Thiopurine therapy in inflammatory bowel disease

Proactive Metabolite Testing in Patients on Thiopurine May Yield Long-Term Clinical Benefits in Inflammatory Bowel Disease

BACKGROUND

The thiopurine medications are well established in the treatment of inflammatory bowel disease (IBD). There is significant variation in levels of toxic and therapeutic metabolites. Current data from small or short-term studies support therapeutic drug monitoring (TDM) in assessing azathioprine (AZA) and 6-mercaptopurine (6MP). TDM of thiopurines involves measurement and interpretation of metabolites 6-TGN and 6-MMPR.

AIMS

This study aimed to assess long-cterm outcomes of patients on thiopurines following therapeutic drug monitoring.

METHODS

A multicenter retrospective observational study of outcomes post thiopurine TDM was conducted. Demographics, disease characteristics, physician global assessment, IBD therapy at baseline TDM and again at 12 months were collected. Clinical outcomes were analyzed according to TDM result, and indication for TDM including proactive and other indications.

RESULTS

The study included 541 patients. Only 39% of patients had appropriate dosing of thiopurines. AZA/6MP TDM informed a management change in 61.9%, and enabled 88.8% of the cohort to continue AZA/6MP following TDM. At 12 months following TDM the majority (74.1%) of the cohort remained on AZA/6MP. Clinical remission was higher at 12-months following thiopurines TDM (68%) compared to baseline (37%), including proactive TDM. Post TDM, 13.0% of patients were identified as shunters and commenced on thiopurine-allopurinol co-therapy.

CONCLUSION

Thiopurine TDM resulted in a change in management for the majority of patients. Post TDM significantly more patients were in remission. TDM allowed the identification of non-adherence and shunters who, without intervention, would not reach therapeutic drug levels. Proactive TDM allowed identification and management of inappropriate dosing, and was associated with increased levels of clinical remission.

Mucosal Healing in Ulcerative Colitis: A Comprehensive Review

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by periods of remission and periods of relapse. Patients often present with symptoms such as rectal bleeding, diarrhea and weight loss, and may require hospitalization and even colectomy. Long-term complications of UC include decreased quality of life and productivity and an increased risk of colorectal cancer. Mucosal healing (MH) has gained progressive importance in the management of UC patients. In this article, we review the endoscopic findings that define both mucosal injury and MH, and the strengths and limitations of the scoring systems currently available in clinical practice. The basic mechanisms behind colonic injury and MH are covered, highlighting the pathways through which different drugs exert their effect towards reducing inflammation and promoting epithelial repair. A comprehensive review of the evidence for approved drugs for UC to achieve and maintain MH is provided, including a section on the pharmacokinetics of anti-tumor necrosis factor (TNF)-α drugs. Currently approved drugs with proven efficacy in achieving MH in UC include salicylates, corticosteroids (induction only), calcineurin inhibitors (induction only), thiopurines, vedolizumab and anti-TNFα drugs (infliximab, adalimumab, and golimumab). MH is of crucial relevance in the outcomes of UC, resulting in lower incidences of clinical relapse, the need for hospitalization and surgery, as well as reduced rates of dysplasia and colorectal cancer. Finally, we present recent evidence towards the need for a more strict definition of complete MH as the preferred endpoint for UC patients, using a combination of both endoscopic and histological findings.

Does lymphopenia or macrocytosis reflect 6-thioguanine levels in patients with inflammatory bowel disease treated with azathioprine or 6-mercaptopurine?

BACKGROUND

The thiopurine drugs, 6-mercaptopurine and azathioprine, remain the mainstay of immunomodulator therapy for inflammatory bowel disease (IBD). Optimal management depends on achieving therapeutic levels of 6-thioguanine (6-TGN), but measuring thiopurine metabolites is associated with significant cost. Thiopurines cause lymphopenia and an increase in mean corpuscular volume (MCV). It is unclear whether any clinically useful correlation exists between 6-TGN levels and lymphocyte count or MCV.

AIMS

The aim of this study is to investigate the correlation between 6-TGN levels and lymphocyte count and MCV in thiopurine-treated patients with IBD.

