of mercaptopurine 50 mg in two bioequivalence studies. The volunteers were subsequently genotyped for TPMT *2, *3A, *3B and *3C alleles by real-time PCR. There were four carriers (8.3%) of TPMT*2 and TPMT*3A alleles. Mercaptopurine elimination was affected by TPMT loss-of-function polymorphisms, since heterozygous subjects show 18% higher half-life compared to wild-type individuals. This fact is consistent with the expected since the presence of loss-of-function alleles decreases TPMT enzymatic activity and, thus, affects mercaptopurine elimination. Moreover, mercaptopurine pharmacokinetic parameters were different among races, since Latins showed higher plasma concentrations and lower clearance compared to Caucasians. This fact might be due to a different distribution of polymorphisms in genes, other than TPMT, that also influence the pharmacokinetics of mercaptopurine.
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Affiliation(s)
- Miriam Saiz-Rodríguez
- Clinical Pharmacology Department, Instituto Teófilo Hernando, Instituto de Investigación Sanitaria La Princesa (IP), Universidad Autónoma de Madrid (UAM), Hospital Universitario de La Princesa, Madrid, Spain
| | - Dolores Ochoa
- Clinical Pharmacology Department, Instituto Teófilo Hernando, Instituto de Investigación Sanitaria La Princesa (IP), Universidad Autónoma de Madrid (UAM), Hospital Universitario de La Princesa, Madrid, Spain.,UICEC Hospital Universitario de La Princesa, Plataforma SCReN (Spanish Clinical Research Network), Instituto de Investigación Sanitaria La Princesa (IP), Madrid, Spain
| | - Carmen Belmonte
- Clinical Pharmacology Department, Instituto Teófilo Hernando, Instituto de Investigación Sanitaria La Princesa (IP), Universidad Autónoma de Madrid (UAM), Hospital Universitario de La Princesa, Madrid, Spain.,UICEC Hospital Universitario de La Princesa, Plataforma SCReN (Spanish Clinical Research Network), Instituto de Investigación Sanitaria La Princesa (IP), Madrid, Spain
| | - Manuel Román
- Clinical Pharmacology Department, Instituto Teófilo Hernando, Instituto de Investigación Sanitaria La Princesa (IP), Universidad Autónoma de Madrid (UAM), Hospital Universitario de La Princesa, Madrid, Spain.,UICEC Hospital Universitario de La Princesa, Plataforma SCReN (Spanish Clinical Research Network), Instituto de Investigación Sanitaria La Princesa (IP), Madrid, Spain
| | - Cristina Martínez-Ingelmo
- Clinical Pharmacology Department, Instituto Teófilo Hernando, Instituto de Investigación Sanitaria La Princesa (IP), Universidad Autónoma de Madrid (UAM), Hospital Universitario de La Princesa, Madrid, Spain
| | - Lucía Ortega-Ruíz
- Clinical Pharmacology Department, Instituto Teófilo Hernando, Instituto de Investigación Sanitaria La Princesa (IP), Universidad Autónoma de Madrid (UAM), Hospital Universitario de La Princesa, Madrid, Spain
| | - Carmen Sarmiento-Iglesias
- Clinical Pharmacology Department, Instituto Teófilo Hernando, Instituto de Investigación Sanitaria La Princesa (IP), Universidad Autónoma de Madrid (UAM), Hospital Universitario de La Princesa, Madrid, Spain
| | - Coral Herrador
- Clinical Pharmacology Department, Instituto Teófilo Hernando, Instituto de Investigación Sanitaria La Princesa (IP), Universidad Autónoma de Madrid (UAM), Hospital Universitario de La Princesa, Madrid, Spain
| | - Francisco Abad-Santos
- Clinical Pharmacology Department, Instituto Teófilo Hernando, Instituto de Investigación Sanitaria La Princesa (IP), Universidad Autónoma de Madrid (UAM), Hospital Universitario de La Princesa, Madrid, Spain.,UICEC Hospital Universitario de La Princesa, Plataforma SCReN (Spanish Clinical Research Network), Instituto de Investigación Sanitaria La Princesa (IP), Madrid, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain
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Ma J, Sies CW, Pike LS. Analytical and clinical validation of an LC-MS/MS method to measure thiopurine S-methyltransferase activity by quantifying d3-6-MMP. Clin Biochem 2018; 54:100-105. [PMID: 29425801 DOI: 10.1016/j.clinbiochem.2018.02.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Revised: 01/31/2018] [Accepted: 02/04/2018] [Indexed: 10/18/2022]
Abstract
BACKGROUND Identification of patients with thiopurine S-methyltransferase (TPMT) deficiency prior to thiopurine drug therapy has become routine clinical practice worldwide. To measure TPMT activity, traditional radiochemical assays have been replaced by chromatographic methods. METHOD Inspired by the increasing number of isotope labelled sources that may be of benefit for the TPMT assay, a new LC-MS/MS method for TPMT activity was developed and validated. Isotope labelled d3-S-adenosyl-l-methionine (d3-SAM) was selected for the enzymatic methylation of mercaptopurine during sample incubation; d3-6-methylmercaptopurine (d3-6-MMP) with d2-2, 8-hypoxanthine as the internal standard was quantified to ascertain individual TPMT activity. RESULTS The validation of the analytical part of this method showed good linearity (coefficient of determination 0.9999 in the range of 1-500 ng/mL) with the intra-and inter-day impression CV% between 7.6% and 9.1% and 3.7% and 9.2%, respectively. Recovery ranged from 94.9% to 112.3%. The specificity of the enzymatic reaction was validated by using 108 clinical check samples. After compared with traditional radiochemical assay and genotype results, all homozygous and heterozygous deficiency clinical checks fitted into the nominal groups, inter-batch and intra-batch impression CV% were between 2.3% and 9.7%. CONCLUSION With the inclusion of isotope labelled substrate, interfering non-enzymatic methylation no longer results in potential false assignment of abnormal patients. Furthermore, the method can be applied to patients who have already been prescribed thiopurine drugs. This new LC-MS/MS is therefore a favourable clinical routine application to test TPMT activity, as it shows excellent performance in identifying patients with TPMT deficiency.
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Affiliation(s)
- Jing Ma
- Specialist Chemistry, Canterbury Health Laboratories, Christchurch, New Zealand.
| | - Christiaan W Sies
- Specialist Chemistry, Canterbury Health Laboratories, Christchurch, New Zealand.
| | - Linda S Pike
- Specialist Chemistry, Canterbury Health Laboratories, Christchurch, New Zealand.
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13
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Ramirez-Florencio M, Jiménez-Morales S, Barbosa-Cobos RE, López-Cano DJ, Ramírez-Bello J. High frequency of mutant thiopurine S-methyltransferase genotypes in Mexican patients with systemic lupus erythematosus and rheumatoid arthritis. Clin Rheumatol 2017; 37:963-970. [PMID: 29264794 DOI: 10.1007/s10067-017-3955-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 11/24/2017] [Accepted: 12/12/2017] [Indexed: 12/20/2022]
Abstract
Systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) are treated with immunosuppressive purine analogs, 6-mercaptopurine/6-thioguanine/azathiopurine, which are inactivated by thiopurine S-methyltransferase (TPMT). Non-synonymous polymorphisms in TPMT are associated with increased risk of adverse effects in patients treated with thiopurines. This study aimed to determine the frequency of the most common mutant TPMT alleles in Mexican patients with SLE (a prototype autoimmune disease) and RA (one of the most common autoimmune diseases in Mexico). Five hundred fifty-three consecutive patients from Central Mexico with SLE (178) and RA (375) were included. Subjects were genotyped to identify TPMT*2 (rs1800462), TPMT*3A (rs1800460 and rs1142345), TPMT*3B (rs1800460), and TPMT*3C (rs1142345) mutant alleles. DNA samples were assayed with the 5' exonuclease technique and TaqMan probes. Mutant alleles were detected in 6.2 and 5.2% of SLE and RA cases, respectively. Of note, 12.4% of SLE cases and 10.1% of RA cases carried mutant genotypes. Among those, the null genotype (TPMT*2/*3A, 0.3%) and the TPMT*3B (0.5%) and TPMT*3C (1.0%) alleles were found in RA, but not SLE cases. Mexican SLE cases displayed the highest frequency of mutant TPMT genotypes worldwide. TPMT genotyping should be performed for Mexican patients with SLE and RA before prescribing purine analogs.
