Safety of Tioguanine During Pregnancy in Inflammatory Bowel Disease

Effectiveness and safety of thioguanine as a maintenance therapy of inflammatory bowel disease: Systematic review, meta-analysis and meta-regression

INTRODUCTION

Thiopurines are an important therapy for the maintenance of remission in inflammatory bowel disease (IBD). However, the use of thioguanine has been limited by concerns regarding its toxicity. We performed a systematic review to evaluate its effectiveness and safety in IBD.

METHODS

Electronic databases were searched to identify studies reporting clinical responses and/or adverse events of thioguanine therapy in IBD. We calculated the pooled clinical response and clinical remission rates of thioguanine in IBD. Subgroup analyses were done for the dosage of thioguanine and the type of studies (prospective or retrospective). Meta-Regression was used to analyze the impact of dose on clinical efficacy and occurrence of nodular regenerative hyperplasia.

RESULTS

A total of 32 studies were included. The pooled clinical response rate of thioguanine therapy in IBD was 0.66 (95% C.I. 0.62 - 0.70; I2 = 16%). The pooled clinical response rate with low-dose was similar to high-dose thioguanine therapy [0.65 (95% C.I. 0.59 - 0.70; I2 = 24%) and 0.68 (95% C.I. 0.61 - 0.75; I2 = 18%) respectively]. The pooled remission maintenance rate was 0.71 (95% C.I. 0.58 - 0.81; I2 = 86%). The pooled rates of occurrence of nodular regenerative hyperplasia, liver function tests abnormalities and cytopenia were 0.04 (95% C.I. 0.02 - 0.08; I2 = 75%), 0.11 (95% C.I. 0.08 - 0.16; I2 = 72%) and 0.06 (95% C.I. 0.04 - 0.09; I2 = 62%) respectively. Meta-regression suggested that the risk of nodular regenerative hyperplasia is related to the dose of thioguanine.

CONCLUSION

TG is an efficacious and well-tolerated drug in most patients with IBD. Nodular regenerative hyperplasia, cytopenias, and liver function abnormalities occur in a small subset. Future studies should look into TG as primary therapy in IBD.

Inflammatory bowel disease in pregnancy and breastfeeding

Inflammatory bowel disease (IBD) has a peak age of diagnosis before the age of 35 years. Concerns about infertility, adverse pregnancy outcomes, and heritability of IBD have influenced decision-making for patients of childbearing age and their care providers. The interplay between the complex physiology in pregnancy and IBD can affect placental development, microbiome composition and responses to therapy. Current evidence has shown that effective disease management, including pre-conception counselling, multidisciplinary care and therapeutic agents to minimize disease activity, can improve pregnancy outcomes. This Review outlines the management of IBD in pregnancy and the safety of IBD therapies, including novel agents, with regard to both maternal and fetal health. The vast majority of IBD therapies can be used with low risk during pregnancy and lactation without substantial effects on neonatal outcomes.

Australian inflammatory bowel disease consensus statements for preconception, pregnancy and breast feeding

OBJECTIVE

Because pregnancy outcomes tend to be worse in women with inflammatory bowel disease (IBD) than in those without, we aimed to update consensus statements that guide the clinical management of pregnancy in patients with IBD.

DESIGN

A multidisciplinary working group was established to formulate these consensus statements. A modified RAND/UCLA appropriateness method was used, consisting of a literature review, online voting, discussion meeting and a second round of voting. The overall agreement among the delegates and appropriateness of the statement are reported.

RESULTS

Agreement was reached for 38/39 statements which provide guidance on management of pregnancy in patients with IBD. Most medications can and should be continued throughout pregnancy, except for methotrexate, allopurinol and new small molecules, such as tofacitinib. Due to limited data, no conclusion was reached on the use of tioguanine during pregnancy. Achieving and maintaining IBD remission before conception and throughout pregnancy is crucial to optimise maternofetal outcomes. This requires a multidisciplinary approach to engage patients, allay anxieties and maximise adherence tomedication. Intestinal ultrasound can be used for disease monitoring during pregnancy, and flexible sigmoidoscopy or MRI where clinically necessary.

