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Vasudevan A, Con D, De Cruz P, Sparrow MP, Friedman AB, Garg M, Kashkooli S, Gibson PR, van Langenberg DR. Clinical trial: Combination allopurinol-thiopurine versus standard thiopurine in patients with IBD escalating to immunomodulators (the DECIDER study). Aliment Pharmacol Ther 2024; 59:504-514. [PMID: 38095246 DOI: 10.1111/apt.17831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 09/29/2023] [Accepted: 11/29/2023] [Indexed: 01/23/2024]
Abstract
BACKGROUND Thiopurines are established treatments for inflammatory bowel disease (IBD), yet concerns remain regarding their safety. AIM To evaluate the use of thiopurine-allopurinol combination therapy compared to standard thiopurine therapy in IBD. METHODS We performed a multicentre, randomised, placebo-controlled trial to compare the efficacy and safety of thiopurine-allopurinol versus thiopurine with placebo for adults commencing a thiopurine for IBD. Patients had active disease at baseline; dosing of therapy was based on a pre-specified regimen and subsequent metabolites. The primary outcome was the proportion of patients achieving a composite of symptomatic disease activity remission (Harvey Bradshaw Index <5 for Crohn's disease, Simple Clinical Colitis Activity Index <4 for ulcerative colitis) and a faecal calprotectin <150 μg/g after 26 weeks of treatment. RESULTS The trial was terminated early due to slow recruitment. We randomised 102 participants (54 thiopurine-allopurinol, 48 thiopurine with placebo) with similar age (median 42 vs 48 years) and sex distribution (46% women per group). A higher proportion achieved the primary outcome in the thiopurine-allopurinol group (50% vs 35%, p = 0.14) and fewer participants stopped their allocated therapy due to adverse events (11% vs 29%, p = 0.02). Also, within the thiopurine-allopurinol group, thiopurine dose adjustments were less frequent (69% vs 92%, p = 0.03), a higher proportion achieved an early therapeutic 6-TGN level at week 6 (71% vs 53%, p = 0.19), and adverse events attributed to therapy were less frequent (15% vs 44%, p = 0.002). CONCLUSION Thiopurine-allopurinol therapy is safe and mitigates thiopurine adverse effects, thus enhancing tolerability without compromising efficacy (ACTRN12613001347752).
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Affiliation(s)
- Abhinav Vasudevan
- Department of Gastroenterology and Hepatology, Eastern Health, Box Hill, Victoria, Australia
- Monash University, Eastern Health Clinical School, Box Hill, Victoria, Australia
| | - Danny Con
- Department of Gastroenterology, The Austin Hospital, Melbourne, Victoria, Australia
| | - Peter De Cruz
- Department of Gastroenterology, The Austin Hospital, Melbourne, Victoria, Australia
- Department of Medicine, Austin Academic Centre, University of Melbourne, Melbourne, Victoria, Australia
| | - Miles P Sparrow
- Department of Gastroenterology, Central Clinical School, Monash University and Alfred Health, Melbourne, Victoria, Australia
| | - Antony B Friedman
- Department of Gastroenterology, Central Clinical School, Monash University and Alfred Health, Melbourne, Victoria, Australia
| | - Mayur Garg
- Department of Gastroenterology, Northern Health, Epping, Victoria, Australia
- Department of Medicine, Melbourne University, Melbourne, Australia
| | - Soleiman Kashkooli
- Department of Gastroenterology, Northern Health, Epping, Victoria, Australia
| | - Peter R Gibson
- Department of Gastroenterology, Central Clinical School, Monash University and Alfred Health, Melbourne, Victoria, Australia
| | - Daniel R van Langenberg
- Department of Gastroenterology and Hepatology, Eastern Health, Box Hill, Victoria, Australia
- Monash University, Eastern Health Clinical School, Box Hill, Victoria, Australia
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Abstract
Therapeutic drug monitoring (TDM) is not yet accepted by systemic lupus erythematosus (SLE) treatment guidelines. Studies in SLE, however, have proven benefit in three areas: identification of non-adherence or poor adherence; targets for clinical benefit; and ranges of toxicity. This review covers the data on three medications commonly used for SLE, drawing on studies from both the SLE and non-SLE literature.
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Affiliation(s)
- Michelle Petri
- Johns Hopkins University School of Medicine, Department of Medicine, Division of Rheumatology, 1830 E. Monument Street, Suite 7500, Baltimore, MD, 21205, USA.
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Pavlovska K, Petrushevska M, Gjorgjievska K, Zendelovska D, Ribarska JT, Kikerkov I, Gjatovska LL, Atanasovska E. Importance of 6-Thioguanine Nucleotide Metabolite Monitoring in Inflammatory Bowel Disease Patients Treated with Azathioprine. ACTA ACUST UNITED AC 2019; 40:73-9. [PMID: 31152640 DOI: 10.2478/prilozi-2019-0006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The active metabolite of azathioprine, 6-thioguanine nucleotide (6-TGN) is the main component responsible for the immunosuppressive effect in treatment of inflammatory bowel disease (IBD). The aim of this study was to assess the correlation between the concentration of 6-thioguanine nucleotide and disease activity, azathioprine-related adverse effects and time duration of treatment in patients with inflammatory bowel disease. Thirty-four patients were included in this study. Type of disease, gender, time duration of therapy and adverse effects were recorded. Metabolite concentration was determined by high performance liquid chromatography. Twenty-one percent of patients have experienced an adverse effect, with leucocytopenia most commonly occurring (42.9%). More adverse effects were registered when patients were treated with azathioprine in a period of less than 3 months in comparison to the group of patients that have been under therapy between 3-12 months and more than 12 months (p˂0.05). Most of the patients that presented any adverse effect had high 6-TGN concentration (>450 pmol/8x108 Er). The mean value of 6-TGN metabolite concentration in IBD patients treated with azathioprine was 437.46 pmol/8x108 Er ± 198.82 pmol/8x108. The time duration of azathioprine treatment did not have any significant impact on the achieved 6-TGN concentration (p>0.05).Twenty patients (58.9%) had achieved remission after therapy initiation with azathioprine. More alertness is recommended to clinicians towards patients in the first 3 months of the therapy. Our study demonstrated that higher 6-TGN concentration is associated with azathioprine toxicity.
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Essmann J, Keil C, Unruh O, Otte A, Manns MP, Bachmann O. Fecal calprotectin is significantly linked to azathioprine metabolite concentrations in Crohn's disease. Eur J Gastroenterol Hepatol 2019; 31:99-108. [PMID: 30212402 DOI: 10.1097/MEG.0000000000001262] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND The value of therapeutic drug monitoring during azathioprine (AZA) therapy with respect to clinical outcomes has been convincingly demonstrated in recent meta-analyses. However, the association between AZA metabolites and the mucosal state in inflammatory bowel disease is largely unclear. AIMS We investigated the association between AZA's active metabolite 6-thioguanine nucleotides (6-TGN) and fecal calprotectin (FC) as a well-validated surrogate marker of mucosal inflammation in patients with Crohn's disease (CD) on AZA monotherapy. PATIENTS AND METHODS Of 443 6-TGN measurements, 140 values from 88 patients with CD on AZA monotherapy visiting the inflammatory bowel disease outpatient clinic between 2009 and 2016 were retrospectively analyzed. In a subcohort with serial 6-TGN measurements, longitudinal FC measurements in patients with versus without intervention (dose increase, allopurinol, and education) were assessed. RESULTS In patients with 6-TGN concentrations within a predefined range (250-450 pmol/8×10 red blood cells), FC was significantly lower (median: 119.5 vs. 327.2 mg/kg, P=0.003), and hemoglobin as well as serum protein concentrations were significantly higher than in patients with 6-TGN outside of this range. C-reactive protein and transferrin saturation were not different. In the longitudinal cohort, 6-TGN increased in the intervention group, but only a minority reached the defined range; no significant change in FC was observed. CONCLUSION This study is the first to show that in patients with CD receiving AZA monotherapy, 6-TGN concentrations within a defined range (250-450 pmol/8×10 red blood cells) are associated with significantly lower FC. A treat-to-target concept directed by 6-TGN to reach mucosal healing may thus be a promising approach (DRKS00013246).
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Roberts RL, Wallace MC, Seinen ML, van Bodegraven AA, Krishnaprasad K, Jones GT, van Rij AM, Baird A, Lawrance IC, Prosser R, Bampton P, Grafton R, Simms LA, Studd C, Bell SJ, Kennedy MA, Halliwell J, Gearry RB, Radford-Smith G, Andrews JM, McHugh PC, Barclay ML. Nonsynonymous Polymorphism in Guanine Monophosphate Synthetase Is a Risk Factor for Unfavorable Thiopurine Metabolite Ratios in Patients With Inflammatory Bowel Disease. Inflamm Bowel Dis 2018; 24:2606-2612. [PMID: 29788244 DOI: 10.1093/ibd/izy163] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Indexed: 12/30/2022]
Abstract
BACKGROUND Up to 20% of patients with inflammatory bowel disease (IBD) who are refractory to thiopurine therapy preferentially produce 6-methylmercaptopurine (6-MMP) at the expense of 6-thioguanine nucleotides (6-TGN), resulting in a high 6-MMP:6-TGN ratio (>20). The objective of this study was to evaluate whether genetic variability in guanine monophosphate synthetase (GMPS) contributes to preferential 6-MMP metabolizer phenotype. METHODS Exome sequencing was performed in a cohort of IBD patients with 6-MMP:6-TGN ratios of >100 to identify nonsynonymous single nucleotide polymorphisms (nsSNPs). In vitro assays were performed to measure GMPS activity associated with these nsSNPs. Frequency of the nsSNPs was measured in a cohort of 530 Caucasian IBD patients. RESULTS Two nsSNPs in GMPS (rs747629729, rs61750370) were detected in 11 patients with very high 6-MMP:6-TGN ratios. The 2 nsSNPs were predicted to be damaging by in silico analysis. In vitro assays demonstrated that both nsSNPs resulted in a significant reduction in GMPS activity (P < 0.05). The SNP rs61750370 was significantly associated with 6-MMP:6-TGN ratios ≥100 (odds ratio, 5.64; 95% confidence interval, 1.01-25.12; P < 0.031) in a subset of 264 Caucasian IBD patients. CONCLUSIONS The GMPS SNP rs61750370 may be a reliable risk factor for extreme 6MMP preferential metabolism.