METHODS

We analysed a prospectively acquired database of 67 patients with IBD treated with thiopurine therapy. The data were analysed looking at the relationship between 6-TGN levels and both lymphocyte count and MCV by using the Spearman's rank correlation coefficient.

RESULTS

Twenty-seven (40%) patients had therapeutic 6-TGN levels. Thirty-three (49%) patients had sub-therapeutic 6-TGN levels. A weak positive correlation between 6-TGN levels and lymphocyte count was demonstrated, but this was not statistically significant (Spearman's R = 0.14, P = 0.23). Spearman's rank correlation coefficient between 6-TGN levels and MCV was statistically significant (R = 0.42, P = 0.0005). MCV >101 fL excluded a subtherapeutic 6-TGN level with positive predictive value of 92%.

CONCLUSIONS

There is no specific lymphopenia that can be assumed to indicate a therapeutic 6-TGN level. The relationship between 6-TGN levels and MCV is likely to be clinically relevant. If MCV is elevated, 6-TGN is unlikely to be sub-therapeutic. MCV is a potential surrogate marker which can rule out sub-therapeutic thiopurine metabolites in patients with IBD treated with azathioprine or 6-mercaptopurine.

Predictors of Thiopurine Treatment Failure in Biologic-Naïve Ulcerative Colitis Patients

INTRODUCTION

Thiopurines (azathioprine and 6-mercaptopurine) have been used in the management of UC patients for over three decades. Nearly half of patients with UC treated with thiopurines fail to achieve remission or lose remission during treatment. Factors associated with thiopurine failure are poorly understood. The primary aim of our study was to investigate patient-related factors which are associated with thiopurine failure.

METHODS

TNF-alpha antagonist-naïve patients with histological diagnosis of UC, receiving thiopurine therapy, with follow-up data from 1 to 3 years were included in the study. Data regarding demographics, laboratory results, and disease characteristics were collected. The primary endpoint was failure of thiopurine therapy, defined as treatment with steroids, therapeutic escalation to TNF-alpha antagonist therapy, or need for surgery.

RESULTS

Of the 563 patients identified using ICD-9 codes, 78 TNF-alpha antagonist-naïve patients with a histological diagnosis of UC, receiving thiopurine treatment, were identified. Over the three-year follow-up period, 38 patients failed thiopurine treatment. On adjusted Cox regression, BMI < 25 kg/m(2) (HR 3, 95 % CI 1.55-5.83; p value = 0.001) was significantly associated with thiopurine failure. Furthermore, although not statistically significant, there was a strong trend toward thiopurine failure among patients with serum albumin level < 4 g/dL (HR 1.98, 95 % CI 0.97-4; p value = 0.06), non-smoking status (HR 2.2, 95 % CI 0.96-5.06; p value = 0.06), and higher degree of colon inflammation (HR 1.49, 95 % CI 0.96-2.32; p value = 0.08).

DISCUSSION

Our results show that low body mass index is associated with increased risk of failure of thiopurine treatment. Furthermore, there was a strong trend toward thiopurine failure among patients with low serum albumin level (<4gm/dL). These factors should be considered as markers of non-response to thiopurine monotherapy for patients with moderately severe ulcerative colitis.

Early Thiopurines Versus Conventional Step-Care Therapy for Modifying the Disease Course of Early Crohn's Disease: A Tertiary Referral Center Cohort Study

The impact of thiopurines (TP) on the long-term outcome of early Crohn disease (CD) is still controversial. The present study designed as a comparison of conventional step-care to alternative treatment paradigms for disease progression.This longitudinal cohort study examined the established CD patients from a university-based inflammatory bowel disease referral center. Outcomes of mucosal healing (MH), CD-related surgery or hospitalization, and clinical remission were compared based on timing of initiation of TP therapy. The cumulative incidence of events was estimated by Kaplan-Meier method.One-hundred ninety patients with early CD were included. After a median follow-up of 57 months (interquartile range, 31.3-76.2), 29 patients undergone abdominal surgeries, 48 patients hospitalized, and 68 patients experienced clinical flares. A higher cumulative proportion of patients in the top-down (TD) group achieving MH than both the accelerated step-up (AC) group and conventional management (CM) group at month 36 (78.8% vs 39.9% and 42.2%, respectively; P = 0.001). There was a trend, albeit not significant, for an increased proportion of patients free of CD-related intestinal surgery in the TD group at month 60 (P = 0.16). However, among secondary outcomes, an early TP-based AC or TD strategy was not associated with improvement in clinical remission rates compared with a CM strategy at month 60 (P = 0.79). No significant difference was observed between early TP and CM for rates of MH, CD-related intestinal surgery or hospitalization, and clinical remission.Both AC and CM strategy were minimally effective for disease modification. TD strategy has the potential of achieving higher rates MH. Our results support the TD strategy in patients with early CD at risk for a disabling course.

