Thiopurine metabolites variations during co-treatment with aminosalicylates for inflammatory bowel disease: Effect of N-acetyl transferase polymorphisms

No Benefit of Continuing 5-Aminosalicylates in Patients with Crohn's Disease Treated with Anti-metabolite Therapy

BACKGROUND AND AIMS

5-aminosalicylates (5-ASA) are frequently used in the management of Crohn's disease (CD). We used a de-identified administrative claims database to compare patterns and outcomes of continuing versus stopping 5-ASA in patients with CD who escalated to anti-metabolite monotherapy.

METHODS

Patients with CD on 5-ASA who were new users of anti-metabolite monotherapy and followed for at least 12 months from OptumLabs® Data Warehouse. Three patterns of 5-ASA use were identified: stopped 5-ASA, short-term 5-ASA (use for < 6 months after starting anti-metabolites), or persistent 5-ASA (use for > 6 months after starting anti-metabolites). Outcomes (need for corticosteroids, risk of CD-related hospitalization and/or surgery, treatment escalation to biologic therapy) were compared using Cox proportional hazard analysis adjusting for key covariates, with a 12-month immortal time period.

RESULTS

Of 3036 patients with CD who were new-users of anti-metabolite monotherapy, 667 (21.9%), 626 (20.6%), and 1743 (57.4%) stopped 5-ASA, used 5-ASA transiently or persistently, respectively. Compared to patients who stopped 5-ASA after starting anti-metabolites, persistent 5-ASA use was associated with a higher risk of corticosteroid use (HR, 1.24 [1.08-1.42]), without an increase in risk of CD-related hospitalization (HR, 1.21 [0.98-1.49]), CD-related surgery (HR, 1.28 [0.90-1.80]) or treatment escalation (HR, 0.85 [0.62-1.20]). Sensitivity analyses using a 3-month window after initiation of anti-metabolites to classify patients as continuing vs. stopping 5-ASA showed similar results. Residual confounding by disease severity could not be excluded.

CONCLUSION

5-ASAs are frequently continued long-term even after escalation to anti-metabolite therapy in patients with CD but offer no clinical benefit over stopping 5-ASA.

No benefit of continuing vs stopping 5-aminosalicylates in patients with ulcerative colitis escalated to anti-metabolite therapy

BACKGROUND

Whilst continuation of 5-aminosalicylates (5-ASA) after escalation to biologic therapy is considered ineffective in patients with ulcerative colitis (UC), their role in patients escalated to anti-metabolites is unclear.

AIM

To compared patterns and outcomes of continuing vs stopping 5-ASA in patients with UC who escalated to anti-metabolite monotherapy, using a de-identified administrative claims database.

METHODS

We identified patients with UC who were new users of anti-metabolite monotherapy who were receiving 5-ASA, and were followed for at least 12 months after starting anti-metabolite therapy. We evaluated patterns of 5-ASA use (stopped 5-ASA, short-term 5-ASA use for <6 months after starting anti-metabolites, persistent 5-ASA use for >6 months after starting anti-metabolites). We compared outcomes (risk of UC-related hospitalisation and/or surgery, need for corticosteroids, treatment escalation to biologic therapy) by pattern of 5-ASA use, using Cox proportional hazard analysis adjusting for age, sex, race, comorbidity burden, and hospitalisation or emergency department visit, abdominal surgery and corticosteroid use in the previous 12 months (as measures of disease severity), with a 12-month immortal time period.

RESULTS

Of 4068 patients with UC who were new-users of anti-metabolite monotherapy, 578 (14.2%), 782 (19.2%) and 2708 (66.6%) stopped 5-ASA, used 5-ASA transiently or persistently, respectively. Compared to patients who stopped 5-ASA after starting anti-metabolites, persistent 5-ASA use was associated with a higher risk of UC-related hospitalisation (HR, 1.40 [1.07-1.83]) and corticosteroid use (HR, 1.48 [1.28-1.70]), without an increase in risk of UC-related surgery (HR, 1.32 [0.86-2.00]) or treatment escalation (HR, 0.80 [0.53-1.20]). Sensitivity analyses using a 3 months window after initiation of anti-metabolites to classify patients as continuing vs stopping 5-ASA showed similar results. Residual confounding by disease severity could not be excluded.

CONCLUSION

5-ASA are usually continued long-term even after escalating to anti-metabolite therapy in patients with UC without clinical benefit.

ILC3 function as a double-edged sword in inflammatory bowel diseases

Inflammatory bowel diseases (IBD), composed mainly of Crohn's disease (CD) and ulcerative colitis (UC), are strongly implicated in the development of intestinal inflammation lesions. Its exact etiology and pathogenesis are still undetermined. Recently accumulating evidence supports that group 3 innate lymphoid cells (ILC3) are responsible for gastrointestinal mucosal homeostasis through moderate generation of IL-22, IL-17, and GM-CSF in the physiological state. ILC3 contribute to the progression and aggravation of IBD while both IL-22 and IL-17, along with IFN-γ, are overexpressed by the dysregulation of NCR- ILC3 or NCR+ ILC3 function and the bias of NCR+ ILC3 towards ILC1 as well as regulatory ILC dysfunction in the pathological state. Herein, we feature the group 3 innate lymphoid cells' development, biological function, maintenance of gut homeostasis, mediation of IBD occurrence, and potential application to IBD therapy.

