Towards personalised medicine in autoimmune hepatitis: Measurement of thiopurine metabolites results in higher biochemical response rates.

BACKGROUND & AIMS: Patients with autoimmune hepatitis (AIH) usually receive maintenance therapy with thiopurines, such as azathioprine (AZA) or mercaptopurine. Genetic polymorphisms in AZA metabolism can lead to variations in thioguanine nucleotide (TGN) and 6-methylmercaptopurine, both of which can cause adverse drug reactions (ADRs). In inflammatory bowel disease, a therapeutic TGN range (225-450 pmol/8x108 erythrocytes) has been identified to optimise effectiveness. We evaluated the benefits of a personalised medicine approach to thiopurine dosing, in comparison to standard weight-based dosing. METHODS: A retrospective matched cohort study of 214 patients with AIH who were seen at King's College between 1999-2019 was performed. Metabolite levels were measured in 109 patients. The control group included 105 patients on weight-based thiopurine dosing with no metabolite monitoring. RESULTS: Biochemical response (BR) occurred more frequently at 6-month follow-up in patients with metabolite monitoring compared to those on a weight-based regimen (77% vs. 60%, p = 0.008). This remained true with data analysis based on clinicians who measure metabolites and those who do not (BR at 6 months: 84% vs. 64%, p = 0.016). Patients with BR had TGN levels within the therapeutic range of 225-450 pmol/8x108 erythrocytes significantly more often than those who failed to achieve or lost BR (40% vs. 13%, p <0.0001). Moreover, TGN levels within the pre-defined therapeutic range predicted more stable disease within 6 months of testing compared to levels outside the range (p <0.0001). A high proportion of patients with sub-therapeutic TGN levels (75-225 pmol/8x108 erythrocytes) remained in BR (75% vs. 81%, p = 0.589) with fewer ADRs (44% vs. 86%, p = 0.0002) when compared to patients with therapeutic TGN levels. CONCLUSION: A strategy of personalised medicine using metabolite levels can optimise treatment regimens in AIH, resulting in fewer ADRs whilst maintaining BR. LAY SUMMARY: This study looked to see if measuring the breakdown products of a medication used in autoimmune hepatitis increases the chances of gaining good control of the disease, when compared to a group of patients who were on a dose of this medication based on their weight. A group of 214 patients with autoimmune hepatitis were split into 2 groups: roughly half had their medication dose adjusted according to measurements of breakdown products in the blood, whilst the other half received their weight-based dose as normal. The results confirmed that using a personalised approach and checking drug breakdown products resulted in fewer side effects and potentially improved control of disease.

Azathioprine and the neurologist.

Neurologists are very familiar with using corticosteroids and are aware of their considerable risk of adverse effects with prolonged use. Thus, we frequently consider alternative immunosuppression or corticosteroid sparing agents. However, unlike other specialties, such as rheumatology, there are few indications for corticosteroid-sparing agents in neurology and so our experience is less extensive; even these indications may reduce further as more disease-modifying treatments become available for neurological conditions. Azathioprine is perhaps the most commonly used corticosteroid-sparing agent in neurology. This review aims to remind neurologists of important aspects of azathioprine prescribing, focussing on enhancing patient safety and clinician confidence in its prescribing.

Correlation between Thiopurine S-Methyltransferase Genotype and Adverse Events in Inflammatory Bowel Disease Patients.

Background and Objectives: In patients with inflammatory bowel diseases (IBD), the use of azathioprine results in adverse events at a rate of 5% to 20%. The aim of the study was to assess a possible correlation between genetic variability of the enzyme thiopurine S-methyltransferase (TPMT) and the development of toxicity to azathioprine. Materials and Methods: A retrospective, single center, blind, case-control study was conducted on 200 IBD patients, of whom 60 cases suspended azathioprine due to toxicity (leukopenia, pancreatitis, hepatitis, and nausea or vomiting), and 140 controls continued treatment with the drug without adverse events. Results: In the entire cohort, only 8 cases of heterozygous mutations of TPMT were observed, corresponding to 4% mutated haplotype rate, much lower than that reported in literature (close to 10%). No homozygous mutation was found. Regarding the TPMT allelic variants, we did not find any statistically significant difference between patients who tolerated azathioprine and those who suffered from adverse events. (OR = 0.77, 95% CI = 0.08-7.72; p = 0.82). Conclusions: According to our study, in IBD patients, the search for TPMT gene mutations before starting treatment with azathioprine is not helpful in predicting the occurrence of adverse events. Importantly, patients with allelic variants should not be denied the therapeutic option of azathioprine, as they may tolerate this drug.

