UNASSIGNED: Although immunomodulators are widely prescribed in patients with Crohn\'s disease (CD), it is unclear whether there is a difference in treatment outcomes between thiopurines and methotrexate (MTX).
UNASSIGNED: To compare the risk of clinical failure between thiopurines and MTX in bio-naïve patients with CD.
UNASSIGNED: Nationwide, population-based study.
UNASSIGNED: We used claims data from the Korean National Health Insurance Service. After inverse probability of treatment weighting, logistic regression and Cox proportional hazard analyses were used to evaluate the risk of clinical failure in bio-naïve patients with CD treated with thiopurine (thiopurine group) or MTX (MTX group).
UNASSIGNED: Overall, 10,296 adult and pediatric patients with CD [9912 (96.3%) and 384 (3.7%) in the thiopurine and MTX groups, respectively] were included. The odds ratios (ORs) of failure to induce remission were significantly higher in the MTX group than in the thiopurine group [adjusted OR (aOR), 1.115; 95% confidence interval (CI), 1.045-1.190; p = 0.001]. However, the opposite result was observed only in patients without concomitant steroid use: the MTX group had a lower risk of induction failure than the thiopurine group (aOR, 0.740; 95% CI, 0.673-0.813; p < 0.001). The risk of overall maintenance failure was higher in the MTX group than in the thiopurine group [adjusted hazard ratio (aHR), 1.117; 95% CI, 1.047-1.191; p = 0.001]. The risk of overall maintenance failure was higher in the standard-dose MTX group than in the low-dose MTX group (aHR, 1.296; 95% CI, 1.134-1.480; p < 0.001). There was no significant difference in the risk of maintenance failure according to the administration route of MTX.
UNASSIGNED: Thiopurine is more effective than MTX in inducing and maintaining remission in bio-naïve patients with CD; however, the concomitant use of steroids influences inducing remission.
Differences in treatment efficacy between thiopurine and methotrexate in patients with Crohn’s disease who were not treated with biologics Immunomodulators (IMMs) used in the treatment of Crohn’s disease (CD) include medications such as thiopurine and methotrexate (MTX). Although IMMs are widely prescribed for patients with CD, it remains unclear whether treatment outcomes differ according to the specific types and dosages of IMMs and administration routes of MTX. In this study, we investigated the risk of treatment failure between thiopurines and MTX in CD patients not undergoing biologic treatment. Patients treated with MTX had a higher risk of maintenance failure than those treated with thiopurines. There was no difference in the risk of treatment failure according to the dosage of thiopurine. However, the risk of maintenance failure was higher in patients receiving standard-dose MTX than in those receiving low-dose MTX. There was no difference in the risk of maintenance failure according to the administration route of MTX. Our study enriches the knowledge regarding the treatment efficacy of thiopurines and MTX for patients with CD and may help clinicians develop appropriate treatment plans.

