6-TGN

BACKGROUND: Mercaptopurine is an important component of acute lymphoblastic leukemia (ALL) and lymphoma (LLy) maintenance therapy. The 6-thioguanine nucleosides (6-TGN) are believed to be the primary contributor to myelosuppression and immunosuppressive effects, while 6-methylmercaptopurine (6-MMPN) is believed to be responsible for several toxicities including hepatotoxicity, pancreatitis, and hypoglycemia. Previous reports suggest the addition of allopurinol may reduce these toxicities...

OBJECTIVE: Despite widespread use of azathioprine (AZA) during pregnancy, no studies evaluated the impact of pregnancy on AZA metabolites 6-thioguanine nucleotide (6-TGN) and 6-methylmercaptopurine nucleotide (6-MMPN) disposition in rheumatic diseases. This study characterises changes in AZA metabolite concentrations throughout pregnancy in women with rheumatic disease and explores relationships between metabolite concentrations, maternal disease activity, and neonatal outcomes. METHODS: Patients with rheumatic disease from a single centre prescribed AZA prior to pregnancy and ≥1 blood sample during pregnancy (5/2016 to 4/2022) were included...

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...

BACKGROUND: 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. METHODS: Available blood samples from patients treated with AZA or 6-MP were retrieved from the Swiss IBD Cohort Study (SIBDCS)...

This study focuses on the use of thiopurines for treating inflammatory bowel diseases (IBD). These drugs undergo enzymatic changes within the body, resulting in active and inactive metabolites that influence their therapeutic effects. The research examines the role of genetic polymorphisms in the enzyme thiopurine S-methyltransferase (TPMT) in predicting the therapeutic response and adverse effects of thiopurine treatment. The TPMT genotype variations impact the individual responses to thiopurines. Patients with reduced TPMT activity are more susceptible to adverse reactions (AEs), such leukopenia, hepatotoxicity, pancreatitis, and nausea, which are common adverse effects of thiopurine therapy...

BACKGROUND: Thiopurines continue to play an important role in the treatment of inflammatory bowel disease (IBD). It is well known that thiopurines can cause several adverse reactions. Especially, hematopoietic toxicity may lead to severe agranulocytosis. In a previous prospective study, we investigated the relationship between inosine triphosphate pyrophosphatase (ITPA) c.94c > a polymorphism, 6-thioguanine nucleotide (6-TGN) concentration and toxicity. METHODS: To clarify the cause of thiopurine toxicity, we analysed nucleoside disphosphate-linked moiety X-type motif 15 (NUDT15) gene polymorphisms, i...

OBJECTIVE: Combination therapy with infliximab and a thiopurine has been shown to be more effective than monotherapy in patients with inflammatory bowel disease (IBD). The therapeutic efficacy of thiopurines is correlated with 6-thioguanine (6-TGN) levels between 235 and 450 pmol/8×108 erythrocytes. The primary aim of the study was to investigate the association between 6-TGN levels and inhibition prevention of the production of antibodies to infliximab (ATI). DESIGN: We performed a retrospective review of the medical records of patients being treated with infliximab for IBD at University Hospitals Bristol NHS Foundation Trust...

About 15% to 28% of patients treated with thiopurines experienced adverse drug reactions, such as haematological and hepatic toxicities. Some of these related to the polymorphic activity of the thiopurine S-methyltransferase (TPMT), the key detoxifying enzyme of thiopurine metabolism. We report here a case of thiopurine-induced ductopenia with a comprehensive pharmacological analysis on thiopurine metabolism. A 34-year-old woman, with a medical history of severe systemic lupus erythematosus with recent introduction of azathioprine therapy, presented with mild fluctuating transaminase blood levels consistent with a hepatocellular pattern, which evolved to a cholestatic pattern over the next weeks...

BACKGROUND: Crohn's disease with upper gastrointestinal tract involvement occurs more often in children than adults and has the potential to interfere with oral drug absorption. We aimed to compare disease outcomes in children receiving oral azathioprine for the treatment of Crohn's disease with (DP) and without (NDP) duodenal pathology at diagnosis. METHODS: Duodenal villous length, body mass index (BMI), and laboratory studies were compared in DP vs. NDP during the first year post-diagnosis, using parametric/nonparametric tests and regression analysis (SAS v9...

A rapid, specific and accurate high-performance liquid chromatography with tunable ultraviolet detection method was developed to simultaneously determine azathioprine metabolites, 6-thioguanine nucleotides (6-TGN) and 6-methyl mercaptopurine riboside (6-MMPr) in human red blood cells. Erythrocyte lysate sample was precipitated by perchloric acid under the protection of dithiothreitol, with 6-TGN and 6-MMPr being acid hydrolyzed to produce 6-thioguanine (6-TG) and 6-methymercaptopurine (6-MMP). A Waters Cortecs C18 column (2...

OBJECTIVES: Immune responses following SARS-CoV-2 vaccination in patients with inflammatory bowel disease (IBD) are not well characterized. The aims of this study were to explore the serological response associated with IBD, and immunosuppressive medications including serum concentrations of biologics and thiopurine metabolites. MATERIALS AND METHODS: This prospective, observational study included adult patients with ulcerative colitis (UC) and Crohn's disease (CD), and healthy controls...

