Lower doses of 6-mercaptopurine/azathioprine bring enough clinical efficacy and therapeutic concentration of erythrocyte 6-mercaptopurine metabolite in Japanese IBD patients

Glycolytic metabolite phosphoenolpyruvate protects host from viral infection through promoting AATK expression

Viral infections can result in metabolism rewiring of host cells, which in turn affects the viral lifecycle. Phosphoenolpyruvate (PEP), a metabolic intermediate in the glycolytic pathway, plays important roles in several biological processes including anti-tumor T cell immunity. However, whether PEP might participate in modulating viral infection remains largely unknown. Here, we demonstrate that PEP generally inhibits viral replication via upregulation of apoptosis-associated tyrosine kinase (AATK) expression. Targeted metabolomic analyses have shown that the intracellular level of PEP was increased upon viral infection. PEP treatment significantly restricted viral infection and hence declined subsequent inflammatory response both in vitro and in vivo. Besides, PEP took inhibitory effect on the stage of viral replication and also decreased the mortality of mice with viral infection. Mechanistically, PEP significantly promoted the expression of AATK. Knockdown of AATK led to enhanced viral replication and consequent increased levels of cytokines. Moreover, AATK deficiency disabled the antiviral effect of PEP. Together, our study reveals a previously unknown role of PEP in broadly inhibiting viral replication by promoting AATK expression, highlighting the potential application of activation or upregulation of the PEP-AATK axis in controlling viral infections.

Long-term safety and effectiveness of azathioprine in the management of inflammatory bowel disease: A real-world experience

Background and Aim

Azathioprine (AZA) forms the cornerstone for maintenance of sustained remission in inflammatory bowel disease (IBD). There is apprehension regarding the long-term effectiveness and safety of AZA in IBD. We present our experience with AZA use and outcomes in a cohort of IBD patients followed up over a long period of time.

Methods

Records of 507 IBD patients under treatment at a single, tertiary care center in south India between 2013 and 2022 were evaluated retrospectively. Long-term compliance, tolerance, clinical outcome at the point of last follow-up, type and duration to the onset of adverse events, and subsequent amendment to treatment with regard to AZA were analyzed.

Results

Of 507 patients with IBD, 320 patients (207 Crohn's disease [CD], 113 ulcerative colitis [UC]) who received AZA were included. The median follow-up was 41 months (interquartile range 15.5-77.5). Total duration of exposure was 1359 patient-years with median usage of 33 months. Of the patients, 26.9% received AZA for >5 years. Mean initiation and maximum doses of AZA were 0.97 and 1.72 mg/kg/day. Among the participants, 20.6% experienced side effects, including myelotoxicity (7.2%) and gastrointestinal intolerance (5.6%). Six patients developed malignancy. Among the side effects, 39.4% of side effects were dose-dependent. Among the patients, 38.1% had relapses requiring pulse corticosteroid therapy, and 16.2% had more than one relapse after commencement of AZA. AZA was continued till the last follow-up in 76.5%. Among the patients, 49.7% (UC 51.3, CD 48.8) attained durable remission without biologics, and 5.3% continued to have active disease.

Conclusion

AZA is safe and effective in the long-term in IBD. Effectiveness, tolerance, and compliance with AZA are well sustained beyond 5 years of usage and comparable between UC and CD.

Time to incorporate preemptive NUDT15 testing before starting thiopurines in inflammatory bowel disease in Asia and beyond: a review

INTRODUCTION

Thiopurine toxicity is related to genetic polymorphism. Thiopurine methyltransferase (TPMT) variants do not explain thiopurine toxicity in more than half of patients. Asians, despite the low prevalence of TPMT variants, are more susceptible to thiopurine toxicity. Since 2014, studies from many Asian countries have shown a strong association between nucleoside diphosphate-linked moiety X-type motif (NUDT) 15 polymorphism and thiopurine-induced myelotoxicity.

AREAS COVERED

An English language literature search was performed for TPMT and NUDT15 genetic variants in inflammatory bowel disease and other diseases. This article discusses the merits of preemptive NUDT15 and TPMT testing in Asian and non-Asian IBD populations.

EXPERT OPINION

The NUDT polymorphism occurs in up to 27% of the Asian and Hispanic population. Hematological toxicity occurs in up to one-third of patients with this genetic variant. Given this, preemptive testing for NUDT15 variant is worthwhile and is probably more cost-effective than TPMT testing in these groups. Prevalence of NUDT15 variants is low in non-Finnish European population, but NUDT15 variants have been linked to myelotoxicity along with TPMT genetic variants. NUDT15 preemptive testing should be considered in the migrant Asian population in Europe and North America and in Caucasian populations who develop myelotoxicity.

