The thiopurine drugs-azathioprine and mercaptopurine-are purine antimetabolites used for the treatment of autoimmune hepatitis. These drugs undergo metabolism through genetically determined pathways, which influences their effectiveness and toxicity. There is scarce information regarding the clinical effects of measuring drug metabolites in these patients. The goal of the study is to test the clinical significance of measuring thiopurine metabolites in patients unsuccessfully treated with thiopurines. Clinical and laboratory data collected for patients who were treated for autoimmune hepatitis between 2015 and 2018, and did not achieve full remission under thiopurine therapy and had thiopurine metabolite levels measured due to lack of response and suspicious side effects were chosen. We compared clinical and laboratory data before and after the therapy change. The study included 25 tests of thiopurine metabolites in 21 patients. Six tests had therapeutic levels. Three tests showed high levels leading to lowering the drug dose. In 11 cases, levels of 6-thioguanine nucleotide were low; the dose was not changed in 3 of these, and the dose was increased in the remaining 8. Shunting was observed in 5 cases, 2 of which were mild and the dose was not changed. In the remaining 3, the dose was decreased, and allopurinol was added. Significant improvements in liver enzymes were observed following dose adjustments. We showed that, in cases of suboptimal response to thiopurine treatment, measuring thiopurine metabolites had an important role in optimizing therapy. In most patients, changing the dose led to a significant improvement with no need to switch to secondline therapies.

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OBJECTIVE: Hematotoxicity is a life-threatening condition that has become the major cause of drug discontinuation in patients with acute lymphoblastic leukemia (ALL). The nudix hydrolase 15 (NUDT15) gene polymorphism (c.415C>T) is reported to have an association with the hematotoxicity of 6-mercaptopurine (6-MP) as maintenance therapy in patients with ALL. However, the prevalence of this genetic polymorphism in the Indonesian population is unknown. This study aimed to assess the frequency of NUDT15 polymorphism among Indonesian pediatric patients with ALL and its association with the hematotoxicity of 6-MP.
METHODS: A total of 101 stored DNA samples from pediatric patients with ALL receiving 6-MP treatment were used for genetic testing. Direct sequencing was conducted to determine the NUDT15 c.415C>T genotype. Chi-square or Fisher\'s exact test were employed to examine the association between the NUDT15 c.415C>T genotype and hematotoxicity.
RESULTS: All (100%) of the DNA samples from patients with ALL treated with 6-MP exhibited a homozygous variant of the NUDT15 c.415C>T genotype, 70.3% of which showed hematotoxicity to some extent. We found no significant differences in NUDT15 gene polymorphism among patients with ALL with different states of hematotoxicity.
CONCLUSIONS: The observed high frequency of NUDT15 c.415C>T in our study population might explain the elevated prevalence of 6-MP-associated hematotoxicity in pediatric patients with ALL within the Indonesian population. Our study provides new insight regarding the NUDT15 gene polymorphism and its relation to hematotoxicity. Further studies are required to determine the necessity of adjusting the initial dose of 6-MP for Indonesian pediatric patients with ALL.

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.

UNASSIGNED: Polymorphisms in NUDT15 may result in differences in mercaptopurine-induced toxicity. This study aimed to identify the frequency of the NUDT15 (c.415C>T; rs116855232) polymorphism and investigate the effect of this polymorphism on mercaptopurine-induced toxicity in a population of Syrian patients with childhood acute lymphoblastic leukemia (ALL).
UNASSIGNED: This is a retrospective study that included children with ALL reaching at least 6 months of maintenance therapy. The NUDT15 genotyping was determined using standard targeted sequencing of polymerase chain reaction products. The odds ratio (OR) for the association between toxicity and genotype was evaluated.
UNASSIGNED: A total of 92 patients were enrolled. The majority of the patients in the study population were low-risk (63.04%), followed by intermediate-risk (25%), and high-risk (11.96%). There were 5 patients (5.4%) with NUDT15 (c.415C>T; rs116855232) CT genotype, and 1 patient (1.08%) with NUDT15 TT genotype, with allele frequencies of C=0.962 and T=0.038. The mercaptopurine median dose intensity was 100%, 54.69%, and 5% for the genotypes CC, CT, and TT, respectively (P=0.009). Early onset leukopenia was significantly associated with the NUDT15 polymorphism (OR: 6.16, 95% CI: 1.11-34.18, P=0.037). There was no association between the NUDT15 genotype and hepatotoxicity.
UNASSIGNED: Approximately 6.5% of the study population exhibited reduced NUDT15 activity. The mercaptopurine dose intensity was considerably low in NUDT15 rs116855232 TT genotype compared with CT and CC. The dosage of mercaptopurine should be adjusted according to the NUDT15 genotype in pediatric patients with ALL.

