Optimising use of thiopurines in inflammatory bowel disease

Key factors associated with 6-thioguanine and 6-methylmercaptopurine nucleotide concentrations in children treated by thiopurine for acute leukaemia and inflammatory bowel disease

AIMS

Azathioprine (AZA) and 6-mercaptopurine are prescribed in acute lymphoblastic leukaemia (ALL) and inflammatory bowel diseases (IBD). Metabolism to active 6-thioguanine (6TGN) and 6-methylmercaptopurine nucleotides (6MMPN) is variable but therapeutic drug monitoring (TDM) remains debatable. This study reports on factors impacting on red blood cell (RBC) metabolites concentrations in children to facilitate TDM interpretation.

METHODS

The first paediatric TDM samples received during year 2021 were analysed, whatever indication and thiopurine drug. Target concentration ranges were 200-500, <6000 pmol/8 × 108 RBC for 6TGN and 6MMPN.

RESULTS

Children (n = 492) had IBD (64.8%), ALL (22.6%) or another autoimmune disease (12.6%): mean ages at TDM were 7.5 in ALL and 13.7 years in IBD (P < .0001). ALL received 6-mercaptopurine (mean dose 1.7 mg/kg/d with methotrexate), IBD received AZA (1.9 mg/kg/d with anti-inflammatory drugs and/or monoclonal antibodies). Median 6TGN and 6MMPN concentrations were 213.7 [interquartile range: 142.5; 309.6] and 1144.6 [419.4; 3574.3] pmol/8 × 108 RBC, 38.8% of patients were in the recommended therapeutic range for both compounds. Aminotransferases and blood tests were abnormal in 57/260 patients: 8.1% patients had high alanine aminotransaminase, 3.4% of patients had abnormal blood count. Factors associated with increased 6TGN were age at TDM and thiopurine methyltransferase genotype in ALL and AZA dose in IBD. The impact of associated treatment in IBD patients was also significant.

CONCLUSION

TDM allowed identification of children who do not reach target levels or remain over treated. Including TDM in follow-up may help physicians to adjust dosage with the aim of reducing adverse effects and improve treatment outcome.

A Review of Therapeutic Drug Monitoring in Patients with Inflammatory Bowel Disease Receiving Combination Therapy

Background: Inflammatory Bowel Disease (IBD) impacts millions worldwide, presenting a major challenge to healthcare providers and patients. The advent of biologic therapies has enhanced the prognosis, but many patients exhibit primary or secondary non-response, underscoring the need for rigorous monitoring and therapy optimization to improve outcomes. Objective: This narrative review seeks to understand the role of therapeutic drug monitoring (TDM) in optimizing treatment for IBD patients, especially for those on combination therapies of biologics and immunomodulators. Methods: A comprehensive synthesis of the current literature was undertaken, focusing on the application, benefits, limitations, and future directions of TDM in patients receiving a combination of biologic therapies and immunomodulators. Results: While biological therapies have improved outcomes, rigorous monitoring and therapy optimization are needed. TDM has emerged as a pivotal strategy, enhancing outcomes cost-effectively while reducing adverse events. While most data pertain to monotherapies, TDM's applicability also extends to combination therapy. Conclusion: TDM plays a crucial role in the treatment optimization of IBD patients on combination therapies. Further research is needed to fully understand its potential and limitations in the broader context of IBD management.

Azathioprine monotherapy withdrawal in inflammatory bowel diseases: A retrospective mono-centric study

BACKGROUND

There is no consensus on the recommended duration of and optimal time to stop azathioprine (AZA) therapy in inflammatory bowel disease (IBD). Determining the optimal duration and cessation time can help to balance the risks of long-term intake with the possibility of relapse after cessation.

AIM

To describe the events following AZA cessation.

METHODS

Retrospective analysis was performed to examine data from adult patients affected by IBD who were followed at the University of Padua and had started but then discontinued AZA between 1995 and 2022. Data on therapy duration, reasons for cessation, and type of relapse after cessation were collected. Cox regression models were used to estimate the risk of relapse in different subgroups.

RESULTS

A total of 133 ulcerative colitis patients and 141 Crohn’s disease patients were included. Therapy with AZA was stopped in the 1^st year in approximately 34% of patients but was continued for more than 10 years in approximately 10% of cases. AZA discontinuation was due to primary failure or disease relapse in 30% of patients and due to disease remission in 25.2% of patients. Most of the remaining cases stopped AZA therapy due to side effects (primarily clinical intolerance, cytopenia, and pancreatic disease). Patients who stopped AZA for clinical remission had an 83% lower risk of relapse during the observation time than other groups, with a relapse-free rate of 89% after 1 year and 79% after 2 years.

CONCLUSION

AZA administration is effective and safe, but it requires careful monitoring for potential minor and major side effects. Only 10% of patients who achieved remission with AZA needed a new treatment within 1 year of drug interruption.