[Two Cases at Community Pharmacies of Mercaptopurine Removal from a Disk-type Powder-packaging Machine by Wiping It with Water]

"Leukerin^® powder 10%" containing mercaptopurine (6-MP) is an oral anticancer drug that requires careful handling. As a powder formulation, there are risks of exposure due to scattering during dispensing and possible 6-MP contamination to other drugs due to adhesion to the packaging machine. We previously reported that wiping with an alcohol-containing towel is useful for removing scattered powder after dispensing. However, it is recommended to wipe disk-type powder-packaging machines with water instead of cleaning with the alcohol-containing towel. Hence, we scattered 6-MP powder 100 mg (total amount of 6-MP: 10 mg), and then wiped with water three times using different types of cloth each time. We confirmed that third time wiping cloth did not have any 6-MP. Furthermore, we confirmed that the adhering 6-MP could be removed by wipe-cleaning (water-wiping twice and dry-wiping once) after dispensing 6-MP powder at two pharmacies that routinely dispensed 6-MP powder using a disk-type powder-packaging machine. In addition, we confirmed the adhesion of 6-MP in parts of the machine not cleaned by wipe-cleaning and also in parts that were washed only with water, in both the pharmacies. Based on the above observations, we recommend the following steps for cleaning disk-type powder-packaging machines after dispensing 6-MP powder: (1) wipe-cleaning that includes water-wiping twice and then dry-wiping once, (2) cleaning all areas of the packaging machine, and (3) wipe-cleaning with water before washing with water.

Increased DNA-incorporated thiopurine metabolite as a possible mechanism for leukocytopenia through cell apoptosis in inflammatory bowel disease patients with NUDT15 mutation

BACKGROUND AND AIMS

Polymorphisms in the nucleotide diphosphate-linked moiety X-type motif 15 (NUDT15) gene are associated with thiopurine-induced leukopenia in patients with inflammatory bowel disease (IBD). NUDT15-associated subcellular thiopurine metabolism has not been investigated in primary lymphocytes. We hypothesized that NUDT15 mutation increases DNA-incorporated deoxythioguanosine (dTG) and induces apoptosis in lymphocytes.

METHODS

DNA-incorporated dTG in peripheral blood mononuclear cells (PBMCs) and 6-thioguanine nucleotides (6-TGN) in red blood cells were measured in patients with IBD undergoing thiopurine treatment. The association of a single nucleotide polymorphism for NUDT15 (rs116855232) with dTG^PBMC was examined. The pro-apoptotic effect of DNA-incorporated dTG was examined ex vivo in association with NUDT15 genotypes by co-culturing patient-derived peripheral CD4⁺ T lymphocytes with 6-thioguanine (6-TG).

RESULTS

dTG^PBMC was significantly higher in NUDT15 variants than in non-variants. dTG^PBMC, but not 6-TGN^RBC, negatively correlated with peripheral lymphocyte counts (r =  - 0.31 and  - 0.12, p = 0.012 and 0.173, respectively). DNA-incorporated dTG significantly accumulated to a greater extent in lymphocytes from NUDT15 variants when co-cultured with 6-TG ex vivo than in those from non-variants and was associated with decreased proliferation and increased apoptosis.

CONCLUSION

Increased DNA-incorporated dTG may be responsible for thiopurine-induced leukocytopenia through cell apoptosis in IBD patients with NUDT15 mutation.

Differential effects of mesalazine formulations on thiopurine metabolism through thiopurine S-methyltransferase inhibition

BACKGROUND AND AIM

Thiopurines are often used in combination with mesalazine for the treatment of ulcerative colitis (UC). Mesalazine formulations are delivered to the digestive tract by various delivery systems and absorbed as 5-aminosalicylic acid (5-ASA). 5-ASA is known to inhibit thiopurine S-methyltransferase (TPMT) activity and to affect thiopurine metabolism. There have been no studies comparing TPMT inhibition by multimatrix mesalazine (MMX) with other formulations. We investigated the difference in TPMT inhibition by different mesalazine formulations and prospectively confirmed the clinical relevance.

METHODS

Plasma concentrations of 5-ASA, N-acetyl-5-aminosalicylic acid (N-Ac-5-ASA), and TPMT activities were measured in UC patients receiving various mesalazine formulations (time-dependent or pH-dependent mesalazine or MMX) as monotherapy. Patients already on both time-dependent or pH-dependent mesalazine and thiopurines switched their mesalazine to MMX, examining 6-thioguanine nucleotide (6-TGN) and 6-methylmercaptopurine (6-MMP) 0 and 8 weeks after switching. Clinical relapse after switching was also monitored for 24 weeks.

RESULTS

Plasma 5-ASA and N-Ac-5-ASA levels were significantly higher in patients receiving time-dependent mesalazine (n = 12) compared with pH-dependent mesalazine (n = 12) and MMX (n = 15), accompanied by greater TPMT inhibition. Prospective switching from time-dependent mesalazine to MMX decreased 6-TGN levels, increased those of 6-MMP, and increased 6-MMP/6-TGN ratios. Furthermore, this resulted in significantly more relapses than switching from pH-dependent mesalazine to MMX.

CONCLUSIONS

Time-dependent mesalazine has higher plasma 5-ASA and N-Ac-5-ASA levels and greater TPMT inhibition than MMX. Therefore, switching from time-dependent mesalazine to MMX may lead to an increase of 6-MMP/6-TGN, which may reduce the clinical effectiveness of thiopurines, warranting close monitoring after switch.