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Affiliation(s)
- Rebecca L Roberts
- Department of Surgical Sciences (Dunedin), University of Otago, Otago, New Zealand
| | - Mary C Wallace
- Department of Surgical Sciences (Dunedin), University of Otago, Otago, New Zealand
| | - Margien L Seinen
- Department of Gastroenterology and Hepatology, VU University Medical Center, Amsterdam, the Netherlands.,Department of Internal Medicine, Gastroenterology and Geriatrics, Atrium-ORBIS Medical Center, Heerlen-Sittard, the Netherlands
| | - Adriaan A van Bodegraven
- Department of Gastroenterology and Hepatology, VU University Medical Center, Amsterdam, the Netherlands.,Department of Internal Medicine, Gastroenterology and Geriatrics, Atrium-ORBIS Medical Center, Heerlen-Sittard, the Netherlands
| | | | - Gregory T Jones
- Department of Surgical Sciences (Dunedin), University of Otago, Otago, New Zealand
| | - Andre M van Rij
- Department of Surgical Sciences (Dunedin), University of Otago, Otago, New Zealand
| | - Angela Baird
- Centre for Inflammatory Bowel Disease, Saint John of God Hospital, Subiaco, WA, Australia
| | - Ian C Lawrance
- Centre for Inflammatory Bowel Disease, Saint John of God Hospital, Subiaco, WA, Australia.,Harry Perkins Institute of Medical Research, School of Medicine and Pharmacology, University of Western Australia, Murdoch, WA, Australia
| | - Ruth Prosser
- Flinders Medical Centre, Flinders University of South Australia, Bedford Park, South Australia, Australia
| | - Peter Bampton
- Flinders Medical Centre, Flinders University of South Australia, Bedford Park, South Australia, Australia
| | - Rachel Grafton
- Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Lisa A Simms
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Corrie Studd
- Department of Gastroenterology, St Vincent's Hospital, Melbourne, Victoria, Australia
| | - Sally J Bell
- Department of Gastroenterology, St Vincent's Hospital, Melbourne, Victoria, Australia
| | - Martin A Kennedy
- Department of Pathology, University of Otago Christchurch, Christchurch, New Zealand
| | - Jacob Halliwell
- Centre for Biomarker Research, School of Applied Sciences, University of Huddersfield, Huddersfield, UK
| | - Richard B Gearry
- Department of Gastroenterology, Christchurch Hospital, Christchurch, New Zealand
| | - Graham Radford-Smith
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.,Department of Gastroenterology, Royal Brisbane and Women's Hospital, Brisbane, Queensland, Australia
| | - Jane M Andrews
- Department of Gastroenterology and Hepatology, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Patrick C McHugh
- Centre for Biomarker Research, School of Applied Sciences, University of Huddersfield, Huddersfield, UK
| | - Murray L Barclay
- Department of Gastroenterology, Christchurch Hospital, Christchurch, New Zealand
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Abstract
BACKGROUND The thiopurines azathioprine and mercaptopurine remain pivotal maintenance treatments in inflammatory bowel disease (IBD); however, up to 15%-20% of patients preferentially produce the hepatotoxic metabolite 6-methylmercaptopurine (6MMP) at the expense of the therapeutic 6-thioguanine nucleotides (6TGN). This metabolic shunting usually begins within 3 months of therapy. We noted patients developing shunting many months or years after starting treatment and aimed to determine how often this late shunting occurs and whether this could be explained by patient factors or concomitant medications. METHODS The New Zealand database of thiopurine metabolite results from 2002 to 2016 (19085 6TGN/6MMP pairs from 7130 patients) was interrogated to identify patients developing a 6MMP/6TGN ratio >20 after at least 4 months treatment. Dosing history, concomitant therapy, and comorbidity data were assessed. RESULTS Fifteen percent of database patients developed preferential 6-MMP production, and of these, 29 patients had late-onset shunting with sufficient data available for validation. This extrapolates to 90 patients in total, representing 1.7% of IBD patients on thiopurines, or 10% of all those with preferential 6-MMP production. Time from starting therapy to shunting was 5 months to 10.4 years (median, 21 months). Eleven patients had abnormal liver function when shunting was recognized, all with 6MMP >5900 pmol/8 × 108 red blood cells. No common factors were found to explain the late onset. CONCLUSIONS Some IBD patients develop preferential 6MMP production many months or years after commencing therapy. This is important when considering frequency of metabolite monitoring, failure of therapy, or abnormal liver function. 10.1093/ibd/izx081_video1izx081.video15746667546001.
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Affiliation(s)
- Erik Munnig-Schmidt
- Department of Gastroenterology, VU Medical Centre, Amsterdam, the Netherlands
| | - Mei Zhang
- Department of Medicine, University of Otago Christchurch, Christchurch, New Zealand
| | - Chris J Mulder
- Department of Gastroenterology, VU Medical Centre, Amsterdam, the Netherlands
| | - Murray L Barclay
- Department of Medicine, University of Otago Christchurch, Christchurch, New Zealand.,Departments of Gastroenterology and Clinical Pharmacology, Christchurch Hospital, Christchurch, New Zealand
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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8
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Heerasing NM, Ng JF, Dowling D. Does lymphopenia or macrocytosis reflect 6-thioguanine levels in patients with inflammatory bowel disease treated with azathioprine or 6-mercaptopurine? Intern Med J 2017; 46:465-9. [PMID: 26425841 DOI: 10.1111/imj.12915] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Accepted: 09/18/2015] [Indexed: 12/19/2022]
Abstract
BACKGROUND The thiopurine drugs, 6-mercaptopurine and azathioprine, remain the mainstay of immunomodulator therapy for inflammatory bowel disease (IBD). Optimal management depends on achieving therapeutic levels of 6-thioguanine (6-TGN), but measuring thiopurine metabolites is associated with significant cost. Thiopurines cause lymphopenia and an increase in mean corpuscular volume (MCV). It is unclear whether any clinically useful correlation exists between 6-TGN levels and lymphocyte count or MCV. AIMS The aim of this study is to investigate the correlation between 6-TGN levels and lymphocyte count and MCV in thiopurine-treated patients with IBD. METHODS We analysed a prospectively acquired database of 67 patients with IBD treated with thiopurine therapy. The data were analysed looking at the relationship between 6-TGN levels and both lymphocyte count and MCV by using the Spearman's rank correlation coefficient. RESULTS Twenty-seven (40%) patients had therapeutic 6-TGN levels. Thirty-three (49%) patients had sub-therapeutic 6-TGN levels. A weak positive correlation between 6-TGN levels and lymphocyte count was demonstrated, but this was not statistically significant (Spearman's R = 0.14, P = 0.23). Spearman's rank correlation coefficient between 6-TGN levels and MCV was statistically significant (R = 0.42, P = 0.0005). MCV >101 fL excluded a subtherapeutic 6-TGN level with positive predictive value of 92%. CONCLUSIONS There is no specific lymphopenia that can be assumed to indicate a therapeutic 6-TGN level. The relationship between 6-TGN levels and MCV is likely to be clinically relevant. If MCV is elevated, 6-TGN is unlikely to be sub-therapeutic. MCV is a potential surrogate marker which can rule out sub-therapeutic thiopurine metabolites in patients with IBD treated with azathioprine or 6-mercaptopurine.
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Affiliation(s)
| | - J F Ng
- Barwon Health, Geelong, Victoria, Australia
| | - D Dowling
- Barwon Health, Geelong, Victoria, Australia
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Di Salvo A, Fabiano C, Mannara V, Dimarco M, Orlando A, Affronti M, Macaluso FS, Cottone M. Frequency of thiopurine methyltransferase mutation in patients of Mediterranean area with inflammatory bowel disease and autoimmune disorders. Dig Liver Dis 2016; 48:1506-1509. [PMID: 27665263 DOI: 10.1016/j.dld.2016.08.125] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 08/04/2016] [Accepted: 08/05/2016] [Indexed: 12/11/2022]
Abstract
BACKGROUND AND AIMS Few studies exist on the frequency of thiopurine methyltransferase (TPMT) mutation in patients from Southern Europe. We aimed to evaluate the frequency of TPMT mutation in a homogeneous Sicilian cohort of patients with inflammatory bowel disease (IBD), autoimmune and hematological disorders, the rate of thiopurine-related adverse events, and its association with the TPMT genotype. RESULTS Among 105 patients with IBD, 45 with autoimmune disease, and 34 with hematologic diseases, the homozygous TPMT variant genotype was found in one patient only (0.5%), while the heterozygous TPMT genotype was identified in 8 patients (4.3%). In patients with IBD, leukopenia was observed in ten patients: one had the homozygous TPMT genotype, one the heterozygous genotype, and the remaining eight the wild type genotype. CONCLUSIONS The frequency of TPMT mutation in a Mediterranean area was low. TPMT genotyping is not a sensitive tool for predicting thiopurine-induced leukopenia.
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Affiliation(s)
- Angela Di Salvo
- Di.Bi.M.I.S., Division of Internal Medicine, "Villa Sofia-Cervello" Hospital, Palermo, Italy
| | - Carmelo Fabiano
- Laboratory of Molecular Genetics, "Villa Sofia-Cervello" Hospital, Palermo, Italy
| | - Vincenza Mannara
- Di.Bi.M.I.S., Division of Internal Medicine, "Villa Sofia-Cervello" Hospital, Palermo, Italy
| | - Mariangela Dimarco
- Di.Bi.M.I.S., Division of Internal Medicine, "Villa Sofia-Cervello" Hospital, Palermo, Italy
| | - Ambrogio Orlando
- Di.Bi.M.I.S., Division of Internal Medicine, "Villa Sofia-Cervello" Hospital, Palermo, Italy
| | - Marco Affronti
- Di.Bi.M.I.S., Division of Internal Medicine, "Villa Sofia-Cervello" Hospital, Palermo, Italy
| | | | - Mario Cottone
- Di.Bi.M.I.S., Division of Internal Medicine, "Villa Sofia-Cervello" Hospital, Palermo, Italy.