Thiopurine therapy in inflammatory bowel disease in the pandemic era: Safe or unsafe?

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract. Crohn's disease (CD) and Ulcerative colitis (UC) are the two major types affecting millions across the globe. Various immunomodulatory drugs consisting of small molecules (thiopurines, methotrexate and tofacitinib) and biologics are used to treat IBD. Thiopurines (TP) are widely used in the treatment of IBD and it plays an important role both alone and in combination with anti-TNF agents as IBD maintenance therapy. Although the advent of biologics therapy has significantly advanced the management of IBD, TP remains the mainstay of treatment in resource-limited and low economic settings. However, the recently commenced pandemic has raised uncertainty over the safety of the use of immunosuppressant drugs such as TP among healthcare care providers and patients, as there is a scarcity of data on whether IBD patients are at higher risk of COVID-19 infection or more prone to its severe outcomes.

AIM

This review aims to encapsulate evidence on the risk of COVID-19 infection and its severe prognosis in IBD patients on TP. Additionally, it also evaluates the role of TP in inhibiting the viral protease, a potential drug target, essential for the replication and pathogenesis of the virus.

CONCLUSION

Emerging evidence suggests that TP therapy is safe during the current pandemic and does not carry an elevated risk when used as monotherapy or in combination with other IBD drugs. In-vitro studies demonstrate that TP is a potential therapeutic for present and future betacoronavirus pandemics.

Drug therapy and monitoring for inflammatory bowel disease: a multinational questionnaire investigation in Asia

Background/Aims

The incidence and prevalence of inflammatory bowel disease (IBD) is rising in Asia recently. The study aimed to obtain a comprehensive understanding of the current status of drug therapy and monitoring for IBD in Asia.

Methods

A questionnaire investigation on drug therapy and monitoring for IBD was conducted right before the 6th Annual Meeting of Asian Organization for Crohn’s & Colitis. Questionnaires were provided to Asian physicians to fill out via emails between March and May 2018.

Results

In total, responses of 166 physicians from 129 medical centers were included for analysis. Among the surveyed regions, the most average number of IBD specialist gastroenterologists and nurses was 4.8 per center in Taiwan and 2.5 per center in Mainland China, respectively. 5-Aminosalicylic acid/sulfasalazine (99.4%) was the most preferred first-line choice for mild-moderate ulcerative colitis (UC), meanwhile corticosteroid (83.7%) was widely applied for severe UC. The first-line medication for Crohn’s disease (CD) markedly varied as corticosteroid (68.1%) was the most favored in Mainland China, Japan, and South Korea, followed by infliximab (52.4%) and azathioprine (47.0%). Step-up strategy was preferred in mild-moderate UC (96.4%), while 51.8% of the physicians selected top-down treatment for CD. Only 25.9% and 17.5% of the physicians could test blood concentration of infliximab and antibody to infliximab in their hospitals, respectively.

Conclusions

The current status of drug therapy and monitoring for IBD in Asia possesses commonalities as well as differences. Asian recommendations, IBD specialist teams and practice of therapeutic drug monitoring are required to improve IBD management in Asia.

Optimizing Therapies Using Therapeutic Drug Monitoring: Current Strategies and Future Perspectives

Therapeutic drug monitoring (TDM) has emerged as a strategy for treatment optimization in inflammatory bowel diseases to maximize benefit and to reach more stringent, objective end points. Optimal drug concentrations in inflammatory bowel disease vary according to treatment target, disease phenotype, inflammatory burden, and timing of sampling during the treatment cycle. This review provides an update on TDM with biologic and oral small molecules, evaluates the role of reactive vs proactive TDM, and identifies the gaps in current evidence. In the future, adaptations to how we use TDM may contribute further to the goal of personalized treatment in patients with IBD.

Thiopurines: Use them or lose them? International survey on current and future use of thiopurines in inflammatory bowel disease

BACKGROUND AND AIMS

The role of thiopurines in therapeutic algorithms of Crohn's disease (CD) and Ulcerative colitis (UC) is being questioned. This work aimed to investigate current practice and future perspectives of Inflammatory Bowel Disease (IBD) physicians regarding the efficacy, safety, and role of precision medicine with thiopurines in IBD.

METHODS

A 29-questions web-based survey was developed and distributed to IBD physicians worldwide.

RESULTS

We collected the complete answers of 408 physicians from 50 countries. Most participants were experienced physicians in IBD; 26.0% met our definition of "IBD expert". Four physicians reported to not use thiopurines in clinical practice. Most respondents used thiopurines in monotherapy and in combination therapy, both in CD and UC. Respondents tended to consider thiopurines as drugs with a good safety profile, with the agreement of 61.5% of the overall cohort. A minority of physicians (~6%) considered that thiopurines will not be used in the future in IBD patients, while 57.8% believed that these drugs will still be used, in mono and combination therapy.