Toxicity and response to thiopurines in patients with inflammatory bowel disease

The use of thiopurines is well established in the management of inflammatory bowel disease. A wealth of data and experience, amassed over several decades, supporting their efficacy has recently been challenged by trials that failed to show a benefit in Crohn's disease when used early in the disease course, although other trials continue to support their role both as monotherapy and in combination with anti-TNF. Recent reports of previously unrecognized toxicity have also emerged. Fortunately, the absolute incidence of serious toxicity remains low, and an improved understanding of how best to minimize risk and the recognition of groups of patients at higher risk of toxicity from thiopurines means that they remain a relatively safe therapy in the majority of patients. In this paper, we review the literature evaluating the role of thiopurines in inflammatory bowel disease as well as their toxicity. We conclude that education regarding the spectrum of thiopurine side effects and optimal monitoring during therapy may help with optimizing safety and efficacy of these important medications.

Leukopenia predicts remission in patients with inflammatory bowel disease and Behcet's disease on thiopurine maintenance

BACKGROUNDS

The thiopurine drugs, azathioprine (AZA), and 6-mercaptopurine (6-MP) are well-established drugs for the treatment of inflammatory bowel disease (IBD). Although leukopenia is a well-recognized side effect of AZA/6-MP treatment, its association with therapeutic effects has yet to be determined. We therefore evaluated the influences of thiopurine-induced leukopenia on the long-term prognosis of IBD.

METHODS

We included 196 IBD patients [45 with ulcerative colitis (UC), 68 with Crohn's disease (CD), and 83 with intestinal Behçet's disease (BD)] who were treated with AZA/6-MP and achieved remission between January 2006 and December 2012. We retrospectively analyzed patient characteristics, AZA/6-MP maintenance dose (mg/kg), the lowest white blood cell (WBC) count during AZA/6-MP treatment, duration of remission, and the occurrence of relapse. We compared the clinical variables between leukopenic (n = 120, WBC count <4,000/μL) and nonleukopenic (n = 76, WBC count ≥ 4,000/μL) patients.

RESULTS

The two groups were well matched for baseline clinical characteristics. The cumulative relapse-free survival rate was higher in the leukopenic group than the nonleukopenic group by Kaplan-Meier survival analysis (log-rank test, P < 0.001). On multivariate analysis, age, duration of AZA/6-MP treatment, presence of macrocytosis, and the presence of leukopenia were negatively associated with relapse (odds ratios 0.975, 0.988, 0.563, and 0.390, respectively). On subgroup analysis, the cumulative relapse-free survival rate was significantly higher in the leukopenic group than in the nonleukopenic group for all types of IBDs, including UC, CD, and intestinal BD (log-rank test, P = 0.032, 0.047, and 0.002, respectively).

CONCLUSION

Leukopenia during thiopurine maintenance therapy was associated with prolonged remission in patients with IBD and Behcet's disease.

Use of thiopurines in inflammatory bowel disease: Safety issues

Thiopurines are widely used for maintenance treatment of inflammatory bowel disease. Inter-individual variability in clinical response to thiopurines may be attributed to several factors including genetic polymorphisms, severity and chronicity of disease, comorbidities, duration of administration, compliance issues and use of concomitant medication, environmental factors and clinician and patient preferences. The purpose of this review is to summarise the current evidence on thiopurine safety and toxicity, to describe adverse drug events and emphasise the significance of drug interactions, and to discuss the relative safety of thiopurine use in adults, elderly patients, children and pregnant women. Thiopurines are safe to use and well tolerated, however dose adjustment or discontinuation of treatment must be considered in cases of non-response, poor compliance or toxicity. Drug safety, clinical response to treatment and short to long term risks and benefits must be balanced throughout treatment duration for different categories of patients. Treatment should be individualised and stratified according to patient requirements. Enzymatic testing prior to treatment commencement is advised. Surveillance with regular clinic follow-up and monitoring of laboratory markers is important. Data on long term efficacy, safety of thiopurine use and interaction with other disease modifying drugs are lacking, especially in paediatric inflammatory bowel disease. High quality, collaborative clinical research is required so as to inform clinical practice in the future.