Azathioprine Biotransformation in Young Patients with Inflammatory Bowel Disease: Contribution of Glutathione-S Transferase M1 and A1 Variants

The contribution of candidate genetic variants involved in azathioprine biotransformation on azathioprine efficacy and pharmacokinetics in 111 young patients with inflammatory bowel disease was evaluated. Azathioprine doses, metabolites thioguanine-nucleotides (TGN) and methylmercaptopurine-nucleotides (MMPN) and clinical effects were assessed after at least 3 months of therapy. Clinical efficacy was defined as disease activity score below 10. Candidate genetic variants (TPMT rs1142345, rs1800460, rs1800462, GSTA1 rs3957357, GSTM1, and GSTT1 deletion) were determined by polymerase chain reaction (PCR) assays and pyrosequencing. Statistical analysis was performed using linear mixed effects models for the association between the candidate variants and the pharmacological variables (azathioprine doses and metabolites). Azathioprine metabolites were measured in 257 samples (median 2 per patient, inter-quartile range IQR 1-3). Clinical efficacy at the first evaluation available resulted better in ulcerative colitis than in Crohn’s disease patients (88.0% versus 52.5% responders, p = 0.0003, linear mixed effect model, LME). TGN concentration and the ratio TGN/dose at the first evaluation were significantly higher in responder. TPMT rs1142345 variant (4.8% of patients) was associated with increased TGN (LME p = 0.0042), TGN/dose ratio (LME p < 0.0001), decreased azathioprine dose (LME p = 0.0087), and MMPN (LME p = 0.0011). GSTM1 deletion (58.1% of patients) was associated with a 18.5% decrease in TGN/dose ratio (LME p = 0.041) and 30% decrease in clinical efficacy (LME p = 0.0031). GSTA1 variant (12.8% of patients) showed a trend (p = 0.046, LME) for an association with decreased clinical efficacy; however, no significant effect on azathioprine pharmacokinetics could be detected. In conclusion, GSTs variants are associated with azathioprine efficacy and pharmacokinetics.

Pharmacogenetics of treatments for inflammatory bowel disease

INTRODUCTION

Inflammatory bowel disease is a chronic inflammation of the gut whose pathogenesis is still unclear. Although no curative therapy is currently available, a number of drugs are used in induction and maintenance therapy; however, for most of these drugs, a high inter-individual variability in response is observed. Among the factors of this variability, genetics plays an important role. Areas covered: This review summarizes the results of pharmacogenetic studies, considering the most important drugs used and in particular aminosalycilates, glucocorticoids, thiopurines, monoclonal antibodies and thalidomide. Most studies used a candidate gene approach, even if significant breakthroughs have been obtained recently from applying genome-wide studies. When available, also investigations considering epigenetics and pharmacogenetic dosing guidelines have been included. Expert opinion: Only for thiopurines, genetic markers identified as predictors of efficacy or adverse events have allowed the development of dosing guidelines. For the other drugs, encouraging results are available and great expectations rely on the study of epigenetics and integration with pharmacokinetic information, especially useful for biologics. However, to improve therapy of IBD patients with these drugs, for implementation in the clinics of pharmacogenetics, informatic clinical decision support systems and training about pharmacogenetics of health providers are needed.

Treating children with inflammatory bowel disease: Current and new perspectives

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gut characterised by alternating periods of remission and relapse. Whilst the mechanism underlying this disease is yet to be fully understood, old and newer generation treatments can only target selected pathways of this complex inflammatory process. This narrative review aims to provide an update on the most recent advances in treatment of paediatric IBD. A MEDLINE search was conducted using “paediatric inflammatory bowel disease”, “paediatric Crohn’s disease”, “paediatric ulcerative colitis”, “treatment”, “therapy”, “immunosuppressant”, “biologic”, “monitoring” and “biomarkers” as key words. Clinical trials, systematic reviews, and meta-analyses published between 2014 and 2016 were selected. Studies referring to earlier periods were also considered in case the data was relevant to our scope. Major advances have been achieved in monitoring the individual metabolism, toxicity and response to relevant medications in IBD including thiopurines and biologics. New biologics acting on novel mechanisms such as selective interference with lymphocyte trafficking are emerging treatment options. Current research is investing in the development of reliable prognostic biomarkers, aiming to move towards personalised treatments targeted to individual patients.

Inflammatory Bowel Disease Drugs: A Focus on Autophagy

Inflammatory bowel disease [IBD] is characterized by chronic inflammation of the gastrointestinal tract. Medications such as corticosteroids, thiopurines, immunomodulators and biologic agents are used to induce and maintain remission; however, response to these drugs is variable and can diminish over time. Defective autophagy has been strongly linked to IBD pathogenesis, with evidence showing that enhancing autophagy may be therapeutically beneficial by regulating inflammation and clearing intestinal pathogens. It is plausible that the therapeutic effects of some IBD drugs are mediated in part through modulation of the autophagy pathway, with studies investigating a wide range of diseases and cell types demonstrating autophagy pathway regulation by these agents. This review will highlight the current evidence, both in vitro and in vivo, for the modulation of autophagy by drugs routinely used in IBD. A clearer understanding of their mechanisms of action will be invaluable to utilize these drugs in a more targeted and personalized manner in this diverse and often complex group of patients.

Monitoring thiopurine metabolites in inflammatory bowel disease

Thiopurines (azathioprine and mercaptopurine) are one of the immunosuppressive mainstays for the treatment of inflammatory bowel disease. In spite of its widespread use, thiopurine metabolism is still not fully understood, and a significant proportion of patients suffer toxicity or lack of efficacy. Different enzymatic pathways with individual variations constitute a pharmacogenetic model that seems to be suitable for monitoring and therapeutic intervention. This review is focused on current concepts and recent research that may help clinicians to rationally optimise thiopurine treatment in patients with inflammatory bowel disease.