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Mlakar V, Huezo-Diaz Curtis P, Satyanarayana Uppugunduri CR, Krajinovic M, Ansari M. Pharmacogenomics in Pediatric Oncology: Review of Gene-Drug Associations for Clinical Use. Int J Mol Sci 2016; 17:ijms17091502. [PMID: 27618021 PMCID: PMC5037779 DOI: 10.3390/ijms17091502] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 08/02/2016] [Accepted: 08/15/2016] [Indexed: 02/07/2023] Open
Abstract
During the 3rd congress of the European Society of Pharmacogenomics and Personalised Therapy (ESPT) in Budapest in 2015, a preliminary meeting was held aimed at establishing a pediatric individualized treatment in oncology and hematology committees. The main purpose was to facilitate the transfer and harmonization of pharmacogenetic testing from research into clinics, to bring together basic and translational research and to educate health professionals throughout Europe. The objective of this review was to provide the attendees of the meeting as well as the larger scientific community an insight into the compiled evidence regarding current pharmacogenomics knowledge in pediatric oncology. This preliminary evaluation will help steer the committee’s work and should give the reader an idea at which stage researchers and clinicians are, in terms of personalizing medicine for children with cancer. From the evidence presented here, future recommendations to achieve this goal will also be suggested.
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Affiliation(s)
- Vid Mlakar
- Cansearch Research Laboratory, Geneva University Medical School, Avenue de la Roseraie 64, 1205 Geneva, Switzerland.
| | - Patricia Huezo-Diaz Curtis
- Cansearch Research Laboratory, Geneva University Medical School, Avenue de la Roseraie 64, 1205 Geneva, Switzerland.
| | | | - Maja Krajinovic
- Charles-Bruneau Cancer Center, Centre hospitalier universitaire Sainte-Justine, 4515 Rue de Rouen, Montreal, QC H1V 1H1, Canada.
- Department of Pediatrics, University of Montreal, 2900 Boulevard Edouard-Montpetit, Montreal, QC H3T 1J4, Canada.
- Department of Pharmacology, Faculty of Medicine, University of Montreal, 2900 Boulevard Edouard-Montpetit, Montreal, QC H3T 1J4, Canada.
| | - Marc Ansari
- Cansearch Research Laboratory, Geneva University Medical School, Avenue de la Roseraie 64, 1205 Geneva, Switzerland.
- Pediatric Department, Onco-Hematology Unit, Geneva University Hospital, Rue Willy-Donzé 6, 1205 Geneva, Switzerland.
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11
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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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12
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Han Y, Zhang F, Wang J, Zhu Y, Dai J, Bu Y, Yang Q, Xiao Y, Sun X. Application of Glutamine-enriched nutrition therapy in childhood acute lymphoblastic leukemia. Nutr J 2016; 15:65. [PMID: 27401338 PMCID: PMC4940940 DOI: 10.1186/s12937-016-0187-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 06/22/2016] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND We investigated the effects of glutamine (Gln)-enriched nutritional therapy during chemotherapy on the nutritional status and immune function of children with acute lymphoblastic leukemia (ALL). METHODS We enrolled 48 children who were newly diagnosed with ALL in our department during the period of 2013.1-2014.12. The patients (follow random number table) were randomly divided into the control group (peptamen) and the treatment group (peptamen + glutamine), 24 cases in each group. The remission induction regimens were all based on VDLP (D) chemotherapy (VCR (Vincrisstine), DNR (Daunomycin), L-ASP (L-Asparagiase), Prednisolone and Dexamethasone). The treatment group received Gln-enriched nutritional therapy every day during the full course of chemotherapy,and the control group is as same as the treatment group except without glutamine. The indicators of general nutritional status, such as weight, height, and triceps skinfold thickness, and the indicators of biochemical tests, such as serum albumin, prealbumin, creatinine-height index, retinol binding protein, and urinary hydroxyproline index, were compared between the two groups at the end of the first, second, third and the fourth week when the chemotherapy was completed. And in the fourth week, flow cytometry was applied to detect the levels of T cell subsets and the activities of natural killer (NK) cells in peripheral blood of the two groups. RESULTS 1. after 4 weeks nutritional therapy, there is no significant difference (p > 0.05) between the two groups of children in weight, height and other indicators. 2. At the end of 2 weeks treatment, the level of prealbumin (PA) and retinol-binding protein (RBP) is higher in treatment group than that in the control group (P <0.05), at the end of 3 weeks treatment, the thickness of triceps skinfold is higher (P <0.05) than that in the control group; 3. At the end of 3 and 4 weeks, the concentrations serum ALB, PA, RBP and UHI were higher than in the control group (P <0.05); 4. There is statistically significant (p < 0.05) between the two groups in edema incidence; 5. At the end of treatment (4 weeks), the percentages of CD3 +, CD4 +, CD4 +/CD8 +, NK cell are significantly decreased in the two groups (P <0.05). CONCLUSION Gln-enriched nutritional therapy can effectively improve the systemic nutritional status of children with leukemia, improve immune function.
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Affiliation(s)
- Yueqin Han
- Department of Pediatrics, Liaocheng People's Hospital, Liaocheng, Shandong Province, Zip 252000, People's Republic of China.
- Department of Pediatric Hematology, Liaocheng People's Hospital, Research direction: childhood leukemia and cancer, Liaocheng, People's Republic of China.
| | - Fengzhi Zhang
- Department of Nutrition, Liaocheng People's Hospital, Liaocheng, Shandong Province, Zip 252000, People's Republic of China
- Department of Nutrition, Liaocheng People's Hospital, Research direction: nutrition interventions in patients with cancer and wasting syndrome, Liaocheng, People's Republic of China
| | - Jinshen Wang
- Department of Pediatrics, Liaocheng People's Hospital, Liaocheng, Shandong Province, Zip 252000, People's Republic of China
| | - Yanping Zhu
- Department of Pediatrics, Liaocheng People's Hospital, Liaocheng, Shandong Province, Zip 252000, People's Republic of China
| | - Jianhua Dai
- Department of Pediatrics, Liaocheng People's Hospital, Liaocheng, Shandong Province, Zip 252000, People's Republic of China
| | - Yueqing Bu
- Department of Pediatrics, Liaocheng People's Hospital, Liaocheng, Shandong Province, Zip 252000, People's Republic of China
| | - Qiaozhi Yang
- Department of Pediatrics, Liaocheng People's Hospital, Liaocheng, Shandong Province, Zip 252000, People's Republic of China
| | - Yingying Xiao
- Department of Pediatrics, Liaocheng People's Hospital, Liaocheng, Shandong Province, Zip 252000, People's Republic of China
| | - Xiaojing Sun
- Department of Pediatrics, Liaocheng People's Hospital, Liaocheng, Shandong Province, Zip 252000, People's Republic of China
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Jayachandran D, Laínez-Aguirre J, Rundell A, Vik T, Hannemann R, Reklaitis G, Ramkrishna D. Model-Based Individualized Treatment of Chemotherapeutics: Bayesian Population Modeling and Dose Optimization. PLoS One 2015; 10:e0133244. [PMID: 26226448 PMCID: PMC4520687 DOI: 10.1371/journal.pone.0133244] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 06/25/2015] [Indexed: 11/18/2022] Open
Abstract
6-Mercaptopurine (6-MP) is one of the key drugs in the treatment of many pediatric cancers, auto immune diseases and inflammatory bowel disease. 6-MP is a prodrug, converted to an active metabolite 6-thioguanine nucleotide (6-TGN) through enzymatic reaction involving thiopurine methyltransferase (TPMT). Pharmacogenomic variation observed in the TPMT enzyme produces a significant variation in drug response among the patient population. Despite 6-MP's widespread use and observed variation in treatment response, efforts at quantitative optimization of dose regimens for individual patients are limited. In addition, research efforts devoted on pharmacogenomics to predict clinical responses are proving far from ideal. In this work, we present a Bayesian population modeling approach to develop a pharmacological model for 6-MP metabolism in humans. In the face of scarcity of data in clinical settings, a global sensitivity analysis based model reduction approach is used to minimize the parameter space. For accurate estimation of sensitive parameters, robust optimal experimental design based on D-optimality criteria was exploited. With the patient-specific model, a model predictive control algorithm is used to optimize the dose scheduling with the objective of maintaining the 6-TGN concentration within its therapeutic window. More importantly, for the first time, we show how the incorporation of information from different levels of biological chain-of response (i.e. gene expression-enzyme phenotype-drug phenotype) plays a critical role in determining the uncertainty in predicting therapeutic target. The model and the control approach can be utilized in the clinical setting to individualize 6-MP dosing based on the patient's ability to metabolize the drug instead of the traditional standard-dose-for-all approach.