UNASSIGNED: Single nucleotide polymorphisms in the gene encoding proteins involved in mercaptopurine metabolism can influence drug efficacy and safety. This study aims to assess clinical pharmacists\' knowledge about mercaptopurine-related genes and their polymorphisms and investigate their attitudes, perceptions, and beliefs about the need for and importance of pharmacogenetic testing for mercaptopurine.
UNASSIGNED: A cross-sectional descriptive study was conducted among oncology/hematology clinical pharmacists in Saudi Arabia using an online-questionnaire developed by experts in the field. The questionnaire consists of four-sections exploring clinical pharmacists\' knowledge, attitudes, perceptions, and beliefs about the importance of gene testing and genes polymorphism when prescribing mercaptopurine. Descriptive statistics were used to analyze the data in the study.
UNASSIGNED: A total of 41 oncology/hematology clinical pharmacists responded to the survey invitation. Almost half of them had more than 10 years of work experience, but only 17 % of them received formal training in pharmacogenetics. The overall level of knowledge about pharmacogenetics among participants was low, with a mean score of 2.8 points (1.7) out of 8 items. However, around 76 % agreed that it is important to perform pharmacogenetic screening prior to prescribing mercaptopurine, and almost 93 % state that it will influence their dosage recommendation. Most of the participants had a good perception (95.1 %) of their role in genetic testing for medication selection, dosing, and monitoring; however, about 10 % of surveyed pharmacists reported not being completely responsible about recommending pharmacogenetic testing. The surveyed pharmacists had a good belief in the importance of pharmacogenetic testing and their overall attitude was positive toward the use of pharmacogenetic testing, with emphasis on the importance of training on the proper assessment and interpretation of pharmacogenetic tests.
UNASSIGNED: Pharmacists demonstrated good perception and positive attitude toward pharmacogenetic testing, despite the low level of knowledge and limited formal training. Thus, more attention to developing national guidelines on pharmacogenetic testing is warranted to ensure successful pharmacogenetic testing implementation.

Despite progressive improvements in the survival rate of pediatric B-cell lineage acute lymphoblastic leukemia (B-ALL), chemoresistance-induced disease progression and recurrence still occur with poor prognosis, thus highlighting the urgent need to eradicate drug resistance in B-ALL. The 6-mercaptopurine (6-MP) is the backbone of ALL combination chemotherapy, and resistance to it is crucially related to relapse. The present study couples chemoresistance in pediatric B-ALL with histidine metabolism deficiency. Evidence was provided that histidine supplementation significantly shifts the 6-MP dose-response in 6-MP-resistant B-ALL. It is revealed that increased tetrahydrofolate consumption via histidine catabolism partially explains the re-sensitization ability of histidine. More importantly, this work provides fresh insights into that desuccinylation mediated by SIRT5 is an indispensable and synergistic requirement for histidine combination therapy against 6-MP resistance, which is undisclosed previously and demonstrates a rational strategy to ameliorate chemoresistance and protect pediatric patients with B-ALL from disease progression or relapse.

Sweet\'s syndrome is an acute febrile neutrophilic dermatosis. Drug-induced Sweet\'s syndrome typically occurs soon after drug administration, with rapid resolution of symptoms with cessation of the offending agent. We report a man in his early 40s who presented with fever and widespread erythematous rash on a background of recently diagnosed mild stricturing ileal Crohn\'s disease. He was commenced on 6-mercaptopurine 12 days before presentation. Skin biopsy demonstrated diffuse infiltration of neutrophils in the upper dermis, dermal oedema, eosinophils and fibrin deposition. Symptoms rapidly improved with cessation of 6-mercaptopurine without requiring systemic corticosteroids.

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.

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract that encompasses two major conditions: Crohn\'s disease (CD) and ulcerative colitis (UC). Historically, IBD has been primarily reported in western countries, but over the past decades, its prevalence is rapidly increasing, especially in lower and middle-income countries (LMICs) such as India and China and also in Sub-Saharan Africa. The prevalence of IBD in LMICs has been the subject of growing concern due to the impact of access to public healthcare and the burden it places on healthcare resources. The classical thiopurines face significant challenges due to cessation of therapy in approximately half of patients within one year due to side effects or ineffectiveness. In this article, we highlight innovating thiopurine treatment for IBD patients in downregulating side effects and improving efficacy.