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Affiliation(s)
- Mireya Ramirez-Florencio
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Periferico Sur 4809, Tlalpan, Arenal Tepepan, 14610, Mexico City, CDMX, Mexico
| | - Silvia Jiménez-Morales
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Periferico Sur 4809, Tlalpan, Arenal Tepepan, 14610, Mexico City, CDMX, Mexico.
| | | | - Daniela Josabeth López-Cano
- Unidad de Investigación en Enfermedades Endócrinas y Metabólicas, Hospital Juárez de México, Av. Instituto Politécnico Nacional No. 5160 Delegación Gustavo A. Madero, C.P. 07760, Mexico City, D.F., Mexico
| | - Julian Ramírez-Bello
- Unidad de Investigación en Enfermedades Endócrinas y Metabólicas, Hospital Juárez de México, Av. Instituto Politécnico Nacional No. 5160 Delegación Gustavo A. Madero, C.P. 07760, Mexico City, D.F., Mexico.
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14
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Singh M, Bhatia P, Khera S, Trehan A. Emerging role of NUDT15 polymorphisms in 6-mercaptopurine metabolism and dose related toxicity in acute lymphoblastic leukaemia. Leuk Res 2017; 62:17-22. [DOI: 10.1016/j.leukres.2017.09.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 09/24/2017] [Indexed: 01/28/2023]
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15
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Pranzatelli MR, Tate ED, Allison TJ. 6-Mercaptopurine modifies cerebrospinal fluid T cell abnormalities in paediatric opsoclonus-myoclonus as steroid sparer. Clin Exp Immunol 2017; 190:217-225. [PMID: 28710878 DOI: 10.1111/cei.13015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/12/2017] [Indexed: 11/26/2022] Open
Abstract
The purpose of this study was to evaluate the capacity of 6-mercaptopurine (6-MP), a known immunosuppressant, to normalize cerebrospinal fluid (CSF) lymphocyte frequencies in opsoclonus-myoclonus syndrome (OMS) and function as a steroid sparer. CSF and blood lymphocytes were immunophenotyped in 11 children with OMS (without CSF B cell expansion) using a comprehensive panel of cell surface adhesion, activation and maturation markers by flow cytometry, and referenced to 18 paediatric controls. Drug metabolites, lymphocyte counts and liver function tests were used clinically to monitoring therapeutic range and toxicity. In CSF, adjunctive oral 6-MP was associated with a 21% increase in the low percentage of CD4+ T cells in OMS, restoring the CD4/CD8 ratio. The percentage of CD4+ T cells that were interferon (IFN)-γ+ was reduced by 66%, shifting the cytokine balance away from T helper type 1 (Th1) (proinflammatory) predominance. The percentage of natural killer (NK) cells decreased significantly in CSF (-32%) and blood (-67 to -82%). Low blood absolute lymphocyte count was more predictive of improvement in CSF lymphocyte proportions (correlated with % CD4+ T cells) than the 6-thioguanine level (no correlation). 6-MP was difficult to titrate: 50% achieved the target absolute lymphocyte count (< 1·5 K/mm); 20%, the 'therapeutic' 6-thioguanine level; and 40% the non-toxic 6-methylmercaptopurine level. Side effects and transaminase elevation were mild and reversible. Clinical steroid-sparing properties and lowered relapse frequency were demonstrated. 6-MP displayed unique pharmacodynamic properties that may be useful in OMS and other autoimmune disorders. Its steroid sparer capacity is limited to children in whom the therapeutic window can be reached without limiting pharmacokinetic factors or side effects.
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Affiliation(s)
- M R Pranzatelli
- National Pediatric Neuroinflammation Organization, Inc., the National Pediatric Myoclonus Center, Orlando, FL, USA
| | - E D Tate
- National Pediatric Neuroinflammation Organization, Inc., the National Pediatric Myoclonus Center, Orlando, FL, USA
| | - T J Allison
- National Pediatric Neuroinflammation Organization, Inc., the National Pediatric Myoclonus Center, Orlando, FL, USA
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16
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Pecher D, Dokupilová S, Zelinková Z, Peppelenbosch M, Mikušová V, Mikuš P. Determination of thiopurine S-methyltransferase activity by hydrophilic interaction liquid chromatography hyphenated with mass spectrometry. J Pharm Biomed Anal 2017; 142:244-251. [PMID: 28525791 DOI: 10.1016/j.jpba.2017.05.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Revised: 05/05/2017] [Accepted: 05/08/2017] [Indexed: 12/18/2022]
Abstract
Thiopurine S-methyltransferase (TPMT) plays an important role in the metabolism of thiopurines used in the therapy of inflammatory bowel diseases (IBD). In this work a new progressive method for the determination of TPMT activity in red blood cells lysates was developed. Analysis was carried out by means of hydrophilic interaction liquid chromatography (HILIC) hyphenated with mass spectrometry (MS). In comparison with reversed-phase high-performance liquid chromatography (RP-HPLC), that has been typically applied in determination of TPMT activity, the HILIC significantly improved the analytical signal provided by MS, shortened analysis time, and improved chromatographic resolution. The HILIC-HPLC-MS method was optimized and validated, providing favorable parameters of detection and quantitation limits (5.5 and 16.5pmol/mL, respectively), linearity (coefficient of determination 0.9999 in the range of 0.01-1.0nmol/mL), recovery and precision (93.25-100.37% with RSD 1.06-1.32% in the whole concentration range of QC samples). Moreover, in contrast to the conventional RP-HPLC-UV approach, the complex phenotype TPMT profiles can be reliably and without interferences monitored using the HILIC-HPLC-MS method. Such advanced monitoring can provide valuable detail information on the thiopurines (e.g. evaluating ratio of methylated and non-methylated 6-mercaptopurine) and, by that, TPMT action in biological systems before and during the therapy of IBD.
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Affiliation(s)
- Daniel Pecher
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic; Toxicological and Antidoping center, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic
| | - Svetlana Dokupilová
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic; Toxicological and Antidoping center, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic
| | - Zuzana Zelinková
- Department of Gastroenterology, St Michael's Hospital, Bratislava, Slovak Republic
| | | | - Veronika Mikušová
- Toxicological and Antidoping center, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic; Department of Cell and Molecular Biology of Drugs, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic
| | - Peter Mikuš
- Department of Pharmaceutical Analysis and Nuclear Pharmacy, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic; Toxicological and Antidoping center, Faculty of Pharmacy, Comenius University in Bratislava, Odbojárov 10, SK-832 32 Bratislava, Slovak Republic.