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Affiliation(s)
- Devaraj Jayachandran
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Way, West Lafayette, IN, 47907, United States of America
| | - José Laínez-Aguirre
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Way, West Lafayette, IN, 47907, United States of America
| | - Ann Rundell
- Weldon School of Biomedical Engineering, Purdue University, 206 South Martin Jischke Drive, West Lafayette, IN, 47907, United States of America
| | - Terry Vik
- Riley Hospital for Children, 702 Barnhill Drive, Indianapolis, IN, 46202, United States of America
| | - Robert Hannemann
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Way, West Lafayette, IN, 47907, United States of America
- Weldon School of Biomedical Engineering, Purdue University, 206 South Martin Jischke Drive, West Lafayette, IN, 47907, United States of America
| | - Gintaras Reklaitis
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Way, West Lafayette, IN, 47907, United States of America
| | - Doraiswami Ramkrishna
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Way, West Lafayette, IN, 47907, United States of America
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14
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Affiliation(s)
- Edouard Louis
- Department of Gastroenterology, University Hospital CHU of Liège, Liège, Belgium
| | - Peter Irving
- Department of Gastroenterology, Guy's & St Thomas' NHS Foundation Trust, London, UK
| | - Laurent Beaugerie
- Department of Gastroenterology, Hôpital St-Antoine and UPMC Univ Paris 06, Paris, France
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15
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Jayachandran D, Rundell AE, Hannemann RE, Vik TA, Ramkrishna D. Optimal chemotherapy for leukemia: a model-based strategy for individualized treatment. PLoS One 2014; 9:e109623. [PMID: 25310465 PMCID: PMC4195683 DOI: 10.1371/journal.pone.0109623] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 09/12/2014] [Indexed: 12/11/2022] Open
Abstract
Acute Lymphoblastic Leukemia, commonly known as ALL, is a predominant form of cancer during childhood. With the advent of modern healthcare support, the 5-year survival rate has been impressive in the recent past. However, long-term ALL survivors embattle several treatment-related medical and socio-economic complications due to excessive and inordinate chemotherapy doses received during treatment. In this work, we present a model-based approach to personalize 6-Mercaptopurine (6-MP) treatment for childhood ALL with a provision for incorporating the pharmacogenomic variations among patients. Semi-mechanistic mathematical models were developed and validated for i) 6-MP metabolism, ii) red blood cell mean corpuscular volume (MCV) dynamics, a surrogate marker for treatment efficacy, and iii) leukopenia, a major side-effect. With the constraint of getting limited data from clinics, a global sensitivity analysis based model reduction technique was employed to reduce the parameter space arising from semi-mechanistic models. The reduced, sensitive parameters were used to individualize the average patient model to a specific patient so as to minimize the model uncertainty. Models fit the data well and mimic diverse behavior observed among patients with minimum parameters. The model was validated with real patient data obtained from literature and Riley Hospital for Children in Indianapolis. Patient models were used to optimize the dose for an individual patient through nonlinear model predictive control. The implementation of our approach in clinical practice is realizable with routinely measured complete blood counts (CBC) and a few additional metabolite measurements. The proposed approach promises to achieve model-based individualized treatment to a specific patient, as opposed to a standard-dose-for-all, and to prescribe an optimal dose for a desired outcome with minimum side-effects.
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Affiliation(s)
- Devaraj Jayachandran
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana, United States of America
| | - Ann E. Rundell
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
| | - Robert E. Hannemann
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana, United States of America
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, United States of America
| | - Terry A. Vik
- Riley Hospital for Children, Indianapolis, Indiana, United States of America
| | - Doraiswami Ramkrishna
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana, United States of America
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16
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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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17
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Abstract
Crohn's disease is a chronic incurable condition that normally requires lifelong treatment. Whilst the anti-TNF agents have revolutionised the management of Crohn's disease over the last fifteen years, they are not a panacea. In particular, in part due to their immunogenic nature, loss of response limits their long term effectiveness in many patients. The only other long term disease-modifying options are the immunomodulators, methotrexate, azathioprine and mercaptopurine. Therefore, given the limited number of drugs available to treat Crohn's disease, it is important that efforts are made to ensure that drugs are used in the best way possible as once a drug is deemed ineffective, it is rarely used again. For the growing number of patients who have active disease despite having been exposed to all standard therapies, failure to optimise drug therapy may lead to missed opportunities in the management of their disease. In this review, optimisation of drugs commonly used in the management of Crohn's disease will be discussed.
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Affiliation(s)
- Peter M Irving
- Department of Gastroenterology, Guy's and St. Thomas' NHS Foundation Trust, Diabetes and Nutritional Sciences Division, King's College London, London, UK.
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18
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Carvalho ATP, Esberard BC, Fróes RSB, Rapozo DCM, Grinman AB, Simão TA, Santos JCVC, Carneiro AJV, Ribeiro-Pinto LF, Souza HSPD. Thiopurine-methyltransferase variants in inflammatory bowel disease: Prevalence and toxicity in Brazilian patients. World J Gastroenterol 2014; 20:3327-3334. [PMID: 24696613 PMCID: PMC3964403 DOI: 10.3748/wjg.v20.i12.3327] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Revised: 10/17/2013] [Accepted: 11/30/2013] [Indexed: 02/06/2023] Open
Abstract
AIM: To analyze the prevalence of thiopurine-methyltransferase (TPMT) genotypes and their association with drug toxicity in inflammatory bowel disease (IBD) patients from southeastern Brazil.
METHODS: A total of 219 consecutive patients with IBD, of which 146 had Crohn’s disease and 73 had ulcerative colitis, regularly seen at the outpatient unit of the Division of Gastroenterology at the University Hospital Pedro Ernesto of the State University of Rio de Janeiro, a tertiary referral center, were enrolled in this study from February 2009 to January 2011. We analyzed the presence of major TPMT genetic variants (TPMT*2, *3A, *3C) in IBD patients by means of a specific allele and RFLP-PCR. Genomic DNA was isolated from peripheral blood leukocytes by proteinase-K/Sodium Dodecyl Sulfate digestion and phenol-chloroform extraction. TPMT*2 (C238G), TPMT*3A (G460A/A719G), and TPMT*3C (A719G) genotypes were detected by real-time polymerase chain reaction followed by direct sequencing with specific primers. Clinical data were systematically recorded, and correlated with the genotype results.
RESULTS: The distribution of the selected TPMT gene polymorphism TPMT*2 (C238G), TPMT*3A (G460A/A719G), and TPMT*3C (A719G) genotypes was 3.6%, 5.4%, and 7.7% of the patients, respectively. Among the side effects recorded from patients taking azathioprine, 14 patients presented with pancreatitis and/or an elevation of pancreatic enzymes, while 6 patients had liver toxicity, and 2 patients exhibited myelosuppression/neutropenia. TPMT polymorphisms were detected in 37/219 patients (8 heterozygous for *2, 11 heterozygous for *3A, and 18 heterozygous for *3C). No homozygotic polymorphisms were found. Despite the prevalence of the TPMT*3C genotype, no differences among the genotype frequencies were significant. Although no association was detected regarding myelotoxicity or hepatotoxicity, a trend towards the elevation of pancreatic enzymes was observed for TPMT*2 and TPMT*3C genotypes.
CONCLUSION: The prevalence of TPMT genotypes was high among Brazilian patients. Variants genes *2 and *3C may be associated with azathioprine pancreatic toxicity in a IBD southeastern Brazilian population.
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Kennedy NA, Asser TL, Mountifield RE, Doogue MP, Andrews JM, Bampton PA. Thiopurine metabolite measurement leads to changes in management of inflammatory bowel disease. Intern Med J 2013; 43:278-86. [PMID: 22946880 DOI: 10.1111/j.1445-5994.2012.02936.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 08/23/2012] [Indexed: 12/17/2022]
Abstract
BACKGROUND The thiopurines azathioprine and 6-mercaptopurine are recommended for maintenance of remission in inflammatory bowel disease (IBD). Measurement of concentrations of the metabolites 6-thioguanine nucleotide and 6-methylmercaptopurine helps delineate interindividual variation in metabolism that may underlie variability in efficacy and toxicity. AIMS We aimed to perform a retrospective observational study to determine the utility of thiopurine metabolite testing following its introduction into South Australia. METHODS All patients having thiopurine metabolite tests done at Flinders Medical Centre between November 2008 and January 2010 were identified. Case notes of patients with testing done in the context of treatment for IBD were interrogated to determine the reason for testing, clinical context and outcome. RESULTS One hundred and fifty-one patients were identified with thiopurine metabolite testing for IBD with 157 testing episodes. Eighty (51.0%) had testing done for flare or inefficacy, 18 (11.5%) for adverse effects, 5 (3.2%) for a combination of inefficacy and adverse effects, and 54 (34.4%) for routine or other reasons. Testing was followed by improved outcomes of increased efficacy, reduced toxicity or change to alternative therapy in 55.0% of the inefficacy/flare group, 27.8% of the suspected adverse reaction group, 60.0% of the combination group, and 13.0% of the routine/other group. Allopurinol was used as cotherapy in 16 patients and led to marked improvements in metabolite concentrations. CONCLUSIONS Thiopurine metabolite testing has quickly become established in South Australia. When used for inefficacy or adverse effects, it often leads to improved outcomes. Prospective studies are needed to determine whether routine testing to guide dosing is of benefit.
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Affiliation(s)
- N A Kennedy
- Gastrointestinal Unit, Centre for Molecular Medicine, MRC IGMM, Western General Hospital, University of Edinburgh, Edinburgh, UK.
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20
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Abstract
Chronic pruritus in the adult patient is both an underappreciated and a difficult to treat condition. In the vast majority of cases, itch is the result of inflammatory skin disease and therefore may be responsive to systemic anti-inflammatory therapies. Urticarial dermatitis is an under-recognized cause of chronic itch in the adult population. Patients with this disorder are characterized by prolonged, prednisone-responsive pruritus, often in the absence of substantial cutaneous findings. Skin findings, when present, can range from subtle, persistent urticarial lesions to excoriated papules, often intermixed with urticaria, eczematous change, and lichenification secondary to chronic scratching. Hereby, we describe our algorithm for evaluation and management of adult patients with refractory pruritus (urticarial dermatitis in particular), including evaluation for other etiologies of pruritus, pre-immunosuppression workup, and the use of azathioprine and other steroid-sparing agents for treatment of recalcitrant itch.
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Affiliation(s)
- Maren E S Cotes
- Emory Department of Dermatology, Emory University, Atlanta, Georgia 30322, USA
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21
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van Egmond R, Barclay ML, Chin PKL, Sies CW, Florkowski CM. Preanalytical stringency: what factors may confound interpretation of thiopurine S-methyl transferase enzyme activity? Ann Clin Biochem 2013; 50:479-84. [DOI: 10.1177/0004563212474558] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background Measurement of red blood cell thiopurine S-methyl transferase (TPMT) enzyme activity before commencing thiopurine therapy is recommended to avoid severe bone marrow suppression in TPMT-deficient patients. Patient's samples go through preanalytical transportation and storage steps before measurement. We studied patient's TPMT activity sample data to assess the effect of preanalytical variables including transportation time. Methods A total of 8524 TPMT enzyme activity analyses were conducted from 2002 to 2010 in a single laboratory, with samples sent from seven centres throughout New Zealand. TPMT activity was correlated with time of arrival at the reference laboratory, patient gender and age and centre of sample collection. Results The 6348 (74%) selected TPMT measurements that fulfilled selection criteria ranged from 0 to 25.8 IU/mL. Median delay to sample analysis was 42 h. Median TPMT activity was significantly lower for all centres compared with the reference centre ( P < 0.001). Delay in sample arrival was significantly and independently correlated with TPMT enzyme activity (ANCOVA; P < 0.001), which showed a 0.011 (95% CI, 0.008–0.014) IU/mL decrease per extra hour of delay. After correcting for these data, one centre still had a significantly lower TPMT enzyme activity compared with the reference centre. Conclusions There was a significant negative correlation between TPMT enzyme activity and delay from sample collection to analysis. Transportation time is therefore an important preanalytical variable influencing TPMT activity. Samples from one centre had a lower TPMT activity after correcting for transportation delay, suggesting that other factors related to sample processing may also be relevant.
