Safe treatment of thiopurine S-methyltransferase deficient Crohn's disease patients with azathioprine

Personalized Treatment for Crohn's Disease: Current Approaches and Future Directions

Crohn's disease is a complex, relapsing and remitting inflammatory disorder of the gastrointestinal tract with a variable disease course. While the treatment options for Crohn's disease have dramatically increased over the past two decades, predicting individual patient response to treatment remains a challenge. As a result, patients often cycle through multiple different therapies before finding an effective treatment which can lead to disease complications, increased costs, and decreased quality of life. Recently, there has been increased emphasis on personalized medicine in Crohn's disease to identify individual patients who require early advanced therapy to prevent complications of their disease. In this review, we summarize our current approach to management of Crohn's disease by identifying risk factors for severe or disabling disease and tailoring individual treatments to patient-specific goals. Lastly, we outline our knowledge gaps in implementing personalized Crohn's disease treatment and describe the future directions in precision medicine.

LC-MS/MS Method for Measurement of Thiopurine Nucleotides (TN) in Erythrocytes and Association of TN Concentrations With TPMT Enzyme Activity

Monitoring concentrations of thiopurine metabolites is used clinically to prevent adverse effects in patients on thiopurine drug therapy. We developed a LC-MS/MS method for the quantification of 6-thioguanine (6-TG) and 6-methylmercaptopurine (6-MMP) in red blood cells (RBCs). This method utilizes an automated cell washer for RBC separation from whole blood samples and washing of the separated RBCs. The lower limit of quantification of the method was 0.2 μmol/L for 6-TG (∼50 pmol/8 × 10⁸ RBC) and 4 μmol/L for 6-MMP (∼1,000 pmol/8 × 10⁸ RBC). The total imprecision of the assay was <3.0%. The upper limit of linearity for 6-TG and 6-MMP was 7.5 μmol/L and 150 μmol/L, respectively. The stability of the thiopurine metabolites under pre- and post-analytically relevant conditions was also evaluated. A good agreement was observed between this method and validated LC-MS/MS methods from three laboratories, except for ∼40% low bias for 6-MMP observed in one of the methods. The assessment of the association between 6-TG and 6-MMP concentrations with thiopurine S-methyltransferase (TPMT) phenotype and genotype demonstrated a statistically significant difference in the thiopurine metabolite concentrations between the TPMT groups with normal and intermediate activity of 6-MMP (p < 0.0001), while the difference in 6-TG concentrations was statistically not significant (p = 0.096). Among the samples with normal TPMT activity, higher concentrations of 6-MMP (p = 0.015) were observed in pediatric samples than in the samples of adults. No statistically significant differences were observed in the distributions of 6-TG and 6-MMP concentrations among the evaluated genotypes.

Perspectives from the Society for Pediatric Research: pharmacogenetics for pediatricians

This review evaluates the pediatric evidence for pharmacogenetic associations for drugs that are commonly prescribed by or encountered by pediatric clinicians across multiple subspecialties, organized from most to least pediatric evidence. We begin with the pharmacogenetic research that led to the warning of increased risk of death in certain pediatric populations ("ultrarapid metabolizers") who are prescribed codeine after tonsillectomy or adenoidectomy. We review the evidence for genetic testing for thiopurine metabolism, which has become routine in multiple pediatric subspecialties. We discuss the pharmacogenetic research in proton pump inhibitors, for which clinical guidelines have recently been made available. With an increase in the prevalence of behavioral health disorders including attention deficit hyperactivity disorder (ADHD), we review the pharmacogenetic literature on selective serotonin reuptake inhibitors, selective norepinephrine reuptake inhibitors, and ADHD medications. We will conclude this section on the current pharmacogenetic data on ondansetron. We also provide our perspective on how to integrate the current research on pharmacogenetics into clinical care and what further research is needed. We discuss how institutions are managing pharmacogenetic test results and implementing them clinically, and how the electronic health record can be leveraged to ensure testing results are available and taken into consideration when prescribing medications. IMPACT: While many reviews of pharmacogenetics literature are available, there are few focused on pediatrics. Pediatricians across subspecialties will become more comfortable with pharmacogenetics terminology, know resources they can use to help inform their prescribing habits for drugs with known pharmacogenetic associations, and understand the limitations of testing and where further research is needed.

NUDT15: A bench to bedside success story

Recently, the enzyme nudix hydrolase 15 (NUDT15) has been identified as an additional component of the thiopurine metabolism pathway. NUDT15 (also known as MTH2) catalyzes the dephosphorylation of 6-thioguanosine triphosphate (6-TGTP) and 6-thio-deoxyguanosine triphosphate (6-TdGTP), which is the active metabolite of thiopurine medications. Thiopurine compounds, which were first synthesized in the 1950s, are widely used in the treatment of childhood leukemia, inflammatory bowel disease, and autoimmune disorders. For many years, TPMT has been recognized as an enzyme that is involved in thiopurine metabolism, and interindividual variation in TPMT activity has been known to contribute to differences in risk of thiopurine toxicity. Genetic variation that leads to decreased NUDT15 activity has been recognized as an additional contributor, beyond TPMT, to thiopurine toxicity. In some populations, including Asian and Latino populations, NUDT15 genetic variants are more common than TPMT variants, making this a significant biomarker of toxicity. Clinical genetic testing is now available for a subset of NUDT15 variants, representing a remarkably fast translation from bench to bedside. This review will focus on NUDT15 - from discovery to clinical implementation.