Thiopurines: Recent Topics and Their Role in the Treatment of Inflammatory Bowel Diseases

Ulcerative colitis (UC) and Crohn's disease (CD) are chronic inflammatory bowel diseases (IBD) of unknown etiology, characterized by repeated relapse and remission. The efficacy of thiopurine in IBD was first reported in the late 1960s. Thiopurines are used to alleviate the symptoms of IBD, especially UC. These drugs have a steroid-sparing potential and are widely used for the purpose of maintaining long-term remission in steroid-dependent cases. Therefore, thiopurines tend to be used long-term, but adverse events that accompany long-term use, such as lymphoproliferative disorders, must be monitored with care. In contrast, thiopurine plays a critical role in controlling the immunogenicity of biologics. Furthermore, although thiopurine is an old drug, new findings, including the prediction of serious adverse events such as severe alopecia and acute advanced leukopenia, by nudix hydrolase 15 gene polymorphism analysis, as well as the possibility of appropriate drug monitoring by detailed analysis of 6-thioguanine nucleotides have been clarified. However, the consequences of thiopurine withdrawal have not been determined and further studies, including randomized controlled trials, are necessary to answer the clinical question regarding the scenarios in which thiopurine withdrawal is possible.

Nucleoside diphosphate-linked moiety X-type motif 15 R139C genotypes impact 6-thioguanine nucleotide cut-off levels to predict thiopurine-induced leukopenia in Crohn’s disease patients

BACKGROUND

Thiopurine-induced leukopenia (TIL) is a life-threatening toxicity and occurs with a high frequency in the Asian population. Although nucleoside diphosphate-linked moiety X-type motif 15 (NUDT15) variants significantly improve the predictive sensitivity of TIL, more than 50% of cases of this toxicity cannot be predicted by this mutation. The potential use of the 6-thioguanine nucleotide (6TGN) level to predict TIL has been explored, but no decisive conclusion has been reached. Can we increase the predictive sensitivity based on 6TGN by subgrouping patients according to their NUDT15 R139C genotypes?

AIM

To determine the 6TGN cut-off levels after dividing patients into subgroups according to their NUDT15 R139C genotypes.

METHODS

Patients’ clinical and epidemiological characteristics were collected from medical records from July 2014 to February 2017. NUDT15 R139C, thiopurine S-methyltransferase, and 6TGN concentrations were measured.

RESULTS

A total of 411 Crohn’s disease patients were included. TIL was observed in 72 individuals with a median 6TGN level of 323.4 pmol/8 × 10⁸ red blood cells (RBC), which was not different from that of patients without TIL (P = 0.071). Then, we compared the 6TGN levels based on NUDT15 R139C. For CC (n = 342) and CT (n = 65) genotypes, the median 6TGN level in patients with TIL was significantly higher than that in patients without (474.8 vs 306.0 pmol/8 × 10⁸ RBC, P = 9.4 × 10^-5; 291.7 vs 217.6 pmol/8 × 10⁸ RBC, P = 0.039, respectively). The four TT carriers developed TIL, with a median 6TGN concentration of 135.8 pmol/8 × 10⁸ RBC. The 6TGN cut-off levels were 411.5 and 319.2 pmol/8 × 10⁸ RBC for the CC and CT groups, respectively.

CONCLUSION

The predictive sensitivity of TIL based on 6TGN is dramatically increased after subgrouping according to NUDT15 R139C genotypes. Applying 6TGN cut-off levels to adjust thiopurine therapies based on NUDT15 is strongly recommended.

Use of corticosteroids for remission induction therapy in patients with new-onset ulcerative colitis in real-world settings

Background: Corticosteroids may be temporarily effective for ulcerative colitis (UC), but long-term use increases the risk of adverse drug reactions. Objective: The goal of the study was to examine steroid use in remission induction therapy after diagnosis of UC. Study Design: A retrospective observational study using the Japan Medical Data Center (JMDC) Claims Database from January 2008 to December 2014. Setting: Clinics, university hospitals, and national/public hospitals. Intervention: Initiation of steroids after diagnosis of UC. Main outcome measures: Start time and annual rate of steroid use, and use during the first 6 months of remission induction therapy. Results: The subjects were 399 patients were newly diagnosed with UC in the study period. The rate of steroid use after diagnosis was 58.4% in 2009, and showed a significant decreasing trend yearly after 2010 (p ≤ 0.0001). Regarding the start time, 52.2% of patients began steroids within 60 days after diagnosis of UC. At 6 months after initiation, 23.7% continued to use steroids and 73.9% of these patients used high-dose steroids. Conclusion: In treatment of UC after diagnosis, many patients continue to use steroids for >6 months after initiation. Reduced use of steroids based on clinical practice guidelines for UC should be promoted.

Revisiting the Role of Thiopurines in Inflammatory Bowel Disease Through Pharmacogenomics and Use of Novel Methods for Therapeutic Drug Monitoring

Azathioprine and 6-mercaptopurine, often referred to as thiopurine compounds, are commonly used in the management of inflammatory bowel disease. However, patients receiving these drugs are prone to developing adverse drug reactions or therapeutic resistance. Achieving predefined levels of two major thiopurine metabolites, 6-thioguanine nucleotides and 6-methylmercaptopurine, is a long-standing clinical practice in ensuring therapeutic efficacy; however, their correlation with treatment response is sometimes unclear. Various genetic markers have also been used to aid the identification of patients who are thiopurine-sensitive or refractory. The recent discovery of novel Asian-specific DNA variants, namely those in the NUDT15 gene, and their link to thiopurine toxicity, have led clinicians and scientists to revisit the utility of Caucasian biomarkers for Asian individuals with inflammatory bowel disease. In this review, we explore the limitations associated with the current methods used for therapeutic monitoring of thiopurine metabolites and how the recent discovery of ethnicity-specific genetic markers can complement thiopurine metabolites measurement in formulating a strategy for more accurate prediction of thiopurine response. We also discuss the challenges in thiopurine therapy, alongside the current strategies used in patients with reduced thiopurine response. The review is concluded with suggestions for future work aiming at using a more comprehensive approach to optimize the efficacy of thiopurine compounds in inflammatory bowel disease.