American Gastroenterological Association Institute Technical Review on the Role of Therapeutic Drug Monitoring in the Management of Inflammatory Bowel Diseases.

Therapeutic drug monitoring (TDM), which involves measurement of drug or active metabolite levels and anti-drug antibodies, is a promising strategy that can be used to optimize inflammatory bowel disease therapeutics. It is based on the premise that there is a relationship between drug exposure and outcomes, and that considerable inter-individual variability exists in how patients metabolize the drug (pharmacokinetics) and the magnitude and duration of response to therapy (pharmacodynamics). Therefore, the American Gastroenterological Association has prioritized clinical guidelines on the role of TDM in the management of inflammatory bowel disease. To inform these clinical guidelines, this technical review was developed in accordance with the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) framework for interventional and prognostic studies, and focused on the application of TDM for biologic therapy, specifically anti-tumor necrosis factor-α agents, and for thiopurines. Focused questions address the benefits and risks of a strategy of reactive TDM (in patients with active inflammatory bowel disease) to guide treatment changes compared with empiric treatment changes, and the benefits and risks of a strategy of routine proactive TDM (during routine clinical care in patients with quiescent disease) compared with no routine TDM. Additionally, the review addresses the benefits and risks of routine measurement of thiopurine methyltransferase enzyme activity or genotype before starting thiopurine therapy compared with empiric weight-based dosing and explores the performance of different trough drug concentrations for anti-tumor necrosis factor agents and thiopurines to inform clinical decision making when applying TDM in a reactive setting. Due to a paucity of data, this review does not address the role of TDM for more recently approved biologic agents, such as vedolizumab or ustekinumab.

Validation of a high-performance liquid chromatography method for thiopurine S-methyltransferase activity in whole blood using 6-mercaptopurine as substrate.

BACKGROUND: Variation in metabolism, toxicity and therapeutic efficacy of thiopurine drugs is largely influenced by genetic polymorphisms in the thiopurine S-methyltransferase (TPMT) gene. Determination of TPMT activity is routinely performed in patients to adjust drug therapy. METHODS: We further optimized a previously established high-performance liquid chromatography (HPLC) method by measuring TPMT activity in whole blood instead of isolated erythrocytes, which is based on conversion of 6-mercaptopurine to 6-methylmercaptopurine using S-adenosyl-methionine as methyl donor. RESULTS: The simplified TPMT whole-blood method showed similar or better analytical and diagnostic performance compared with the former erythrocyte assay. The whole-blood method was linear for TPMT activities between 0 and 40 nmol/(mL·h) with a quantification limit of 0.1 nmol/(mL·h). Within-day imprecision and between-day imprecision were ≤5.1% and ≤8.5%, respectively. The optimized method determining TPMT activity in whole blood (y) showed agreement with the former method determining TPMT activity in erythrocytes (x) (n=45, y=1.218+0.882x; p>0.05). Phenotype-genotype concordance (n=300) of the whole-blood method was better when TPMT activity was expressed per volume of whole blood (specificity 92.2%), whereas correction for hematocrit resulted in lower genotype concordance (specificity 86.9%). A new cutoff for the whole-blood method to distinguish normal from reduced TPMT activity was determined at ≤6.7 nmol/(mL·h). CONCLUSIONS: This optimized TPMT phenotyping assay from whole blood using 6-MP as substrate is suitable for research and routine clinical analysis.

Monitoring recommendations for oral azathioprine, methotrexate and cyclosporin in a paediatric dermatology clinic and literature review.