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17
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Jourdil N, Fonrose X, Boulieu R, Stanke-Labesque F. [Not Available]. Therapie 2016; 65:177-86. [PMID: 27392984 DOI: 10.2515/therapie/2010030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Accepted: 03/03/2010] [Indexed: 01/29/2023]
Abstract
Azathioprine, 6-mercaptopurine, and 6-thioguanine are immunosuppressive drugs indicated in the prevention of graft rejection, and treatment of auto-immune disease or inflammatory bowel disease. Their anti-nucleotidic properties are also used for the treatment of acute leukaemia. Their metabolism involves thiopurine methyl transferase, which activity varies according to genetic polymorphisms. In inflammatory bowel disease patients, there is no recommended therapeutic range of intra-erythrocyte 6-thioguanine nucleotide concentration, the active metabolite. Therapeutic drug monitoring of 6-thioguanine nucleotide concentrations is however proposed in the following clinical situations: to check the observance, to try to explain therapeutic failure, to manage patients with limited thiopurine methyl transferase activity or patients treated with associated drugs that can modify thiopurine methyl transferase activity. The literature review shows that high concentrations of 6-thioguanine nucleotides and methylated metabolites are associated with an increased risk of bone marrow toxicity. In addition, high concentrations of methylated metabolite might increase the risk of hepatic toxicity. These major side-effects can be prevented by the use of pre-treatment screening for thiopurine methyl transferase activity or genotype in inflammatory bowel disease patients in order to propose an adapted dosing.
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Affiliation(s)
- Nicole Jourdil
- Laboratoire de Pharmacologie-Toxicologie du CHU de Grenoble, France
| | - Xavier Fonrose
- Laboratoire de Pharmacologie-Toxicologie du CHU de Grenoble, France
| | - Roselyne Boulieu
- Département de Pharmacie Clinique, de Pharmacocinétique et d'Évaluation du Médicament - Inserm ERI 22, Université Lyon 1 et Laboratoire de Pharmacocinétique Clinique, CHU de Lyon, France
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18
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Manzi SF, Fusaro VA, Chadwick L, Brownstein C, Clinton C, Mandl KD, Wolf WA, Hawkins JB. Creating a scalable clinical pharmacogenomics service with automated interpretation and medical record result integration - experience from a pediatric tertiary care facility. J Am Med Inform Assoc 2016; 24:74-80. [PMID: 27301749 DOI: 10.1093/jamia/ocw052] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 02/01/2016] [Accepted: 03/12/2016] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVE This paper outlines the implementation of a comprehensive clinical pharmacogenomics (PGx) service within a pediatric teaching hospital and the integration of clinical decision support in the electronic health record (EHR). MATERIALS AND METHODS An approach to clinical decision support for medication ordering and dispensing driven by documented PGx variant status in an EHR is described. A web-based platform was created to automatically generate a clinical report from either raw assay results or specified diplotypes, able to parse and combine haplotypes into an interpretation for each individual and compared to the reference lab call for accuracy. RESULTS Clinical decision support rules built within an EHR provided guidance to providers for 31 patients (100%) who had actionable PGx variants and were written for interacting medications. A breakdown of the PGx alerts by practitioner service, and alert response for the initial cohort of patients tested is described. In 90% (355/394) of the cases, thiopurine methyltranferase genotyping was ordered pre-emptively. DISCUSSION This paper outlines one approach to implementing a clinical PGx service in a pediatric teaching hospital that cares for a heterogeneous patient population. There is a focus on incorporation of PGx clinical decision support rules and a program to standardize report text within the electronic health record with subsequent exploration of clinician behavior in response to the alerts. CONCLUSION The incorporation of PGx data at the time of prescribing and dispensing, if done correctly, has the potential to impact the incidence of adverse drug events, a significant cause of morbidity and mortality.
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Affiliation(s)
- Shannon F Manzi
- Clinical Pharmacogenomics Service, Boston Children's Hospital, Boston, MA, USA
| | - Vincent A Fusaro
- Clinical Pharmacogenomics Service, Boston Children's Hospital, Boston, MA, USA.,Comptational Health Informatics Program, Boston Children's Hospital, Boston, MA, USA
| | - Laura Chadwick
- Clinical Pharmacogenomics Service, Boston Children's Hospital, Boston, MA, USA.,Massachusetts College of Pharmacy and Allied Health Sciences University, Boston, MA, USA
| | | | - Catherine Clinton
- Clinical Pharmacogenomics Service, Boston Children's Hospital, Boston, MA, USA
| | - Kenneth D Mandl
- Comptational Health Informatics Program, Boston Children's Hospital, Boston, MA, USA.,Department of Biomedical Informatics, Harvard Medical School, Boston, MA, USA
| | - Wendy A Wolf
- Clinical Pharmacogenomics Service, Boston Children's Hospital, Boston, MA, USA
| | - Jared B Hawkins
- Clinical Pharmacogenomics Service, Boston Children's Hospital, Boston, MA, USA.,Comptational Health Informatics Program, Boston Children's Hospital, Boston, MA, USA
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19
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Roy LM, Zur RM, Uleryk E, Carew C, Ito S, Ungar WJ. Thiopurine S-methyltransferase testing for averting drug toxicity in patients receiving thiopurines: a systematic review. Pharmacogenomics 2016; 17:633-56. [PMID: 27020704 PMCID: PMC4931919 DOI: 10.2217/pgs.16.12] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
AIM Thiopurine S-methyltransferase (TPMT) testing is used in patients receiving thiopurines to identify enzyme deficiencies and risk for adverse drug reactions. It is uncertain whether genotyping is superior to phenotyping. The objectives were to conduct a systematic review of TPMT-test performance studies. MATERIALS & METHODS Electronic and grey literature sources were searched for studies reporting test performance compared with a reference standard. Sixty-six eligible studies were appraised for quality. RESULTS Thirty phenotype-genotype and six phenotype-phenotype comparisons were of high quality. The calculated sensitivity and specificity for genotyping to identify a homozygous mutation ranged from 0.0-100.0% and from 97.8-100.0%, respectively. CONCLUSION Clinical decision-makers require high-quality evidence of clinical validity and clinical utility of TPMT genotyping to ensure appropriate use in patients.
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Affiliation(s)
- Lilla M Roy
- Child Health Evaluative Sciences, The Hospital for Sick Children Research Institute, Toronto, Canada
| | - Richard M Zur
- Child Health Evaluative Sciences, The Hospital for Sick Children Research Institute, Toronto, Canada
| | - Elizabeth Uleryk
- Library Services, The Hospital for Sick Children, Toronto, Canada
| | - Chris Carew
- Centre for Genetic Medicine, The Hospital for Sick Children, Toronto, Canada
| | - Shinya Ito
- Division of Clinical Pharmacology & Toxicology, The Hospital for Sick Children, Toronto, Canada
- Departments of Pharmacology & Pharmacy, Faculty of Medicine Department of Paediatrics, University of Toronto, Canada
| | - Wendy J Ungar
- Child Health Evaluative Sciences, The Hospital for Sick Children Research Institute, Toronto, Canada
- Institute for Health Policy, Management & Evaluation, University of Toronto, Canada
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20
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Moon W, Loftus EV. Review article: recent advances in pharmacogenetics and pharmacokinetics for safe and effective thiopurine therapy in inflammatory bowel disease. Aliment Pharmacol Ther 2016; 43:863-883. [PMID: 26876431 DOI: 10.1111/apt.13559] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 08/26/2015] [Accepted: 01/26/2016] [Indexed: 12/16/2022]
Abstract
BACKGROUND Azathioprine and mercaptopurine have a pivotal role in the treatment of inflammatory bowel disease (IBD). However, because of their complex metabolism and potential toxicities, optimal use of biomarkers to predict adverse effects and therapeutic response is paramount. AIM To provide a comprehensive review focused on pharmacogenetics and pharmacokinetics for safe and effective thiopurine therapy in IBD. METHODS A literature search up to July 2015 was performed in PubMed using a combination of relevant MeSH terms. RESULTS Pre-treatment thiopurine S-methyltransferase typing plus measurement of 6-tioguanine nucleotides and 6-methylmercaptopurine ribonucleotides levels during treatment have emerged with key roles in facilitating safe and effective thiopurine therapy. Optimal use of these tools has been shown to reduce the risk of adverse effects by 3-7%, and to improve efficacy by 15-30%. For the introduction of aldehyde oxidase (AOX) into clinical practice, the association between AOX activity and AZA dose requirements should be positively confirmed. Inosine triphosphatase assessment associated with adverse effects also shows promise. Nucleoside diphosphate-linked moiety X-type motif 15 variants have been shown to predict myelotoxicity on thiopurines in East Asian patients. However, the impact of assessments of xanthine oxidase, glutathione S-transferase, hypoxanthine guanine phosphoribosyltransferase and inosine monophosphate dehydrogenase appears too low to favour incorporation into clinical practice. CONCLUSIONS Measurement of thiopurine-related enzymes and metabolites reduces the risk of adverse effects and improves efficacy, and should be considered part of standard management. However, this approach will not predict or avoid all adverse effects, and careful clinical and laboratory monitoring of patients receiving thiopurines remains essential.
