The Impact of Thiopurine Metabolite Monitoring on the Durability of Thiopurine Monotherapy in Pediatric IBD

Thiopurines Maintenance Therapy in Children With Ulcerative Colitis: A Multicenter Retrospective Study

BACKGROUND AND AIMS

Thiopurines are an established treatment for pediatric ulcerative colitis (UC). However, data regarding safety and efficacy are lacking. We aimed to determine short and long-term outcome following thiopurines use in children with UC.

METHODS

We conducted a retrospective review of children (2-18 years) with UC treated with thiopurines between January 2008 and January 2019 at 7 medical centers in Israel. The primary outcome was corticosteroid (CS)-free clinical remission at week 52 following thiopurines initiation without the need for rescue therapy (infliximab, calcineurin inhibitors, or colectomy).

RESULTS

A total of 133 children were included [median age at diagnosis of 12.4 (interquartile range 11.0-15.8) years, 30 (23%) left-sided colitis, 113 (85%) with moderate or severe disease at diagnosis]. At diagnosis 58 patients (44%) were treated with 5-aminosalicylates and 72 (54%) with CS. Sixty patients (45%) received thiopurines as 1st line maintenance therapy. Seventy-four patients (56%) had CS-free clinical remission at week 52 without rescue therapy. Predictors of clinical remission were not identified. In a sub-analysis among patients with steroid-responsive moderate to severe UC, 59 (55%) patients achieved this outcome. The likelihood of remaining free of rescue therapy among thiopurines-treated patients was 83%, 62%, 45%, and 37% at 1, 2, 3, and 4 years, respectively.

CONCLUSION

More than half of children with UC starting thiopurines without previous or concomitant biologic therapy have CS-free clinical remission at 52 weeks later without the need for rescue therapy. Thiopurines are effective in pediatric UC and could be considered prior to biologics.

Drug-Related Adverse Events Necessitating Treatment Discontinuation in Pediatric Inflammatory Bowel Disease Patients

OBJECTIVES

Inflammatory bowel disease (IBD) requires long-term drug therapy in most patients, posing a risk for adverse drug events with the need for discontinuation. In this study, we investigated adverse events (AE) necessitating drug discontinuation in pediatric and adolescent IBD patients.

METHODS

We used data prospectively collected from IBD patients below the age of 18 enrolled in the Swiss Inflammatory Bowel Disease Cohort Study (SIBDCS), namely demographic variables, medical characteristics, drug treatments, and related AE. We analyzed the frequency, type, and risk factors for AE necessitating drug discontinuation.

RESULTS

A total of 509 pediatric IBD patients fulfilled the inclusion criteria of which 262 (51.5%) were diagnosed with Crohn disease (CD), 206 (40.5%) with ulcerative colitis (UC), and 41 (8%) with IBD-unclassified (IBD-U). In total, 132 (25.9%) presented with at least 1 drug-related AE that required drug cessation. Immunomodulators [methotrexate 29/120 (24.2%), azathioprine 57/372 (15.3%)] followed by tumor necrosis factor (TNF)-alpha antagonists [adalimumab 8/72 (11.1%), infliximab 22/227 (9.7%)] accounted for the highest proportions of AE necessitating treatment discontinuation. Treatment schemes with at least 3 concomitant drugs significantly amplified the risk for development of drug-related AE [odds ratio = 2.50, 95% confidence interval (1.50-4.17)] in all pediatric IBD patients.

CONCLUSIONS

Drug-related AE necessitating discontinuation are common in pediatric and adolescent IBD patients. Caution needs to be taken in the case of concomitant drug use.

Safety of Thioguanine in Pediatric Inflammatory Bowel Disease: A Multi-Center Case Series

OBJECTIVES

Thioguanine (TG) has been shown as a safe alternative in adults with inflammatory bowel disease (IBD) who did not tolerate conventional thiopurines [azathioprine (AZA)/mercaptopurine]. However, data in pediatric IBD are scarce. Therefore, we aimed to assess the safety of TG as maintenance therapy.