Precision medicine for rheumatologists: lessons from the pharmacogenomics of azathioprine

Precision medicine aims to personalize treatment for both effectiveness and safety. As a critical component of this emerging initiative, pharmacogenomics seeks to guide drug treatment based on genetics. In this review article, we give an overview of pharmacogenomics in the setting of an immunosuppressant frequently prescribed by rheumatologists, azathioprine. Azathioprine has a narrow therapeutic index and a high risk of adverse events. By applying candidate gene analysis and unbiased approaches, researchers have identified multiple variants associated with an increased risk for adverse events associated with azathioprine, particularly bone marrow suppression. Variants in two genes, TPMT and NUDT15, are widely recognized, leading drug regulatory agencies and professional organizations to adopt recommendations for testing before initiation of azathioprine therapy. As more gene-drug interactions are discovered, our field will continue to face the challenge of balancing benefits and costs associated with genetic testing. However, novel approaches in genomics and the integration of clinical and genetic factors into risk scores offer unprecedented opportunities for the application of pharmacogenomics in routine practice. Key Points • Pharmacogenomics can help us understand how individuals' genetics may impact their response to medications. • Azathioprine is a success story for the clinical implementation of pharmacogenomics, particularly the effects of TPMT and NUDT15 variants on myelosuppression. • As our knowledge advances, testing and dosing recommendations will continue to evolve, with our field striving to balance costs and benefits to patients. • As we aim toward the goals of precision medicine, future research may integrate increasingly individualized traits-including clinical and genetic characteristics-to predict the safety and efficacy of particular medications for individual patients.

Biomarkers Predictive of Response to Thiopurine Therapy in Inflammatory Bowel Disease

The complex nature of inflammatory bowel disease (IBD) often results in treatment failure for many patients. With some patients cycling through multiple therapies before achieving a sustained period of remission, the ability to predict a patient's response to therapeutics could decrease the time from active disease to clinical remission and mucosal healing. The prospect of such individualized treatment of IBD would be aided by accurate biomarkers, both fecal and serological, which have to date shown value as indicators of IBD activity. Here we review the utility of generic biomarkers for inflammation or mucosal healing, such as calprotectin, C-reactive protein (CRP), and fecal hemoglobin (fHb) as predictors of response to treatment of IBD. We further provide a deeper insight into the utility of monitoring the thiopurine treatment by thiopurine metabolites or alternative hematologic parameters. In light of multiple recent publications of biomarkers and biological therapy, our focus in this review is predicting response to thiopurine treatment only, that is, Azathioprine and 6-Mercaptopurine.

Clinical Pharmacokinetic and Pharmacodynamic Considerations in the Treatment of Inflammatory Bowel Disease

According to recent clinical consensus, pharmacotherapy of inflammatory bowel disease (IBD) is, or should be, personalized medicine. IBD treatment is complex, with highly different treatment classes and relatively few data on treatment strategy. Although thorough evidence-based international IBD guidelines currently exist, appropriate drug and dose choice remains challenging as many disease (disease type, location of disease, disease activity and course, extraintestinal manifestations, complications) and patient characteristics [(pharmaco-)genetic predisposition, response to previous medications, side-effect profile, necessary onset of response, convenience, concurrent therapy, adherence to (maintenance) therapy] are involved. Detailed pharmacological knowledge of the IBD drug arsenal is essential for choosing the right drug, in the right dose, in the right administration form, at the right time, for each individual patient. In this in-depth review, clinical pharmacodynamic and pharmacokinetic considerations are provided for tailoring treatment with the most common IBD drugs. Development (with consequent prospective validation) of easy-to-use treatment algorithms based on these considerations and new pharmacological data may facilitate optimal and effective IBD treatment, preferably corroborated by effectiveness and safety registries.

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.

Clinical Pharmacogenetics Implementation Consortium Guideline for Thiopurine Dosing Based on TPMT and NUDT15 Genotypes: 2018 Update

Thiopurine methyltransferase (TPMT) activity exhibits a monogenic codominant inheritance and catabolizes thiopurines. TPMT variant alleles are associated with low enzyme activity and pronounced pharmacologic effects of thiopurines. Loss-of-function alleles in the NUDT15 gene are common in Asians and Hispanics and reduce the degradation of active thiopurine nucleotide metabolites, also predisposing to myelosuppression. We provide recommendations for adjusting starting doses of azathioprine, mercaptopurine, and thioguanine based on TPMT and NUDT15 genotypes (updates on www.cpicpgx.org).

Thiopurine Methyltransferase Genetic Polymorphisms and Activity and Metabolic Products of Azathioprine in Patients with Inflammatory Bowel Disease

BACKGROUND

Thiopurine S-methyltransferase (TPMT) is a cytoplasmic enzyme that catalyzes thiopurine drugs such as 6-mercaptopurine, 6-thioguanine, and azathioprine. There is a correlation between thiopurine drug metabolism, response, and toxicity and genetic polymorphism of TPMT. The aim of this study is to assess TPMT genetic polymorphisms activity and metabolic products of AZA in patients with IBD.

METHODS

Blood samples were obtained from 50 IBD unrelated patients from a private laboratory. We used polymerase chain reaction-restriction length polymorphism (PCR-RFLP) and allele-specific PCRbased assays to determine the TPMT gene for the different variants. A high-performance liquid chromatography system (HPLC) was carried out to determine the whole blood 6-TGN concentration. Determination of serum TMPT activity was done by ELISA kit.

RESULTS

In IBD patients, 46/50 (92%) subjects were homozygous for the wild-type allele (TPMT*1/*1). Mutant TPMT*1/*2 and TPMT*1/*3C alleles were found in 4/46 (8%) and 3/47 (6%) of IBD patients, respectively. TPMT*1/*3B variant was not detected in any of the IBD patients. TPMT enzyme activity was higher in wild-type than that mutant variants TPMT*1/*2 and TPMT*1/*3C, suggesting that there are statistically significant differences between 6-TG levels and polymorphisms of TMPT enzyme. 6-TG levels significantly increased in IBD patients mutant variants TPMT*1/*2 and TPMT*1/*3C.

CONCLUSIONS

Our results showed that TPMT polymorphisms are associated with 6-TGN levels in patients using AZA. This study suggests that AZA dosage may be determined according to the high or low prevalence of a TPMT genotype. Moreover, the results present the determination of metabolite for assessing possible safe effective dosage of the drug.