Analytical and Sample Preparation Protocol for Therapeutic Drug Monitoring of 12 Thiopurine Metabolites Related to Clinical Treatment of Inflammatory Bowel Disease

Thiopurines (TP) represent an important therapeutic tool for the treatment of inflammatory bowel diseases (IBD) in the current situation of rising incidence and health care costs. The results of multiple clinical studies aimed at finding correlations between levels of TP metabolites and response of IBD patients to the treatment are, however, often controversial due to variability in analytical and sample preparation procedures among these studies. In this work, therefore, an updated analytical and sample preparation procedure for therapeutic drug monitoring (TDM) of TP metabolites in blood samples obtained from patients with IBD was proposed to establish a unified protocol. An advanced analytical method based on ion-exchange liquid chromatography hyphenated with tandem mass spectrometry (IEC-ESI-MS/MS) was used for the determination of the profiles of 12 individual TP metabolites in the particular steps of sample preparation procedure including blood collection, red blood cells (RBC) isolation, lysis, and storage. Favorable performance parameters of the IEC-ESI-MS/MS method (LLOQs 1⁻10 nmol/L, accuracy 95⁻105%, intra-day and inter-day precision < 10%, selectivity demonstrated via no sample matrix interferences) and acceptable stability (peak area fluctuations < 15%) of clinical samples under the proposed sample preparation conditions {(i) EDTA anticoagulant tube for the blood collection; (ii) 4 °C and 4 h between the sample collection and RBC isolation; (iii) phosphate-buffered saline for RBC washing and re-suspendation; (iv) -20 °C for RBC lysis and short-term storage; (v) 50 mmol/L phosphate buffer, pH 7.4, 10 mmol/L DTT as a stabilizing medium for TPN in RBC lysates} demonstrated the suitability of such protocol for a well-defined and reliable routine use in studies on thiopurines TDM.

Measurements of 6-thioguanine nucleotide levels with TPMT and NUDT15 genotyping in patients with Crohn's disease

The association between the 6-thioguanine nucleotide (6-TGN) level and clinical remission in Crohn’s disease (CD) remains controversial. Thiopurine-induced leukopenia is a life-threatening complication of CD in Asians that was recently shown to strongly correlate with NUDT15 genetic variants. This study aimed to determine the relationship between thiopurine metabolite levels and therapeutic response, and to investigate the association of NUDT15, TPMT, and thiopurine metabolites with leukopenia in patients with CD. We enrolled 165 adult patients with CD undergoing thiopurine treatment. Clinical evaluation and laboratory examinations were carried out every 2–3 months. We measured thiopurine metabolites levels and genotyped NUDT15 and TPMT. During the median 12-month observational period, 95 (67.9%) patients exhibited clinical response and 45 (32.1%) did not respond to the treatment. The median 6-TGN level was significantly higher in responders than in non-responders (P < 0.001). The odds ratio of patients with a 6-TGN level ≥230 pmol/8 × 10⁸ red blood cells for showing a clinical response was 4.63 (95% CI 1.62–11.9). NUDT15 variant types were strongly associated with developing leukopenia. Patients with NUDT15 homozygous variant genotype developed severe early leukopenia with an average reduction of 88.2% (range, 84–94%) from the baseline white blood cell count at 4 weeks. Our findings support the role of therapeutic drug monitoring in thiopurine maintenance treatment to optimize thiopurine therapy, especially, for non-responding CD patients. Thiopurine treatment should not be recommended to patients with NUDT15 homozygous variant genotype due to severe early leukopenia.

NUDT15, FTO, and RUNX1 genetic variants and thiopurine intolerance among Japanese patients with inflammatory bowel diseases

Background/Aims

Recent genome-wide analyses have provided strong evidence concerning adverse events caused by thiopurine drugs such as azathioprine (AZA) and 6-mercaptopurine. The strong associations identified between NUDT15 p.Arg139Cys and thiopurine-induced leukopenia and severe hair loss have been studied and confirmed over the last 2 years. However, other coding variants, including NUDT15 p.Val18_Val19insGlyVal, NUDT15 p.Val18Ile, and FTO p.Ala134Thr, and a noncoding variation in RUNX1 (rs2834826) remain to be examined in detail in this respect. Therefore, we investigated the correlation between these adverse events and the 5 recently identified variants mentioned above among Japanese patients with inflammatory bowel diseases (IBD).

Methods

One hundred sixty thiopurine-treated patients with IBD were enrolled. Genotyping was performed using TaqMan SNP Genotyping Assays or Sanger sequencing.