Clinical implications of ageing for the management of IBD

As the global population ages, the number of older people (≥65 years) living with IBD is expected to increase. IBD therapeutics have advanced considerably over the past few decades with the introduction of multiple steroid-sparing agents as well as numerous clinical trials that have tested new therapeutic targets. However, the current paradigms for IBD management might not be directly translatable to older patients with IBD. Age-related factors such as immunodeficiency relative to younger patients, comorbidity, polypharmacy and diminished physical reserve directly or indirectly affect the natural history of their disease. This Review highlights how these age-associated variables can affect older patients with IBD and also illustrates the multiple gaps in our current knowledge of IBD in the elderly.

Randomised clinical trial: individualised vs. weight-based dosing of azathioprine in Crohn's disease

BACKGROUND

Azathioprine (AZA), a pro-drug metabolised to the active metabolites 6-tioguanine nucleotides (6TGN), is a steroid-sparing therapy for Crohn's disease (CD).

AIM

To investigate whether AZA therapy is optimised by individualised dosing based on thiopurine methyltransferase (TPMT) activity and 6TGN concentrations.

METHODS

This multicentre, double-blind, randomised controlled trial compared the efficacy and safety of weight-based vs. individualised AZA dosing in inducing and maintaining remission in adults and children with steroid-treated CD. The primary outcome was clinical remission (CR) at 16 weeks. In the weight-based arm, subjects received 2.5 mg/kg/day. In the individualised dosing arm, the initial AZA dose was 1.0 mg/kg/day (if intermediate TPMT) or 2.5 mg/kg/day (if normal TPMT). Starting at week 5, the dose was adjusted to target 6TGN concentrations of 250-400 pmol/8 × 10(8) red blood cells (RBC), or to a maximal dose of 4 mg/kg/day.

RESULTS

After randomising 50 subjects, the trial was stopped prematurely due to insufficient enrolment. In intention-to-treat analysis, CR rates at week 16 were 40% in the individualised arm vs. 16% in the weight-based arm (P = 0.11). In per-protocol (PP) analysis, week 16 CR rates were 60% in the individualised arm and 25% in the weight-based arm (P = 0.12). At week 16, median 6TGN concentrations in PP remitters and nonremitters were 216 and 149 pmol/8 × 10(8) RBC respectively (P = 0.07).

CONCLUSIONS

Despite trends favouring individualised over weight-based AZA dosing, there were no statistically significant differences in efficacy, likely due to low statistical power and inability to achieve the target 6TGN concentrations in the individualised arm. [Clinicaltrials.Gov Identifier Nct00113503].

A pooled analysis of infections, malignancy, and mortality in infliximab- and immunomodulator-treated adult patients with inflammatory bowel disease

OBJECTIVES

The objective of this study was to analyze the safety of long-term infliximab treatment, with/without concomitant immunomodulators, across Crohn's disease (CD) and ulcerative colitis (UC) clinical trials.

METHODS

To maximize sample size, we pooled primary safety data across 10 CD or UC trials, including five randomized, controlled trials contributing data from patients who received intravenous infliximab 5 or 10 mg/kg (n=1,713; ±azathioprine) or placebo (n=406; ±azathioprine). Pooled incidences and 95% confidence intervals (CIs) were determined for mortality, infection, and malignancy. Standardized incidence ratios and 95% CIs were also determined for malignancies using the Surveillance, Epidemiology, and End Results database.