CONCLUSION

Despite the many emerging treatments in IBD, according to the beliefs of most physicians surveyed, thiopurines will still be an important part of the treatment algorithm of both CD and UC.

Effects of various genetic polymorphisms on thiopurine treatment-associated outcomes for Korean patients with Crohn's disease

AIMS

This study explores the effects of various genetic polymorphisms in candidate genes on thiopurine metabolism and toxicity in adult patients with Crohn's disease in Korea.

METHODS

A total of 131 adult patients with Crohn's disease receiving thiopurine treatment were included. The TPMT and NUDT15 genes and an additional 116 genetic polymorphisms (in 40 genes and 3 intergenic locations) were screened for genotyping. Among the polymorphisms screened, 91 genetic polymorphisms (in 34 genes and 3 intergenic locations) in addition to TPMT and NUDT15 genotypes were included for statistical analyses to investigate their effects on thiopurine metabolites and adverse outcomes (leukopenia, hepatotoxicity, gastrointestinal intolerance, skin rash and alopecia).

RESULTS

The median duration of thiopurine treatment was 47.0 months (range 6.0-153.4 months). Patient sex, maintenance dose of thiopurine, and use of anti-tumour necrosis factor agents were associated with thiopurine metabolite concentrations (P < .05). In the univariate analysis, the TPMT genotype was associated with 6-thioguanine level (P < .05), although the significance of this did not remain in multivariate analysis. Genetic polymorphisms in the ATIC (rs3821353 and rs16853834), IMPDH2 (rs11706052) and ITPA (rs6139036) genes were associated with thiopurine metabolism (P < .05). Genetic polymorphisms in the ABCC5 (rs8180093) and NUDT15 genotypes were associated with leukopenia (P < .05).

CONCLUSION

The results of this study may help clinicians to understand the effects of other various polymorphisms in addition to TPMT and NUDP15 in thiopurine metabolism for management of Crohn's disease patients.

Persistence of antibodies to pneumococcal conjugate vaccine compared to polysaccharide vaccine in patients with Crohn's disease - one year follow up

Background: Patients suffering from Crohn's disease (CD) are at increased risk of infectious diseases, such as pneumococcal infection. The risk increases with immunotherapy. Pneumococcal infection can be prevented by vaccination. Methods: We conducted a randomized trial of the 23-valent pneumococcal polysaccharide vaccine (PPV23) and the 13-valent pneumococcal conjugated vaccine (PCV13) in groups of CD patients treated with immunosuppressive (IS) drugs in the form of thiopurines (PPV23 n = 28, PCV13 n = 28) alone or in combination with TNF-α antagonists (PPV23 n = 13, PCV13 n = 13) and CD patients not treated with any of these drugs (untreated) (PPV23 n = 30, PCV13 n = 24). In this article, we report the immunogenicity of PPC23 and PCV13 one year after vaccination. Results: No overall differences in vaccine-induced serotype-specific immunoglobulin G (IgG) antibodies or functional antibodies (opsonophagocytic activity (OPA)) were found between the two vaccines. PCV13 induced a higher concentration of IgG antibodies for serotype 9V than PPV23 in untreated patients. In contrast, PPV23 induced higher OPA for serotypes 6B and 19F than PCV13 in IS treated patients. Untreated patients showed generally higher IgG and OPA antibody levels than patients treated with IS and TNF-α antagonists. Conclusions: In conclusion, we found no general differences in the persistence of induced antibodies when comparing PPV23 with PCV13 regardless of treatment and also within treatment groups (IS, IS + TNF-α and untreated). This was demonstrated for both serotype-specific IgG antibodies and as functional antibodies (OPA). Patients treated with thiopurines in combination with TNF-α inhibitors have an impaired immune response against both PPV23 and PCV13, as compared to untreated patients. This study has been registered in the European Clinical Trials Database (EudraCT, record no 2012-002867-86) and ClinicalTrials.gov (record no. NCT01947010).

A Concise History of Thiopurines for Inflammatory Bowel Disease: From Anecdotal Reporting to Treat-to-Target Algorithms

BACKGROUND

The need for immune suppressive strategies in the control of chronic inflammatory bowel diseases originated in the 1960s following the perception of a relative inefficacy of salazopyrin and its derivatives. In some 50 years upon an anecdotal claim, the indication for thiopurines in the management of inflammatory bowel diseases has come of age.

OBJECTIVE

The aim of this minireview is to give an overview, after the historical premises, of the current use of thiopurines in the context of inflammatory bowel diseases.

METHOD

Through MEDLINE searches, we reviewed the literature of the last two decades.

