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Background and AimsThioguanine is a well-tolerated and effective therapy for inflammatory bowel disease [IBD] patients. Prospective effectiveness data are needed to substantiate the role of thioguanine as a maintenance therapy for IBD.MethodsIBD patients who previously failed azathioprine or mercaptopurine and initiated thioguanine were prospectively followed for 12 months starting when corticosteroid-free clinical remission was achieved (Harvey–Bradshaw Index [HBI] ≤ 4 or Simple Clinical Colitis Activity Index [SCCAI] ≤ 2). The primary endpoint was corticosteroid-free clinical remission throughout 12 months. Loss of clinical remission was defined as SCCAI > 2 or HBI > 4, need of surgery, escalation of therapy, initiation of corticosteroids or study discontinuation. Additional endpoints were adverse events, drug survival, physician global assessment [PGA] and quality of life [QoL].ResultsSustained corticosteroid-free clinical remission at 3, 6 or 12 months was observed in 75 [69%], 66 [61%] and 49 [45%] of 108 patients, respectively. Thioguanine was continued in 86 patients [80%] for at least 12 months. Loss of response [55%] included escalation to biologicals in 15%, corticosteroids in 10% and surgery in 3%. According to PGA scores, 82% of patients were still in remission after 12 months and QoL scores remained stable. Adverse events leading to discontinuation were reported in 11%, infections in 10%, myelo- and hepatotoxicity each in 6%, and portal hypertension in 1% of patients.ConclusionSustained corticosteroid-free clinical remission over 12 months was achieved in 45% of IBD patients on monotherapy with thioguanine. A drug continuation rate of 80%, together with favourable PGA and QoL scores, underlines the tolerability and effectiveness of thioguanine for IBD.

Contains fulltext : 291394.pdf (Publisher’s version ) (Open Access) BACKGROUND & AIMS: Discontinuation of anti-tumor necrosis factor-α treatment (anti-TNF) (infliximab and adalimumab) in patients with inflammatory bowel disease (IBD) is associated with a high relapse risk that may be influenced by endoscopic activity at the time of stopping. We assessed the relapse rate after anti-TNF withdrawal in patients with endoscopic healing and studied predictors of relapse including the depth of endoscopic healing. METHODS: This was a multicenter, prospective study in adult patients with Crohn's disease (CD), ulcerative colitis (UC), or IBD-unclassified (IBDU), with ≥6 months of corticosteroid-free clinical remission (confirmed at baseline) and endoscopic healing (Mayo

Background & Aims: Clinicians face difficulty in when and in what order to position biologics and Janus kinase inhibitors in patients with anti-tumor necrosis factor-alpha (TNF) refractory ulcerative colitis (UC). We aimed to compare the effectiveness and safety of vedolizumab and tofacitinib in anti-TNF-exposed patients with UC in our prospective nationwide Initiative on Crohn and Colitis Registry. Methods: Patients with UC who failed anti-TNF treatment and initiated vedolizumab or tofacitinib treatment were identified in the Initiative on Crohn and Colitis Registry in the Netherlands. We selected patients with both clinical as well as biochemical or endoscopic disease activity at initiation of therapy. Patients previously treated with vedolizumab or tofacitinib were excluded. Corticosteroid-free clinical remission (Simple Clinical Colitis Activity Index ≤2), biochemical remission (C-reactive protein ≤5 mg/L or fecal calprotectin ≤250 μg/g), and safety outcomes were compared after 52 weeks of treatment. Inverse propensity score-weighted comparison was used to adjust for confounding and selection bias. Results: Overall, 83 vedolizumab- and 65 tofacitinib-treated patients were included. Propensity score-weighted analysis showed that tofacitinib-treated patients were more likely to achieve corticosteroid-free clinical remission and biochemical remission at weeks 12, 24, and 52 compared with vedolizumab-treated patients (odds ratio [OR], 6.33; 95% confidence interval [CI], 3.81–10.50; P < .01; OR, 3.02; 95% CI, 1.89–4.84; P < .01; and OR, 1.86; 95% CI, 1.15–2.99; P = .01; and OR, 3.27; 95% CI, 1.96–5.45; P < .01; OR, 1.87; 95% CI, 1.14–3.07; P = .01; and OR, 1.81; 95% CI, 1.06–3.09; P = .03, respectively). There was no difference in infection rate or severe adverse events. Conclusions: Tofacitinib was associated with superior effectiveness outcomes compared with vedolizumab in anti-TNF-experienced patients with UC along with comparable safety outcomes.