RESULTS

We observed no increase in infections, serious infections, or malignancy with infliximab vs. placebo in these patients with inflammatory bowel disease (IBD). In patients with UC, but not CD, immunomodulator treatment (vs. treatment without immunomodulator) yielded a higher incidence (95% CI) of infections (120.07 (110.66, 130.08)/100 patient-years (pt-yrs) vs. 92.47 (84.54, 100.94)/100 pt-yrs). Among placebo-treated patients with CD, but not UC, those with immunomodulator use demonstrated a higher incidence (95% CI) of malignancy vs. no immunomodulator treatment (1.84 (0.22, 6.66)/100 pt-yrs vs. 0.00 (0.00, 0.00)/100 pt-yrs). Mortality and infection-related mortality appeared unaffected by infliximab or immunomodulator treatment.

CONCLUSIONS

Infliximab treatment of IBD did not appear to affect incidences of infection, mortality, or malignancy. Relative to patients with no immunomodulator use, immunomodulator-treated UC patients demonstrated a higher incidence of infection and immunomodulator-plus-placebo-treated CD patients demonstrated a higher incidence of malignancy.

Clinical outcomes and prognostic factors for thiopurine maintenance therapy in patients with intestinal Behcet's disease

BACKGROUND

To date, there have been no studies focusing on the efficacy of thiopurine therapy in intestinal Behcet's disease (BD). We conducted this study to investigate clinical outcomes and predictors of clinical relapse in intestinal BD patients receiving thiopurine maintenance therapy.

METHODS

We reviewed the medical records of all patients with intestinal BD who received thiopurine therapy in a single tertiary academic medical center between March 1986 and October 2010. The cumulative probabilities of clinical relapse after remission were calculated using the Kaplan-Meier method. Predictors of clinical relapse were identified by univariate analysis using the log-rank test and by multivariate analysis using Cox proportional hazards regression models.

RESULTS

Of a total of 272 patients with intestinal BD, 67 (24.6%) received their first course of thiopurine therapy at our center. Thirty-nine (58.2%) of the 67 patients constantly received thiopurines for maintaining medically or surgically induced remission. The cumulative relapse rates at 1 year, 2 years, 3 years, and 5 years after remission were 5.8%, 28.7%, 43.7%, and 51.7%, respectively. On multivariate analysis, a younger age (<25 years) at diagnosis and a lower hemoglobin level (<11 g/dL) were independent predictive factors for relapse in intestinal BD patients receiving thiopurine maintenance therapy.

CONCLUSIONS

Thiopurine therapy showed a relatively good effect for maintenance of remission in intestinal BD patients. However, a younger age at diagnosis and a lower hemoglobin level were associated with a poor response to thiopurines, necessitating early adoption of effective alternative therapeutic options in these risk groups.

Outcome predictors for thiopurine maintenance therapy in patients with Crohn's disease

BACKGROUND

Little is known about the factors that predict clinical relapse in Crohn's disease patients receiving thiopurine therapy to maintain remission. The objective of this study was, therefore, to investigate these factors.

METHODS

A total of 82 Crohn's disease patients who received their first course of azathioprine or 6-mercaptopurine treatment at Severance Hospital between June 1996 and July 2007 were recruited to the study. During the follow-up period (25.5 ± 16.6 months) 19 patients (23.2%) discontinued the medication because of significant adverse effects. Forty-five patients who continued to receive thiopurines to maintain medically or surgically induced remission were enrolled in the study. After adjusting the maintenance dose, patients in remission were followed at 2-3 month intervals. Relapse was defined as a Crohn's disease activity index ≥ 150.

RESULTS

The male-to-female ratio was 1.5:1 and the mean age was 26.3 ± 7.1 years. Cumulative relapse was 18.0% after one year and 49.2% after three years. According to multivariate Cox regression analysis, younger age (<30 years) at thiopurine therapy and increased C-reactive protein level (≥ 0.5 mg/dL) at remission were independent predictors of relapse (hazard ratio 19.751, 95%-confidence interval (CI) 1.996-195.402, P = 0.011 and hazard ratio 9.001, 95% CI 1.583-51.181, P = 0.013, respectively).

CONCLUSIONS

Younger age (<30 years) and increased C-reactive protein level at remission were independent predictors of relapse in Crohn's disease patients receiving thiopurines to maintain remission. These high-risk groups warrant closer observation and possibly early introduction of biological agents.