Results

None of the 5 variants were associated with gastrointestinal intolerance to AZA. However, NUDT15 p.Arg139Cys was significantly associated with the interval between initiation and discontinuation of AZA among patients with gastrointestinal intolerance. This variant was strongly associated with early (<8 weeks) and late (≥8 weeks) leukopenia and severe hair loss. Moreover, it correlated with the interval between initiation of thiopurine therapy and leukopenia occurrence, and average thiopurine dose. NUDT15 p.Val18_Val19insGlyVal, NUDT15 p.Val18Ile, FTO p.Ala134Thr, and RUNX1 rs2834826 exhibited no significant relationship with the adverse events examined.

Conclusions

Of the 5 variants investigated, NUDT15 p.Arg139Cys had the strongest impact on thiopurine-induced leukopenia and severe hair loss; therefore, its genotyping should be prioritized over that of other variants in efforts to predict these adverse events in Japanese patients with IBD.

A Retrospective Claims Database Study on Drug Utilization in Japanese Patients with Crohn's Disease Treated with Adalimumab or Infliximab

Introduction

Crohn’s disease (CD) is a chronic and progressive disease in which the long-term management is important. This study sought to assess treatment persistence and dose escalation in the maintenance phase with adalimumab (ADA) or infliximab (IFX) in a Japanese real-world setting.

Methods

A retrospective analysis was conducted using the Japan Medical Data Center database. CD patients with either ADA or IFX prescriptions between January 2012 and February 2015 were included. Outcomes of interest were (1) failure in the induction phase (defined as switch or discontinuation) and (2) persistence in the maintenance phase (defined as the absence of switch or discontinuation over 12 months since maintenance initiation).

Results

Overall, 133 patients (53 ADA; 80 IFX) were included. Of them, treatment failed in 26 patients (19.6%) in the induction phase. During the induction phase, there was a trend towards fewer treatment failures with ADA than IFX (88.7% vs. 75.0%; p = 0.051). Of those who completed induction, 64 patients (33 ADA; 31 IFX) had at least 12 months of valid insurance enrolment after the initiation of maintenance and 13 (5 ADA; 8 IFX) had either switch or discontinuation within 12 months after the initiation of maintenance. Probabilities of switch or discontinuation over 12 months after the maintenance date were 15.2% and 20.9% for ADA and IFX groups, respectively (p-log rank = 0.7764).

Conclusion

Japanese patients have a high primary response to anti-tumor necrosis factor therapy in the real-world setting, in line with the results of clinical trials. This initial therapeutic advantage can be lost during the maintenance phase, leading to dose escalation, treatment switch, or discontinuation. This study suggests that those events occurred in comparable proportions of patients treated with either ADA or IFX. However, these findings should be considered with caution given the retrospective nature and small size of the study.

Funding

Abbvie GK, Tokyo, Japan.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-016-0406-6) contains supplementary material, which is available to authorized users.

Combination therapy with infliximab and thiopurine compared to infliximab monotherapy in maintaining remission of postoperative Crohn's disease

BACKGROUND AND AIMS

Infliximab is an efficacious agent used for the induction and maintenance of remission in Crohn's disease (CD), and recent studies suggested that it may also prevent the recurrence of this disease after surgery. The present study was performed to assess the efficacy and safety of infliximab in the postoperative setting, and to identify whether combination treatment with thiopurines had any additional beneficial effect as compared to mono-therapy.

METHODS

We performed a retrospective cohort study to compare the efficacy of infliximab mono-therapy and combination treatment with a thiopurine in preventing recurrence after surgery.

RESULTS

Forty-one patients who received infliximab as maintenance treatment following surgery from May 2002 to April 2010 were identified. Twenty-four were naive to infliximab, and 17 who underwent surgery during infliximab treatment were continued on it following surgery. The median follow-up period was 27 months (range 12-66 months). All patients continued infliximab as maintenance treatment, but 10 required dose intensification due to clinical recurrence. Kaplan-Meier analysis demonstrated that the use of concomitant thiopurine was correlated with the continuation of infliximab treatment at an 8-week interval (log-rank test p = 0.018). The rate of adverse event was 9.8% with no patient experiencing severe adverse reactions.

CONCLUSION

Infliximab appears to be safe and it prevented clinical recurrence after surgery. Concomitant thiopurine use predicted response toward continuation of therapy at an 8-week interval. Prospective controlled studies to assess the efficacy of combination treatment in the postoperative setting are warranted.

Relationship between azathioprine dosage, 6-thioguanine nucleotide levels, and therapeutic response in pediatric patients with IBD treated with azathioprine

BACKGROUND

Azathioprine (AZA) is commonly used to treat IBD either alone or in combination with mesalazine. However, there are relatively few studies concerning the relationship between AZA dose, thiopurine metabolite levels, and therapeutic response in pediatric patients treated with both AZA and mesalazine.

METHODS

We retrospectively investigated the relationship between AZA dose, thiopurine metabolite levels, and therapeutic response in 137 pediatric patients with IBD treated with AZA using multilevel analysis. Additional factors affecting metabolite levels and therapeutic response were also analyzed.