Effective long-term solution to therapeutic remission in Inflammatory Bowel Disease: Role of Azathioprine

Azathioprine (AZA) is a well-known immunosuppressant used for many years for its ability to ensure long term disease remission in inflammatory bowel diseases (IBD) at an affordable cost to the public. However, the side effect profile has raised many concerns with numerous investigations into the risk, cause and prevention of these effects. Much of the side effect profile of AZA can be linked to a single nucleotide polymorphism (SNP) in the thiopurine methyltransferase (TPMT) gene which ensures the breakdown and efficacy of AZA. Mutated TPMT alleles result in low or deficient TPMT levels which directly correlate to cytotoxity. This is a review of the role of AZA in the treatment of IBD. Knowing a patient's TPMT status allows the prescribing doctor to make an informed decision about dosage and be more alert to the signs of cytotoxicity. It is essential to include "early warning" SNP testing into common practice to ensure therapeutic efficacy.

A practical guide to thiopurine prescribing and monitoring in IBD

Thiopurines are often the mainstay of treatment for many patients with inflammatory bowel disease. As such, a general understanding of the evidence behind their use and of their metabolism is extremely useful in clinical practice. This review gives a practical overview of thiopurine metabolism, the importance of thiopurine S-methyltransferase testing prior to the start of therapy and the monitoring of thioguanine nucleotide levels while on treatment, guiding a personalised approach to optimising thiopurine therapy.

Azathioprine Therapy in a Pediatric TPMT-Deficient Patient-Still an Option

We describe the case of a pediatric patient on azathioprine therapy with previously undiagnosed homozygote thiopurine S-methyltransferase (TPMT) deficiency, resulting in myelotoxic thiopurine metabolite levels. The patient was successfully treated with a very low azathioprine dose of 50 mg once a week (4% of standard dose), guided by frequent thiopurine metabolite measurement and a close clinical surveillance. We demonstrate that azathioprine therapy still might be an effective and safe therapeutic option in pediatric thiopurine S-methyltransferase-deficient IBD patients.

Thiopurines Dosed to a Therapeutic 6-Thioguanine Level in Combination with Adalimumab Are More Effective Than Subtherapeutic Thiopurine-based Combination Therapy or Adalimumab Monotherapy During Induction and Maintenance in Patients with Long-standing Crohn's Disease

BACKGROUND

The benefit of concomitant immunomodulation with adalimumab (ADA) in Crohn's disease is poorly understood. We aimed to compare ADA monotherapy with combination therapy with thiopurines, stratified by thioguanine nucleotides (TGNs).

METHODS

Retrospective observational study of ADA induction and maintenance. Thiopurines were classified according to TGNs (>235 pmol/8 × 10 red blood cell therapeutic).

RESULTS

At induction, response was more frequent in combination than ADA monotherapy (83% versus 61%, P = 0.02) and with therapeutic compared with subtherapeutic TGNs (87% versus 70% P = 0.011). Among 280 maintenance semesters in 91 patients, remission was higher with combination than monotherapy (81% versus 60%, P < 0.0001) and therapeutic versus subtherapeutic TGNs (85% versus 58%, P = 0.004). Therapeutic TGN (odds ratio [OR] 4.32, 95% CI, 1.41-13.29, P = 0.01) and albumin (OR 1.09, 95% CI, 1.01-1.18, P = 0.03) were predictors of response to induction. Therapeutic TGN (OR 3.71, 95% CI, 1.87-7.34, P < 0.0001) and ileal disease (OR 0.21, 95% CI, 0.08-0.57, P = 0.002) were predictors of remission semesters. Concomitant immunomodulation at induction was associated with longer time to failure (69 versus 36 months, P = 0.009). Therapeutic TGN at induction (P = 0.03) and male sex (P = 0.026) were associated with time to failure.

CONCLUSIONS

Combination therapy was superior to ADA monotherapy for induction and during maintenance. This benefit was increased further when thiopurines resulted in therapeutic TGNs. Early use of adequately dosed thiopurines (≥3 months before starting ADA) was associated with improved clinical outcomes.

Pharmacogenetics of immunosuppressants: State of the art and clinical implementation - recommendations from the French National Network of Pharmacogenetics (RNPGx)

Therapeutic drug monitoring is already widely used for immunosuppressive drugs due to their narrow therapeutic index. This article summarizes evidence reported in the literature regarding the pharmacogenetics of (i) immunosuppressive drugs used in transplantation and (ii) azathioprine used in chronic inflammatory bowel disease. The conditions of use of currently available major pharmacogenetic tests are detailed and recommendations are provided based on a scale established by the RNPGx scoring tests as "essential", "advisable" and "potentially useful". Other applications for which the level of evidence is still debated are also discussed.

Pharmacology and Optimization of Thiopurines and Methotrexate in Inflammatory Bowel Disease

Improving the efficacy and reducing the toxicity of thiopurines and methotrexate (MTX) have been areas of intense basic and clinical research. An increased knowledge on pharmacodynamics and pharmacokinetics of these immunomodulators has optimized treatment strategies in inflammatory bowel disease (IBD). This review focuses on the metabolism and mode of action of thiopurines and MTX, and provides an updated overview of individualized treatment strategies in which efficacy in IBD can be increased without compromising safety. The patient-based monitoring instruments adapted into clinical practice include pretreatment thiopurine S-methyltransferase testing, thiopurine metabolite monitoring, and blood count measurements that may help guiding the dosage to improve clinical outcome. Other approaches for optimizing thiopurine therapy in IBD include combination therapy with allopurinol, 5-aminosalicylates, and/or biologics. Similar strategies are yet to be proven effective in improving the outcome of MTX therapy. Important challenges for the management of IBD in the future relate to individualized dosing of immunomodulators for maximal efficacy with minimal risk of side effects. As low-cost conventional immunomodulators still remain a mainstay in pharmacotherapy of IBD, more research remains warranted, especially to substantiate these tailored management strategies in controlled clinical trials.

Pharmacogenomics in Pediatric Oncology: Review of Gene-Drug Associations for Clinical Use

During the 3rd congress of the European Society of Pharmacogenomics and Personalised Therapy (ESPT) in Budapest in 2015, a preliminary meeting was held aimed at establishing a pediatric individualized treatment in oncology and hematology committees. The main purpose was to facilitate the transfer and harmonization of pharmacogenetic testing from research into clinics, to bring together basic and translational research and to educate health professionals throughout Europe. The objective of this review was to provide the attendees of the meeting as well as the larger scientific community an insight into the compiled evidence regarding current pharmacogenomics knowledge in pediatric oncology. This preliminary evaluation will help steer the committee’s work and should give the reader an idea at which stage researchers and clinicians are, in terms of personalizing medicine for children with cancer. From the evidence presented here, future recommendations to achieve this goal will also be suggested.