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Affiliation(s)
- W Moon
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA.,Department of Internal Medicine, Kosin University College of Medicine, Busan, Korea
| | - E V Loftus
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA
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21
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Vestergaard C, Deleuran M. Chronic spontaneous urticaria: latest developments in aetiology, diagnosis and therapy. Ther Adv Chronic Dis 2015; 6:304-13. [PMID: 26568807 PMCID: PMC4622315 DOI: 10.1177/2040622315603951] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Chronic urticaria is a debilitating disease characterized by itching and hives with or without angioedema lasting for more than 6 weeks. The disease carries a significant emotional and economic burden for the patient and often results in an odyssey between doctors of different specialities. Patients suffering from chronic urticaria are considered more difficult to satisfy, treat and to have a bigger emotional burden than the average patient in dermatology, paediatric and general practice settings. A joint initiative under the Dermatology section of the European Academy of Allergy and Clinical immunology (EAACI), the Global Allergy and Asthma European Network (GA(2)LEN), the European Dermatology Forum (EDF) and the World Allergy Organization (WAO) has resulted in recently published guidelines for the diagnosis, classification and treatment of chronic urticarial: these guidelines are clinically useful and have a high success rate when followed in daily clinical practice. The treatment of choice for chronic urticaria is still nonsedating antihistamines although other treatments are available, with omalizumab (humanized IgG anti IgE antibodies) as the newest therapy. The pathogenesis of urticaria is poorly understood but autoimmunity is considered as one of the major underlying causes for this disease, although other theories exist.
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Affiliation(s)
| | - Mette Deleuran
- Department of Dermatology, Aarhus University Hospital, Aarhus, Denmark
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22
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Affiliation(s)
- Jeremy D Sanderson
- Department of Gastroenterology, Guy's & St. Thomas' Hospitals NHS Foundation Trust, London, United Kingdom.
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23
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Dooley MJ, Dixon B, Poole SG, Chiang C, Whitlock A, Schneider H. Phenotyping for Thiopurine Therapy in Clinical Practice. JOURNAL OF PHARMACY PRACTICE AND RESEARCH 2015. [DOI: 10.1002/j.2055-2335.2008.tb00835.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
| | | | | | | | | | - Hans Schneider
- Department of Medicine, Central and Eastern Clinical School; Monash University; Clayton Victoria
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24
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Abstract
Substantial progress in molecular immunology, coupled with an increasing focus on translational research and an enthusiasm for personalized medicine, has resulted in a rapid expansion in the field of immune biomarkers in recent years. In this Science and Society article, we provide a conceptual overview of the field and discuss the progress that has been made so far, as well as the future potential in the context of the scientific, logistical, financial, legal and ethical framework within which this research is being carried out and translated into clinical use.
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25
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Keung YK, Keung LW, Hong-Lung Hu E. A case of recurrent pancytopenia in a patient with acute promyelocytic leukemia on maintenance chemotherapy and concomitant methyltetrahydrofolate reductase and thiopurine S-methyltransferase mutation - review of literature. J Oncol Pharm Pract 2015; 22:548-51. [DOI: 10.1177/1078155215577235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Pharmacogenetics is a study of how genetic variation of an individual affects the drug response. We report a case of recurrent pancytopenia resulting from maintenance chemotherapy in a patient with acute promyelocytic leukemia and two pharmacogenetic mutations, namely, methylene tetrahydrofolate reductase C677T homozygous mutation and thiopurine methyltransferase mutation.
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Affiliation(s)
- Yi-Kong Keung
- UCLA, Hematology-Oncology Division Clinic, Alhambra, USA
| | - Lap-Woon Keung
- UCLA, Hematology-Oncology Division Clinic, Alhambra, USA
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26
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Burnett HF, Tanoshima R, Chandranipapongse W, Madadi P, Ito S, Ungar WJ. Testing for thiopurine methyltransferase status for safe and effective thiopurine administration: a systematic review of clinical guidance documents. THE PHARMACOGENOMICS JOURNAL 2014; 14:493-502. [DOI: 10.1038/tpj.2014.47] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 06/10/2014] [Accepted: 07/14/2014] [Indexed: 01/04/2023]
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27
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Abstract
The use of biologics and thiopurines in patients with inflammatory bowel disease has increased rapidly over the last 2 decades with both classes of drugs being used more frequently and earlier in the disease course. This vogue has come about through a realisation that for some patients Crohn's disease and ulcerative colitis are progressive diseases and that use of these therapies can sometimes prevent that progression. However, knowledge about the optimal way in which to use these drugs continues to evolve. In this paper, the evidence regarding optimal timing and dosing of thiopurines and biologics will be reviewed as will the role of thiopurine methyltransferase testing along with therapeutic drug monitoring of both thiopurines and biologics. In addition, possible future applications of biologic drug level and anti-drug antibody testing will be considered.
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Affiliation(s)
- Peter M Irving
- Department of Gastroenterology, Guy's and St Thomas' Hospital, and Division of Diabetes and Nutritional Sciences, School of Medicine, King's College London, London, UK
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28
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Demlova R, Mrkvicova M, Sterba J, Bernatikova H, Stary J, Sukova M, Mikuskova A, Chocholova A, Mladosievicova B, Soltysova A, Behulova D, Pilatova K, Zdrazilova-Dubska L, Valik D. Augmenting Clinical Interpretability of Thiopurine Methyltransferase Laboratory Evaluation. Oncology 2014; 86:152-8. [DOI: 10.1159/000357407] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 11/08/2013] [Indexed: 11/19/2022]
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29
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Richard VS, Al-Ismail D, Salamat A. Should we test TPMT enzyme levels before starting azathioprine? Hematology 2013; 12:359-60. [PMID: 17654066 DOI: 10.1080/10245330701283959] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Thiopurine methyltransferase (TPMT) is the main enzyme responsible for inactivating toxic products of azathioprine (AZA) metabolism. Patients with homozygous deficiency of this enzyme have no enzyme activity and ideally should not be given AZA. Patients with heterozygous deficiency have 50% of enzyme activity and have been shown to respond well and tolerate half a standard dose. We describe a patient with homozygous deficiency of TPMT who developed life threatening neutropenic sepsis, and advocate that all patients should be tested for TPMT activity prior to starting AZA therapy.