OBJECTIVE: The impact of thiopurine de-escalation while on vedolizumab versus continuing thiopurine therapy in ulcerative colitis (UC) is unclear. We aimed to determine the effect of thiopurine withdrawal for patients with UC in remission on vedolizumab.
METHODS: This multicenter randomized controlled trial recruited UC patients on vedolizumab 300 mg intravenously every 8 weeks and a thiopurine. Patients in steroid-free clinical remission for ≥6 months and endoscopic remission/improvement (Mayo endoscopic subscore ≤1) were randomized 2:1 to withdraw or continue thiopurine. Primary outcome was comparing week 48 vedolizumab trough concentrations. Secondary outcomes were clinical relapse (partial Mayo score ≥3 and fecal calprotectin >150 μg/g or increase in Mayo endoscopic subscore ≥1 from baseline), fecal calprotectin remission (<150 μg/g), C-reactive protein remission (<5 mg/L), centrally read endoscopic remission (Mayo endoscopic subscore = 0), histologic remission (Nancy index = 0), histo-endoscopic remission, and adverse events.
RESULTS: In total, 62 patients were randomized to continue (n = 20) or withdraw (n = 42) thiopurine. At week 48, vedolizumab trough concentrations were not significantly different between continue and withdrawal groups (14.7 μg/mL, interquartile rate [IQR], 12.3-18.5 μg/mL versus 15.9 μg/mL, IQR, 10.1-22.7 μg/mL, respectively, P = 0.36). The continue group had significantly higher fecal calprotectin remission (95.0%, 19/20 versus 71.4%, 30/42; P = .03), histologic remission (80.0%, 16/20 versus 48.6%, 18/37; P = .02), and histo-endoscopic remission (75.0%, 15/20 versus 32.4%, 12/37; P = .002) than the withdrawal group. Histologic activity (hazard ratio [HR], 15.5; 95% confidence interval [CI], 1.6-146.5; P = .02) and prior anti-tumor necrosis factor exposure (HR, 6.5; 95% CI, 1.3-33.8; P = .03) predicted clinical relapse after thiopurine withdrawal.
CONCLUSIONS: Thiopurine withdrawal did not affect vedolizumab trough concentrations. However, it may increase fecal calprotectin, histologic, and histo-endoscopic activity. Histologic activity and prior anti-tumor necrosis factor exposure may predict disease relapse on thiopurine withdrawal for patients using vedolizumab for UC. Australian and New Zealand Trial Registry, number ACTRN12618000812291.

This study evaluated the effectiveness of NUDT15 codon 139 genotyping in optimizing thiopurine treatment for inflammatory bowel disease (IBD) in Japan, using real-world data, and aimed to establish genotype-based treatment strategies.
A retrospective analysis of 4628 IBD patients who underwent NUDT15 codon 139 genotyping was conducted. This study assessed the purpose of the genotyping test and subsequent prescriptions following the obtained results. Outcomes were compared between the Genotyping group (thiopurine with genotyping test) and Non-genotyping group (thiopurine without genotyping test). Risk factors for adverse events (AEs) were analyzed by genotype and prior genotyping status.
Genotyping test for medical purposes showed no significant difference in thiopurine induction rates between Arg/Arg and Arg/Cys genotypes, but nine Arg/Cys patients opted out of thiopurine treatment. In the Genotyping group, Arg/Arg patients received higher initial doses than the Non-genotyping group, while Arg/Cys patients received lower ones (median 25 mg/day). Fewer AEs occurred in the Genotyping group because of their lower incidence in Arg/Cys cases. Starting with < 25 mg/day of AZA reduced AEs in Arg/Cys patients, while Arg/Arg patients had better retention rates when maintaining ≥ 75 mg AZA. Nausea and liver injury correlated with thiopurine formulation but not dosage. pH-dependent mesalamine reduced leukopenia risk in mesalamine users.
NUDT15 codon 139 genotyping effectively reduces thiopurine-induced AEs and improves treatment retention rates in IBD patients after genotype-based dose adjustments. This study provides data-driven treatment strategies based on genotype and identifies risk factors for specific AEs, contributing to a refined thiopurine treatment approach.

Silver nitrate reacts with 6-methylmercaptopurine riboside (6-MMPR) in aqueous solution containing methanol and dimethyl sulfoxide at room temperature to give a colourless crystalline complex, namely, bis(6-methylmercaptopurine riboside-κN7)(nitrato-κ2O,O\')silver(I) 2.32-hydrate, [Ag(NO3)(C11H14N4O4S)2]·2.32H2O. The crystal structure, determined from synchrotron diffraction data, shows a central AgI ion on a crystallographic twofold rotation axis, coordinated in an almost linear fashion by two 6-MMPR ligands via atom N7 (purine numbering), with the nitrate counter-ion loosely coordinated as a bidentate ligand, forming a discrete molecular complex as an approximate dihydrate. The complex and water molecules are connected in a three-dimensional network by hydrogen bonding.