RESULTS

A positive correlation was observed between AZA dosage and 6-thioguanine nucleotide (6-TGN) level (P < 0.0001). Variant TPMT genotype (P < 0.001) and concomitant use of mesalazine (P < 0.001) were predictors of higher 6-TGN levels. Leukopenia (P = 0.025) and lymphopenia (P = 0.045) were associated with higher levels of 6-TGN. Poor AZA compliance affected median 6-TGN levels (P < 0.001). The frequency of patients with median 6-TGN levels >235 pmol per 8 × 10(8) red blood cells was the highest in the sustained therapeutic response group (P = 0.015). Age, sex, IBD type, and duration of AZA therapy did not influence 6-TGN levels or therapeutic effect.

CONCLUSIONS

AZA dosage is positively correlated with 6-TGN level. Higher 6-TGN levels are related to leukopenia, lymphopenia, and concurrent use of mesalazine. These results provide the rationale for monitoring metabolites to optimize drug dosing and minimize drug-related toxicity. In addition, maintenance of 6-TGN levels within a beneficial therapeutic range by direct monitoring should be helpful in attaining therapeutic efficacy, although this possibility should be verified in prospective studies.

Monitoring thiopurine metabolites in korean pediatric patients with inflammatory bowel disease

PURPOSE

This study aimed to assess the role of thiopurine S-methyltransferase (TPMT) and 6-thioguanine nucleotide (6-TGN) as predictors of clinical response and side effects to azathioprine (AZA), and estimate the optimal AZA dose in Korean pediatric inflammatory bowel disease (IBD) patients.

MATERIALS AND METHODS

One hundred and nine pediatric IBD patients in whom AZA treatment was required were enrolled. Thiopurine metabolites were monitored since September 2010. Among them, 83 patients who had prescribed AZA for at least 3 months prior to September 2010 were enrolled and followed until October 2011 to evaluate optimal AZA dose, adverse effects and disease activity before and after thiopurine metabolite monitoring.

RESULTS

The result of the TPMT genotype was that 102 patients were *1/*1 (wild type), four were *1/*3C, one was *1/*6, one was *1/*16 (heterozygote) and one was *3C/*3C (homozygote). Adverse effects happened in 31 patients pre-metabolite monitoring and in only nine patients post-metabolite monitoring. AZA dose was 1.4±0.31 mg/kg/day before monitoring and 1.1±0.46 mg/kg/day after monitoring (p<0.001). However, there were no statistical differences in disease activity during metabolite monitoring period (p=0.34). Adverse effects noticeably decreased although reduction of the AZA dose since monitoring.

CONCLUSION

TPMT genotype and thiopurine metabolite monitoring could be helpful to examine TPMT genotypes before administering AZA and to measure 6-TGN concentrations during prescribing AZA in IBD patients.

[Treatment strategy for refractory inflammatory bowel disease to improve endoscopic lesions and long-term prognosis]

Ulcerative colitis (UC) and Crohn's disease (CD) is an inflammatory bowel disease of unknown aetiology characterized by periods of remission and acute episodes of relapse with severe inflammation in the colonic mucosa. Conventional treatments for UC and CD include 5-aminosalicylate, corticosteroid, elemental dietary treatment, corticosteroid, and thiopurine (azathioprine). Recently, new immunomodulators and anti-TNFa agents, such as tacrolimus, infliximab, and adalimumab have been developed and these treatments are available to be treated for patients with refractory UC and CD. Conventional step-up treatment has been replaced by top-down treatment using biologics. Infliximab and adalimumab induce not only clinical remission but also improve relapse rates and surgical rates. Endoscopic mucosal healing predicts short- and long-prognosis for both of these diseases, thus recent treatment strategy should be aimed for endoscopic remission. Although biologics is useful for patients with UC/CD, secondary loss of responses (LOR) for biologics has been partly observed in CD patients. Measuring anti-infliximab antibodies and concentration of infliximab trough level may help considering treatment strategy for patients with LOR.

Monitoring and safety of azathioprine therapy in inflammatory bowel disease

Azathioprine is the most common drug used to maintain clinical remission in inflammatory bowel disease. This drug is also important as a steroid-sparing agent in steroid-dependent and chronically active inflammatory bowel disease. Nevertheless, many questions remain concerning the optimal treatment regimens of azathioprine. The dose of azathioprine has to be reduced or the therapy has to be discontinued frequently because of drug-induced toxicity. In this review, we discuss monitoring of thiopurines, adverse events, malignant complications and how to use azathioprine safely and usefully.

Ulcerative colitis: prevention of relapse

The clinical management of ulcerative colitis (UC) involves first treating the acute symptoms to induce remission, and then successfully maintaining it. Oral 5-aminosalicylic acids are safe and useful for maintaining remission in patients with UC. In terms of adherence, a once-daily form of 5-aminosalicylic acid is superior in maintaining remission as compared with split dosing. Patients at high risk of relapse may be candidates for treatment with thiopurines and/or biologics in the early stages of UC. Calcineurin inhibitors, such as cyclosporine and tacrolimus, are effective for severe, steroid-refractory UC patients. It is suggested that these patients use thiopurines as their maintenance therapy once they achieve remission with calcineurin inhibitors. Recent studies have confirmed that biologics are effective for inducing clinical and endoscopic remission of UC, and thus they may improve long-term prognosis of UC.