METHODS

A retrospective, multicenter cohort study of children with IBD on TG was performed in the Netherlands. TG-related adverse events (AE) were assessed and listed according to the common terminology criteria for AE.

RESULTS

Thirty-six children with IBD (median age 14.5 years) on TG (median dose 15 mg/day) were included in 6 centers. Five AE occurred during follow-up [pancreatitis (grade 3), hepatotoxicity (grade 3) (n = 2), Clostridium difficile infection (grade 2), and abdominal pain (grade 2)]. All patients (n = 8) with a previously AZA-induced pancreatitis did not redevelop pancreatitis on TG.

CONCLUSIONS

In pediatric IBD, TG seems a safe alternative in case of AZA-induced pancreatitis. Further research assessing long-term TG-related safety and efficacy is needed.

Clinical utility of thiopurine metabolite monitoring in inflammatory bowel disease and its impact on healthcare utilization in Singapore

Background and Aim

Thiopurines are recommended for maintenance of steroid‐free remission (SFR) in inflammatory bowel disease (IBD). Thiopurine metabolite monitoring (MM) is increasingly used in the West but remains novel in Singapore, with limited information on its therapeutic and economic benefits. Hence, this study aims to investigate MM's clinical utility and its impact on healthcare resource utilization in Singaporean IBD patients.

Methods

A retrospective observational study was conducted at Singapore General Hospital outpatient IBD Centre. Patients with IBD, baseline MM during 2014–2017, and weight‐based thiopurine doses for ≥4 weeks were followed up for 1 year. Actions were taken to optimize therapy, and metabolite levels before and after the first action were documented. Outcomes assessed included SFR, no therapy escalation or surgery, healthcare resource utilization, and direct healthcare costs.

Results

Ninety IBD patients (50 Crohn's disease, 40 ulcerative colitis) were included. Among them, 40% had baseline metabolite levels within therapeutic range, 31.1% sub‐therapeutic, 21.1% supra‐therapeutic, and 7.8% shunters. Repeated MM with subsequent dose optimization helped 67.2% of patients achieve therapeutic levels after 1 year. Overall, 87.8% of patients achieved SFR and 90% had no therapy escalation or surgery. Despite greater outpatient visits and laboratory investigations with MM, the median total healthcare costs at 1 year only increased marginally (S$6407.66 [shunters] vs S$5215.20 [supra‐therapeutic] vs S$4970.80 [sub‐therapeutic] vs S$4370.48 [control (within therapeutic range)], P = 0.592).

Conclusion

MM guided timely therapy escalation for non‐responders, identification of non‐adherence, and reversal of shunting. Therefore, it is a useful clinical tool to optimize thiopurines without significantly increasing healthcare costs.

Adverse Events of Thiopurine Therapy in Pediatric Inflammatory Bowel Disease and Correlations with Metabolites: A Cohort Study

BACKGROUND

In the recent era of growing availability of biological agents, the role of thiopurines needs to be reassessed with the focus on toxicity.

AIMS

We assessed the incidence and predictive factors of thiopurine-induced adverse events (AE) resulting in therapy cessation in pediatric inflammatory bowel disease (IBD), related to thiopurine metabolites and biochemical abnormalities, and determined overall drug survival.

METHODS

We performed a retrospective, single-center study of children diagnosed with IBD between 2000 and 2019 and treated with thiopurine therapy. The incidence of AE and overall drug survival of thiopurines were evaluated using the Kaplan-Meier method. Correlations between thiopurine metabolites and biochemical tests were computed using Spearman's correlation coefficient.

RESULTS

Of 391 patients with IBD, 233 patients (162 Crohn's disease, 62 ulcerative colitis, and 9 IBD-unclassified) were prescribed thiopurines (230 azathioprine and 3 mercaptopurine), of whom 50 patients (22%) discontinued treatment, at least temporary, due to thiopurine-induced AE (median follow-up 20.7 months). Twenty-six patients (52%) were rechallenged and 18 of them (70%) tolerated this. Sixteen patients (6%) switched to a second thiopurine agent after azathioprine intolerance and 10 of them (63%) tolerated this. No predictive factors for development of AE could be identified. Concentrations of 6-thioguanine nucleotides (6-TGN) were significantly correlated with white blood cell and neutrophil count, 6-methylmercaptopurine (6-MMP) concentrations with alanine aminotransferase and gamma-glutamyltranspeptidase.