Getting the best out of thiopurine therapy: thiopurine S-methyltransferase and beyond

Thiopurines are the cornerstone of treatment for a wide variety of medical disorders, ranging from pediatric leukemia to inflammatory bowel disease. Because of their complex metabolism and potential toxicities, the use of biomarkers to predict risk and response is paramount. Thiopurine S-methyltransferase and thiopurine metabolite levels have emerged as companion diagnostics with crucial roles in facilitating safe and effective treatment. This review serves to update the reader on how these tools are being developed and implemented in clinical practice. A useful paradigm in thiopurine therapeutic strategy is presented, along with fresh insights into the mechanisms underlying these approaches. We elaborate on potential future developments in the optimization of thiopurine therapy.

Optimizing the use of thiopurines in inflammatory bowel disease

Immunomodulator drugs, of which thiopurines can be considered the backbone, are widely used in the treatment of inflammatory bowel disease. They have been shown to be highly effective and safe; however, a significant proportion of patients are deemed to have a poor response or suffer adverse reactions. Knowing how to monitor and optimize thiopurine therapy in these scenarios is crucial to effective management. We discuss the metabolism of thiopurines, the use of enzyme/metabolite testing to guide treatment, as well as strategies to circumvent toxicity and side effects, such as allopurinol coprescription. The indications, use in pregnancy, safety profile and duration of thiopurine therapy are also discussed.

A practical guide to the use of thiopurines in oral medicine

Thiopurines are widely used as first-line immunosuppressive therapies in the management of chronic inflammatory oral disease. However, despite over half a century of clinical experience, the evidence base for their use is limited. The aims of this paper were to review the evidence for the use of thiopurines in oral medicine and provide a contemporary model of thiopurine metabolism and mechanism of action and a rationale for clinical use and safe practice.

Are we using and monitoring thiopurines and biologics optimally?

The use of biologics and thiopurines in patients with inflammatory bowel disease has increased rapidly over the last 2 decades with both classes of drugs being used more frequently and earlier in the disease course. This vogue has come about through a realisation that for some patients Crohn's disease and ulcerative colitis are progressive diseases and that use of these therapies can sometimes prevent that progression. However, knowledge about the optimal way in which to use these drugs continues to evolve. In this paper, the evidence regarding optimal timing and dosing of thiopurines and biologics will be reviewed as will the role of thiopurine methyltransferase testing along with therapeutic drug monitoring of both thiopurines and biologics. In addition, possible future applications of biologic drug level and anti-drug antibody testing will be considered.

Successful azathioprine treatment with metabolite monitoring in a pediatric inflammatory bowel disease patient homozygous for TPMT*3C

Thiopurine S-methyltransferase (TPMT) methylates purine analogues, showing TPMT activity in inverse relation to concentrations of active metabolites such as 6-thioguanine nucleotide (6-TGN). With conventional dosing of thiopurines, patients with homozygous variant TPMT alleles consistently suffer from severe myelosuppression. Here, we report a patient with TPMT*3C/*3C who managed successfully with monitoring of thiopurine metabolites. The patient was an 18-year-old male diagnosed with Crohn's disease. The standard dose of azathioprine (AZA) (1.8 mg/kg/day) with mesalazine (55.6 mg/kg/day) was prescribed. Two weeks after starting AZA treatment, the patient developed leukopenia. The DNA sequence analysis of TPMT identified a homozygous missense variation (NM_000367.2: c.719A>G; p.Tyr240Cys), TPMT*3C/*3C. He was treated with adjusted doses of azathioprine (0.1-0.2 mg/kg/day) and his metabolites were closely monitored. Leukopenia did not reoccur during the follow-up period of 24 months. To our knowledge, this is the first case of a patient homozygous for TPMT*3C successfully treated with azathioprine in Korea. While a TPMT genotyping test may be helpful to determine a safe starting dose, it may not completely prevent myelosuppression. Monitoring metabolites as well as routine laboratory tests can contribute to assessing drug metabolism and optimizing drug dosing with minimized drug-induced toxicity.

Review article: the management of autoimmune hepatitis beyond consensus guidelines

BACKGROUND

Consensus guidelines aid in the diagnosis and management of autoimmune hepatitis, but they are frequently based on low-quality clinical evidence, conflicting experiences and divergent opinions. Recommendations may be weak, discrepant or non-existent at critical decision points.

AIMS

To identify the decision points where guidelines are weak or non-existent and review the evidence essential in the decision process.

METHODS

Full-text articles published in English using the keyword 'autoimmune hepatitis' were identified by PubMed from 1972 to 2013. Personal experience and investigations in autoimmune hepatitis also identified important contributions.

RESULTS

Seventy per cent of the guidelines developed by the American Association for the Study of Liver Diseases and 48% of those proposed by the British Society of Gastroenterology are based on low-quality evidence, conflicting experiences or divergent opinions. The key uncertainties in diagnosis relate to the timing of liver biopsy, recognising acute severe (fulminant) disease, interpreting coincidental nonclassical histological changes, accommodating atypical or deficient features in non-White patients, differentiating drug-induced from classical disease and identifying overlap syndromes. The key uncertainties in management relate to pre-treatment testing for thiopurine methyltransferase activity, treating asymptomatic mild disease, determining treatment end points, managing suboptimal responses, incorporating nonstandard medications as front-line and salvage agents, using azathioprine in pregnancy and instituting surveillance for hepatocellular carcinoma.

CONCLUSIONS

Consensus guidelines are fraught with uncertainties in the diagnosis and management of autoimmune hepatitis. Each decision point must counterbalance the current available evidence and tailor the application of this evidence to the individual patient.

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.