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van Egmond R, Barclay ML, Chin PKL, Sies CW, Florkowski CM. Biological variation of thiopurine methyltransferase enzyme activity: when has a significant change taken place? Ann Clin Biochem 2013; 50:473-8. [DOI: 10.1177/0004563212473441] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Background Thiopurine methyltransferase (TPMT) enzyme activity is measured before initiating thiopurine therapy to reduce the risk of severe drug-associated myelotoxicity in patients with low enzyme activity. TPMT activity may vary over time in relation to drug treatment and patient clinical condition. What constitutes a significant change in TPMT activity can be derived from biological variation and analytical imprecision. Methods A large national laboratory database was used to identify patients with three or more TPMT activity measurements. Variance of TPMT activity was analysed by determining the total coefficient of variation (CVTOT) of repeated measurements and by correlation with parameters including gender and follow-up time. Between-run analytical imprecision (CVa) was determined by replicate analysis ( n = 314). Results Of 7383 patients with TPMT measurements, 136 were identified as having three or more measurements over time (range 3–14). Median CVTOT for individual patient results was 14.5% (range 2.5–36.7%). Analytical imprecision (CVa) was 10.3%. A reference change value (or critical difference) with 95% probability was calculated as 42%. Therefore, a change in measured TPMT activity above 42% should lead to considering sources of variation other than biological variation and analytical imprecision. Conclusions TPMT enzyme activity needs to change by at least 42% to determine that a true change has taken place beyond biological variation and analytical imprecision. A single measurement of TPMT activity is sufficient for most clinical purposes.
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Affiliation(s)
- Remco van Egmond
- Department of Clinical Pharmacology, Christchurch Hospital, New Zealand
| | - Murray L Barclay
- Department of Clinical Pharmacology, Christchurch Hospital, New Zealand
- Department of Gastroenterology, Christchurch Hospital, New Zealand
| | - Paul KL Chin
- Department of Clinical Pharmacology, Christchurch Hospital, New Zealand
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McKeon A. Immunotherapeutics for Autoimmune Encephalopathies and Dementias. Curr Treat Options Neurol 2013; 15:723-37. [DOI: 10.1007/s11940-013-0251-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Duley JA, Somogyi AA, Martin JH. The future of thiopurine pharmacogenomics. Pharmacogenomics 2012; 13:1549-52. [DOI: 10.2217/pgs.12.140] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Affiliation(s)
- John A Duley
- Mater Medical Research Institute & School of Pharmacy, PACE, The University of Queensland, Woolloongabba, QLD 4102, Australia
| | - Andrew A Somogyi
- Discipline of Pharmacology, Faculty of Health Sciences, The University of Adelaide, Adelaide, SA, Australia
| | - Jennifer H Martin
- Division of Medicine, Princess Alexandra Hospital & School of Medicine, The University of Queensland, Woolloongabba, QLD, Australia
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Corrigan A, Arenas-Hernandez M, Blaker P, Sanderson J, Marinaki A. Let's get personal: predicting thiopurine and fluoropyrimidine toxicity. Per Med 2012; 9:859-870. [PMID: 29776234 DOI: 10.2217/pme.12.91] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The US FDA now recognizes the need to individualize treatment paradigms using biomarkers that predict response to therapy. In clinical practice the best example of this is TPMT testing, which is used to rationalize the starting dose of azathioprine and mercaptopurine. The more recent addition of drug metabolite monitoring means that thiopurine therapy can now be personalized to unprecedented levels. Of interest, parallels exist between TPMT deficiency as an explanation for thiopurine toxicity and DPD deficiency in fluoropyrimidine toxicity. For these drugs, variations in a single locus predict severe toxicity. However, while TPMT testing has translated into routine clinical practice, DPD testing has not. This article summarizes the recent research investigating interindividual differences in the metabolism of thiopurine and fluoropyrimidine drugs, and explores the attitudes which influence the uptake of pharmacogenetic testing.
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Affiliation(s)
- Adele Corrigan
- Purine Research Laboratory, GSTS Pathology, Guy's & St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK
| | - Monica Arenas-Hernandez
- Purine Research Laboratory, GSTS Pathology, Guy's & St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK
| | - Paul Blaker
- Department of Gastroenterology, 1st Floor College House, St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK
| | - Jeremy Sanderson
- Department of Gastroenterology, 1st Floor College House, St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK
| | - Anthony Marinaki
- Purine Research Laboratory, GSTS Pathology, Guy's & St Thomas' Hospital, Westminster Bridge Road, London SE1 7EH, UK.
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Gene polymorphisms involved in manifestation of leucopenia, digestive intolerance, and pancreatitis in azathioprine-treated patients. Dig Dis Sci 2012; 57:2394-401. [PMID: 22535280 DOI: 10.1007/s10620-012-2163-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 04/03/2012] [Indexed: 01/26/2023]
Abstract
BACKGROUND Approximately 10-28 % of patients experience adverse drug reactions related to treatment with thiopurines. The most serious reaction is myelosuppression, typically manifested as leucopenia, which occurs in approximately 2-5 % of patients. Other adverse drug reactions that often accompany thiopurine therapy are pancreatitis, hepatotoxicity, allergic reactions, digestive intolerance, arthralgia, febrile conditions, and rash. OBJECTIVE The objective of this study was to assess the relationship between variant alleles of thiopurine S-methyltransferase (SNPs 238G > C, 460G > A and 719A > G), inosine triphosphate diphosphatase (SNPs 94C > A and IVS2 + 21A > C), and xanthine dehydrogenase (837C > T) and the occurrence of adverse drug reactions to azathioprine therapy. METHODS Genotype was determined for 188 Caucasians diagnosed with inflammatory bowel disease treated with a standard dose of azathioprine (1.4-2.0 mg/kg/day). Allelic variants were determined by PCR-REA and real-time PCR methods. Results were statistically evaluated by use of Fisher's test and by odds ratio calculation. RESULTS Variant genotype thiopurine S-methyltransferase predisposes to development of leucopenia (P = 0.003, OR = 5, CI 95 %, 1.8058-13.8444). Although not statistically significant, we observed a trend that suggested correlation between the occurrence of digestive intolerance and the variant genotype inosine triphosphate diphosphatase (P = 0.1102; OR 15.63, CI 95 %, 1.162-210.1094), and between the occurrence of pancreatitis and the variant allele xanthine dehydrogenase 837T (P = 0.1124; OR 12,1, CI 95 %, 1.15-126.37). CONCLUSION The variant genotype thiopurine S-methyltransferase has been associated with the occurrence of leucopenia. The involvement of polymorphisms in inosine triphosphate diphosphatase and xanthine dehydrogenase genes in the development of digestive intolerance and pancreatitis will require further verification.
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Louis E, Baumgart DC, Ghosh S, Gomollón F, Hanauer S, Hart A, Irving P. What changes in inflammatory bowel disease management can be implemented today? J Crohns Colitis 2012; 6 Suppl 2:S260-7. [PMID: 22463933 DOI: 10.1016/s1873-9946(12)60506-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Innovative ideas are required to improve the management of inflammatory bowel disease and to share best practice that can be implemented into clinical practice today. The use of biomarkers such as calprotectin to monitor disease progression and treatment response could help to improve management of inflammatory bowel disease, but several strategies need to be implemented to make this a reality in clinical practice. The use of calprotectin as a biomarker and the manipulation of the thiopurine pathway to extend the use of current therapies are examples of how basic research can translate into patient benefit. Translational research into the use of microbiota and predictive factors for response and toxicity to drugs, may provide future clinical applications. Global improvement in care in inflammatory bowel disease could also be advanced by improving service provision. For example, the establishment of 'Centres of Excellence', a global interactive inflammatory disease map, and the alignment of processes and standards of care within treatment centres may help to achieve better outcomes for patients with inflammatory bowel disease. Realization of this goal, as well as a better understanding of the aetiology of the disease, may be furthered by collaborative efforts between organizations involved in inflammatory bowel disease as well as wider collaboration across countries and globally.
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Affiliation(s)
- Edouard Louis
- Department of Gastroenterology, Centre Hospitalier Universitaire de Liège, Liège, Belgium.