Background Safety of thioguanine in pregnant patients with inflammatory bowel disease [IBD] is sparsely recorded. This study was aimed to document the safety of thioguanine during pregnancy and birth. Methods In this multicentre case series, IBD patients treated with thioguanine during pregnancy were included. Data regarding disease and medication history, pregnancy course, obstetric complications, and neonatal outcomes were collected. Results Data on 117 thioguanine-exposed pregnancies in 99 women were collected. Most [78%] had Crohn’s disease and the mean age at delivery was 31 years. In 18 pregnancies [15%], IBD flared. Obstetric and infectious complications were seen in 15% [n = 17] and 7% [n = 8] of pregnancies, respectively. Ten pregnancies [8.5%] resulted in a first trimester miscarriage, one in a stillbirth at 22 weeks of gestational age and one in an induced abortion due to trisomy 21. In total, 109 neonates were born from 101 singleton pregnancies and four twin pregnancies. One child was born with a congenital abnormality [cleft palate]. In the singleton pregnancies, 10 children were born prematurely and 10 were born small for gestational age. Screening for myelosuppresion was performed in 16 neonates [14.7%]; two had anaemia in umbilical cord blood. All outcomes were comparable to either the general Dutch population or to data from three Dutch cohort studies on the use of conventional thiopurines in pregnant IBD patients. Conclusion In this large case series, the use of thioguanine during pregnancy is not associated in excess with adverse maternal or neonatal outcomes.

BACKGROUND Inflammatory bowel disease (IBD) is often managed with anti-tumour necrosis factor-α therapy (anti-TNFα), but treatment efficacy is compromised by high annual rates of loss of response (13%-21% per patient-year). AIMS To assess whether the incidence of loss of response decreases with longer treatment duration METHODS: This was a multicentre, retrospective cohort study of patients with ulcerative colitis (UC) or Crohn's disease (CD) who received anti-TNFα for at least 4 months between 2011 and 2019. We studied the incidence of loss of response as a function of treatment duration, employing parametric survival modelling. Predictors of loss of response were identified by Cox regression analysis. Secondary outcomes included overall anti-TNFα discontinuation and dose escalation. RESULTS We included 844 anti-TNFα treatment episodes in 708 individuals. Loss of response occurred in 211 (25.0%) episodes, with anti-drug antibodies detected in 66 (31.3%). During the first year, the incidence of loss of response was three-fold higher than after four years of treatment (17.2% vs 4.8% per patient-year, P