Gene polymorphisms involved in manifestation of leucopenia, digestive intolerance, and pancreatitis in azathioprine-treated patients

BACKGROUND

Approximately 10-28 % of patients experience adverse drug reactions related to treatment with thiopurines. The most serious reaction is myelosuppression, typically manifested as leucopenia, which occurs in approximately 2-5 % of patients. Other adverse drug reactions that often accompany thiopurine therapy are pancreatitis, hepatotoxicity, allergic reactions, digestive intolerance, arthralgia, febrile conditions, and rash.

OBJECTIVE

The objective of this study was to assess the relationship between variant alleles of thiopurine S-methyltransferase (SNPs 238G > C, 460G > A and 719A > G), inosine triphosphate diphosphatase (SNPs 94C > A and IVS2 + 21A > C), and xanthine dehydrogenase (837C > T) and the occurrence of adverse drug reactions to azathioprine therapy.

METHODS

Genotype was determined for 188 Caucasians diagnosed with inflammatory bowel disease treated with a standard dose of azathioprine (1.4-2.0 mg/kg/day). Allelic variants were determined by PCR-REA and real-time PCR methods. Results were statistically evaluated by use of Fisher's test and by odds ratio calculation.

RESULTS

Variant genotype thiopurine S-methyltransferase predisposes to development of leucopenia (P = 0.003, OR = 5, CI 95 %, 1.8058-13.8444). Although not statistically significant, we observed a trend that suggested correlation between the occurrence of digestive intolerance and the variant genotype inosine triphosphate diphosphatase (P = 0.1102; OR 15.63, CI 95 %, 1.162-210.1094), and between the occurrence of pancreatitis and the variant allele xanthine dehydrogenase 837T (P = 0.1124; OR 12,1, CI 95 %, 1.15-126.37).

CONCLUSION

The variant genotype thiopurine S-methyltransferase has been associated with the occurrence of leucopenia. The involvement of polymorphisms in inosine triphosphate diphosphatase and xanthine dehydrogenase genes in the development of digestive intolerance and pancreatitis will require further verification.

The pharmacogenetic basis of individual variation in thiopurine metabolism

Thiopurines are an important class of immunosuppressive therapy, which have been used in clinical practice for over 50 years. Despite this extensive experience many of the pharmacodynamic and pharmacokinetic properties of these drugs remain unknown. As a consequence there is often no clear explanation for the individual variation in response to treatment, both in terms of efficacy or adverse drug reactions. This review, which emphasizes practice in gastroenterology, summarizes the current understanding of thiopurine drug metabolism and highlights the role of nongenetic and genetic factors other than TPMT, which should be a focus for future research. Correlation of polymorphic variations in these genes with clinical outcomes is expected to clarify the basis for interindividual differences in thiopurine metabolism and enable a more personalized approach to therapy.

Therapeutic drug monitoring of thiopurine metabolites in adult thiopurine tolerant IBD patients on maintenance therapy

BACKGROUND AND AIMS

Therapeutic drug monitoring of active metabolites of thiopurines, azathioprine and 6-mercaptopurine, is relatively new. The proposed therapeutic threshold level of the active 6-thioguanine nucleotides (6-TGN) is ≥235 pmol/8×10(8) erythrocytes. The aim of this prospective cross-sectional study was to compare 6-TGN levels in adult thiopurine tolerant IBD patients with an exacerbation with those in remission, and to determine the therapeutic 6-TGN cut-off level.

METHODS

Hundred IBD patients were included. Outcome measures were thiopurine metabolite levels, calculated therapeutic 6-TGN cut-off level, CDAI/CAI scores, thiopurine dose and TPMT enzyme activity.

RESULTS

Forty-one patients had an exacerbation, 59 patients were in remission. In 17% of all patients 6-TGN levels were compatible with non-compliance. The median 6-TGN levels were not significantly different between the exacerbation and remission group (227 versus 263 pmol/8×10(8) erythrocytes, p=0.29). The previous reported therapeutic 6-TGN cut-off level of 235 pmol/8×10(8) erythrocytes was confirmed in this study. Twenty-six of the 41 patients (63%) with active disease had 6-TGN levels below this threshold and 24 of 59 IBD patients (41%) in clinical remission (p=0.04).

CONCLUSIONS

Thiopurine non-compliance occurs frequently both in active and quiescent disease. 6-TGN levels below or above the therapeutic threshold are associated with a significant higher chance of IBD exacerbation and remission, respectively. These data support the role of therapeutic drug monitoring in thiopurine maintenance therapy in IBD to reveal non-compliance or underdosing, and can be used as a practical tool to optimize thiopurine therapy, especially in case of thiopurine non-response.

Validation of a genotyping method for analysis of TPMT polymorphisms

BACKGROUND

Thiopurine methyltransferase (TPMT) catalyzes the methylation of thiopurine drugs such as azathioprine and 6-mercaptopurine. Several mutations in the TPMT gene correlate with low enzyme activity and adverse effects such as myelotoxicity. Hence, genotyping TPMT makes it possible to identify patients at high risk for drug toxicity.

OBJECTIVE

The aim of this study was to validate a TPMT genotyping method by comparing it with a conventional polymerase chain reaction (PCR) approach.

METHODS

LightSNiP is a real-time PCR method for the detection of TPMT*2, *3B, and *3C without a sequencing step. We evaluated the frequencies of 3 TPMT alleles in 111 white adult patients by comparing genotyping by LightSNiP with conventional PCR (sequencing).

RESULTS

No differences were observed between conventional genotyping with sequencing and LightSNiP for *2, *3B, and *3C, suggesting the validity of this method.

CONCLUSIONS

Compared with the conventional PCR sequencing method, the data suggest that LightSNiP correctly detected the TPMT *2, *3B, and *3C in this select population.