BACKGROUND: Split-dose thiopurine and allopurinol-thiopurine co-therapy strategies have been suggested as rescue therapeutic options for children with inflammatory bowel disease (IBD) and impaired thiopurine metabolism. We compared efficacy and safety of these regimens in patients who previously failed conventional thiopurine treatment. METHODS: Children with IBD treated with split-dose thiopurine or low-dose thiopurine-allopurinol co-therapy were retrospectively identified...

BACKGROUND AND AIMS: Thioguanine is a well-tolerated and effective therapy for inflammatory bowel disease [IBD] patients. Prospective effectiveness data are needed to substantiate the role of thioguanine as a maintenance therapy for IBD. METHODS: IBD patients who previously failed azathioprine or mercaptopurine and initiated thioguanine were prospectively followed for 12 months starting when corticosteroid-free clinical remission was achieved (Harvey-Bradshaw Index [HBI] ≤ 4 or Simple Clinical Colitis Activity Index [SCCAI] ≤ 2)...

BACKGROUND AND AIMS: The aim of this study was to assess how 6-thioguanine nucleotide (6-TGN) levels and use of oral methotrexate relate to the pharmacokinetics of biologics. METHODS: This was a prospective cohort study including patients with inflammatory bowel diseases on maintenance doses of infliximab, vedolizumab, or ustekinumab on monotherapy or combination with a thiopurine or oral methotrexate. We collected 6-TGN concentrations, biomarker levels, and clinical and endoscopic disease activity...

Thiopurine drugs azathioprine (AZA) and 6-mercaptopurine (6-MP) are used extensively in pediatric and adult patients with inflammatory and neoplastic diseases. They are metabolized to 6-thioguanine nucleotides (6-TGN) or to 6-methyl-mercaptopurine nucleotides (6-MMPN). The balance between 6-TGN and 6-MMPN is highly variable and monitoring is recommended, but its benefit in outcome gives rise to conflicting results, potentially increased by differences in quantifying 6-MP metabolism. Our aim was to report (1) the HPLC-UV procedure used in our laboratory to quantify red blood cells (RBCs) with 6-TGN and 6-MMPN (as its derivate: 6-MMP(d)) in patients treated with thiopurines and (2) additional tests, sometimes confirmatory, to improve method standardization...

Mycophenolate rapidly substituted azathioprine (AZA) in transplant immunosuppression regimens since the 1990s, when early clinical trials indicated better outcomes, although opposite results were also observed. However, none of these trials used the well-established optimization methods for AZA dosing, namely, thiopurine methyltransferase pharmacogenetics combined with monitoring of the thiopurine metabolites 6-thioguanine nucleotides (6-TGN) and 6-methylmercaptopurine (6-MMP). Resistance to optimize AZA therapy remains today in transplant therapy, despite the fact that thiopurine metabolite testing is being used by other medical disciplines with evident improvement in clinical results...

BACKGROUND: The thiopurine medications are well established in the treatment of inflammatory bowel disease (IBD). There is significant variation in levels of toxic and therapeutic metabolites. Current data from small or short-term studies support therapeutic drug monitoring (TDM) in assessing azathioprine (AZA) and 6-mercaptopurine (6MP). TDM of thiopurines involves measurement and interpretation of metabolites 6-TGN and 6-MMPR. AIMS: This study aimed to assess long-cterm outcomes of patients on thiopurines following therapeutic drug monitoring...

Adverse reactions to azathioprine (AZA) vary greatly among individuals, which is associated with the variable levels of its major metabolites 6-thioguanine nucleotides (6-TGN) and 6-methylmercaptopurine (6-MMP). The intestinal microbiota has been proven to contain AZA-metabolizing enzymes, although the explicit role of the intestinal microbiota in AZA metabolism in vivo remains poorly comprehended. In this study, the pharmacokinetic behaviours of 6-TGN and 6-MMP were assessed in the pseudo germ-free (PGF) group and control group following oral administration of AZA...

BACKGROUND: Although the relationship between NUDT15 and thiopurine-induced leukopenia has been proven in previous studies, no prominent factors explaining interindividual variations in its active metabolite, 6-thioguanine nucleotide (6-TGN), and clinical efficacy have been identified. In this study, the correlation between genotypes (thiopurine S-methyltransferase, NUDT15, and ITPA polymorphisms), 6-TGN concentrations, and clinical outcomes (efficacy and side effects) in patients with inflammatory bowel disease were investigated...

BACKGROUND: NUDT15 polymorphisms are associated with leukopenia during treatment with thiopurines. However, data regarding its effect on treatment outcomes are scarce. AIMS: To investigate the outcomes between NUDT15 normal and intermediate metabolisers in paediatric patients with Crohn's disease (CD) treated with a combination therapy of infliximab (IFX) and azathioprine (AZA). METHODS: In this retrospective observational study, 143 patients categorised into the NUDT15 normal and intermediate metaboliser groups were compared based on clinical remission (CR), biochemical remission (BR), mucosal healing (MH) at 1 year treatment, IFX trough levels (TLs), antibodies to IFX (ATIs), 6-thioguanine nucleotide (6-TGN) levels, loss of response (LOR) and IFX durability...