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Affiliation(s)
- Remco van Egmond
- Department of Clinical Pharmacology, Christchurch Hospital, Christchurch, New Zealand
| | - Murray L Barclay
- Department of Clinical Pharmacology, Christchurch Hospital, Christchurch, New Zealand
- Department of Gastroenterology, Christchurch Hospital, Christchurch, New Zealand
| | - Paul K L Chin
- Department of Clinical Pharmacology, Christchurch Hospital, Christchurch, New Zealand
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Affiliation(s)
| | - Ogechi N. Ikediobi
- Department of Clinical Pharmacy; School of Pharmacy; University of California San Francisco; San Francisco; CA; USA
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23
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Smith M, Blaker P, Patel C, Marinaki A, Arenas M, Escuredo E, Anderson S, Irving P, Sanderson J. The impact of introducing thioguanine nucleotide monitoring into an inflammatory bowel disease clinic. Int J Clin Pract 2013; 67:161-9. [PMID: 23253089 DOI: 10.1111/ijcp.12039] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Thioguanine nucleotides (TGNs) are the active product of thiopurine metabolism. Levels have been correlated with effective clinical response. Nonetheless, the value of TGN monitoring in clinical practice is debated. We report the influence of introducing TGN monitoring into a large adult inflammatory bowel disease (IBD) clinic. PATIENTS AND METHODS Patients with IBD undergoing TGN monitoring were identified from Purine Research Laboratory records. Whole blood TGNs and methylated mercaptopurine nucleotides were hydrolysed to the base and measured using HPLC. Clinical and laboratory data were obtained retrospectively. RESULTS One hundred and eighty-nine patients with 608 available TGN results were identified. In non-responders, TGNs directed treatment change in 39/53 patients. When treatment was changed as directed by TGN, 18/20 (90%) improved vs. 7/21 (33%) where the treatment decision was not TGN-directed, p < 0.001. Where treatment change was directed at optimisation of thiopurine therapy, 14/20 achieved steroid-free remission at 6 months vs. 3/10 where the TGN was ignored, (p = 0.037). Six per cent of patients were non-adherent, 25% under-dosed and 29% over-dosed by TGN. Twelve per cent of patients predominantly methylated thiopurines, this group had low TGN levels and high risk of hepatotoxicity. In responders, adherence and dosing issues were identified and TGN-guided dose-reduction was possible without precipitating relapse. Mean cell volume (MCV), white blood cell count (WBC) and lymphocyte counts were not adequate surrogate markers. MCV/WBC ratio correlated with clinical response, but was less useful than TGN for guiding clinical decisions. CONCLUSIONS Monitoring TGNs enables thiopurine therapy to be optimised and individualised, guiding effective treatment decisions and improving clinical outcomes.
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Affiliation(s)
- M Smith
- Department of Gastroenterology, St Thomas' Hospital, London, UK
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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25
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van Egmond R, Chin P, Zhang M, Sies CW, Barclay ML. High TPMT enzyme activity does not explain drug resistance due to preferential 6-methylmercaptopurine production in patients on thiopurine treatment. Aliment Pharmacol Ther 2012; 35:1181-9. [PMID: 22486532 DOI: 10.1111/j.1365-2036.2012.05084.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 12/07/2011] [Accepted: 03/13/2012] [Indexed: 12/11/2022]
Abstract
BACKGROUND Up to 20% of patients on thiopurine therapy fail to achieve adequate drug response. Many of these patients preferentially produce the toxic 6-methylmercaptopurine metabolites (6-MMP) rather than the active 6-thioguanine nucleotides (6-TGN) resulting in a high 6-MMP/6-TGN ratio (>20) and increased risk of hepatotoxicity. AIM To determine the prevalence of preferential 6-MMP producers and define the relationships between 6-TGN, 6-MMP and thiopurine methyltransferase (TPMT). METHODS The database of 6-TGN, 6-MMP and TPMT measurements from patients throughout New Zealand was used to calculate patients' 6-MMP/6-TGN ratios and identify those with high (>20) or normal ratio (≤20).The TPMT enzyme activity was compared amongst the groups. RESULTS Of 1879 patients with TPMT, 6-TGN and 6-MMP results, 349 (19%) had a 6-MMP/6-TGN ratio >20. The mean TPMT enzyme activity was slightly lower for those with a 6-MMP/6-TGN ratio ≤20 vs. >20, which achieved statistical significance (12.2 vs. 13.2; P < 0.001). However, the distributions of TPMT enzyme activity were similar, with 97% of TPMT results falling between 5.0 and 17.6 IU/mL for both groups. In all, 17% of those with 6-MMP/6-TGN ratio ≤20 were intermediate TPMT metabolisers (TPMT 5.0-9.2 IU/mL) vs. 7% in those with a ratio >20. CONCLUSIONS In this patient population with measured 6-MMP/6-TGN ratios, 19% of patients were preferential 6-MMP producers. The results show that high TPMT enzyme activity is not the major reason for preferential 6-MMP production in most patients with a high metabolite ratio. This suggests that there are one or more important alternative mechanisms for preferentially producing 6-MMP.
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Affiliation(s)
- R van Egmond
- Department of Clinical Pharmacology, Department of Gastroenterology, Christchurch Hospital, New Zealand
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Abstract
The majority of patients with IBD use conventional therapy (namely, aminosalicylates, antibiotics, corticosteroids and immunomodulatory agents) for prolonged periods of time, to both induce and maintain remission. Treatment paradigms in IBD have evolved towards a rapid escalation of therapy to achieve stringent goals, including mucosal healing and a reduction in the need for hospital admission and surgery. In this context, the failure to optimize conventional therapy can lead to a potentially effective treatment being abandoned too early, which is undesirable when only a limited number of drugs are effective in the management of IBD, and could also lead to patients being unnecessarily exposed to potentially toxic and/or expensive biologic drugs. This Review provides an overview of the many ways in which conventional therapy can be optimized, and describes strategies to improve adherence to drug regimens, such as simplifying the dosing regimen, optimizing drug delivery and dose, and tailoring medication on the basis of metabolite levels.
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Affiliation(s)
- Kirstin M Taylor
- Department of Gastroenterology, Guy's & St Thomas' Hospitals, Westminster Bridge Road, London SE1 7EH, UK
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Chevaux JB, Peyrin-Biroulet L, Sparrow MP. Optimizing thiopurine therapy in inflammatory bowel disease. Inflamm Bowel Dis 2011; 17:1428-35. [PMID: 20949566 DOI: 10.1002/ibd.21494] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2010] [Accepted: 08/13/2010] [Indexed: 02/06/2023]
Abstract
Despite recent advances, the therapeutic armamentarium for inflammatory bowel disease (IBD) is still limited. In addition, a step-up approach is recommended for most IBD patients. Thus, optimizing each medical therapy before switching to another drug class is the rule in clinical practice. Conventional therapies for IBD have not received the same amount of attention as biologic therapies over the last decade. However, due to their efficacy, safety, and low cost the thiopurine drugs azathioprine and 6-mercaptopurine remain the backbone of therapy for IBD. Pharmacogenomic advances and increased knowledge of their metabolism are allowing dosage optimization. Herein, after describing the pharmacogenetics and pharmacokinetics of thiopurines, we will discuss how to optimize thiopurine therapy. We will then underscore the need to take into account safety issues when optimizing thiopurine treatment.
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Affiliation(s)
- Jean-Baptiste Chevaux
- Department of Hepato-Gastroenterology and Inserm U954, University Hospital of Nancy, Vandoeuvre-lès-Nancy, France
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Haines ML, Ajlouni Y, Irving PM, Sparrow MP, Rose R, Gearry RB, Gibson PR. Clinical usefulness of therapeutic drug monitoring of thiopurines in patients with inadequately controlled inflammatory bowel disease. Inflamm Bowel Dis 2011; 17:1301-7. [PMID: 20812329 DOI: 10.1002/ibd.21458] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 07/19/2010] [Indexed: 12/13/2022]
Abstract
BACKGROUND Circulating concentrations of 6-thioguanine nucleotide (6-TGN) and 6-methyl mercaptopurine (6-MMP) are associated with thiopurine efficacy and may predict toxicity. This study aimed to examine retrospectively the utility of measuring metabolite concentrations in patients with inflammatory bowel disease (IBD) who had continuing symptoms despite stable thiopurine treatment. METHODS Concentrations of 6-TGN and 6-MMP were measured in lysates of washed red cells by high-performance liquid chromatography in peripheral blood drawn from 63 symptomatic patients with IBD (63% men, mean age 37, range 14-74 years, 67% Crohn's disease, 33% ulcerative colitis) treated with azathioprine or 6-mercaptopurine. Short-term clinical outcomes were examined. RESULTS 6-TGN concentrations weakly correlated with the thiopurine dose (r = 0.28, P = 0.08). On weight-based criteria, 50% of patients were underdosed. However, metabolite patterns suggested 7 (11%) patients were noncompliant, 18 (29%) were being underdosed, 33 (52%) were refractory to treatment with either appropriate (41%) or elevated (11%) metabolite concentrations, and 6 (10%) had a raised 6-MMP:6-TGN ratio consistent with aberrant thiopurine metabolism. The clinical outcome improved in 40 of 46 (87%) of patients in whom the course of action taken was as recommended by a metabolite-directed algorithm, while 3 of 17 patients (18%) improved where discordant actions were taken (P = 0.0001; Fisher's exact test). Fifteen patients (24%) avoided inappropriate escalation of therapy. CONCLUSIONS Dose-optimization or toxicity-avoidance strategies frequently result from metabolite testing in patients with inadequate efficacy from thiopurines, with evidence of better outcomes. Thiopurine metabolite testing is a potentially powerful tool for optimizing thiopurine usage in IBD.