A prospective analysis of the incidence of and risk factors for opportunistic infections in patients with inflammatory bowel disease

BACKGROUND

Immunosuppressants lead to an increased risk of infection, but few prospective studies have assessed the incidence of opportunistic infections in inflammatory bowel disease (IBD) patients, a high proportion of whom are treated with immunosuppressants. The aim of this study was to assess the age distribution of Japanese IBD patients with opportunistic infections and the risk factors associated with these infections.

METHODS

A multicenter, prospective study of 570 IBD patients was conducted. The patients were followed for up to 12 months to identify any new infections. The incidence of opportunistic infections and the age distribution of patients with these infections were analyzed. We carried out a case-control study in which 2 non-infected IBD patients were selected as controls for each case (infected IBD patient); the effect of medications on the infection rate was also examined.

RESULTS

Fifty-two (9.1 %) of 570 IBD patients developed opportunistic infections. Herpes simplex virus and herpes zoster virus infections were observed in 29 and 16 patients, respectively. No cases of active tuberculosis were observed. The incidence of opportunistic infections in patients aged 50 years or over was significantly higher than that in the other age groups (p = 0.01). The use of steroids (p = 0.02), thiopurine (p < 0.01), and immunosuppressant combination therapy (p < 0.01) was associated with an increased rate of opportunistic infections. However, the use of infliximab was not associated with an increased rate of opportunistic infections (p = 0.62). Multivariate analysis indicated that the use of thiopurine was an independent risk factor for opportunistic infections (p < 0.01).

CONCLUSIONS

Age ≥50 years and the use of immunosuppressants are risk factors for opportunistic infections in patients with IBD. In our cohort, tuberculosis was not seen as a complication of immunosuppressant therapy.

Use of thiopurines in inflammatory bowel disease

The use of thiopurines as immunosuppression for the treatment of refractory or chronic active inflammatory bowel disease is established for both Crohn's disease and ulcerative colitis. Nevertheless, many questions remain concerning the optimal treatment regimens of azathioprine, 6-mercaptopurine and thioguanine. We will briefly summarize dose recommendations, indications for thiopurine therapy and side effects which are relevant in clinical practice. We discuss some currently debated topics, including the combination of azathioprine and allopurinol, switching of thiopurine therapy in case of side effects, the use of azathioprine in pregnancy, the infection risk using thiopurines and the evidence when to stop thiopurines. Excellent reviews have been published on the thiopurine metabolic pathway which will not be discussed here in detail.

Poor recall of prior exposure to varicella zoster, rubella, measles, or mumps in patients with IBD

BACKGROUND

Few studies have measured the levels of antibodies specific for measles, mumps, rubella, and varicella zoster/chickenpox viruses in inflammatory bowel disease (IBD) patients undergoing treatment with immunomodulators/biologics.

METHODS

We prospectively recruited 139 IBD outpatients. Enzyme-linked immunosorbent assays were used as the serological tests for measles, mumps, rubella, and varicella zoster. We defined anti-rubella IgG < 10 IU/mL, anti-measles IgG < 16 IU/mL, and anti-mumps/varicella zoster IgG <4 IU/mL as seronegative for viruses. We also asked participants about past immunizations against or infections with measles, mumps, rubella, and varicella zoster viruses.

RESULTS

The proportion of patients with seronegative levels of antibodies specific for varicella zoster, rubella, measles, and mumps viruses was 5%, 30%, 34%, and 37%, respectively. Approximately 40% of the IBD patients did not remember whether they had previously been infected with any of the viruses, and almost one-third of the patients could not remember whether they had previously been vaccinated. Almost 30% of the patients with a past history of rubella or measles did not have seropositive antibody levels. A total of 54% of the patients being treated with immunosuppressant displayed seronegative levels of antibodies specific for at least one of the viruses.

CONCLUSIONS

Many IBD patients were unaware of whether they had previously been vaccinated against or infected with the viruses causing varicella zoster, rubella, measles, or mumps. Therefore, measuring the current levels of antibodies specific for such viruses is useful for determining whether patients have seropositive antibody levels before immunomodulators/biologics are used for therapy.

The use of infliximab in the prevention of postsurgical recurrence in polysurgery Crohn's disease patients: a pilot open-labeled prospective study

PURPOSE

Crohn's disease (CD) commonly recurs after surgery, and a number of patients need repeated surgery, especially smokers and those with repeated surgeries or penetrating disease. Whether infliximab prevents postsurgical recurrence in high-risk CD remains unknown. In the present pilot open-labeled study, we investigated the safety and efficacy of scheduled infliximab, which was started early after surgery, in maintaining remission of CD patients who have undergone multiple surgeries due to penetrating disease.

METHODS

Eleven patients (nine male, two female; age range, 26-48 years) who had undergone repeated surgeries (median, 4; range, 2-5) for penetrating disease were enrolled. Two to 4 weeks after surgery, the patients were started on intravenous infliximab (5 mg/kg) at an 8-week interval. The primary end points were the proportion of patients in clinical remission at the end of the study, the rate of endoscopic/radiologic remission at 24 months, and the rate of adverse effects.