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Donnan JR, Ungar WJ, Mathews M, Hancock-Howard RL, Rahman P. A cost effectiveness analysis of thiopurine methyltransferase testing for guiding 6-mercaptopurine dosing in children with acute lymphoblastic leukemia. Pediatr Blood Cancer 2011; 57:231-9. [PMID: 21344614 DOI: 10.1002/pbc.22936] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 11/02/2010] [Indexed: 01/26/2023]
Abstract
BACKGROUND An increased understanding of the genetic basis of disease creates a demand for personalized medicine and more genetic testing for diagnosis and treatment. The objective was to assess the incremental cost-effectiveness per life-month gained of thiopurine methyltransferase (TPMT) genotyping to guide doses of 6-mercaptopurine (6-MP) in children with acute lymphoblastic leukemia (ALL) compared to enzymatic testing and standard weight-based dosing. PROCEDURE A cost-effectiveness analysis was conducted from a health care system perspective comparing costs and consequences over 3 months. Decision analysis was used to evaluate the impact of TPMT tests on preventing myelosuppression and improving survival in ALL patients receiving 6-MP. Direct medical costs included laboratory tests, medications, physician services, pharmacy and inpatient care. Probabilities were derived from published evidence. Survival was measured in life-months. The robustness of the results to variable uncertainty was tested in one-way sensitivity analyses. Probabilistic sensitivity analysis examined the impact of parameter uncertainty and generated confidence intervals around point estimates. RESULTS Neither of the testing interventions showed a benefit in survival compared to weight-based dosing. Both test strategies were more costly compared to weight-based dosing. Incremental costs per child (95% confidence interval) were $277 ($112, $442) and $298 ($392, $421) for the genotyping and phenotyping strategies, respectively, compared to weight-based dosing. CONCLUSIONS The present analysis suggests that screening for TPMT mutations using either genotype or enzymatic laboratory tests prior to the administration of 6-MP in pediatric ALL patients is not cost-effective.
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Affiliation(s)
- Jennifer R Donnan
- Department of Health Policy, Management & Evaluation, University of Toronto, Toronto, Ontario, Canada
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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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Payne K, Fargher EA, Roberts SA, Tricker K, Elliott RA, Ratcliffe J, Newman WG. Valuing pharmacogenetic testing services: a comparison of patients' and health care professionals' preferences. VALUE IN HEALTH : THE JOURNAL OF THE INTERNATIONAL SOCIETY FOR PHARMACOECONOMICS AND OUTCOMES RESEARCH 2011; 14:121-34. [PMID: 21211494 DOI: 10.1016/j.jval.2010.10.007] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
OBJECTIVE The study compared the preferences of patients and health-care professionals for the key attributes of a pharmacogenetic testing service to identify a patient's risk of developing a side effect (neutropenia) from the immunosuppressant, azathioprine. METHODS A discrete choice experiment was posted to a sample of patients (n=309) and health-care professionals (HCPs) (n=410), as part of the TARGET study. Five attributes, with four levels each, described the service as follows: level of information given; predictive ability of the test; how the sample is collected; turnaround time for a result; who explains the test result. Data from each sample were first analyzed separately and responses were compared by 1) identifying the impact of the scale parameter, and 2) estimating marginal rates of substitution. RESULTS The final analysis included 159 patients and 138 HCPs (50% & 34% response rates). Estimated attribute coefficients from the patient and HCP sample differed in size, after taking into account the impact of the scale parameter. Patients and HCPs had similar preferences for predictive accuracy of the test and were willing to wait 2 days for a 1% improvement in test accuracy. Patients preferred to obtain more information and were willing to wait 19 days compared to 8 days for HCPs for providing higher levels of information. CONCLUSIONS Patients demanded accurate and timely information from health-care professionals about why it was necessary to have a pharmacogenetic test and what the test results mean. In contrast, health-care professionals appear to focus more exclusively or entirely upon the predictive accuracy and waiting time for a test result.
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Dewit O, Starkel P, Roblin X. Thiopurine metabolism monitoring: implications in inflammatory bowel diseases. Eur J Clin Invest 2010; 40:1037-47. [PMID: 20629710 DOI: 10.1111/j.1365-2362.2010.02346.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Thiopurines (TP) are widely used in the management of inflammatory bowel diseases. Side effects and inefficacy are a major concern as they lead to withdrawal of the drug. MATERIALS AND METHODS Tools investigating TP metabolism are useful to avoid inadequate cessation of TP therapy. RESULTS TP metabolism is complex and many enzymes are involved. Among them, Thiopurine methyl transferase is the only one routinely measured by pheno- or genotyping. A decreased TPMT activity results in a potential overdosing of TP drugs leading to myelotoxicity, whereas an ultra-high activity leads to TP ineffectiveness and overproduction of methylated compounds responsible for hepatotoxicity. TPMT determination prior to TP treatment results in an individual adapted dose. Xanthine oxidase/dehydrogenase (XOD), inosine triphosphate pyrophosphatase (ITPA) and glutathion-S-transferase (GST) are other promising enzyme targets that might help to explain TP efficacy or toxicity. ITPA and GST polymorphisms might potentially be related to some TP side effects, while a XOD inhibition by allopurinol could avoid TP-related hepatotoxicity. CONCLUSIONS Utilization of thiopurine metabolites, 6-thioguanine nucleotides and 6-methylmercaptopurine, is discussed, specifically, in case of thiopurine failure and recommendations are given about their interpretation and potential dose optimization. These enzymes and metabolites tests are complementary to the regular monitoring of blood cells count and liver tests which remains mandatory.
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Affiliation(s)
- Olivier Dewit
- St. Luc University Hospital, Catholic University of Louvain Brussels, Brussels, Belgium CHU Saint-Etienne, Saint-Etienne, France.
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[Azathioprine-associated severe myelosuppression: indication of routine determination of thiopurine S-methyltransferase variant?]. Rev Med Interne 2010; 32:373-6. [PMID: 20970225 DOI: 10.1016/j.revmed.2010.09.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 09/16/2010] [Accepted: 09/20/2010] [Indexed: 01/06/2023]
Abstract
INTRODUCTION Myelotoxicity is a well-known adverse effect of azathioprine, leading mainly to leukopenia. Other azathioprine associated hematological adverse effects are uncommon. CASE REPORT We report a 49-year-old woman with rheumatoid arthritis and acquired hemophilia, who presented a severe myelosuppression occurring 3 weeks after an increase of her azathioprine regimen (at a daily dose of 150 mg). The patient had a heterozygous mutation of the thiopurine S-methyltransferase gene (TPMT*3A). Azathioprine therapy was discontinued and she recovered at 3 weeks. The patient had no relapse of pancytopenia after a 1 year follow-up. CONCLUSION Routine measurement of TPMT activity or determination of TPMT variant allele may be useful tests, in order to identify the subgroup of patients who are at risk to develop azathioprine induced severe myelosuppression.
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Ford LT, Berg JD. Thiopurine S-methyltransferase (TPMT) assessment prior to starting thiopurine drug treatment; a pharmacogenomic test whose time has come. J Clin Pathol 2010; 63:288-95. [PMID: 20354201 DOI: 10.1136/jcp.2009.069252] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Thiopurine S-methyltransferase (TPMT) is involved in the metabolism of thiopurine drugs. Patients that due to genetic variation lack this enzyme or have lower levels than normal, can be adversely affected if normal doses of thiopurines are prescribed. The evidence for measuring TPMT prior to starting patients on thiopurine drug therapy has been reviewed and the various approaches to establishing a service considered. Until recently clinical guidelines on the use of the TPMT varied by medical specialty. This has now changed, with clear guidance encouraging clinicians to use the TPMT test prior to starting any patient on thiopurine therapy. The TPMT test is the first pharmacogenomic test that has crossed from research to routine use. Several analytical approaches can be taken to assess TPMT status. The use of phenotyping supported with genotyping on selected samples has emerged as the analytical model that has enabled national referral services to be developed to a high level in the UK. The National Health Service now has access to cost-effective and timely TPMT assay services, with two laboratories undertaking the majority of the work at national level and with several local services developing. There appears to be adequate capacity and an appropriate internal market to ensure that TPMT assay services are commensurate with the clinical demand.