UNASSIGNED: Thiopurines are commonly used to treat inflammatory bowel disease but withdrawal due to side effects are common. Thioguanine has been suggested to be better tolerated than conventional thiopurines.
UNASSIGNED: We studied drug-survival of low dose of thioguanine in real-life clinical practice in comparison to conventional thiopurines.
UNASSIGNED: Retrospective observational study.
UNASSIGNED: All patients born 1956 and later, and who at least once started thiopurine treatment between 2006 and 2022 were included. A medical chart review was performed that noted drug-survival for every thiopurine treatment attempt. The Mantel-Cox rank test was used to test differences in drug-survival for different thiopurines. Blood chemistry analysis and faecal calprotectin levels were registered for the first 5 years of treatment.
UNASSIGNED: In the study population, there was 379 initiated thiopurine treatments (210 for Crohn\'s disease and 169 for ulcerative colitis) in 307 patients with inflammatory bowel disease (IBD). Low-dose thioguanine (median dose 11 mg; 25-75th percentile 7-19 mg) had been initiated in 31 patients. Overall, when including all thiopurine attempts, thioguanine had the longest drug-survival [Mantel-Cox rank test: thioguanine versus azathioprine p = 0.014; thioguanine versus 6-mercaptopurine (6-MP) p < 0.001]. For second-line thiopurine treatment thioguanine had longer drug-survival than 6-MP (Mantel-Cox rank test: p = 0.006). At 60 months, 86% of the patients who started low-dose thioguanine were still on treatment compared to 42% of the patients who started 6-MP (p = 0.022). The median 6-thioguanine nucleotide levels in patients treated with thioguanine was 364 pmol/8 × 108. Patients on thioguanine treatment showed significantly lower values of median mean corpuscular volume at follow-up than patients treated with azathioprine and 6-MP. Patients treated with 6-MP showed significantly lower levels of FC in the third year of treatment compared to patient treated with azathioprine (59 versus 109 µg/g; p = 0.023), but there was no significant difference in FC levels for thioguanine compared to azathioprine (50 versus 109 µg/g; p = 0.33).
UNASSIGNED: Treatment with a low dose of thioguanine is well-tolerated in patients with IBD and had a significantly higher drug-survival than conventional thiopurines.
Low-dose of the immunomodulator drug thioguanine are well tolerated by patients with inflammatory bowel disease Thiopurines are commonly used to treat inflammatory bowel disease but it is common that patients end treatment due to side-effects. The thiopurine thioguanine has been suggested to be better tolerated than other thiopurines. We aimed to study if a low-dose of thioguanine had been tolerated better and used longer than other thiopurines in patients with inflammatory bowel disease at our clinic. In the study population there was 379 initiated thiopurine treatments in 307 patients with inflammatory bowel disease. Among those patients a low-dose thioguanine had been initiated in 31 patients. Overall, when including all thiopurine attempts, thioguanine had longest drug-survival of all thiopurines. For second line thiopurine treatment thioguanine had longer drug-survival than the thiopurine 6-mercaptopurine that are usually used as second line thiopurine treatment. At 60 months, 86% of the patients who started low dose thioguanine was still on treatment compared to 42% of the patients who started 6-mercaptopurine.There was a similar response on inflammatory markers the first five years from starting treatment with thioguanines compared to conventional used thiopurines. We conclude that treatment with a low-dose of thioguanine is well tolerated in patients with inflammatory bowel disease and have a significantly higher drug survival than conventional thiopurines.