RESULTS

One patient dropped out due to non-compliance, and ten patients were eligible for analysis. Clinical remission was maintained in six of ten patients (60.0%) at the end of the study. At 24 months, four out of ten patients were in endoscopic or radiological remission (40.0%). Two patients experienced adverse effects (18.2%), one of whom elected to withdraw from the study.

CONCLUSION

The findings of no major safety concern and possible clinical benefit in our study suggest that further investigation of infliximab as a treatment for prevention of postsurgical recurrence in high-risk CD is warranted.

Thiopurine treatment in inflammatory bowel disease: response predictors, safety, and withdrawal in follow-up

BACKGROUND AND AIMS

Thiopurines represent the mainstay of immunosuppressive therapy in inflammatory bowel diseases. Since it is likely that response to therapy and adverse events depends on the genetic background of patients our study aimed to evaluate retrospectively response to therapy and safety in a mixed IBD population in Southern Europe.

METHODS

We evaluated demographic and clinical data of our patients treated with thiopurines. after 6 months in responders and non-responders to therapy. Moreover the likelihood to remain in thiopurine monotherapy was evaluated in responders, whereas adverse events were investigated in all patients.

RESULTS

Among disease- and patient-related parameters a shorter disease duration, female gender and ileal disease in Crohn's patients were associated with better response. By ROC analysis, the best predictors of response were decreasing values of C-reactive protein and erythrocyte sedimentation rate. In the long-term more than half of IBD patients who responded at 6 months remained on monotherapy at 42 months. Flu-like syndrome represented the most frequent adverse event followed by abnormalities of liver function tests and myelotoxicity. Adverse events did occur at any time and were frequently impredictable.

CONCLUSIONS

In this retrospective study, thiopurines showed a good clinical efficacy, especially in patients with short duration of disease. Normalization of markers of systemic inflammation represents the most useful tool to assess response. Careful monitoring of patients is required during the whole duration of treatment although it may not prevent all severe complications.

Intermittent granulocyte and monocyte apheresis versus mercaptopurine for maintaining remission of ulcerative colitis: a pilot study

The effect of granulocyte and monocyte adsorption apheresis (GMA) on prevention of relapse of ulcerative colitis (UC) is not clear. This was a pilot open-labeled, prospective, randomized, unblinded study to compare the tolerability and efficacy of intermittent GMA (once every 2 weeks) with mercaptopurine to maintain remission of UC. Twenty-one patients with UC, who had achieved remission by induction therapies were randomly assigned to receive either intermittent GMA (N = 10) or oral mercaptopurine (0.5 mg/kg per day; N = 11). The study period was 24 months. The rate of the patients maintaining remission and the incidences of adverse effects were compared between the two groups. At 24 months, seven of 10 patients (70.0%) on intermittent GMA and seven of 11 patients (63.6%, P = 1.00) on oral mercaptopurine were still in remission. Three patients relapsed in each group. One patient taking mercaptopurine, but none receiving intermittent GMA, dropped out because of adverse effects. Intermittent therapy with GMA was well tolerated and a substantial proportion of patients maintained remission. Intermittent GMA therapy in maintaining remission of UC merits further investigation.

Thiopurine maintenance therapy for ulcerative colitis: the clinical significance of monitoring 6-thioguanine nucleotide

BACKGROUND

6-Mercaptopurine (6-MP) is an effective maintenance medication in patients with ulcerative colitis (UC), but toxic effects like myelosuppression limit its clinical benefit. In the blood, 6-thioguanine (6-TGN) is formed from 6-MP and mediates the therapeutic efficacy and most of the toxicities of 6-MP. The level of 6-TGN depends on the activity of thiopurine methyltransferase (TPMT), inherited as 1 of its 3 polymorphic forms with low, moderate, or normal/high activity. Accordingly, the 6-MP dose needs to be pharmacogenetically guided.

METHODS

Patients with quiescent UC received 6-MP as maintenance therapy and 6-TGN was assayed as its concentrations in red blood cells (RBCs) done by high-performance liquid chromatography. In a preliminary investigation, 30 mg/day 6-MP (n = 50) was given orally over 12 weeks to determine the time course of blood 6-TGN level. Then 257 patients were given 6-MP at 15-80 mg/day in a stepwise manner based on RBC 6-TGN, white blood cell count, and body weight to monitor 6-MP efficacy and safety profiles.

RESULTS

At 30 mg/day 6-MP, RBC 6-TGN peaked over 4-8 weeks. In the main dosing study, the mean RBC 6-TGN level in patients who remained in remission during the 1-year observation time (n = 151) was 322.3 +/- 119.5 pmole/8 x 10(8) RBC versus 204.8 +/- 78.7 pmole/8 x 10(8) RBC in patients (n = 19) who relapsed (P < 0.001). Bone marrow suppression was seen almost exclusively at high 6-TGN concentration ranges. Further, a regression plot showed an inverse relationship between 6-TGN levels in RBC and TPMT enzyme activity.

CONCLUSIONS

By regularly measuring RBC 6-TGN in patients with quiescent UC receiving 6-MP as maintenance therapy, we could monitor bone marrow suppression as well as other toxic side effects. Potentially, this strategy should enable physicians to avoid thiopurine-related adverse effects and identify individuals who may benefit most from 6-MP maintenance therapy.