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Affiliation(s)
- L T Ford
- Clinical Biochemistry Department, SWBH NHS Trust, City Hospital, Dudley Road, Birmingham B18 5HQ, UK
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Barlow NL, Graham V, Berg JD. Expressing thiopurine S-methyltransferase activity as units per litre of whole-blood overcomes misleading high results in patients with anaemia. Ann Clin Biochem 2010; 47:408-14. [PMID: 20595409 DOI: 10.1258/acb.2010.010058] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
BACKGROUND Thiopurine S-methyltransferase (TPMT) phenotype analysis, expressed as TPMT activity, is established as a routine pharmacogenomic test to screen patients prior to initiating thiopurine drug therapy. Conventionally measured TPMT activity is corrected for red blood cell (RBC) parameters. Here we present evidence that supports the simplification of the TPMT assay: by expressing TPMT activity in mU/L whole blood, without undertaking any haemoglobin (Hb) correction. METHODS Hb concentrations were compared in consecutive samples that had been received for TPMT phenotype analysis and which were stratified into samples with high (n = 111) and samples with normal (n = 50) Hb-corrected enzyme activity. TPMT activity was also measured in samples received for full blood count determination, stratified into those with low (n = 50) and normal (n = 50) Hb. A reference interval for TPMT activity in mU/L was derived from a correlation between activity expressed in conventional units and that expressed in mU/L (n = 1563), supported by comparison with associated genotype (n = 201). RESULTS In the high TPMT activity group, 83% of specimens had a low Hb concentration compared with 14% of specimens in the normal TPMT group. Samples with a low Hb concentration were found to have significantly higher Hb-corrected TPMT activity than samples with a normal Hb concentration: 83 versus 44 nmol 6-methyl thioguanine /g Hb/h, P < 0.0001. These results strongly suggest that misleading high Hb-corrected TPMT activity is found in anaemic patients. Based on the reference interval for enzyme activity of 70-150 mU/L, phenotype-genotype concordance compared well with the conventional approach (88% versus 89%). Furthermore, distribution of TPMT phenotypes with activity expressed in mU/L was identical: 0.5% deficient, 11% low, 86% normal and 2.5% high, to when it was expressed in conventional units. CONCLUSION Expressing TPMT activity in mU/L can overcome misleading high Hb-corrected TPMT results occurring in patients with anaemia, which could lead to inappropriate treatment. Removing the need to measure RBC indices further simplifies TPMT phenotyping, leading to a more robust assay, with reduced turn-around time and cost.
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Affiliation(s)
- N L Barlow
- Clinical Biochemistry Department, City Hospital, Sandwell and West Birmingham Hospitals NHS Trust, Birmingham B187QH, UK
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Gazouli M, Pachoula I, Panayotou I, Mantzaris G, Syriopoulou VP, Goutas N, Vlachodimitropoulos D, Anagnou NP, Roma-Giannikou E. Thiopurine S-methyltransferase genotype and the use of thiopurines in paediatric inflammatory bowel disease Greek patients. J Clin Pharm Ther 2010; 35:93-7. [PMID: 20175817 DOI: 10.1111/j.1365-2710.2009.01041.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND AND OBJECTIVE Azathioprine (AZA) and 6-mercaptopurine (6MP) are used in the treatment of paediatric inflammatory bowel disease (IBD). Genetic variations in thiopurine S-methyltranfarase (TPMT) gene have been correlated with enzyme activity and with the occurrence of adverse events to AZA and 6MP. The aim of the present study was to investigate the frequency of the functional TPMT polymorphisms and their association with the occurrence of adverse events during azathioprine therapy in a paediatric IBD cohort. METHODS Ninety-seven thiopurine-treated paediatric IBD patients (41.24% boys and 58.76% girls) with a mean age 11.25 years (range 3-16), were assessed for TPMT polymorphisms and adverse events. RESULTS Of the 97 patients enrolled in the study, 18 (18.56%) were heterozygous mutated; two (2.06%) were homozygous for a mutated TPMT gene. Ten patients (10.31%) developed adverse effects, and four of them (40%) had one of the variant alleles. CONCLUSIONS In this small cohort of subjects, no association was found between TPMT polymorphisms and the occurrence of thiopurines-related adverse events.
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Affiliation(s)
- M Gazouli
- Department of Biology, School of Medicine, University of Athens, Athens, Greece
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Werner M, Wallerstedt S, Lindgren S, Almer S, Björnsson E, Bergquist A, Prytz H, Sandberg-Gertzén H, Hultcrantz R, Sangfelt P, Weiland O, Ohlsson B, Danielsson A. Characteristics and long-term outcome of patients with autoimmune hepatitis related to the initial treatment response. Scand J Gastroenterol 2010; 45:457-67. [PMID: 20082594 DOI: 10.3109/00365520903555861] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVES Autoimmune hepatitis (AIH) is a liver disease which, if untreated, may lead to liver cirrhosis and hepatic failure. Limited data exist regarding factors predicting the long-term outcome. The aims of this study were to investigate symptoms at presentation, prognostic features, management and treatment in relation to long-term outcome of AIH. MATERIAL AND METHODS A cohort of 473 Swedish patients with AIH was characterized regarding initial symptoms and signs, factors predicting death and future need for liver transplantation. Survival and causes of death were retrieved from Swedish national registers. RESULTS At diagnosis, fatigue was a predominant symptom (69%), 47% of the patients were jaundiced and 30% had liver cirrhosis. Another 10% developed cirrhosis during follow-up. Markedly elevated alanine aminotransferase levels at presentation were correlated with a better outcome. A high international normalized ratio (INR) at diagnosis was the only risk factor predicting a need for later liver transplantation. Histological cirrhosis, decompensation and non-response to initial treatment were all factors that correlated with a worse outcome. Overall life expectancy was generally favourable. However, most deaths were liver-related, e.g. liver failure, shock and gastrointestinal bleeding. CONCLUSIONS Cirrhosis at diagnosis, a non-response to initial immune-suppressive treatment or elevated INR values were associated with worse outcome and a need for later liver transplantation. In contrast, an acute hepatitis-like onset with intact synthetic capacity indicated a good response to treatment and favourable long-term prognosis. Lifetime maintenance therapy is most often required.
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Affiliation(s)
- Mårten Werner
- Department of Medicine, Sections for Hepatology and Gastroenterology, Umeå University Hospital, Umeå, Sweden.
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Abstract
Azathioprine (AZA) and 6-mercaptopurine (6-MP) are the most widely used immunosuppressive therapies in inflammatory bowel disease. Pretreatment measurement of thiopurine methyltransferase (TPMT) activity is recommended and although conventional practice is to use a dose of 2 mg/kg AZA (1 mg/kg 6-MP), higher doses of 2.5 mg/kg AZA or more may be required in some patients, particularly if TPMT activity is high. Dose raising is limited by toxicity, and a robust monitoring system is mandatory. Patients with side effects to AZA may tolerate 6-MP but pancreatitis is a contraindication to switching. Metabolite monitoring is not widely available but may be useful, particularly if non-compliance is possible or where metabolite shunting to 6-methylmercaptopurine is suspected, on the basis of non-response or toxicity. It may allow dose optimisation before switching to alternative immunosuppressants. The drug appears safe in pregnancy and breast feeding. Long term duration of therapy is a balance between benefits in relation to the underlying disease extent, activity and aggressiveness, and the risk of neoplasia, particularly lymphoma.