BACKGROUND/OBJECTIVES: Systemic oral immunomodulators azathioprine, methotrexate and cyclosporin are widely used in paediatric dermatology. Routine blood tests are performed to minimise drug-related adverse events. However, the frequency of monitoring tests may lead to significant fearful experiences for patients. We reviewed haematological abnormalities and clinical side-effects in a paediatric clinic population commencing immunomodulators for dermatological conditions, where haematological profiles are monitored less frequently than in current recommendations. METHODS: A retrospective chart review of children started on azathioprine, methotrexate or cyclosporin for a dermatological condition between 2001-2015 from a primarily paediatric, private dermatology practice was performed. Blood tests were done at baseline, 1 month, 2 months and then 3-monthly for children on azathioprine. Children on methotrexate and cyclosporin had tests done at baseline, after 1 month and then 3-monthly. RESULTS: In total, 242 children were included in this study. Azathioprine, methotrexate and cyclosporin cohorts had 95, 97 and 50 patients treated for a mean duration of 656, 758 and 313 days, respectively. Isolated abnormal blood tests indicated the cessation of azathioprine in 3/95 (3%), methotrexate in 5/97 (5%) and cyclosporin in 2/50 (4%) of patients. Abnormal blood test results were not associated with any reported clinical side-effects in the azathioprine (P = 0.726), methotrexate (P = 0.06) or cyclosporin groups (P = 0.250). CONCLUSION: In our experience, less frequent monitoring did not result in any significant adverse events over a 15-year period. We suggest that haematological monitoring during immunosuppressants use can be safely reduced from current recommendations.

Genetic Variants of Pre-microRNAs A-499G(rs3746444) and T-196a2C(rs11614913) with Ulcerative Colitis (UC) and Investigated with Thiopurine-S-Methyltransferase (TPMT) Activity.

BACKGROUND: Abnormal expression and different splicing of miRNAs are involved in several human inflammatory disorders. It has been suggested that gene variants of miRNAs may be associated with increased risk of ulcerative colitis (UC). We aimed to evaluate the association of two SNPs (miRNA-A-499G(rs3746444) and miRNA-T196a2C(rs11614913)) with the risk of UC and monitor their effect on thiopurine-S-methyltransferase (TPMT) activity in Kurdish population of Iran. METHODS: This case-control study was performed on 210 UC patients and 212 healthy individuals. Genotyping assay was performed using PCR-RFLP and the TPMT-activity was measured via non-extraction-HPLC method. RESULTS: We found that the existence of GG genotypes and G allele of miRNA-A-499G SNPs significantly increased the risk of UC by 1.76 and 1.32 times, respectively. The distribution of GG genotype (23.8% vs. 16%, χ2 = 4.2, p = 0.041) and G allele (46.4% vs. 39.4%, χ2 = 4, p = 0.046) of miRNA-A-499G, were significantly higher in UC patients compared to control group. Our results indicate that miRNA SNPs (miRNA-T-196a2C and miRNA-A-499G) have no significant effect on TPMT activity of studied population. CONCLUSIONS: Our results, for the first time, demonstrate that the GG genotype and G allele of miRNA-A-499G significantly increase the risk of UC. However, miRNA SNPs showed no significant effect on TPMT activity in studied population.

Comparison of 6-mercaptopurine with 6-thioguanine for the analysis of thiopurine S-methyltransferase activity in human erythrocyte by LC-MS/MS.

Thiopurines (TPDs) are first-line drugs in treating neuromyelitis optica spectrum disorders (NMOSD). Evaluation of thiopurine S-methyltransferase activity (TPMT), a major determinant of TPD toxicity, before TPD treatment using 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG) as substrate was suggested. However, the equivalent of the two substrates in TPMT activity evaluation was unknown, and an alternative substrate was required in TPMT activity evaluation in patients who were already taking 6-MP or 6-TG. Before evaluating the agreement of 6-MP and 6-TG in TPMT activity measurement in patients with NMOSD, the affinity of the two substrates for the active center of TPMT should be established. A computer-based simulation indicated that 6-MP and 6-TG had similar affinities for the two active sites of TPMT. According to the guidelines, an LC-MS/MS method was developed and validated to evaluate the TPMT activity in human erythrocyte hemolysate using 6-MP or 6-TG as substrates via 1 h incubation at 37°C. The method was applied in 81 patients with NMOSD. Evaluated by Bland-Altman plot, 6-methylmercaptopurine and 6-methylthioguanine represented TPMT activities were in agreement with each other. Further studies are warranted to confirm the results.