Background: A treat-to-target strategy, in which strictly defined treatment targets facilitate decision making in clinical practice, is advocated as an optimised management approach for some chronic disorders. The aim of the STARDUST trial was to assess whether a treat-to-target strategy with early endoscopy, regular biomarker and clinical symptom monitoring, and dose intensification for persistent inflammatory activity, was more successful in achieving endoscopic improvement at week 48 than a clinically driven maintenance strategy in patients with moderate-to-severe active Crohn's disease receiving ustekinumab. Methods: This open-label, multicentre, randomised phase 3b trial included adults with active, moderate-to-severe Crohn's disease (Crohn's Disease Activity Index [CDAI] 220–450 and Simple Endoscopic Score in Crohn's Disease [SES-CD] ≥3) for whom conventional therapy or one biologic therapy, or both, had failed. Patients received intravenous ustekinumab approximating 6 mg/kg at baseline and subcutaneous ustekinumab 90 mg at week 8. At week 16, patients with a CDAI improvement of 70 or more points from baseline were randomly assigned (1:1) to receive standard-of-care or treat-to-target maintenance treatment through week 48. Randomisation was balanced by using randomly permuted blocks and was stratified by biologic history status and baseline SES-CD score. All patients who signed informed consent, who were not screening failures, and who received at least one dose of study treatment were included in week 16 analyses. All patients included in week 16 analyses and randomly assigned to one of the maintenance treatment regimens were included in the week 48 efficacy and safety analyses (ie, on an intention-to-treat basis). Patients assigned to the treat-to-target arm received ustekinumab every 12 weeks or every 8 weeks based on SES-CD improvement from baseline and could escalate to every 4 weeks through week 48 if prespecified targets were missed. Patients assigned to the standard-of-care arm received ustekinumab every 12 weeks or every 8 weeks; those receiving treatment every 12 weeks could escalate per European labelling. The primary efficacy endpoint was endoscopic response at week 48 (SES-CD score ≥50% decrease from baseline), analysed by non-responder imputation. This trial is registered at ClinicalTrials.gov, NCT03107793, and is active but not recruiting. Findings: 498 patients received standard induction treatment, of whom 440 were randomly assigned to the treat-to-target group (n=219) or the standard-of-care group (n=221). At week 48, there was no significant difference in endoscopic response (83 [38%] of 219 patients vs 66 [30%] of 221 patients; p=0·087), endoscopic remission (25 [11%] vs 32 [15%]; p=0·334), mucosal healing (31 [14%] vs 37 [17%]; p=0·449), and clinical remission (135 [62%] vs 154 [70%]; p=0·072) between the two groups; clinical response was significantly lower in the treat-to-target group than in the standard-of-care group (149 [68%] vs 172 [78%]; p=0·020). Other endoscopic, clinical, and biomarker outcomes were generally not significantly different between groups. The most commonly reported treatment-emergent adverse events were nasopharyngitis (29 [13%] of 219 patients in the treat-to-target group vs 29 [13%] of 221 patients in the standard-of-care group), abdominal pain (23 [11%] vs 19 [9%]), arthralgia (24 [11%] vs 19 [9%]), and headache (24 [11%] vs 21 [10%]). Interpretation: Timely escalation of ustekinumab therapy for patients with Crohn's disease, based on early endoscopic response, clinical symptoms, and biomarkers, did not result in significantly better endoscopic outcomes at week 48 than symptom-driven decisions alone. Future studies need to confirm if some subgroups of patient might benefit from a treat-to-target strategy with ustekinumab. Funding: Janssen-Cilag.

Background and Aims Anti-tumour necrosis factor alpha [anti-TNF] treatment accounts for 31% of health care expenditures associated with ulcerative colitis [UC]. Withdrawal of anti-TNF in patients with UC in remission may decrease side effects and infections, while promoting cost containment. Approximately 36% of patients relapse within 12–24 months of anti-TNF withdrawal, but reintroduction of treatment is successful in 80% of patients. We aimed to evaluate the cost-effectiveness of continuation versus withdrawal of anti-TNF in patients with UC in remission. Methods We developed a Markov model comparing cost-effectiveness of anti-TNF continuation versus withdrawal, from a health care provider perspective. Transition probabilities were calculated from literature, or estimated by an expert panel of 11 gastroenterologists. Deterministic and probabilistic sensitivity analyses were performed to account for assumptions and uncertainty. The cost-effectiveness threshold was set at an incremental cost-effectiveness ratio of €80,000 per quality-adjusted life-year [QALY]. Results At 5 years, anti-TNF withdrawal was less costly [-€10,781 per patient], but also slightly less effective [-0.04 QALY per patient] than continued treatment. Continuation of anti-TNF compared with withdrawal costs €300,390/QALY, exceeding the cost-effectiveness threshold. Continued therapy would become cost-effective if the relapse rate following anti-TNF withdrawal was ≥43% higher, or if adalimumab or infliximab [biosimilar] prices fell below €87/40 mg and €66/100 mg, respectively. Conclusions Continuation of anti-TNF in UC patients in remission is not cost-effective compared with withdrawal. A stop-and-reintroduction strategy is cost-saving but is slightly less effective than continued therapy. This strategy could be improved by identifying patients at increased risk of relapse.