[Significance of thiopurine s-methyltransferase gene test in a clinical case]

Thiopurine s-methyltransferase enzyme is responsible for the metabolism of immunosuppressant thiopurines, which are used in inflammatory bowel diseases, acute lymphoblastic leukemia and autoimmune diseases. Because of the relative narrow therapeutic index of thiopurines serious or life threatening side effects can occur. A total of 28 variant alleles of the gene coding for the thiopurine s-methyltransferase enzyme are responsible for altered catalytic activity of the enzyme. Patients with one non-functional (heterozygous) allele have intermediate, while those with two non-functional (homozygous) alleles have low enzyme activity. Using polymerase chain reaction/restriction fragment length polymorphism and direct DNA sequencing the authors determined the G238C, G460A and A719G polymorphisms of the thiopurine s-methyltransferase gene in a child with Crohn's disease who developed thiopurine-induced severe agranulocytosis. The presence of the G460A and A719G polymorphic alleles in homozygous forms were detected which corresponded to the *3A variant allele. This variant has been shown to be associated with lower enzyme activity and low amount of the enzyme resulting in thiopurine toxicity and agranulocytosis. These findings underline the need for genotyping of the thiopurine s-methyltransferase variants prior to thiopurine treatment.

Physician perspectives on unresolved issues in the use of conventional therapy in Crohn's disease: results from an international survey and discussion programme

BACKGROUND AND AIMS

Data on the optimal use of conventional therapies in Crohn's disease are lacking in guidelines. An educational programme was established to explore questions raised in clinical practice and to provide practical answers.

METHODS

Telephone interviews with 96 gastroenterologists and a web survey of 1370 gastroenterologists identified 26 key questions. Ten questions were taken forward to the next stage based on the opinion of an International Steering Committee. Draft answers to the questions were prepared from available evidence following a literature search. The draft answers were debated in national meetings of participating countries (n=36) and voted on using a standard scoring system. Revised answers went forward to an international meeting and were debated and voted on using the same methodology. Final answers were developed, based on evidence and clinical experience of the participants.

RESULTS

Evidence on corticosteroid and immunomodulator use such as dosage, timing and duration, choice of drug or regimen, and safety is scarce. Key points of the answers included the importance of: identifying patients with poor prognosis; early intervention with optimal doses of immunomodulators; avoiding prolonged or repetitive corticosteroid therapy; achieving corticosteroid-free remission; achieving a balance between clinical benefit and safety when intensifying or prolonging therapy or combining different agents; re-evaluating therapy at appropriate time points; and considering the role of biomarkers and mucosal healing.

CONCLUSIONS

The answers to 10 key questions were based on available evidence and clinical experience of programme participants. It is hoped they will be of practical use in everyday gastroenterology practice.

Simultaneous quantification of eleven thiopurine nucleotides by liquid chromatography-tandem mass spectrometry

The prodrugs azathioprine and 6-mercaptopurine, which are well-established anticancer and immunosuppressive agents, are extensively metabolized by activating and inactivating enzymes. Whereas the 6-thioguanine nucleotides (TGN) are currently being considered as major active metabolites, methylthioinosine nucleotides seem to contribute to the cytotoxic effect as well. Thiopurine-related adverse drug reactions and thiopurine failure are frequent. Thus, therapeutic monitoring of TGN and methylthioinosine derivatives has been suggested to improve thiopurine therapy, however with limited success. To elucidate systematically underlying molecular mechanisms as potential explanation for interindividual variability of thiopurine response, we developed a novel highly specific and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous quantitation of eleven mono-, di-, and triphosphates of thioguanosine, methylthioinosine, methylthioguanosine, and thioinosine. Using stable isotope-labeled analogues as internal standards obtained by chemical synthesis, an intra- and interassay variability below 8% and an accuracy of 92% to 107% were achieved in spiked quality control samples with known standards. All eleven metabolites could be determined in red blood cells from patients with inflammatory bowel diseases and long-term azathioprine therapy. Thus, our novel method opens a new avenue for the understanding of the thiopurine metabolism by quantitation of all important thiopurine nucleotide metabolites in one run.

Review article: the benefits of pharmacogenetics for improving thiopurine therapy in inflammatory bowel disease

BACKGROUND

Thiopurines represent an effective and widely prescribed therapy in inflammatory bowel disease (IBD). Concerns about toxicity, mainly resulting from a wide inter-individual variability in thiopurine metabolism, restrict their use. Optimal thiopurine dosing is challenging for preventing adverse drug reactions and improving clinical response.

AIM

To review efficacy and toxicity of thiopurines in IBD. To provide pharmacogenetic-based therapeutic recommendations.

METHODS

We conducted a query on PubMed database using 'inflammatory bowel disease', 'thiopurine', 'azathioprine', '6-mercaptopurine', 'TPMT', 'pharmacogenetics', 'TDM', and selected relevant articles, especially clinical studies.

RESULTS

Thiopurine metabolism - key enzyme: thiopurine S-methyltransferase (TPMT) - modulates clinical response, as it results in production of the pharmacologically active and toxic metabolites, the thioguanine nucleotides (6-TGN). Adjusting dosage according to TPMT status and/or metabolite blood levels is recommended for optimising thiopurine therapy (e.g. improving response rate up to 30% or decreasing haematological adverse events of 25%). Other enzymes or transporters of interest, as inosine triphosphatase (ITPase), glutathione S-transferase (GST), xanthine oxidase (XO), aldehyde oxidase (AOX), methylene tetrahydrofolate reductase (MTHFR) and ATP-binding cassette sub-family C member 4 (ABCC4) are reviewed and discussed for clinical relevance.

CONCLUSIONS

Based on the literature data, we provide a therapeutic algorithm for thiopurines therapy with starting dose recommendations depending on TPMT status and thereafter dose adjustments according to five metabolite profiles identified with therapeutic drug monitoring (TDM). This algorithm allows a dosage individualisation to optimise the management of patients under thiopurine. Furthermore, identification of new pharmacogenetic biomarkers is promising for ensuring maximal therapeutic response to thiopurines with a minimisation of the risk for adverse events.

Pharmacogenetics of drug-metabolizing enzymes: the prodrug hypothesis

The hope of individualized drug therapy has been bolstered by the knowledge that drug-metabolizing enzymes can be affected by genetic polymorphisms. The initial flurry of potential examples has been muted somewhat by the failure of most predictions to be translated into clinical practice. Perhaps the only real example with reasonable evidence is that of azathioprine/6-mercaptopurine and thiopurine methyl-transferase. A few other examples such as tamoxifen, clopidogrel, irinotecan and warfarin warrant further discussion. An interesting feature of these drugs is that all except warfarin are prodrugs. We propose the hypothesis that prodrugs are over-represented in drugs that may be affected by genetic polymorphisms. Understanding this may assist our efforts to advance the field.

