BACKGROUND: Low thiopurine-methyl-transferase (TPMT) activity and high 6-thioguanine-nucleotide (6TGN) concentrations have been linked to therapeutic success in inflammatory bowel disease patients treated with thiopurines; however, this has not been implemented in clinical practice. AIM: To identify a therapeutic threshold value for TPMT or 6TGN concentrations, and their capability to predict treatment safety and efficacy. METHODS: Prospective multicentre study including steroid-resistant/dependent patients starting thiopurines. The TPMT activity was determined at inclusion (>5 U/mL required). Azathioprine metabolites [6TGN, 6-methyl-mercaptopurine ribonucleotides (6MMP), and 6TGN/6MMP and 6TGN/TPMT ratios] were periodically monitored during steroid tapering and after withdrawal for 6 months or until a new flare occurred. RESULTS: A total of 113 patients were analysed (62% clinical response). Areas under the receiver operating characteristic (ROC) curve (AUC) relating clinical response and metabolite levels at 2, 4 and 6 months after steroid withdrawal were less than 0.7. The AUCs relating final response and initial TPMT activity or metabolite concentrations at 2, 4, 8 and 16 weeks after starting thiopurines were less than 0.7. No cut-off point with worthwhile sensitivity/specificity was found. Eight (7%) patients developed thiopurine-related toxicity that could not be linked to TPMT activity or 6TGN levels. CONCLUSIONS: Our results do not support determination of TPMT activity or 6TGN concentrations to predict treatment outcome, and no useful serum metabolites threshold value to adjust the drug's dose was identified.
BACKGROUND: Low thiopurine-methyl-transferase (TPMT) activity and high 6-thioguanine-nucleotide (6TGN) concentrations have been linked to therapeutic success in inflammatory bowel diseasepatients treated with thiopurines; however, this has not been implemented in clinical practice. AIM: To identify a therapeutic threshold value for TPMT or 6TGN concentrations, and their capability to predict treatment safety and efficacy. METHODS: Prospective multicentre study including steroid-resistant/dependent patients starting thiopurines. The TPMT activity was determined at inclusion (>5 U/mL required). Azathioprine metabolites [6TGN, 6-methyl-mercaptopurine ribonucleotides (6MMP), and 6TGN/6MMP and 6TGN/TPMT ratios] were periodically monitored during steroid tapering and after withdrawal for 6 months or until a new flare occurred. RESULTS: A total of 113 patients were analysed (62% clinical response). Areas under the receiver operating characteristic (ROC) curve (AUC) relating clinical response and metabolite levels at 2, 4 and 6 months after steroid withdrawal were less than 0.7. The AUCs relating final response and initial TPMT activity or metabolite concentrations at 2, 4, 8 and 16 weeks after starting thiopurines were less than 0.7. No cut-off point with worthwhile sensitivity/specificity was found. Eight (7%) patients developed thiopurine-related toxicity that could not be linked to TPMT activity or 6TGN levels. CONCLUSIONS: Our results do not support determination of TPMT activity or 6TGN concentrations to predict treatment outcome, and no useful serum metabolites threshold value to adjust the drug's dose was identified.
Authors: E G Quetglas; A Armuzzi; S Wigge; G Fiorino; L Barnscheid; M Froelich; Silvio Danese Journal: Eur J Clin Pharmacol Date: 2015-05-27 Impact factor: 2.953
Authors: M V Relling; E E Gardner; W J Sandborn; K Schmiegelow; C-H Pui; S W Yee; C M Stein; M Carrillo; W E Evans; J K Hicks; M Schwab; T E Klein Journal: Clin Pharmacol Ther Date: 2013-01-17 Impact factor: 6.875
Authors: Christopher Andrew Lamb; Nicholas A Kennedy; Tim Raine; Philip Anthony Hendy; Philip J Smith; Jimmy K Limdi; Bu'Hussain Hayee; Miranda C E Lomer; Gareth C Parkes; Christian Selinger; Kevin J Barrett; R Justin Davies; Cathy Bennett; Stuart Gittens; Malcolm G Dunlop; Omar Faiz; Aileen Fraser; Vikki Garrick; Paul D Johnston; Miles Parkes; Jeremy Sanderson; Helen Terry; Daniel R Gaya; Tariq H Iqbal; Stuart A Taylor; Melissa Smith; Matthew Brookes; Richard Hansen; A Barney Hawthorne Journal: Gut Date: 2019-09-27 Impact factor: 23.059
Authors: Akbar K Waljee; Kay Sauder; Anand Patel; Sandeep Segar; Yiwei Zhang; Ji Zhu; Ryan W Stidham; Ulysses Balis; Peter D R Higgins Journal: J Crohns Colitis Date: 2018-01-05 Impact factor: 9.071