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Affiliation(s)
- Melissa L Haines
- Department of Medicine, Eastern Health, Monash University, Victoria, Australia
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Nguyen CM, Mendes MAS, Ma JD. Thiopurine methyltransferase (TPMT) genotyping to predict myelosuppression risk. PLoS Curr 2011; 3:RRN1236. [PMID: 21593964 PMCID: PMC3094768 DOI: 10.1371/currents.rrn1236] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/16/2011] [Indexed: 01/17/2023]
Abstract
Azathioprine (AZA), 6-mercaptopurine (6-MP), and thioguanine (TG) are thiopurine drugs. These agents are indicated for the treatment of various diseases including hematologic malignancies, inflammatory bowel disease (IBD), rheumatoid arthritis, and as immunosuppressants in solid organ transplants. Thiopurine drugs are metabolized, in part, by thiopurine methyltransferase (TPMT). TPMT displays genetic polymorphism resulting in null or decreased enzyme activity. At least 20 polymorphisms have been identified, of which, TPMT *2, *3A, *3B, *3C, and *4 are the most commonly studied. These polymorphisms have been associated with increased myelosuppression risk. TPMT genotyping may be useful to predict this risk.
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Affiliation(s)
- Christine M Nguyen
- VA San Diego Healthcare System and UCSD Skaggs School of Pharmacy and Pharmaceutical Sciences
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Gardiner SJ, Gearry RB, Burt MJ, Chalmers-Watson T, Chapman BA, Ross AG, Stedman CAM, Huelsen A, Barclay ML. Allopurinol might improve response to azathioprine and 6-mercaptopurine by correcting an unfavorable metabolite ratio. J Gastroenterol Hepatol 2011; 26:49-54. [PMID: 21175793 DOI: 10.1111/j.1440-1746.2010.06489.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND AND AIM Allopurinol potentiates azathioprine and 6-mercaptopurine (6-MP) by increasing 6-thioguanine nucleotide (6-TGN) metabolite concentrations. The outcome might also be improved by adding allopurinol in individuals who preferentially produce 6-methylmercaptopurine nucleotides (6-MMPN), rather than 6-TGN. The aim of the present study was to investigate the effect of allopurinol on concentrations of 6-MMPN and 6-TGN in individuals with a high ratio of these metabolites (>20), which is indicative of a poor thiopurine response. METHODS Sixteen individuals were identified who were taking azathioprine or 6-MP, and were commenced on allopurinol to improve a high 6-MMPN:TGN ratio. Metabolite concentrations were compared before and after commencing allopurinol, and markers of disease control were compared. RESULTS The addition of 100-300 mg allopurinol daily and thiopurine dose reduction (17-50% of the original dose) resulted in a reduction of the median (and range) 6-MMPN concentration, from 11,643 (3,365-27,832) to 221 (55-844) pmol/8×10(8) red blood cells (RBC; P=0.0005), increased 6-TGN from 162 (125-300) to 332 (135-923) pmol/8×10(8) RBC (P=0.0005), and reduced the 6-MMPN:6-TGN ratio from 63 (12-199) to 1 (0.1-4.5) (P=0.0005). There was a significant reduction in steroid dose requirements at 12 months (P=0.04) and trends for improvement in other markers of disease control. One patient developed red cell aplasia that resolved upon stopping azathioprine and allopurinol. CONCLUSIONS In those with a high 6-MMPN:6-TGN ratio (>20), response to thiopurine treatment might be improved by the addition of allopurinol, together with a reduced thiopurine dose and close hematological monitoring.
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Affiliation(s)
- Sharon J Gardiner
- Department of Medicine, University of Otago, Christchurch, New Zealand
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Gerich ME, Quiros JA, Marcin JP, Tennyson L, Henthorn M, Prindiville TP. A prospective evaluation of the impact of allopurinol in pediatric and adult IBD patients with preferential metabolism of 6-mercaptopurine to 6-methylmercaptopurine. J Crohns Colitis 2010; 4:546-52. [PMID: 21122558 DOI: 10.1016/j.crohns.2010.03.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 03/12/2010] [Accepted: 03/13/2010] [Indexed: 02/08/2023]
Abstract
BACKGROUND 6-mercaptopurine (6-MP) is used for the induction and maintenance of remission of inflammatory bowel disease (IBD). 6-MP is converted into 6-methylmercaptopurine (6-MMP) or 6-thioguanine nucleotides (6-TGN) intracellularly. Treatment response in IBD patients correlates with 6-TGN levels. This study prospectively evaluated the effect of allopurinol on 6-MP metabolites in adult and pediatric IBD patients. Additionally, we quantified the prevalence of preferential metabolism towards 6-MMP through a retrospective analysis of IBD patients. METHODS Twenty patients (10 adult; 10 pediatric) with evidence of preferential metabolism towards 6-MMP, (6-TGN<250 pmol/8×10⁸ RBCs and 6-MMP>5000 pmol/8×10⁸ RBCs) were prospectively treated with allopurinol 100 mg daily and up to 100 mg of 6-MP. 6-MP dose was adjusted after a 3-week metabolite measurement. RESULTS The median dose of 6-MP for adults decreased from 100mg daily (range: 37.5-150 mg) to 25mg daily (range: 12.5-50 mg). The median dose of 6-MP for pediatric patients decreased from 50 mg (range: 25-50 mg) to 10.7 mg (range: 10.7 to 21.4 mg). Mean 6-TGN levels in all subjects increased from 197.4 (± 59) to 284.8 (± 107) pmol/8×10⁸ RBCs (p=0.0005). Mean 6-MMP levels in all subjects decreased from a mean of 7719.8 (± 4716) to 404.8 (± 332) pmol/8×10⁸ RBCs (p=0.0004). There were no complications associated with allopurinol therapy. Eighty-eight (30.9%) of 285 IBD patients had evidence of preferential metabolism towards 6-MMP. The proportion of preferential metabolism was equal in adults and pediatric patients. CONCLUSION Our results indicate that the addition of allopurinol safely shifts metabolite production in both adult and pediatric IBD patients and that there is a high prevalence of preferential metabolism towards 6-MMP among IBD patients.
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Affiliation(s)
- Mark E Gerich
- Department of Internal Medicine, Division of Gastroenterology, University of California Davis Health System, Sacramento, CA 95817, United States
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Abstract
Conventional therapies remain the mainstay of treatment for most patients with inflammatory bowel disease (IBD), with only a minority of patients requiring biologic therapies. Recently, attention has focused on optimizing dosing strategies for biologic agents; however, of equal importance are recent advances in the optimization of conventional IBD therapies. Newer aminosalicylate formulations demonstrate similar efficacy with a reduced pill burden and less frequent dosing, while new corticosteroid preparations may retain efficacy with a significantly improved safety profile. The limited indications for antibiotics and probiotics have been further refined by recent data, although uncertainties remain. Advances in the understanding of thiopurine metabolism continue to improve dose optimization and the potential for deliberate therapeutic manipulation with adjunctive therapies. An improved knowledge of intracellular methotrexate metabolism may translate to similar opportunities in the future. This article discusses recent advances relevant to clinical practice today.
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Affiliation(s)
- Miles P Sparrow
- Department of Gastroenterology, The Alfred Hospital, Victoria, Australia.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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ASKANASE ANCAD, WALLACE DANIELJ, WEISMAN MICHAELH, TSENG CHUNGE, BERNSTEIN LANA, BELMONT HMICHAEL, SEIDMAN ERNEST, ISHIMORI MARIKO, IZMIRLY PETERM, BUYON JILLP. Use of Pharmacogenetics, Enzymatic Phenotyping, and Metabolite Monitoring to Guide Treatment with Azathioprine in Patients with Systemic Lupus Erythematosus. J Rheumatol 2009; 36:89-95. [DOI: 10.3899/jrheum.070968] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Objective.Individualized therapy based on genetic background and monitoring of metabolites can optimize drug safety and efficacy. Such an approach is available for azathioprine (AZA), the thiopurine antimetabolite. AZA exerts therapeutic effects when metabolized to the active thiopurine nucleotide, 6-thioguanine (6-TGN). In inflammatory bowel disease (IBD), 6-TGN levels in the target range of 235–400 pmol/8 ×108 red blood cells (RBC) are associated with a high likelihood of response. Our objective was to evaluate whether drug escalation based on metabolite levels improves efficacy and maintains safety in patients with systemic lupus erythematosus (SLE).Methods.We conducted a 6-month open-label dose-escalation clinical study of patients with active SLE treated with azathioprine dosed by body weight and metabolite levels. The primary endpoint was ≥50% improvement in any one parameter of disease activity, or 50% decrease in glucocorticoid dose.Results.Of 50 patients enrolled in the study, 21 achieved clinical responses, 13 of whom had 6-TGN < 235 pmol/8 ×108 RBC. Ten patients had no clinical response at 6 months, yet achieved either therapeutic IBD 6-TGN levels (> 235, n = 4) or received maximum AZA dose ≥3.5 mg/kg (n = 6). In 19 patients the drug was discontinued prematurely due to side effects or SLE activity. For those patients in whom either liver function test or white blood cell count abnormalities were encountered, metabolites guided attribution to drug or disease activity.Conclusion.Clinical responses in SLE can occur at levels of 6-TGN lower than the target range established for IBD. During followup, measurements of AZA metabolites may provide a rational approach to safety.