Background Adherence to adalimumab in inflammatory bowel disease (IBD) patients is reported to be below par. Non-adherence may result in loss-of-response and increased hospitalization. We analyzed the effect of an electronic needle container (ENC) on adherence to adalimumab. Methods In this multicenter, 12-months observational study, we included adalimumab treated IBD patients. All patients were invited to receive an ENC. Patients who declined or did not complete the registration for an ENC served as controls. Primary endpoint was whether an ENC increased adherence, calculated from pharmacy refills as proportion of days covered (PDC). Secondary endpoints were clinical outcomes, including loss-of-response, identification of predictors of adherence and correlation between different modalities for measuring adherence. Loss-of-response was defined as a disease flare, dose-escalation or IBD-related hospitalization or surgery. Results The pharmacies’ records identified 198 eligible patients, of whom 32 were excluded. The ENC was supplied to 69 patients, the remaining 97 patient formed the control group. Median baseline PDC (98.4% vs. 96.1%, p = 0.047) and the proportion of adherent (PDC ≥ 86%) patients (87.0% vs. 74.2%, p = 0.045) was higher for the ENC group. The ENC did not improve the adherence of patients during follow-up (odds ratio 1.26, 95% CI 0.55–2.86). During follow-up, five (7.2%) patients in the ENC group and 13 (13.4%) in the control group discontinued adalimumab (log-rank p = 0.22). Loss-of-response occurred in 12 (17.4%) and 14 (14.4%) patients, respectively (log-rank p = 0.66). Conclusions Our results show no beneficial effect of a reminder-based intervention on adherence or treatment outcomes.

Background Globally, the prevalences of both inflammatory bowel diseases (IBD) and obesity have increased over the past decades. Recently, obesity has been linked to treatment failure in anti-TNF-treated patients with inflammatory bowel disease (IBD). We assessed whether obesity was associated with an increased risk of treatment failure and immunogenicity (i.e. anti-drug antibodies) among IBD patients treated with adalimumab (ADA) or infliximab (IFX). Methods This was a multicenter, retrospective cohort study of adult patients with IBD, treated with ADA or IFX for at least four months between 2011-2019 at a general hospital or a tertiary referral center. Obesity was defined as body mass index (BMI) >30kg/m2. Adjusted hazard rates (aHR) were calculated by mixed-effects Cox regression analysis, accounting for multiple treatment episodes in individual patients and adjusted for sex, prior anti-TNF exposure, immunomodulator use, IBD phenotype (ulcerative colitis versus Crohn’s disease), age, disease duration, smoking and rheumatological comorbidity. Multiple imputation was used to replace missing values (5% for BMI). Results We included 728 patients, providing 2339 patient-years of follow-up and 868 treatment episodes with anti-TNF; 130 (17.9%) patients were obese. Obesity was associated with female sex (67% vs 54%), smoking (36% vs 22%), older age (median 42 vs 36 years) and prior exposure to methotrexate (25% vs 15%). In patients receiving ADA, obesity was significantly and independently associated with a higher risk of immunogenicity (Figure 1a, aHR: 2.15, 95%CI: 1.10 – 4.19) and treatment failure (Figure 2a), although significance of the latter association was lost after correcting for relevant confounders (aHR: 1.33, 95%CI: 0.87 – 2.03). In patients treated with IFX, obesity was not associated with immunogenicity (Figure 1b, aHR: 1.05, 95%CI: 0.54 – 2.03) or treatment failure (Figure 2b, aHR: 0.98, 95%CI: 0.70 – 1.39). Trough levels were significantly lower in obese patients treated with ADA, but not IFX. Conclusion In patients treated with ADA, but not IFX, obesity is associated with immunogenicity and possibly a higher risk of treatment failure. Proactive therapeutic drug monitoring may be warranted in obese patients treated with ADA.

The benefit of concomitant immunomodulators (thiopurines or methotrexate) in patients with inflammatory bowel disease (IBD) on anti-tumor necrosis factor α (anti-TNF) (infliximab or adalimumab) maintenance therapy is debated. We compared outcomes after immunomodulator withdrawal vs continuation of combination therapy.This was a retrospective cohort study in a general hospital and a tertiary referral center. We included adult IBD patients, receiving anti-TNF therapy for ≥4 months, plus an immunomodulator at baseline, between January 1, 2011, and January 1, 2019. The primary endpoints were loss of response (LOR) (ie, anti-TNF discontinuation because of disease activity) and anti-drug antibodies. Adjusted hazard ratios (aHRs) were calculated by mixed-effects Cox regression analysis.We included 614 treatment episodes of combination therapy in 543 individuals, yielding 1664 patient-years of follow-up. The immunomodulator was withdrawn in 296 (48.2%) episodes after 0.9 (interquartile range, 0.6-2.1) years, which was not associated with a higher risk of LOR (aHR, 1.08; 95% confidence interval [CI], 0.72-1.61), although anti-drug antibodies were detected more frequently (aHR, 2.14; 95% CI, 1.17-3.94), compared with continuation. Clinical remission at the time of withdrawal reduced the risk of LOR (aHR, 0.48; 95% CI, 0.25-0.93), while longer duration of combination therapy before withdrawal decreased the risk of anti-drug antibodies (HR per year, 0.56; 95% CI, 0.32-0.91). Higher prewithdrawal infliximab trough levels reduced the subsequent risks of anti-drug antibodies and LOR. Infliximab trough levels were lower after immunomodulator withdrawal (P = .01).Patients who withdrew the immunomodulator in this retrospective cohort were not at increased risk of LOR within the following 1-2 years, but an increase in anti-drug antibodies was observed. Our findings require prospective validation, preferably in adequately powered randomized controlled trials.