Randomized clinical trial: a pilot study comparing efficacy of low-dose azathioprine and allopurinol to azathioprine on clinical outcomes in inflammatory bowel disease.

BACKGROUND: Treating inflammatory bowel diseases (IBD) using thiopurines is effective; however, a high rate of adverse effects and lack of efficacy limit its use. Retrospective studies have suggested that treatment with low-dose thiopurines in combination with allopurinol is associated with higher remission rates and lower incidence of adverse events. AIM: To compare the rates of clinical remission and the rates of adverse events in IBD patients treated with either standard treatment with azathioprine or low-dose azathioprine in combination with allopurinol. METHODS: A prospective, open-label study, randomizing thiopurine-naïve IBD patients with normal thiopurine methyltransferase to 24 weeks of treatment with either standard azathioprine dose or low-dose azathioprine and allopurinol. RESULTS: A total of 46 patients with ulcerative colitis or Crohn's disease were randomized. We conducted an intention to treat analysis and found a significant (69.6%) proportion of the patients treated with low-dose azathioprine in combination with allopurinol was in clinical remission without the need for steroid or biologic treatment at week 24 compared to 34.7% of the patients treated with azathioprine monotherapy (RR, 2.10 [95% CI: 1.07-4.11]). In the azathioprine group, 47.8% of the patients compared to 30.4% of the patients in the azathioprine-allopurinol group had to withdraw from the study due to adverse events (RR, 1.47 [95% CI: 0.76-2.85]) Conclusions: This study indicated that by changing the treatment strategy from standard weight-based dosing of azathioprine to weight-based low-dose azathioprine in combination with allopurinol, we can increase remission rates in patients with IBD.

Plasma thiopurine S-methyltransferase levels and azathioprine-related adverse events in patients with Behçet's disease.

OBJECTIVES: Thiopurine S-methyltransferase (TPMT) is the key enzyme inactivating azathioprine (AZA), an immunosuppressive agent commonly used for treating inflammatory diseases including Behçet's disease (BD), systemic lupus erythematosus (SLE) and systemic vasculitis. Low TPMT levels facilitate occurrence of AZA-related adverse effects. We investigated TPMT levels in patients with BD, compared to healthy controls and patients with SLE or systemic vasculitis. METHODS: This cross-sectional study included 101 BD (77 using AZA), 74 SLE (35 using AZA), and 44 vasculitis (18 using AZA) patients and 101 healthy controls. Plasma TPMT levels were measured using ELISA. Student's t- and Kruskal-Wallis tests were used to compare TPMT levels according to possible risk factors. Receiver operating characteristic (ROC) analysis was used to determine whether a cut-off TPMT level could be found to predict AZA-related adverse effects. RESULTS: Plasma TPMT levels (mean± SD ng/mL) in BD (22.80±13.81) were comparable with healthy controls (22.71±13.49), but significantly lower than in SLE group (29.37±11.39) (p<0.001). TPMT levels in 130 patients receiving AZA were similar to the rest of the group. AZA-related adverse effects were identified in only 8 patients (5 with BD and 3 with SLE). TPMT levels were significantly lower in those 8 patients (14.08±9.49 vs. 25.62±12.68) (p=0.013), besides a cut-off value for predicting adverse effects was determined for the BD group with ROC analysis (area under the curve: 0.813). CONCLUSIONS: This is the first study to evaluate TPMT activity in a Turkish adult population. Although low plasma TPMT level is not the only factor determining AZA toxicity, a TPMT cut-off value may help to predict AZA-related adverse effects in BD.

RNA methylation machinery and m6A target genes as circulating biomarkers of ulcerative colitis and Crohn's disease: Correlation with disease activity, location, and inflammatory cytokines.