RESULTS

For Crohn's disease, the 1980 trial of 6-mercaptopurine for steroid sparing and fistula closure proved pivotal. The analysis of withdrawal experiments and of numerous open trials has established the efficacy of thiopurines for ulcerative colitis. In this indication, cutting-edge data are now showing that because targeting dysplasia, thiopurines can induce mucosal/histological healing, thus abolishing or delaying the need for pre-emptive (tumor prophylactic) colectomy.

CONCLUSION

In UC thiopurines may be recognized to effect a treat-to-target strategy, joining the modern algorithms of rheumatologic disorders.

Clinical experience of optimising thiopurine use through metabolite measurement in inflammatory bowel disease

INTRODUCTION

Thiopurine therapy can be optimised by determining the concentration of the drug's metabolites.

PATIENTS AND METHODS

Retrospective analysis on a prospective database of 31 patients with inflammatory bowel disease who failed therapy with thiopurines. Thiopurine metabolites (6-thioguanine, 6-TGN and 6-methylmercaptopurine, 6-MMP) were measured by high-performance liquid chromatography (Laboratorios Cerba, Barcelona) and treatment was duly adjusted in accordance with the results. Clinical response was reassessed after six months.

RESULT

Despite the appropriate theoretical dose of thiopurines being administered, the dose was insufficient in 45.6% of patients (nonadherence to treatment suspected in 6.45%) and 16.2% received an excessive dose or the drug was metabolised by other metabolic pathways. After treatment was optimised based on metabolite levels, only 25.8% (8/31) were prescribed a biological agent, while 74.2% of cases (23/31) were managed through dose optimisation alone.

DISCUSSION

Monitoring thiopurine metabolite levels may help clinicians to assess non-responsive patients before adding or switching to another drug (generally a biological agent), thereby avoiding any additional costs or potential toxicity. This strategy may also help to identify patients receiving an insufficient dose and those with an alternative metabolic pathway, who could be candidates for low-dose AZA with allopurinol, as well as patients who are suspected of being non-adherent. In three out of four patients, switching to a biological agent can be avoided.

Recommendations of the Spanish Working Group on Crohn's Disease and Ulcerative Colitis (GETECCU) on the use of thiopurines in inflammatory bowel disease

Thiopurines (azathioprine and mercaptopurine) are widely used in patients with inflammatory bowel disease. In this paper, we review the main indications for their use, as well as practical aspects on efficacy, safety and method of administration. They are mainly used to maintain remission in steroid-dependent disease or with ciclosporin to control a severe ulcerative colitis flare-up, as well as to prevent postoperative Crohn's disease recurrence, and also in combination therapy with biologics. About 30-40% of patients will not respond to treatment and 10-20% will not tolerate it due to adverse effects. Before they are prescribed, immunisation status against certain infections should be checked. Determination of thiopurine methyltransferase activity (TPMT) is not mandatory but it increases initial safety. The appropriate dose is 2.5mg/kg/day for azathioprine and 1.5mg/kg/day for mercaptopurine. Some adverse effects are idiosyncratic (digestive intolerance, pancreatitis, fever, arthromyalgia, rash and some forms of hepatotoxicity). Others are dose-dependent (myelotoxicity and other types of hepatotoxicity), and their surveillance should never be interrupted during treatment. If therapy fails or adverse effects develop, management can include switching from one thiopurine to the other, reducing the dose, combining low doses of azathioprine with allopurinol and assessing metabolites, before their use is ruled out. Non-melanoma skin cancer, lymphomas and urinary tract tumours have been linked to thiopurine therapy. Thiopurine use is safe during conception, pregnancy and breastfeeding.

Inflammatory Bowel Diseases and Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols: An Overview

Inflammatory bowel diseases (IBDs) are mainly represented by ulcerative colitis and Crohn's disease, and the increase in the incidence tends to follow the rapid industrialization and lifestyle of modern societies. FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) consist of molecules that are poorly absorbed in the small intestine and are fermented by bacteria in the colon leading to symptoms such as bloating, flatulence, diarrhea, and abdominal pain. Reduction of the ingestion of FODMAP could reduce the symptoms and improve the quality of life. This review aimed to summarize some important aspects of IBD and evaluate the effects of this diet on this inflammatory condition. Studies including the term FODMAP (and similar terms) and IBD were selected for this review (MEDLINE database was used PubMed/PMC). A low FODMAP diet may be an effective tool to the management of the common abdominal symptoms in patients with functional gastrointestinal symptoms once these molecules trigger these symptoms. This diet may also reduce the expression of pro-inflammatory markers such as C-reactive protein and fecal calprotectin and may interfere with the microbiome and its metabolites. The use of a low FODMAP diet can bring benefits to the IBD patients, but may also modify their nutritional status. Thus it should be utilized in appropriated conditions, and dietary supplements should be necessary to avoid deficiencies that could be caused by a low FODMAP diet over long periods. We suggest that further investigations are required to elucidate when and how to apply the FODMAP diet in IBD patients.