Background: Thioguanine is associated with liver toxicity, especially nodular regenerative hyperplasia (NRH). We assessed if liver histology alters during long-term maintenance treatment with thioguanine in patients with inflammatory bowel disease (IBD). Methods: Liver specimens of thioguanine treated IBD patients with at least two liver biopsies were revised by two independent liver pathologists, blinded to clinical characteristics. Alterations in histopathological findings between first and sequential liver specimen were evaluated and associated clinical data, including laboratory parameters and abdominal imaging reports, were collected. Results: Twenty-five IBD patients underwent sequential liver biopsies prior to, at time of, or after cessation of thioguanine treatment. The median time between the first and second biopsy was 25 months (range: 14–54). Except for one normal liver specimen, any degree of irregularities including inflammation, steatosis, fibrosis and some vascular disturbances were observed in the biopsies. The rates of perisinusoidal fibrosis (91%), sinusoidal dilatation (68%) and nodularity (18%) were the same in the first and second liver biopsies. A trend towards statistical significance was observed for phlebosclerosis (36% of the first vs. 68% of the second biopsies, p = .092). Presence of histopathological liver abnormalities was not associated with clinical outcomes. Furthermore, two patients in this cohort had portal hypertension in presence of phlebosclerosis. In another two patients, nodularity of the liver resolved upon thioguanine withdrawal. Conclusion: Vascular abnormalities of the liver were commonly observed in thioguanine treated IBD patients, although these were not progressive and remained of limited clinical relevance over time.

Background and Aims The COVID-19 risk and disease course in inflammatory bowel disease [IBD] patients remains uncertain. Therefore, we aimed to assess the clinical presentation, disease course, and outcomes of COVID-19 in IBD patients. Second, we determined COVID-19 incidences in IBD patients and compared this with the general population. Methods We conducted a multicentre, nationwide IBD cohort study in The Netherlands and identified patients with COVID-19. First, we assessed the COVID-19 disease course and outcomes. Second, we compared COVID-19 incidences between our IBD study cohort and the general Dutch population. Results We established an IBD cohort of 34 763 patients. COVID-19 was diagnosed in 100/34 763 patients [0.29%]; 20/100 of these patients [20%] had severe COVID-19 defined as admission to the intensive care unit, mechanical ventilation, and/or death. Hospitalisation occurred in 59/100 [59.0%] patients and 13/100 [13.0%] died. All patients who died had comorbidities and all but one were ≥65 years old. In line, we identified ≥1 comorbidity as an independent risk factor for hospitalisation (odds ratio [OR] 4.20, 95% confidence interval [CI] 1.58–11.17,; p = 0.004). Incidences of COVID-19 between the IBD study cohort and the general population were comparable (287.6 [95% CI 236.6–349.7] versus 333.0 [95% CI 329.3–336.7] per 100000 patients, respectively; p = 0.15). Conclusions Of 100 cases with IBD and COVID-19, 20% developed severe COVID-19, 59% were hospitalised and 13% died. A comparable COVID-19 risk was found between the IBD cohort [100/34 763 = 0.29%] and the general Dutch population. The presence of ≥1 comorbidities was an independent risk factor for hospitalisation due to COVID-19.