Accurate diagnosis of ulcerative colitis (UC) and Crohn's disease (CD), the main subtypes of inflammatory bowel disease (IBD), has been challenging due to the constraints of the current techniques. N6-methyl adenosine (m6A) regulators have evolved as key players in IBD pathogenesis; however, their relation to its clinical setting is largely unexplored. This study investigated the potential of selected RNA methylation machinery and m6A target genes as serum biomarkers of UC and CD, their predictive and discriminating capabilities, and their correlations with laboratory data, interleukin (IL)-6, interferon-γ, disease activity scores, and pathological features. Fifty UC and 45 CD patients, along with 30 healthy volunteers were enlisted. The mRNA expression levels of the m6A writers methyltransferase-like 3 (METTL3) and Wilms-tumor associated protein (WTAP), and the reader YTH domain family, member 1 (YTHDF1), along with the m6A candidate genes sex determining region Y-box 2 (SOX2), hexokinase 2 (HK2), and ubiquitin-conjugating enzyme E2 L3 (UBE2L3) were upregulated in UC patients, whereas only METTL3, HK2, and UBE2L3 were upregulated in CD patients versus controls. Serum WTAP (AUC = 0.94, 95 %CI = 0.874-1.006) and HK2 (AUC = 0.911, 95 %CI = 0.843-0.980) expression levels showed excellent diagnostic accuracy for UC, METTL3 showed excellent diagnostic accuracy for CD (AUC = 0.91, 95 %CI = 0.828-0.992), meanwhile, WTAP showed excellent discriminative power between the two diseases (AUC = 0.91, 95 %CI = 0.849-0.979). Multivariate logistic analysis unveiled the association of METTL3 and UBE2L3 expression with the risk of CD and UC diagnosis, respectively, controlled by age and sex as confounders. Remarkable correlations were recorded between the gene expression of studied m6A regulators and targets in both diseases. Among UC patients, serum METTL3 and WTAP were correlated with UC extent/type, while WTAP was correlated with IL-6. Among CD patients, serum METTL3 and HK2 were correlated with CD activity index (CDAI) and CD location. In conclusion, m6A regulators and target genes are distinctly expressed in UC and CD clinical samples, correlate with disease activity and extent/location, and could serve as a novel approach to empower the diagnosis and stratification of IBD subtypes.

Diagnostic and Prognostic Value of Methyltransferase Like 13 in Hepatocellular Carcinoma Based on Bioinformatics Analysis.

BACKGROUND/AIMS:  Hepatocellular carcinoma (HCC) is one of the cancers with the highest incidence and mortality rates. This study aims to explore the diagnostic and prognostic utility of methyltransferase like 13 (METTL13) in patients with HCC via bioinformatics analysis. MATERIALS AND METHODS:  We obtained mRNA data of HCC from the database of the Cancer Genome Atlas (TCGA), drawing survival curve by R 4.2.1 software. Cox regression analysis was conducted based on tumor stage and METTL13 expression. The GSE114564 dataset was chosen from the Gene Expression Omnibus. The differences in serum METTL13 levels between the groups of early HCC (eHCC) and non-cancer controls were evaluated. Using a receiver operating characteristic curve, we calculated the area under the curve (AUC) of serum METTL13 for diagnosing eHCC. RESULTS:  A total of 225 cases with HCC were screened from TCGA, and 29 cases were normal controls. The results showed that the METTL13 expression in the HCC group was higher than that in the normal controls (P <.001). The univariate [hazard ratio (HR) = 1.895, P = .006] and multivariate Cox regression (HR = 1.702, P = .037) analyses showed that high METTL13 expression reduced overall survival in HCC. Serum METTL13 levels were higher in the eHCC group than in the non-cancer controls (P = .008). The optimum AUC for predicting eHCC by serum METTL13 was 0.7091. CONCLUSION:  Serum METTL13 has a moderate diagnostic value for eHCC. High METTL13 expression is correlated with a worse prognosis in patients with HCC. Methyltransferase like 13 possesses the potential to be a novel biomarker for HCC.

Oral azathioprine for recalcitrant pediatric atopic dermatitis: clinical response and thiopurine monitoring.