Thiopurine is metabolized to 6-thio-(deoxy) guanosine triphosphate (6-thio-(d) GTP), which is then incorporated into DNA or RNA and causes cytotoxicity. Nudix hydrolase 15 (NUDT15) reduces the cytotoxic effects of thiopurine by converting 6-thio-(d) GTP to 6-thio-(d) guanosine monophosphate (6-thio-(d) GMP). NUDT15 polymorphisms like the Arg139Cys variant are strongly linked to thiopurine-induced severe leukocytopenia and alopecia. Therefore, measurement of NUDT15 enzymatic activity in individual patients can help predict thiopurine tolerability and adjust the dosage. We aimed to develop a quantitative assay for NUDT15 enzymatic activity in human blood samples. Blood samples were collected from donors whose NUDT15 genetic status was determined. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to assess the 6-thio-GTP metabolic activity in cell extracts. Because 6-thio-guanosine diphosphate (6-thio-GDP) and 6-thio-GMP were generated upon incubation of 6-thio-GTP with human blood cell extracts, the method detecting 6-thio-GTP, 6-thio-GDP, and 6-thio-GMP was validated. All three metabolites were linearly detected, and the lower limit of quantification (LLOQ) of 6-thio-GTP, 6-thio-GDP, and 6-thio-GMP were 5 μM, 1 μM, and 2 μM, respectively. Matrix effects of human blood cell extracts to detect 6-thio-GTP, 6-thio-GDP, and 6-thio-GMP were 99.0 %, 100.5 %, and 101.4 %, respectively, relative to the signals in the absence of blood cell extracts. The accuracy and precision of the method and the stability of the samples were also assessed. Using this established method, the genotype-dependent differences in NUDT15 activities were successfully determined using cell extracts derived from human blood cells with NUDT15 wild-type (WT) or Arg139Cys variant and 6-thio-GTP (100 μM) as a substrate (18.1, 14.9, and 6.43 μM/h/106 cells for WT, Arg139Cys heterozygous, and homozygous variant, respectively). We developed a method for quantifying intracellular NUDT15 activity in peripheral blood mononuclear cells (PBMCs), which we defined as the conversion of 6-thio-GTP to 6-thio-GMP. Although PBMCs preparation takes some time, its reproducibility in experiments makes it a promising candidate for clinical application. This method can tell the difference between WT and Arg139Cys homozygous blood samples. Even in patients with WT NUDT15, WT samples showed variations in NUDT15 activity, which may correlate with variations in thiopurine dosage.

Recent clinical data have identified infant patients with lethal ITPA deficiencies. ITPA is known to modulate ITP concentrations in cells and has a critical function in neural development which is not understood. Polymorphism of the ITPA gene affects outcomes for both ribavirin and thiopurine based therapies and nearly one third of the human population is thought to harbor ITPA polymorphism. In a previous site-directed mutagenesis alanine screen of the ITPA substrate selectivity pocket, we identified the ITPA mutant, E22A, as a gain-of function mutant with enhanced ITP hydrolysis activity. Here we report a rational enzyme engineering experiment to investigate the biochemical properties of position 22 ITPA mutants and find that the E22D ITPA has two- and four-fold improved substrate selectivity for ITP over the canonical purine triphosphates ATP and GTP, respectively, while maintaining biological activity. The novel E22D ITPA should be considered as a platform for further development of ITPA therapies.

UNASSIGNED: There are conflicting data as to whether co-treatment with 5-aminosalicylic acid (5-ASA) in patients with inflammatory bowel disease (IBD) under azathioprine (AZA) or 6-mercaptopurine (6-MP) therapy may influence 6-thioguanine nucleotide (6-TGN) concentrations, and whether this combination puts patients at risk of side-effects. The aim of the study was to determine 6-TGN levels in patients treated with AZA/6-MP, either alone or in combination with 5-ASA.
UNASSIGNED: Available blood samples from patients treated with AZA or 6-MP were retrieved from the Swiss IBD Cohort Study (SIBDCS). The eligible individuals were divided into 2 groups: those with vs. without 5-ASA co-medication. Levels of 6-TGN and 6-methylmercaptopurine ribonucleotides (6-MMPR) were determined and compared. Potential confounders were compared between the groups, and also evaluated as potential predictors for a multivariate regression model.
UNASSIGNED: Of the 110 patients enrolled in this analysis, 40 received concomitant 5-ASA at the time of blood sampling. The median 6-TGN levels in patients with vs. those without 5-ASA co-treatment were 261 and 257 pmol/8×108 erythrocytes, respectively (P=0.97). Likewise, there were no significant differences in 6-MMPR levels (P=0.79). Through multivariate analysis, 6-TGN levels were found to be significantly higher in non-smokers, patients without prior surgery, and those without signs of stress-hyperarousal.
UNASSIGNED: Blood concentrations of 6-TGN and 6-MMPR did not differ between patients with vs. those without 5-ASA co-treatment. Our data warrant neither more frequent lab monitoring nor dose adaptation of AZA in patients receiving concomitant 5-ASA treatment.