Background & aims: It is currently unclear whether reported changes in the gut microbiome are cause or consequence of inflammatory bowel disease (IBD). Therefore, we studied the gut microbiome of IBD-discordant and -concordant twin pairs, which offers the unique opportunity to assess individuals at increased risk of developing IBD, namely healthy cotwins from IBD-discordant twin pairs. Methods: Fecal samples were obtained from 99 twins (belonging to 51 twin pairs), 495 healthy age-, sex-, and body mass index–matched controls, and 99 unrelated patients with IBD. Whole-genome metagenomic shotgun sequencing was performed. Taxonomic and functional (pathways) composition was compared among healthy cotwins, IBD-twins, unrelated patients with IBD, and healthy controls with multivariable (ie, adjusted for potential confounding) generalized linear models. Results: No significant differences were observed in the relative abundance of species and pathways between healthy cotwins and their IBD-twins (false discovery rate

Background: The understanding of gender differences in inflammatory bowel disease (IBD) patients is an important step towards tailored treatment for the individual patient. The aim of this study was to compare disease phenotype, clinical manifestations, disease activity, and healthcare utilization between men and women with Crohn's disease (CD) and ulcerative colitis (UC).Methods: Two multicenter observational cohort studies with a prospective design were used to explore the differences between men and women regarding demographic and phenotypic characteristics and healthcare utilization. Detailed data on IBD-phenotype was mainly available from the Dutch IBD Biobank, while the COIN cohort provided healthcare utilization data.Results: In the Dutch IBD Biobank study, 2118 CD patients and 1269 UC patients were analyzed. Female CD patients were more often current smokers, and male UC patients were more often previous smokers. Early onset CD (Conclusions: Sex differences in patients with IBD include age of onset, disease location, and EIM prevalence. No large differences in therapeutic management of IBD were observed between men and women with IBD.

Background Inflammatory bowel disease (IBD) is often managed with anti-tumour necrosis factor-α (anti-TNFα) compounds, but only few studies have reported on long-term outcomes. We aimed to determine whether the incidence of loss-of-response decreases with longer treatment duration. Methods In a multicentre, retrospective cohort study of patients with IBD who received anti-TNFα for at least 4 months between 2011-2019, we compared incidence rates of loss-of-response between different intervals of treatment duration and performed parametric survival modelling to assess changes with longer treatment duration. Cox regression analysis was performed to identify predictors of loss-of-response. Secondary outcomes included overall anti-TNFα discontinuation and dose escalation. Results We included 900 anti-TNFα treatment episodes in 746 individual patients, with up to 9 years of follow-up. During follow-up, the most frequently observed reason for anti-TNFα discontinuation was loss-of-response (Figure 1), which occurred in 231 (25.7%) episodes, with presence of anti-drug antibodies in 67/231 (29%). Within the first year, the incidence of loss-of-response was threefold higher than after four years of treatment (17.3% versus 4.7% per patient-year, p Conclusion Long-term use of anti-TNFα maintenance treatment is associated with a reduced risk of loss-of-response in patients with IBD.

Background Prehabilitation strategies to improve the postoperative course after intestinal resections in Crohn’s disease (CD) are mostly non-evidence-based. Prehabilitation strategies may include preoperative nutritional, physical and psychological management and optimization of medical treatment prior to surgery. In this study, we explore whether and to what extent prehabilitation strategies are currently used in a real-world prospective cohort. Methods In this multicenter prospective cohort study, data were collected in three secondary and two tertiary Dutch hospitals. CD patients (pts) aged ≥ 18 years who underwent ileocecal or ileocolonic (re)resection were included between November 2017 and January 2021. Data were collected on disease severity, IBD medication at time of surgery, preoperative BMI, weight loss within a year prior to resection, assessment of sarcopenia and hand grip strength (HGS), laboratory assessment, including albumin and micronutrients, and preoperative visits to a dietician, physiotherapist and psychologist. In addition, the 30-day postoperative complication rate was recorded. Results To date, 90 pts were included (38% male, median age 35.6 years) (Table 1). The main indications for ileocolonic resection were stenosis (55 (61%)), therapy refractory inflammation (15 (17%)) and penetrating disease (14 (18.9%)). At time of surgery, 60 pts (67%) were on IBD medication (immunomodulator n=16; biological n=22; combination therapy n=11, corticosteroids n=19). Median preoperative BMI was 23.7 kg/m2 (IQR 20.9–27.2). Sarcopenia and HGS were not assessed. Preoperative weight within a year prior to resection was recorded in only 31/90 (34%) pts. During the preoperative period, 32/90 pts (36%) visited a dietician, of whom 25/32 (78%) received a nutritional intervention (enteral support 16 (64%), parenteral support 0, exclusive enteral nutrition (EEN) 7 (28%), total parenteral nutrition (TPN) 2 (8%)). 4/90 pts (4%) visited a physiotherapist and 6/90 (7%) a psychologist. Albumin was assessed in 52/90 (58%) pts (median 38 (IQR 32–45); ferritin, vitamin B12 and D in 9/90 (10%), 10/90 (11%), 6/90 (7%) patients. Postoperative complication occurred in 32/90 (36%) pts, most often infections (68%) (Table 2). Four pts underwent a re-intervention for abdominal infection (2/4), anastomotic leakage (1/4) or ileus (1/4). Five pts (16%) were readmitted for anastomotic leakage (2/5), ileus (1/5), abdominal pain (1/5) and infection (1/5). Conclusion Prehabilitation strategies are not routinely applied in CD patients scheduled for ileocolonic resection and, since postoperative complications occur in more than a third of patients, further research into the yield of implementing multimodal prehabilitation is indicated.