BACKGROUND: Azathioprine is prescribed as a corticosteroid-sparing agent for many inflammatory conditions, including refractory atopic dermatitis (AD). There are limited prospective data on its appropriate use and monitoring for children with AD. OBJECTIVES: This study was designed to assess clinical response to azathioprine, determine the necessity for repeated measurement of thiopurine methyltransferase (TPMT) activity during treatment, and test the utility of measuring levels of the metabolites 6-thioguanine nucleotide and 6-methylmercaptopurine. METHODS: Twelve children with severe, recalcitrant AD were treated with oral azathioprine and followed prospectively. Disease severity was determined by the SCORing AD index. Baseline TPMT activity was measured and this was repeated along with 6-thioguanine nucleotide and 6-methylmercaptopurine measurement at times of stable improvement, inadequate response, or change in response. RESULTS: Azathioprine therapy was associated with clinical improvement in all but 1 patient. There were few adverse effects. Three patients showed a significant change in TPMT activity during treatment: 2 had a mild decrease and 1 demonstrated enzyme inducibility with an increase from the intermediate to the normal activity range. These changes, but not 6-thioguanine nucleotide or 6-methylmercaptopurine levels, inversely correlated with the clinical response to therapy. LIMITATIONS: Small sample size is a limitation. CONCLUSIONS: Azathioprine can be of benefit in the treatment of recalcitrant pediatric AD. Repeat assessment of TPMT activity may be helpful for evaluation of nonresponse or change in response and warrants further study. In contrast, measurement of thiopurine metabolites during treatment was not clinically useful.

Role of thiopurine metabolite testing and thiopurine methyltransferase determination in pediatric IBD.

Thiopurines have been used in inflammatory bowel disease (IBD) for >30 years, and measurements of both thiopurine methyltransferase (TPMT) and thiopurine (TP) metabolites, 6-thioguanine nucleotides (6-TGN) and 6-methylmercaptopurine (6-MMP), have been readily available. The North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN) Committee on Inflammatory Bowel Disease thought it appropriate to review the present indications for use of TPMT and TP metabolite testing. Substantial evidence demonstrates that TP therapy is useful for both Crohn disease and ulcerative colitis. Review of the existing data yielded the following recommendations. TPMT testing is recommended before initiation of TPs to identify individuals who are homozygote recessive or have extremely low TPMT activity, with the latter having more reliability than the former. Individuals who are homozygous recessive or have extremely low TPMT activity should avoid the use of TPs because of concerns for significant leukopenia. TMPT testing does not predict all cases of leukopenia and has no value to predict hypersensitivity adverse effects such as pancreatitis. Any potential value to reduce the risk of malignancy has not been studied. All individuals taking TPs should have routine monitoring with complete blood cell count and white blood cell count differential to evaluate for leukopenia regardless of TPMT testing results. Metabolite testing can be used to determine adherence with TP therapy. Metabolite testing can be used to guide dose increases or modifications in patients with active disease. Consideration would include either increasing the dose, changing therapy or for those with elevated transaminases or an elevated 6-MMP, using adjunctive allopurinol to help raise 6-thioguanine metabolites and suppress formation of 6-MMP. Routine and repetitive metabolite testing has little or no role in patients who are doing well and taking an acceptable dose of a TP.

Thiopurine S-methyltransferase phenotype-genotype correlation in children with acute lymphoblastic leukemia.

Thiopurine S-methyltransferase (TPMT) is an enzyme that catalyzes the S-methylation of thiopurine drugs such as 6-mercaptopurine, 6-thioguanine, and azathioprine. TPMT activity exhibits an interindividual variability mainly as a result of genetic polymorphism. Patients with intermediate or deficient TPMT activity are at risk for toxicity after receiving standard doses of thiopurine drugs. The aim of this study was to determine the TPMT genotype and phenotype (activity) and investigate the correlation between TPMT genotype and enzyme activity in 43 Polish children receiving 6-MP during maintenance therapy in course of acute lymphoblastic leukemia (ALL), in 16 children with ALL at diagnosis and 39 healthy controls. TPMT activity was measured in RBC by HPLC method. Patients were genotyped for TPMT *2, *3A and *3C variant allelesusing PCR-RFLP and allele-specific PCR methods. In the group of children with ALL during maintenance therapy, median TPMT activity (29.3 nmol 6-mMP g(-1) Hb h(-1)) was significantly higher compared to the group of children with ALL at diagnosis (20.6 nmol 6-mMP g(-1) Hb h(-1), p = 0.0028), as well as to the control group (22.8 nmol 6-mMP g(-1) Hb h(-1), p = 0.0002). Percentages of individuals heterozygous for TPMT variant allele in respective groups were: 9.3, 6.2 and 15.5% (p > 0.05). In all the study groups heterozygous patients manifested a significantly lower TPMT activity as compared to the wild type homozygotes (16.7 +/- 2.1 vs. 31.2 +/- 6.8 nmol 6-mMP g(-1) Hb h(-1), p = 0.002, in children during maintenance therapy, 11.9 +/- 2.7 vs. 24.6 +/- 9.5, p = 0.0003, in the combined group of children with ALL at diagnosis and controls). The results present that commencement of the thiopurine therapy caused an increase in the TPMT activity in RBCs by approximately 20%. All patients heterozygous for the TPMT variant allele revealed decreased TPMT activity compared to TPMT wild-type patients. Since decreased TPMT activity is associated with higher risk for toxicity after receiving standard doses of thiopurine drugs, pretreatment determination of TPMT status, with phenotypic or genetic assay, should be performed routinely, also in Poland.