Use of thiopurine testing in the management of inflammatory bowel diseases in clinical practice: a worldwide survey of experts

BACKGROUND

We performed a worldwide survey to evaluate the extent to which gastroenterologists who are experts in the field of inflammatory bowel diseases (IBDs) are utilizing thiopurine metabolism in practice.

METHODS

This was a Web-based cross-sectional survey consisting of 12 multiple-choice and open-ended questions.

RESULTS

Between December 2009 and April 2010, 175 questionnaires were received. The proportion of practitioners with access and reimbursement for thiopurine S-methyltransferase (TPMT) genotype, TPMT phenotype, 6-thioguanine nucleotides (6-TGN) levels, and 6-methylmercaptopurine ribonucleotides (6-MMP) levels was 48%, 54%, 44%, and 35%, respectively. Before azathioprine initiation, TPMT genotype and phenotype were performed by only 30% and 43% of responders, respectively. In patients on thiopurine therapy, 6-TGN and 6-MMP levels were determined by 54% and 44% of responders, respectively. Only 27% of physicians always wait for TMPT activity/genotype results before initiating azathioprine and 81% do not routinely recheck metabolite levels after dose escalation or reduction. In cases of very high or low TPMT activity, 75% and 74% of practitioners take into account TMPT activity result, respectively. If access to all azathioprine metabolite measurements was available and if all these tests were reimbursed by public health insurance, 47% of responders would use these tests more often in their practice. The availability and reimbursement of TPMT status and azathioprine metabolites strongly influenced experts' attitudes.

CONCLUSIONS

Thiopurine testing is relatively underutilized by IBD gastroenterologists. The availability and reimbursement of TPMT status and azathioprine metabolites strongly influence the management of IBD patients treated with thiopurines.

A pragmatic randomized controlled trial of thiopurine methyltransferase genotyping prior to azathioprine treatment: the TARGET study

AIM

To conduct a pragmatic, randomized controlled trial to assess whether thiopurine methyltransferase (TPMT) genotyping prior to azathioprine reduces adverse drug reactions (ADRs).

METHODS

A total of 333 participants were randomized 1:1 to undergo TPMT genotyping prior to azathioprine or to commence treatment without genotyping.

RESULTS

There was no difference in the primary outcome of stopping azathioprine due to an adverse reaction (ADR, p = 0.59) between the two study arms. ADRs were more common in older patients (p = 0.01). There was no increase in stopping azathioprine due to ADRs in TPMT heterozygotes compared with wild-type individuals. The single individual with TPMT variant homozygosity experienced severe neutropenia.

CONCLUSION

Our work supports the strong evidence that individuals with TPMT variant homozygosity are at high risk of severe neutropenia, whereas TPMT heterozygotes are not at increased risk of ADRs at standard doses of azathioprine.

Practical recommendations for pharmacogenomics-based prescription: 2010 ESF-UB Conference on Pharmacogenetics and Pharmacogenomics

The present article summarizes the discussions of the 3rd European Science Foundation-University of Barcelona (ESF-UB) Conference in Biomedicine on Pharmacogenetics and Pharmacogenomics, which was held in June 2010 in Spain. It was focused on practical applications in routine medical practice. We provide practical recommendations for ten different clinical situations, that have either been approved or not approved by regulatory agencies. We propose some comments that might accompany the results of these tests, indicating the best drug and doses to be prescribed. The discussed examples include KRAS, cetuximab, panitumumab, EGFR-gefitinib, CYP2D6-tamoxifen, TPMT-azathioprine-6-mercaptopurine, VKORC1/CYP2C9-warfarin, CYP2C19-clopidogrel, HLA-B*5701-abacavir, HLA-B*5701-flucloxacillin, SLCO1B1-statins and CYP3A5-tacrolimus. We hope that these practical recommendations will help physicians, biologists, scientists and other healthcare professionals to prescribe, perform and interpret these genetic tests.

Clinical Pharmacogenetics Implementation Consortium guidelines for thiopurine methyltransferase genotype and thiopurine dosing

Thiopurine methyltransferase (TPMT) activity exhibits monogenic co-dominant inheritance, with ethnic differences in the frequency of occurrence of variant alleles. With conventional thiopurine doses, homozygous TPMT-deficient patients (~1 in 178 to 1 in 3,736 individuals with two nonfunctional TPMT alleles) experience severe myelosuppression, 30-60% of individuals who are heterozygotes (~3-14% of the population) show moderate toxicity, and homozygous wild-type individuals (~86-97% of the population) show lower active thioguanine nucleolides and less myelosuppression. We provide dosing recommendations (updates at http://www.pharmgkb.org) for azathioprine, mercaptopurine (MP), and thioguanine based on TPMT genotype.

Pharmacological management of autoimmune hepatitis

INTRODUCTION

Without prompt immunosuppressive treatment, autoimmune hepatitis is a devastating, albeit rare, liver disease. It affects both adults and children, being particularly aggressive in the latter. Eighty per cent of patients respond satisfactorily to treatment; the other 20% progress to end-stage liver disease and require transplantation.

AREAS COVERED

This review emphasizes the importance of a timely diagnosis of autoimmune hepatitis and provides a practical guide for its treatment. The authors summarize the treatment options available for autoimmune hepatitis and stress that most patients respond successfully to standard treatment with prednisolone and azathioprine, two well-tried and inexpensive drugs. The authors also review the options for difficult-to-treat patients (non-responders and frequent relapsers), for whom newer immunosuppressive agents--usually employed as anti-rejection drugs--have been tried with variable success.

EXPERT OPINION

Autoimmune hepatitis is exquisitely responsive to immunosuppression but treatment must be started as soon as possible to achieve full remission and halt progression of liver disease. New strategies aiming at treating the unresponsive patients and at specifically curbing the liver autoimmune attack, without provoking unwanted systemic side effects, are being investigated and may be available within the next 5 years.