Purpose: Many patients with Crohn’s disease (CD) and ulcerative colitis (UC) who have a high 6-methylmercaptopurine/6-thioguanine (6-MMP/6-TGN) ratio receive allopurinol 100 mg in addition to thiopurines to optimize metabolite concentrations. However, some patients do not tolerate allopurinol at this dosage. The aim of this study was to determine the intra-patient effect of reducing the allopurinol dosage from 100 to 50 mg, in terms of metabolite concentrations, enzyme activities, efficacy, and tolerability. Methods: A prospective non-inferiority one-way crossover study was performed. CD and UC patients with stable disease using a thiopurine and allopurinol 100 mg were switched to 50 mg for 1 month. Primary outcomes were thiopurine metabolite concentrations. Secondary outcomes were enzyme activities of xanthine oxidase, thiopurine methyltransferase and hypoxanthine-guanine phosphoribosyltransferase, disease activity, and tolerability. Results: Twenty-two patients were included. Treatment with allopurinol 50 mg compared with 100 mg resulted in a significant decrease in mean 6-TGN levels (761 to 625 pmol/8 × 108 RBC; p = 0.005) and a significant increase in mean 6-MMP levels (451 to 665 pmol/8 × 108 RBC; p = 0.01). However, the mean metabolite concentrations were still therapeutic. Enzyme activities, disease activity scores, and patient experiences did not alter significantly. Generally, UC patients were more positive about their improved treatment than CD patients. Conclusion: Combination therapy with 50 mg allopurinol led to a decrease of 6-TGN levels compared with 100 mg allopurinol. Disease activity, side effects, and patient experience, however, were similar between allopurinol 100 and 50 mg. UC patients seem to benefit and prefer lower doses whereas the contrary is seen in CD patients. Trial registration: EudraCT trial registry - number 2016-001638-84.