OBJECTIVE: SELECTION is the first study to assess the impact of concomitant thiopurine and other immunomodulator [IM] use on the efficacy and safety of a Janus kinase inhibitor, filgotinib, in patients with ulcerative colitis.
METHODS: Data from the phase 2b/3 SELECTION study were used for this post hoc analysis. Patients were randomised [2:2:1] to two induction studies [biologic-naive, biologic-experienced] to filgotinib 200 mg, 100 mg, or placebo. At Week 10, patients receiving filgotinib were re-randomised [2:1] to continue filgotinib or to switch to placebo until Week 58 [maintenance]. Outcomes were compared between subgroups with and without concomitant IM use.
RESULTS: At Week 10, similar proportions of patients in the +IM and -IM groups treated with filgotinib 200 mg achieved Mayo Clinic Score [MCS] response [biologic-naive: 65.8% vs 66.9%; biologic-experienced: 61.3% vs 50.5%] and clinical remission [biologic-naive: 26.0% vs 26.2%; biologic-experienced: 11.3% vs 11.5%]. At Week 58, similar proportion of patients in the +IM and -IM groups treated with filgotinib 200 mg achieved MCS response [biologic-naive: 74.2% vs 75.0%; biologic-experienced: 45.5% vs 61.4%] and clinical remission [biologic-naive: 51.6% vs 47.4%; biologic-experienced: 22.7% vs 24.3%]. The probability of protocol-specified disease worsening during the maintenance study in patients treated with filgotinib 200 mg did not differ between +IM and -IM groups [p = 0.6700]. No differences were observed in the incidences of adverse events between +IM and -IM groups in the induction/maintenance studies.
CONCLUSIONS: The efficacy and safety profiles of filgotinib treatment in SELECTION did not differ with or without concomitant IM use.
BACKGROUND: NCT02914522.

UNASSIGNED: Thiopurines are commonly used to treat inflammatory bowel disease (IBD). Thiopurines are considered safe throughout pregnancy. However, a published study suggested the risk of neonatal anemia was increased if exposed to thiopurines in utero. This prospective cohort study aimed to determine if there is an increased risk of cytopenia among infants born to pregnant people with IBD, exposed or unexposed to thiopurines, compared to infants born to those without IBD.
UNASSIGNED: Pregnant IBD patients, with and without thiopurine exposure, and one cohort of control individuals were recruited over a 5-year period. Consenting individuals completed a questionnaire and infants had a complete blood cell count at the newborn heel prick. Anemia was defined as hemoglobin (Hb) < 140g/L. Descriptive statistics were used to characterize the study population. Fisher exact tests were used to examine differences in outcomes between groups, a P-value of < 0.05 was deemed significant.
UNASSIGNED: Three cohorts were recruited: 19 IBD patients on thiopurines, 50 IBD patients not on thiopurines, and 37 controls (total of 106). Neonatal median Hb was not different with 177g/L (IQR 38g/L) for the IBD thiopurine group, 180.5g/L (IQR 40g/L) for the IBD non-thiopurine group, and 181g/L (IQR 37g/L) for the controls. Nineteen infants (18%) were cytopenic with 12 (11%) anemic, 6 (5.6%) thrombocytopenic, and 1 (0.94%) lymphopenic. Thiopurine exposure was only in one, mildly anemic, infant.
UNASSIGNED: These findings further support physicians and IBD patients contemplating pregnancy that current guidelines recommending thiopurine adherence do not lead to increased perinatal risk of anemia or cytopenia.