How are thiopurines used and monitored by Swedish gastroenterologists when treating patients with inflammatory bowel disease?

OBJECTIVE: To perform a survey of thiopurine treatment in inflammatory bowel disease (IBD) among Swedish gastroenterologists. MATERIAL AND METHODS: A web-based questionnaire consisting of 25 multiple-choice questions was sent to 322 gastroenterologists in adult practice. RESULTS: A total of 132 questionnaires were received giving a response rate of 41%. Thiopurines were used by all 122 gastroenterologists in IBD practice and azathioprine was the first-choice thiopurine among 118 (97%) of them. Almost all gastroenterologists (97%) used weight-based dosing that was gradually escalated. The vast majority (89%) considered that efficacy should be evaluated within 6 months of therapy, while opinions regarding the optimal duration of therapy varied considerably. It was seen that 74% switched thiopurine in case of intolerance to the first-line substance. Thiopurine S-methyltransferase (TPMT) determinations were performed by 74% of the gastroenterologists and 67% used metabolite measurements. TPMT analyzers were more likely to measure metabolites (74 vs. 43%, p = 0.002). A quarter of the respondents were familiar with unconventional immunomodulation (co-administration of allopurinol, 6-thioguanine, mycophenolate mofetil or tacrolimus) and these respondents were also more likely to measure metabolites (79 vs. 52%; p = 0.002). CONCLUSIONS: Thiopurines are well established in the treatment of IBD among Swedish gastroenterologists. New and evolving knowledge about thiopurine therapy in IBD has been adapted to a large extent. Whether this change in clinical practice will have an impact on treatment outcomes has yet to be proven.

Systemic treatment of pediatric atopic dermatitis with azathioprine and mycophenolate mofetil.

Severe forms of atopic dermatitis (AD) cause significant morbidity in vulnerable pediatric populations and necessitate treatment with systemic therapy. The existing literature concerning the treatment of severe pediatric AD with azathioprine (AZ) and mycophenolate mofetil (MM) is sparse. The purpose of this case series is to examine the use of these two drugs in the treatment of severe pediatric AD. Medical records of 28 pediatric patients with AD from the University of North Carolina at Chapel Hill pediatric dermatology clinic treated using these two drugs were analyzed for laboratory values, thiopurine methyltransferase (TPMT) levels, symptoms, infections, and other relevant data. Patients were also contacted via the telephone to ascertain outcomes and any missing data. Treatment outcomes were scored into three categories: significant improvement, some improvement, and no improvement. AZ dosing was correlated to TPMT levels successfully, with comparable levels of improvement in the heterozygous and homozygous wild-type groups. Absolute eosinophil count corresponded to AD activity and treatment response across both treatment modalities in 18 of 26 (69%) patients. Seventeen of 28 (61%) patients treated with AZ and eight of 12 (66%) treated with MM reported significant improvement. We had lower rates of laboratory abnormalities and side effects with MM than with AZ but similar rates of cutaneous infections. Treatment outcomes did not appear to differ with race, sex, or TPMT level. We experienced success with AZ and MM in the treatment of severe pediatric AD. Coordinating treatment to each patient's unique morbidities is the best way to choose systemic treatments.