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Abstract
AIM Probably, the most important and potentially lethal adverse event of azathioprine (AZA) and mercaptopurine (MP) is myelosuppression. Our aim was to conduct a review of AZA/MP-induced myelotoxicity in inflammatory bowel disease (IBD) patients. METHODS Bibliographical searches were performed in MEDLINE/EMBASE. The studies evaluating thiopurine-induced myelotoxicity in patients with IBD were reviewed. The cumulative incidence and the incidence rate of AZA/MP-induced myelotoxicity were calculated by a meta-analysis. RESULTS In total, 66 studies (8,302 patients) were included. The cumulative incidence of AZA/MP-induced myelotoxicity was 7% (95% confidence interval [CI] 6-8%). The incidence rate (per patient and year of treatment) of the drug-induced myelotoxicity was 3% (95% CI 3-4%). The risk was roughly similar with AZA and with MP (7%vs 9%). The duration of AZA/MP treatment in patients with myelotoxicity ranged from 12 days to 27 yr. The cumulative incidence of infections among AZA/MP-induced myelotoxicity patients was 6.5%. The cumulative incidence of severe myelotoxicity was 1.1% (incidence rate 0.9%). Three deaths were reported due to myelotoxicity (cumulative incidence 0.06%, 95% CI 0.02-0.17%). The risk of death among patients who developed myelotoxicity was 0.94% (95% CI 0.32-2.70%). CONCLUSION The incidence rate of myelotoxicity in IBD patients receiving AZA/MP is approximately 3% per patient and year of treatment. Although bone marrow toxicity may develop at any time after starting the therapy, this happens more frequently during the first months. The incidence rate of severe myelotoxicity is less than 1% per patient and year of treatment, and the mortality risk is less than 0.1% (which means that the risk of death among IBD patients who develop myelotoxicity is approximately 1%).
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Affiliation(s)
- Javier P Gisbert
- Gastroenterology Unit, Hospital Universitario de la Princesa, Madrid, Spain
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Hawwa AF, Millership JS, Collier PS, Vandenbroeck K, McCarthy A, Dempsey S, Cairns C, Collins J, Rodgers C, McElnay JC. Pharmacogenomic studies of the anticancer and immunosuppressive thiopurines mercaptopurine and azathioprine. Br J Clin Pharmacol 2008; 66:517-28. [PMID: 18662289 DOI: 10.1111/j.1365-2125.2008.03248.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIMS To examine the allelic variation of three enzymes involved in 6-mercaptopurine/azathioprine (6-MP/AZA) metabolism and evaluate the influence of these polymorphisms on toxicity, haematological parameters and metabolite levels in patients with acute lymphoblastic leukaemia (ALL) or inflammatory bowel disease (IBD). METHODS Clinical data and blood samples were collected from 19 ALL paediatric patients and 35 IBD patients who were receiving 6-MP/AZA therapy. All patients were screened for seven genetic polymorphisms in three enzymes involved in mercaptopurine metabolism [xanthine oxidase, inosine triphosphatase (C94-->A and IVS2+21A-->C) and thiopurine methyltransferase]. Erythrocyte and plasma metabolite concentrations were also determined. The associations between the various genotypes and myelotoxicity, haematological parameters and metabolite concentrations were determined. RESULTS Thiopurine methyltransferase variant alleles were associated with a preferential metabolism away from 6-methylmercaptopurine nucleotides (P = 0.008 in ALL patients, P = 0.038 in IBD patients) favouring 6-thioguanine nucleotides (6-TGNs) (P = 0.021 in ALL patients). Interestingly, carriers of inosine triphosphatase IVS2+21A-->C variants among ALL and IBD patients had significantly higher concentrations of the active cytotoxic metabolites, 6-TGNs (P = 0.008 in ALL patients, P = 0.047 in IBD patients). The study confirmed the association of thiopurine methyltransferase heterozygosity with leucopenia and neutropenia in ALL patients and reported a significant association between inosine triphosphatase IVS2+21A-->C variants with thrombocytopenia (P = 0.012). CONCLUSIONS; Pharmacogenetic polymorphisms in the 6-MP pathway may help identify patients at risk for associated toxicities and may serve as a guide for dose individualization.
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Affiliation(s)
- Ahmed F Hawwa
- Clinical and Practice Research Group, School of Pharmacy, Medical Biology Centre, Queen's University Belfast, Belfast, UK
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Gardiner SJ, Gearry RB, Begg EJ, Zhang M, Barclay ML. Thiopurine dose in intermediate and normal metabolizers of thiopurine methyltransferase may differ three-fold. Clin Gastroenterol Hepatol 2008; 6:654-60; quiz 604. [PMID: 18467186 DOI: 10.1016/j.cgh.2008.02.032] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS Patients with inflammatory bowel disease (IBD) may have different thiopurine dose requirements in relation to thiopurine methyltransferase (TPMT) genotype and/or phenotype. The purpose of this study was to determine thiopurine dose requirements in intermediate versus normal TPMT metabolism status. METHODS Consecutive patients starting azathioprine or 6-mercaptopurine for IBD were followed up for 9 months. The thiopurine dose was individualized using 6-thioguanine nucleotide (6-TGN) concentrations (range, 235-450 pmol/8 x 10(8) red blood cells [RBCs]) and clinical status. Additional assessments undertaken every three months included measures of disease activity. RESULTS Eight (10%) of 77 participants were withdrawn because of protocol violation. Fifty-two (75%) of the remaining 69 subjects ( approximately 90% and 10% with the TPMT*1/*1 and *1/*3 genotypes, respectively) completed follow-up on azathioprine (n = 46) or 6-mercaptopurine (n = 6). The mean initial dose (as azathioprine equivalents) was similar ( approximately 1 mg/kg/d) for the 2 TPMT genotypes, but after 9 months the dose was 50% lower in the TPMT*1/*3 group (0.9 vs 1.8 mg/kg/d, P < .0001). Despite dose adjustment, median 6-TGN concentrations still were 2-fold higher in the TPMT*1/*3 group at the end of the follow-up period (505 vs 273 pmol/8 x 10(8) RBCs, P = .02). This difference was 3-fold when the concentration was adjusted for dose (578 vs 183 pmol/8 x 10(8) per mg/kg/d, P = .0007). Results were similar if TPMT phenotype was used instead of genotype. Clinical outcomes did not differ between groups. CONCLUSIONS Initial target doses to attain therapeutic 6-TGN concentrations (>235 pmol/8 x 10(8) RBCs) in patients with IBD might be 1 and 3 mg/kg/d in intermediate and normal metabolizers, respectively.
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Affiliation(s)
- Sharon J Gardiner
- Department of Medicine, Christchurch Hospital and Christchurch School of Medicine, Christchurch, New Zealand.
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Vogeser M, Seger C. A decade of HPLC-MS/MS in the routine clinical laboratory--goals for further developments. Clin Biochem 2008; 41:649-62. [PMID: 18374660 DOI: 10.1016/j.clinbiochem.2008.02.017] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Revised: 02/17/2008] [Accepted: 02/20/2008] [Indexed: 11/20/2022]
Abstract
During the past decade, tandem mass spectrometry hyphenated to liquid chromatography separation systems (HPLC-MS/MS) has developed to an important technology in clinical chemistry - not only for research purposes but also for routine use. At present, most important application fields are target analyses in therapeutic drug monitoring (TDM) and metabolic disorders diagnosis. The essential strengths of HPLC-MS/MS include potentially high analytical specificity, wide range of applicability to small and large molecules, capability of multi- and mega-parametric tests, and the opportunity to develop powerful assays with a high degree of flexibility within a short time frame. The technique has overcome important limitations of GC-MS and is characterized by short analytical runtimes, applicability to thermo labile, polar and large molecules, and straightforward sample preparation. However, implementation of HPLC-MS/MS assays still requires substantial expertise and know-how. At the present, its application is limited to a rather small number of clinical routine laboratories. Nonetheless, HPLC-MS/MS has the potential to be further developed to a commonly applied high-throughput technique in clinical chemistry, complementary to present standard techniques as photometry and ligand binding methods. This review intends to characterize working characteristics of present day HPLC-MS/MS instrumentations used in clinical routine laboratories. Limitations of currently available systems and applications will be critically discussed. Required instrument improvements supporting the successful spreading of HPLC-MS/MS in laboratory medicine within the next decade will be outlined.
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Peng XX, Shi Z, Damaraju VL, Huang XC, Kruh GD, Wu HC, Zhou Y, Tiwari A, Fu L, Cass CE, Chen ZS. Up-regulation of MRP4 and down-regulation of influx transporters in human leukemic cells with acquired resistance to 6-mercaptopurine. Leuk Res 2007; 32:799-809. [PMID: 17996297 DOI: 10.1016/j.leukres.2007.09.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Revised: 08/22/2007] [Accepted: 09/27/2007] [Indexed: 11/19/2022]
Abstract
To investigate the mechanism of cellular resistance to 6-MP, we established a 6-MP resistant cell line (CEM-MP5) by stepwise selection of the human T-lymphoblastic leukemia cell line (CEM). CEM-MP5 cells were about 100-fold resistant to 6-MP compared with parental CEM cells. Western blot analysis demonstrated that multidrug resistant protein 4 (MRP4) was increased in CEM-MP5 cells, whereas the levels of the nucleoside transporters hENT1, hCNT2 and hCNT3 were decreased compared with those of parental CEM cells. Consistent with the operation of an efflux pump, accumulation of [14C]6-MP and/or its metabolites was reduced, and ATP-dependent efflux was increased in CEM-MP5 cells. Taken together these results showed that up-regulation of MRP4 and down-regulation of influx transporters played a major role in 6-MP resistance of CEM-MP5 cells.