CONCLUSIONS

Approximately 20% of pediatric patients with IBD discontinued thiopurine treatment due to AE. A rechallenge or switch to mercaptopurine is an effective strategy after development of AE. Concentrations of 6-TGN and 6-MMP are associated with biochemical abnormalities.

Nurse-Provided Medication Guidance for Improving Drug Adherence to Thiopurines in Outpatients With Inflammatory Bowel Disease: A Single-Center Prospective Study

Background and Aims

Drug adherence is critically important for patients on thiopurines. We examined whether nurse-provided medication guidance improves drug adherence to thiopurines and clinical activity in patients with inflammatory bowel disease (IBD).

Methods

IBD outpatients taking a stable dose of thiopurines for 1 year were enrolled. After a baseline survey including the Morisky Medication Adherence Scale (MMAS)-8, nurses provided medication guidance to each patient using a specialized leaflet. The same survey was conducted 2 and 6 months after the guidance.

Results

Among 110 enrolled patients, 74 met the analysis criteria. In the low adherence group (MMAS-8 <6), the median MMAS-8 score significantly increased from 4 (range 1-5.75) to 5.25 (2-7) at 2 months (P = .0135) to 5.625 (2.5-7.75) at 6 months (P = .0004), but not in overall or the high adherence group (MMAS-8 ≥6). Older age (≥43 years, odds ratio [OR] = 5.63, 95% confidence interval [CI]: 1.59-19.9, P = .0074) and shorter disease duration (<129 months, OR = 6.78, 95% CI: 1.77-26.0, P = .0052) were independently associated with high adherence. Although clinical activity scores did not change during the observation period, the overall mean corpuscular volume (MCV) level significantly increased from 92.3 fL (61.4-105.5) to 92.5 (73.7-107.8) at 2 months (P = .0288) and 93.9 (74.4-107.6) at 6 months (P = .0062). MCV levels significantly increased in the low adherence group at 6 months (92.2 [72.2-105.5] to 94.0 [74.4-107.6], P = .0392) and tended to increase in the high adherence group (92.3 [61.4-101.2] to 93.6 [74.9-99.7], P = .0651).

Conclusions

Nurse-provided medication guidance improved drug adherence to thiopurines in IBD patients with low adherence and can also benefit those with high adherence.

Thiopurines in Pediatric Inflammatory Bowel Disease: Current and Future Place

Thiopurines have been widely used to maintain steroid-free remission in children with inflammatory bowel disease (IBD). However, within the expanding treatment armamentarium, the role of these non-selective immunomodulators has been questioned, especially in pediatric patients, who often present with a more aggressive disease course, which can impact growth and development. The less favorable safety but also inferior efficacy profile associated with thiopurines, in contrast to the newer biological therapies, has interfered with their use. The future place of thiopurines in the management of childhood IBD, therefore, needs revisiting. This review provides a practical overview on the historical and current use of thiopurines in pediatric IBD with specific attention for thiopurine S-methyltransferase testing and monitoring of thiopurine metabolite levels as an approach to improve outcomes. We also give a personal expert opinion on the future role of these drugs in childhood IBD.

Safety of Thiopurine Use in Paediatric Gastrointestinal Disease

Thiopurines, alone or in combination with other agents, have a pivotal role in the treatment of specific gastrointestinal and hepatological disorders. In inflammatory bowel disease and autoimmune hepatitis thiopurines have proven their value as steroid sparing agents for the maintenance of remission and may be considered for preventing postoperative Crohn disease recurrence where there is moderate risk of this occurring. Their use with infliximab therapy reduces antibody formation and increases biologic drug levels. The routine clinical use of thiopurines has, however, been questioned due to a number of potential adverse effects. The aim of this article is to provide information regarding the use, and in particular, safety of these agents in clinical practice in the light of such potentially severe, albeit rare, effects.