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Affiliation(s)
- Lawrence Sunder Raj
- Department of Gastroenterology, University Hospital of Wales, Heath Park, Cardiff, UK
| | - A Barney Hawthorne
- Department of Gastroenterology, University Hospital of Wales, Heath Park, Cardiff, UK
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Smith MA, Marinaki AM, Arenas M, Shobowale-Bakre M, Lewis CM, Ansari A, Duley J, Sanderson JD. Novel pharmacogenetic markers for treatment outcome in azathioprine-treated inflammatory bowel disease. Aliment Pharmacol Ther 2009; 30:375-84. [PMID: 19500084 DOI: 10.1111/j.1365-2036.2009.04057.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Azathioprine (AZA) pharmacogenetics are complex and much studied. Genetic polymorphism in TPMT is known to influence treatment outcome. Xanthine oxidase/dehydrogenase (XDH) and aldehyde oxidase (AO) compete with TPMT to inactivate AZA. AIM To assess whether genetic polymorphism in AOX1, XDH and MOCOS (the product of which activates the essential cofactor for AO and XDH) is associated with AZA treatment outcome in IBD. METHODS Real-time PCR was conducted for a panel of single nucleotide polymorphism (SNPs) in AOX1, XDH and MOCOS using TaqMan SNP genotyping assays in a prospective cohort of 192 patients receiving AZA for IBD. RESULTS Single nucleotide polymorphism AOX1 c.3404A > G (Asn1135Ser, rs55754655) predicted lack of AZA response (P = 0.035, OR 2.54, 95%CI 1.06-6.13) and when combined with TPMT activity, this information allowed stratification of a patient's chance of AZA response, ranging from 86% in patients where both markers were favourable to 33% where they were unfavourable (P < 0.0001). We also demonstrated a weak protective effect against adverse drug reactions (ADRs) from SNPs XDH c.837C > T (P = 0.048, OR 0.23, 95% CI 0.05-1.05) and MOCOS c.2107A > C, (P = 0.058 in recessive model, OR 0.64, 95%CI 0.36-1.15), which was stronger where they coincided (P = 0.019). CONCLUSION These findings have important implications for clinical practice and our understanding of AZA metabolism.
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Affiliation(s)
- M A Smith
- Department of Gastroenterology, Guy's & St. Thomas' NHS Foundation Trust, London, UK
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48
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Karas-Kuzelicki N, Mlinaric-Rascan I. Individualization of thiopurine therapy: thiopurine S-methyltransferase and beyond. Pharmacogenomics 2009; 10:1309-22. [DOI: 10.2217/pgs.09.78] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The metabolism of a given drug depends, not solely on a particular enzyme, but rather on a complex metabolic network. Thiopurine S-methyltransferase (TPMT) catalyzes the methylation, and thus deactivation, of 6-mercaptopurine, a thiopurine used in the treatment of acute lymphoblastic leukemia. Low TPMT activity has been associated with severe toxicity of 6-mercaptopurine. Determination of mutations in the TPMT gene before starting 6-mercaptopurine therapy constitutes a quick, simple and cost-effective strategy to individualize thiopurine dosing. However, TPMT phenotype-to-genotype correlation is not complete, indicating a need for identification of novel biomarkers. Based on our recent findings and reviewing seemingly unrelated literature reports we present a synthesis of the current understanding of factors that influence TPMT activity and consequently modulate responsiveness to thiopurine treatment. Identification and understanding of these factors is crucial for improving the efficacy and safety of acute lymphoblastic leukemia treatment.
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Affiliation(s)
- Natasa Karas-Kuzelicki
- Faculty of pharmacy, University of Ljubljana, Slovenia, Askerceva 7, 1000 Ljubljana, Slovenia
| | - Irena Mlinaric-Rascan
- Faculty of pharmacy, University of Ljubljana, Slovenia, Askerceva 7, 1000 Ljubljana, Slovenia
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49
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Sheffield LJ, Irving P, Gupta A, Byron K, Macrae FA, Phillimore H, Dronavalli M, Rose R, George P, Walmsley T, Dixon B, Poole S, Dooley M, Sparrow M. Thiopurine methyltransferase and thiopurine metabolite testing in patients with inflammatory bowel disease who are taking thiopurine drugs. Pharmacogenomics 2009; 10:1091-9. [DOI: 10.2217/pgs.09.60] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Thiopurine methyltransferase genotyping and thiopurine metabolite testing has been established as an adjunct to monitoring patients taking thiopurine drugs. This special report describes the clinical implications for this type of testing for patients with inflammatory bowel disease who are taking thiopurine drugs. A total of 10% of patients were found to be intermediate metabolizers and the mean dosage (in mg/kg equivalent) was lower in intermediate metabolizers than extensive metabolizers. The metabolite levels did not correlate with scores measuring clinical severity but levels of 6-methylmercaptopurine were related to the dosage of the drugs. Despite considerable study of thiopurine methyltransferase testing in the literature, it is still not widely used in many geographical areas. This study adds to the evidence about using such testing as well as expanding the role of simultaneously measuring thiopurine metabolites. Further work is planned to evaluate the uptake when such testing becomes available locally as a clinical service.
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Affiliation(s)
- Leslie J Sheffield
- Genetic Health Services Victoria, Murdoch Childrens Research Institute, Flemington Road, Parkville, Victoria, Australia, 3052 and GenesFX Health Pty Ltd, Melbourne, Australia
| | | | - Arun Gupta
- The Royal Melbourne Hospital, University of Melbourne, Melbourne, Australia
| | | | - Finlay A Macrae
- The Royal Melbourne Hospital, University of Melbourne, Melbourne, Australia
| | | | - Mithilesh Dronavalli
- University of Melbourne, Melbourne, Australia and Data Clinic, Quakers Hill, Australia
| | | | - Peter George
- Canterbury Health Laboratories, Christchurch, New Zealand
| | | | | | | | - Michael Dooley
- Alfred Health, Melbourne, Australia and Monash University, Melbourne, Australia
| | - Miles Sparrow
- Box Hill Hospital, Melbourne, Australia and Alfred Health, Melbourne, Australia
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50
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Jurecka A. Inborn errors of purine and pyrimidine metabolism. J Inherit Metab Dis 2009; 32:247-63. [PMID: 19291420 DOI: 10.1007/s10545-009-1094-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2008] [Revised: 01/09/2009] [Accepted: 01/19/2009] [Indexed: 12/26/2022]
Abstract
Genetic disorders of purine and pyrimidine (PP) metabolism are under-reported and infrequently mentioned in the general literature, as well as in reviews dedicated to other inborn errors of metabolism. Owing to limited awareness, relatively recent recognition, as well as considerable phenotypic variation, these disorders may often be misdiagnosed or remain undiagnosed. Disorders that arise as a result of dysfunction in PP metabolism represent some of the most challenging diagnostic problems in medicine. In addition to their low prevalence rates, they also present with extremely variable signs and symptoms. They may affect any system in a variety of manners, and often mimic other, more recognizable disorders. The diagnostic problem is compounded by the fact that some biochemically affected patients are symptom-free. Rapidly evolving laboratory techniques such as high-performance liquid chromatography coupled to tandem mass spectrometry are now well established as the preferred method for detection for these defects, but currently the most important step in diagnosis consists of suspecting the disorder. Diagnosis is vital because genetic counselling can be provided and, in some cases, specific treatment can be offered that may slow or even reverse clinical symptoms. If undiagnosed, these disorders can be devastating to patients and their families, resulting in early death or institutionalization for the rest of patient's life. This article describes the current state of knowledge about inborn errors of purine and pyrimidine metabolism, focusing on the varying clinical presentations, the laboratory findings and discusses indications for selective screening for these disorders.
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Affiliation(s)
- A Jurecka
- Department of Metabolic Diseases, Endocrinology and Diabetology, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, 04-730, Warsaw, Poland.
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