Azathioprine versus mesalazine for prevention of postoperative clinical recurrence in patients with Crohn's disease with endoscopic recurrence: efficacy and safety results of a randomised, double-blind, double-dummy, multicentre trial.

OBJECTIVE: The aim of the study was to compare azathioprine versus mesalazine tablets for the prevention of clinical recurrence in patients with postoperative Crohn's disease (CD) with moderate or severe endoscopic recurrence. METHODS: This was a 1 year, double-blind, double-dummy, randomised study which took place in 21 gastroenterology centres in Austria, the Czech Republic, Germany and Israel. The study participants were 78 adults with CD who had undergone resection with ileocolonic anastomosis in the preceding 6-24 months without subsequent clinical recurrence and with a Crohn's disease activity index (CDAI) score <200, but with moderate or severe endoscopic recurrence. The study drugs were azathioprine 2.0-2.5 mg/kg/day or mesalazine 4 g/day over 1 year. The primary end point was therapeutic failure during 1 year, defined as a CDAI score > or = 200 and an increase of > or = 60 points from baseline, or study drug discontinuation due to lack of efficacy or intolerable adverse drug reaction. RESULTS: Treatment failure occurred in 22.0% (9/41) of azathioprine-treated patients and 10.8% (4/37) of mesalazine-treated patients, a difference of 11.1% (95% CI -5.0% to 27.3%, p=0.19). Clinical recurrence was significantly less frequent with azathioprine versus mesalazine (0/41 (0%) vs 4/37 (10.8%), p=0.031), whereas study drug discontinuation due to adverse drug reactions only occurred in azathioprine-treated patients (9/41 (22.0%) vs 0%, p=0.002). The proportion of patients showing > or = 1 point reduction in Rutgeerts score between baseline and month 12 was 63.3% (19/30) and 34.4% (11/32) in the azathioprine and mesalazine groups, respectively (p=0.023). CONCLUSIONS: In this population of patients with postoperative CD at high risk of clinical recurrence, superiority for azathioprine versus mesalazine could not be demonstrated for therapeutic failure.

Characterisation and utility of thiopurine methyltransferase and thiopurine metabolite measurements in autoimmune hepatitis.

BACKGROUND & AIMS: Corticosteroids alone or in conjunction with azathioprine (AZA) is the standard treatment in autoimmune hepatitis (AiH). Individual variations in thiopurine (TP) metabolism may affect both drug efficacy and toxicity. Our aim was to investigate the utility of thiopurine methyltransferase (TPMT) as well as thioguanine nucleotide (TGN) and methylthioinosine monophosphate (meTIMP) metabolite measurements with regard to clinical outcome. METHODS: Two hundred thirty-eight patients with AiH were included in this cross-sectional study. TPMT status was assessed in all patients, while TGN and meTIMP were measured in patients with ongoing TP medication. Clinical outcome was evaluated by liver tests and the ability to withdraw steroids. RESULTS: TPMT genotyping (n=229) revealed 207 (90.4%) wild-type and 22 heterozygous patients. One hundred forty-three patients had ongoing TP therapy with AZA (n=134) or mercaptopurine (MP; n=9); response was judged as complete response (CR) in 113 patients and partial response (PR) in 30 patients. Both TP dose (1.64 vs 1.19 mg/kg; p=0.012) and TPMT activity (14.3 vs 13.5; p=0.05) were higher in PR, resulting in similar TGN levels (PR: 121 pmol/8 x 10(8) red blood cells [RBC]; CR: 113 pmol/8 x 10(8) RBC; p=0.33) but higher meTIMP levels in PR (1350 vs 400 pmol/8 x 10(8) RBC; p=0.004). Patients able to withdraw steroids or who were using 5 mg prednisolone daily were treated with lower TP doses than patients on higher steroid doses (1.15 vs 1.18 vs 1.82 mg/kg; p<0.001). CONCLUSIONS: TP metabolite measurements are of clinical value in AiH patients who do not respond to standard TP treatment and for the identification of a shifted metabolism, which may demand an alternative treatment strategy.