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Affiliation(s)
- Xing-Xiang Peng
- Department of Pharmaceutical Sciences, College of Pharmacy and Allied Health Professions, St. John's University, Jamaica, NY 11439, United States
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Teml A, Schaeffeler E, Herrlinger KR, Klotz U, Schwab M. Thiopurine treatment in inflammatory bowel disease: clinical pharmacology and implication of pharmacogenetically guided dosing. Clin Pharmacokinet 2007; 46:187-208. [PMID: 17328579 DOI: 10.2165/00003088-200746030-00001] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
This review summarises clinical pharmacological aspects of thiopurines in the treatment of chronic inflammatory bowel disease (IBD). Current knowledge of pharmacogenetically guided dosing is discussed for individualisation of thiopurine therapy, particularly to avoid severe adverse effects. Both azathioprine and mercaptopurine are pro-drugs that undergo extensive metabolism. The catabolic enzyme thiopurine S-methyltransferase (TPMT) is polymorphically expressed, and currently 23 genetic variants have been described. On the basis of an excellent phenotype-genotype correlation for TPMT, genotyping has become a safe and reliable tool for determination of a patient's individual phenotype. Thiopurine-related adverse drug reactions are frequent, ranging from 5% up to 40%, in both a dose-dependent and -independent manner. IBD patients with low TPMT activity are at high risk of developing severe haematotoxicity if pharmacogenetically guided dosing is not performed. Based on several cost-benefit analyses, assessment of TPMT activity is recommended prior to thiopurine therapy in patients with IBD. The underlying mechanisms of azathioprine/mercaptopurine-related hepatotoxicity, pancreatitis and azathioprine intolerance are still unknown. Although the therapeutic response appears to be related to 6-thioguanine nucleotide (6-TGN) concentrations above a threshold of 230-260 pmol per 8 x 10(8) red blood cells, at present therapeutic drug monitoring of 6-TGN can be recommended only to estimate patients' compliance.Drug-drug interactions between azathioprine/mercaptopurine and aminosalicylates, diuretics, NSAIDs, warfarin and infliximab are discussed. The concomitant use of allopurinol without dosage adjustment of azathioprine/mercaptopurine leads to clinically relevant severe haematotoxicity due to elevated thiopurine levels. Several studies indicate that thiopurine therapy in IBD during pregnancy is safe. Thus, azathioprine/mercaptopurine should not be withdrawn in strictly indicated cases of pregnant IBD patients. However, breastfeeding is contraindicated during azathioprine/mercaptopurine therapy. Use of azathioprine/mercaptopurine for induction and maintenance of remission in corticosteroid-dependent or corticosteroid-refractory IBD, particularly Crohn's disease, is evidence based. To improve response rates in thiopurine therapy of IBD, comprehensive analyses including metabolic patterns and genome-wide profiling in patients with azathioprine/mercaptopurine treatment are required to identify novel candidate genes.
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Affiliation(s)
- Alexander Teml
- Dr Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany
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Gardiner SJ, Gearry RB, Roberts RL, Zhang M, Barclay ML, Begg EJ. Exposure to thiopurine drugs through breast milk is low based on metabolite concentrations in mother-infant pairs. Br J Clin Pharmacol 2007; 62:453-6. [PMID: 16995866 PMCID: PMC1885151 DOI: 10.1111/j.1365-2125.2006.02639.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
AIMS To determine infant exposure to 6-thioguanine and 6-methylmercaptopurine nucleotides (6-TGN and 6-MMPN, respectively) during maternal use of azathioprine in breastfeeding. METHODS Mother-infant pairs provided blood for determination of 6-TGN and 6-MMPN concentrations, and TPMT genotype. RESULTS Four women taking azathioprine 1.2-2.1 mg kg(-1) day(-1) and their infants were studied. All had the wild-type TPMT genotype. Maternal 6-TGN and 6-MMPN concentrations ranged from 234 to 291 and 284 to 1178 pmol per 8 x 10(8) red blood cells, respectively, and were consistent with those associated with improved therapeutic outcomes. Neither 6-TGN nor 6-MMPN was detected in any of the infants, despite a sensitive assay. CONCLUSIONS The data suggest that azathioprine may be 'safe' during breastfeeding in patients with the wild-type TPMT genotype ( approximately 90% of caucasian patients) taking 'normal' doses.
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Affiliation(s)
- Sharon J Gardiner
- Department of Clinical Pharmacology, Christchurch Hospital and Christchurch School of Medicine, Christchurch, New Zealand.
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Gardiner SJ, Gearry RB, Barclay ML, Begg EJ. Two cases of thiopurine methyltransferase (TPMT) deficiency--a lucky save and a near miss with azathioprine. Br J Clin Pharmacol 2007; 62:473-6. [PMID: 16995868 PMCID: PMC1885160 DOI: 10.1111/j.1365-2125.2005.02474.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND The association between thiopurine methyltransferase (TPMT) deficiency and myelosuppression with azathioprine is well recognized. Two cases are presented that illustrate the very different outcomes that may occur with azathioprine in patients with TPMT deficiency, which affects 0.3-0.6% of caucasians. CASE 1: The first patient's TPMT deficiency was identified following hospitalization for pancytopenia attributed to azathioprine. CASE 2: The second patient was identified as deficient early in treatment and myelosuppression was avoided by treating with a greatly decreased dose (25 mg per week). CONCLUSIONS Testing for TPMT ideally should be performed in every patient commencing a thiopurine drug.
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Affiliation(s)
- Sharon J Gardiner
- Department of Clinical Pharmacology, Christchurch Hospital and Christchurch School of Medicine, Private Bag, Christchurch, New Zealand.
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Gisbert JP, González-Lama Y, Maté J. [Monitoring of thiopurine methyltransferase and thiopurine metabolites to optimize azathioprine therapy in inflammatory bowel disease]. Gastroenterol Hepatol 2007; 29:568-83. [PMID: 17129552 DOI: 10.1157/13094355] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Determination of the activity of thiopurine methyltransferase (TPMT) and of thiopurine metabolites (6-thioguanine and 6-methylmercaptopurine nucleotides) could be useful for individualized monitoring of azathioprine (AZA) and 6-mercaptopurine (6-MP) doses. TPMT activity in the general population follows a trimodal distribution, in which approximately 0.3% of the population is homozygotic for the low-activity allele. A notable correlation has been observed between the low TPMP activity genotype or phenotype and the risk of myelotoxicity. Patients with a high TPMT activity genotype or homozygous phenotype should receive immunosuppressive doses that have clearly been demonstrated to be effective. In contrast, in patients with a low TPMT activity genotype or homozygous phenotype, the use of AZA/6-MP should be contraindicated or only very small doses should be administered. Importantly, TPMP deficiency explains only some cases of myelotoxicity and consequently periodic laboratory testing should be performed in patients receiving AZA/6-MP, even though TPMP function may be normal. Currently, the utility of routine thiopurine metabolite determinations in patients undergoing AZA/6-MP therapy has not been established and this practice should be limited to specific situations such as lack of response to thiopurine therapy or the occurrence of thiopurine-related adverse effects. Randomized trials comparing the routine strategy of AZA/6-MP dosing (based exclusively on the patient's weight) versus individualized monitoring (based on quantification of TPMP activity and/or thiopurine metabolites) are required before definitive conclusions on the most effective alternative can be drawn.
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Affiliation(s)
- Javier P Gisbert
- Servicio de Aparato Digestivo. Hospital Universitario de La Princesa. Universidad Autónoma. Madrid. España.
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Abstract
Cytotoxic chemotherapy is characterised by a low therapeutic index and significant variability in therapeutic and toxic effects. In an attempt to reduce this variability, most chemotherapy doses are individualised according to patient body surface area (BSA). This practice, which was introduced almost 50 years ago, clearly has practical and economic implications for the healthcare system. Furthermore, the clinical value of this approach has, in recent years, been questioned. Despite established practice, chemotherapy dose selection remains complicated, partly because treatment effects are difficult to measure, partly because drugs are used in combination with other treatment modalities, and also because the patient's condition may change with disease progression. Various patient-related factors can affect drug pharmacokinetics (PK) and pharmacodynamics (PD), for example organ function, expression and activity of metabolising enzymes, drug resistance, body size, gender, age, concomitant disease and co-administration of other drugs. These factors may be of clinical significance in chemotherapy dose determination and measures of PK, PD or both feature in attempts to devise more rigorous methods for chemotherapy dosing. Part I of this series of two reviews describes the history and clinical impact of BSA-based chemotherapy, and examines the scientific evidence to support BSA dosing. It evaluates the factors affecting PK and PD for specific drugs that could inform and refine dose determination.
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Affiliation(s)
- S A Kaestner
- Department of Pharmacy and Pharmacology, 5W, University of Bath, Claverton Down, Bath BA2 7AY, UK
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Abstract
PURPOSE OF REVIEW The deciphering of the human genome sequence has enabled the identification of genetic polymorphisms that are responsible for inter-individual variation in the response to drug therapy. This field is referred to as pharmacogenetics. We review the impact of pharmacogenetics on therapy in diseases of the colon using three common variant enzyme systems as examples. RECENT FINDINGS Many enzyme systems impact the treatment of diseases of the colon. Examples include thiopurine S-methyltransferase, dihydropyrimidine dehydrogenase and flavin monooxygenase 3. They affect the management of inflammatory bowel disease, colorectal cancer and the chemoprevention of colorectal adenoma by influencing the metabolism of their respective substrates, azathioprine/6-mercaptopurine, 5-fluorouracil and sulindac. Recent studies have implicated the significance of genetic polymorphisms in each of the three drug-metabolizing enzymes, which impacts on the therapeutic outcome of the stated diseases. These studies highlight the potential role of pharmacogenetics in the design of a therapeutic plan which would increase efficacy and limit toxicity. SUMMARY Pharmacogenetics of drug-metabolizing systems continues to gain significance in the drug therapy of a variety of disease states including those of the gastrointestinal tract.
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Affiliation(s)
- Irfan M. Hisamuddin
- Division of Digestive Diseases, Department of Medicine, Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Mohammad A. Wehbi
- Division of Digestive Diseases, Department of Medicine, Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Vincent W. Yang
- Division of Digestive Diseases, Department of Medicine, Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia, USA
- Department of Hematology and Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia, USA
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Abstract
Around 9% of inflammatory bowel disease (IBD) patients are resistant to azathioprine. We hypothesized that these patients may carry mutations within inosine-5'-monophosphate dehydrogenase (IMPDH). To test this hypothesis, we screened 20 azathioprine-resistant patients for variations in the two IMPDH genes (IMPDH1 and IMPDH2) using dHPLC and DNA sequencing. A 9 bp insertion within the IMPDH1 P3 promoter was found in a patient exhibiting severe azathioprine resistance. The insertion is predicted to abolish a cAMP-response element (CRE) and was found to significantly reduce IMPDH1 P3 promoter activity in a luciferase reporter gene assay (P-value <0.001). This in vitro assay suggests the variant promoter has altered function in vivo and consequently may have contributed to the thiopurine resistance observed in this patient. The absence of functional variants within the other patients indicates that if IMPDH genetic variability contributes to azathioprine resistance it does so infrequently.
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Affiliation(s)
- R L Roberts
- Department of Pathology, Christchurch School of Medicine & Health Sciences, Christchurch, New Zealand.
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