CONCLUSION

These consensus statements provide up-to-date, comprehensive recommendations for the management of pregnancy in patients with IBD. This will enable a high standard of care for patients with IBD across all clinical settings.

Use of medications during pregnancy and breastfeeding for Crohn's disease and ulcerative colitis

Introduction: The peak age of diagnosis of inflammatory bowel disease (IBD) occurs during childbearing years, therefore management of IBD during pregnancy is a frequent occurrence. Maintenance of disease remission is crucial to optimize pregnancy outcomes, and potential maternal or fetal toxicity from medications must be balanced against the risks of untreated IBD.Areas covered: This review summarizes the literature on safety and use of medications for IBD during pregnancy and lactation.Expert opinion: 5-aminosalicylates, corticosteroids and thiopurines are safe for use during pregnancy, while methotrexate and tofacitinib should only be used with extreme caution. Anti-TNF agents (except certolizumab), vedolizumab, ustekinumab and tofacitinib readily traverse the placenta via active transport, therefore theoretically may affect fetal development. Certolizumab only undergoes passive transfer across the placenta, thus has markedly lower cord blood levels making it likely the safest biologic agent for infants. There is reasonable evidence to support the safety of anti-TNF monotherapy and combination therapy during pregnancy and lactation. Vedolizumab and ustekinumab are also thought to be safe in pregnancy and lactation, while tofacitinib is generally avoided due to teratogenic effects in animal studies.

Efficacy, safety and drug survival of thioguanine as maintenance treatment for inflammatory bowel disease: a retrospective multi-centre study in the United Kingdom

BACKGROUND

Thioguanine (TG) is a thiopurine which has been used for patients with inflammatory bowel disease (IBD), who have failed azathioprine (AZA) or mercaptopurine (MP) due to adverse events or suboptimal response. Its widespread use has been hampered due to concerns about nodular regenerative hyperplasia (NRH) of the liver. The aim of this study was to investigate the long-term efficacy and safety of low-dose TG therapy in IBD patients failing AZA and MP.

METHODS

A retrospective multicentre study was performed in IBD patients who failed prior treatment with conventional thiopurines with or without following immunomodulation (thiopurine-allopurinol, biologicals, methotrexate, tacrolimus) and were subsequently treated with TG as rescue monotherapy between 2003 and 2019 at three hospitals in the United Kingdom. Clinical response, adverse events, laboratory results, imaging and liver biopsies were retrospectively collected.

RESULTS

A total of 193 patients (57% female and 64% Crohn's disease) were included, with a median daily TG dose of 20 mg (range: 20-40 mg), a median treatment duration of 23 months (IQR 10-47) and a median follow-up of 36 months (IQR 22-53). The clinical response rate at 12 months was 65 and 54% remained on TG until the end of follow-up. Adverse events consisted primarily of elevated liver tests (6%), myelotoxicity (7%) and rash (5%). NRH was histologically diagnosed in two patients and two other patients (1%) developed non-cirrhotic portal hypertension. The median 6-TGN and TPMT levels were 953 pmol/8 × 10⁵ RBC (IQR 145-1761) and 47 mu/L (IQR 34.5-96).

CONCLUSIONS

Long-term follow-up suggests that TG can be an effective and well-tolerated therapy in more than half of difficult-to-treat and multi-therapy failing IBD patients. Findings of this study indicate that TG can be used safely and the occurrence of hepatotoxicity was low. The incidence rate of NRH was within the background incidence.

The continuous rediscovery and the benefit-risk ratio of thioguanine, a comprehensive review