Thiopurine metabolism monitoring: implications in inflammatory bowel diseases

BACKGROUND

Thiopurines (TP) are widely used in the management of inflammatory bowel diseases. Side effects and inefficacy are a major concern as they lead to withdrawal of the drug.

MATERIALS AND METHODS

Tools investigating TP metabolism are useful to avoid inadequate cessation of TP therapy.

RESULTS

TP metabolism is complex and many enzymes are involved. Among them, Thiopurine methyl transferase is the only one routinely measured by pheno- or genotyping. A decreased TPMT activity results in a potential overdosing of TP drugs leading to myelotoxicity, whereas an ultra-high activity leads to TP ineffectiveness and overproduction of methylated compounds responsible for hepatotoxicity. TPMT determination prior to TP treatment results in an individual adapted dose. Xanthine oxidase/dehydrogenase (XOD), inosine triphosphate pyrophosphatase (ITPA) and glutathion-S-transferase (GST) are other promising enzyme targets that might help to explain TP efficacy or toxicity. ITPA and GST polymorphisms might potentially be related to some TP side effects, while a XOD inhibition by allopurinol could avoid TP-related hepatotoxicity.

CONCLUSIONS

Utilization of thiopurine metabolites, 6-thioguanine nucleotides and 6-methylmercaptopurine, is discussed, specifically, in case of thiopurine failure and recommendations are given about their interpretation and potential dose optimization. These enzymes and metabolites tests are complementary to the regular monitoring of blood cells count and liver tests which remains mandatory.

Thiopurine S-methyltransferase (TPMT) assessment prior to starting thiopurine drug treatment; a pharmacogenomic test whose time has come

Thiopurine S-methyltransferase (TPMT) is involved in the metabolism of thiopurine drugs. Patients that due to genetic variation lack this enzyme or have lower levels than normal, can be adversely affected if normal doses of thiopurines are prescribed. The evidence for measuring TPMT prior to starting patients on thiopurine drug therapy has been reviewed and the various approaches to establishing a service considered. Until recently clinical guidelines on the use of the TPMT varied by medical specialty. This has now changed, with clear guidance encouraging clinicians to use the TPMT test prior to starting any patient on thiopurine therapy. The TPMT test is the first pharmacogenomic test that has crossed from research to routine use. Several analytical approaches can be taken to assess TPMT status. The use of phenotyping supported with genotyping on selected samples has emerged as the analytical model that has enabled national referral services to be developed to a high level in the UK. The National Health Service now has access to cost-effective and timely TPMT assay services, with two laboratories undertaking the majority of the work at national level and with several local services developing. There appears to be adequate capacity and an appropriate internal market to ensure that TPMT assay services are commensurate with the clinical demand.

Expressing thiopurine S-methyltransferase activity as units per litre of whole-blood overcomes misleading high results in patients with anaemia

BACKGROUND

Thiopurine S-methyltransferase (TPMT) phenotype analysis, expressed as TPMT activity, is established as a routine pharmacogenomic test to screen patients prior to initiating thiopurine drug therapy. Conventionally measured TPMT activity is corrected for red blood cell (RBC) parameters. Here we present evidence that supports the simplification of the TPMT assay: by expressing TPMT activity in mU/L whole blood, without undertaking any haemoglobin (Hb) correction.

METHODS

Hb concentrations were compared in consecutive samples that had been received for TPMT phenotype analysis and which were stratified into samples with high (n = 111) and samples with normal (n = 50) Hb-corrected enzyme activity. TPMT activity was also measured in samples received for full blood count determination, stratified into those with low (n = 50) and normal (n = 50) Hb. A reference interval for TPMT activity in mU/L was derived from a correlation between activity expressed in conventional units and that expressed in mU/L (n = 1563), supported by comparison with associated genotype (n = 201).

RESULTS

In the high TPMT activity group, 83% of specimens had a low Hb concentration compared with 14% of specimens in the normal TPMT group. Samples with a low Hb concentration were found to have significantly higher Hb-corrected TPMT activity than samples with a normal Hb concentration: 83 versus 44 nmol 6-methyl thioguanine /g Hb/h, P < 0.0001. These results strongly suggest that misleading high Hb-corrected TPMT activity is found in anaemic patients. Based on the reference interval for enzyme activity of 70-150 mU/L, phenotype-genotype concordance compared well with the conventional approach (88% versus 89%). Furthermore, distribution of TPMT phenotypes with activity expressed in mU/L was identical: 0.5% deficient, 11% low, 86% normal and 2.5% high, to when it was expressed in conventional units.

CONCLUSION

Expressing TPMT activity in mU/L can overcome misleading high Hb-corrected TPMT results occurring in patients with anaemia, which could lead to inappropriate treatment. Removing the need to measure RBC indices further simplifies TPMT phenotyping, leading to a more robust assay, with reduced turn-around time and cost.

Current use of immunosuppressive agents in inflammatory bowel disease patients in East China

AIM: To investigate immunosuppressive agents used to treat inflammatory bowel disease (IBD) in East China.

METHODS: A retrospective review was conducted, involving 227 patients with IBD admitted to Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University from June 2000 to December 2007. Data regarding demographic, clinical characteristics and immunosuppressants usage were analyzed.

RESULTS: A total of 227 eligible patients were evaluated in this study, including 104 patients with Crohn’s disease and 123 with ulcerative colitis. Among the patients, 61 had indications for immunosuppressive agents use. However, only 21 (34.4%) received immunosuppressive agents. Among the 21 patients, 6 (37.5%) received a subtherapeutic dose of azathioprine with no attempt to increase the dosage. Of the 20 patients that received immunosuppressive agent treatment longer than 6 mo, 15 patients went into remission, four patients were not affected and one relapsed. Among these 20 patients, four patients suffered from myelotoxicity and one suffered from hepatotoxicity.

CONCLUSION: Immunosuppressive agents are used less frequently to treat IBD patients from East China compared with Western countries. Monitoring immunosuppressive agent use is recommended to optimize dispensation of drugs for IBD in China.