Introduction: In the 1950s, thioguanine (TG), a thiopurine-derivative together with azathioprine (AZA) and mercaptopurine (MP), were developed for the treatment of childhood leukemia. Over the years, the use of TG was also explored for other, mainly immune-mediated and inflammatory, diseases such as in the field of dermatology and rheumatology (e.g. psoriasis, systemic lupus erythematosus (SLE)) and gastroenterology and hepatology (e.g. inflammatory bowel diseases (IBD), autoimmune hepatitis).Areas covered: This review provides a comprehensive overview of all the clinical uses of TG and describes its mechanism of action, pharmacokinetic/pharmacodynamic features, and toxicity.Expert opinion: Thioguanine has shown beneficial clinical effects in hematological (particularly leukemia) and several immune-inflammatory diseases including psoriasis, SLE, polycythemia vera, Churg-Strauss syndrome, IBD, collagenous sprue, refractory celiac disease, and autoimmune hepatitis. Thioguanine is not effective in treating solid-cancers. At relatively low dosages, i.e. 0.2- 0.3mg/kg/day or 20 mg/day, TG has a favorable risk-benefit ratio and is a safe and effective drug in the long-term treatment of amongst other IBD patients. Thioguanine toxicity, especially myelotoxicity, and hepatotoxicity, including nodular regenerative hyperplasia (NRH) of the liver, is limited when dosed adequately. The occurrence of NRH appears dose-dependent and has been especially described during high dose TG above 40 mg/day.

Hepatotoxicity during 6-thioguanine treatment in inflammatory bowel disease and childhood acute lymphoblastic leukaemia: A systematic review

Background

The recently established association between higher levels of DNA-incorporated thioguanine nucleotides and lower relapse risk in childhood acute lymphoblastic leukaemia (ALL) calls for reassessment of prolonged 6-thioguanine (6TG) treatment, while avoiding the risk of hepatotoxicity.

Objectives

To assess the incidence of hepatotoxicity in patients treated with 6TG, and to explore if a safe dose of continuous 6TG can be established.

Data sources

Databases, conference proceedings, and reference lists of included studies were systematically searched for 6TG and synonyms from 1998–2018.

Methods

We included studies of patients with ALL or inflammatory bowel disorder (IBD) treated with 6TG, excluding studies with 6TG as part of an intensive chemotherapy regimen. We uploaded a protocol to PROSPERO (registration number CRD42018089424). Database and manual searches yielded 1823 unique records. Of these, 395 full-texts were screened for eligibility. Finally, 134 reports representing 42 studies were included.

Results and conclusions

We included data from 42 studies of ALL and IBD patients; four randomised controlled trials (RCTs) including 3,993 patients, 20 observational studies including 796 patients, and 18 case reports including 60 patients. Hepatotoxicity in the form of sinusoidal obstruction syndrome (SOS) occurred in 9–25% of the ALL patients in two of the four included RCTs using 6TG doses of 40–60 mg/m²/day, and long-term hepatotoxicity in the form of nodular regenerative hyperplasia (NRH) was reported in 2.5%. In IBD patients treated with 6TG doses of approximately 23 mg/m²/day, NRH occurred in 14% of patients. At a 6TG dose of approximately 12 mg/m²/day, NRH was reported in 6% of IBD patients, which is similar to the background incidence. According to this review, doses at or below 12 mg/m²/day are rarely associated with notable hepatotoxicity and can probably be considered safe.

Is there a role for thioguanine therapy in IBD in 2017 and beyond?

Conventional thiopurines are effective for the maintenance of remission of Crohn's disease and ulcerative colitis, however, up to half of patients are intolerant or unresponsive to these medications. Thioguanine is an alternative thiopurine that has shown efficacy in inflammatory bowel disease, and is particularly useful to circumvent certain side effects associated with conventional thiopurines, for example, pancreatitis. Its association with nodular regenerative hyperplasia of the liver has hindered its widespread use. Areas covered: We aim to outline the rational use of thioguanine, including safety monitoring, with particular regard to hepatotoxicity. A literature search was performed: PubMed was searched for full papers and abstracts published in English since January 2000 using the following terms, alone and in combination: 'azathioprine', 'thiopurine', 'Crohn's disease', 'inflammatory bowel disease', 'nodular regenerative hyperplasia', 'mercaptopurine', 'thioguanine', 'ulcerative colitis'. Further relevant papers were identified from the reference lists of selected papers. Expert commentary: Despite optimisation strategies such as metabolite measurements and the use of allopurinol, a significant proportion of patients will remain intolerant to thiopurines, especially those with allergic reactions, including pancreatitis. For this subgroup of patients we suggest that low dose thioguanine is an alternative to other therapies that are either parenteral or expensive.