Background Combination therapy with anti-TNF compounds and immunomodulators (IMM; thiopurine or methotrexate) is superior to IMM or anti-TNF monotherapy in patients with inflammatory bowel disease (IBD). IMMs are frequently discontinued during the maintenance phase to mitigate the risk of adverse events, but long-term consequences of this practice are not well studied. We explored the real-world outcomes after IMM discontinuation, including loss-of-response (LOR), dose escalations, immunogenicity and trough levels. Methods This was a multicenter, retrospective cohort study in a general hospital and a tertiary referral center. We included adult patients with IBD, treated >4 months with infliximab (IFX) or adalimumab (ADA) and an IMM at baseline between 2011–2019. The IMM had to be started within 30 days of anti-TNF initiation, or continued for >30 days in case of prior IMM monotherapy. LOR was defined as anti-TNF discontinuation due to disease activity. Adjusted hazards rates (aHR) were calculated using mixed-effects Cox regression analysis with time-varying covariates, accounting for follow-up prior to and after IMM cessation. We adjusted for sex, age, BMI, smoking, Crohn’s disease (CD) vs ulcerative colitis (UC), disease duration, primary sclerosing cholangitis, rheumatological comorbidity, ADA vs IFX, and prior anti-TNF exposure. Results We included 615 episodes of combination therapy (543 individual patients; CD, n=382, 70%). The IMM was discontinued in 296 (48%) episodes after a median of 0.9 (IQR: 0.6 – 2.1) years, at which point 252 (85%) patients were in clinical remission. IMM withdrawal was performed as part of a de-escalation strategy (n=158, 53%), for intolerance (n=86, 29%) or for miscellaneous reasons (n=52, 18%). During a median follow-up of 1.7 (IQR 0.8 – 3.5) years after IMM withdrawal, 46 (16%) patients experienced LOR, 79 (32%) required dose-escalation and 31 (10.3%) developed anti-drug antibodies. Compared to IMM continuation, withdrawal did not significantly increase the risk of LOR (aHR 1.10, 95%CI: 0.74 – 1.64), but more patients required dose escalations (aHR 1.42, 95%CI 1.02 – 1.97) or developed anti-drug antibodies (aHR 2.22, 95%CI 1.21 – 4.08). Among patients who stopped the IMM, clinical remission at IMM withdrawal was the only predictor of LOR (aHR 0.48, 95%CI 0.23 – 0.99), while higher BMI (aHR 1.09, 95%CI 1.01 – 1.17) and shorter duration of combination therapy (Figure 1, aHR 0.57 per year, 95%CI 0.33 – 0.96) increased the risk of immunogenicity. IFX, but not ADA, trough levels decreased significantly after IMM withdrawal. Conclusion Withdrawal of immunomodulators is not associated with higher risk of LOR, but does increase the risk of dose-escalation and unfavorable pharmacokinetics.

Summary Background Adalimumab is approved for use in patients with moderate to severe Crohn's disease (CD) or ulcerative colitis (UC) who have not achieved disease control with conventional therapies including corticosteroids and/or immunomodulators (IMM). Aim To analyse six studies that examined efficacy, pharmacokinetics and safety of combination IMM/adalimumab therapy, compared with adalimumab monotherapy in patients with inadequate disease control on conventional therapy. Methods Patients with moderate to severe CD or UC from randomised, double‐blind, placebo‐controlled trials were analysed. Adalimumab was added to background therapy; patients were categorised as receiving adalimumab monotherapy (CD induction, n = 245, maintenance, n = 185; UC induction, n = 213, maintenance, n = 157) or combination therapy (CD induction, n = 139, maintenance, n = 139; UC induction, n = 140, maintenance, n = 100) according to baseline immunomodulator use. Efficacy was reported for the intent‐to‐treat populations from each study, with remission defined as CD activity index 1 for UC. Safety was assessed via adverse events. Results The proportions of patients achieving remission were similar for adalimumab monotherapy and immunomodulator combination therapy in all studies. Median adalimumab concentrations at week 4 or 8 were numerically but not significantly higher with adalimumab combination therapy vs. monotherapy in the CD and UC studies respectively. Incidence and rate of adverse events was similar for adalimumab monotherapy and combination therapy. Conclusions Post hoc analysis of six randomised, controlled trials demonstrated no efficacy benefits with immunomodulator/adalimumab combination therapy, compared with adalimumab monotherapy in CD and UC patients with inadequate disease control on conventional therapy; the safety of the two treatment approaches was comparable.

Background Inflammatory bowel disease (IBD) and endometriosis are immune-mediated chronic inflammatory disorders affecting young women. The clinical significance of concomitant endometriosis on the course of IBD has not been previously studied. The aim of this study was to determine whether women with concomitant endometriosis and IBD have a unique phenotype and worse prognosis of IBD. Methods This was a case-control study performed at a tertiary referral center. Cases were women with diagnoses of both endometriosis and IBD. Two random IBD controls without endometriosis were selected for each case, frequency matched for age and IBD type, Crohn's disease (CD) or ulcerative colitis. Primary outcomes included disease phenotype; the use of immunomodulators, antiTNF agents, or combination therapy and the need for IBD-related surgery. Results We identified 51 cases with endometriosis and IBD (28 CD, 23 ulcerative colitis). There was no difference in race, age at IBD diagnosis, and mean duration of IBD between endometriosis-IBD cases and controls. Among endometriosis-CD patients whose endometriosis was surgically verified, there was a higher risk for stricturing disease compared with CD controls (odds ratio, 11.8; 95% confidence interval, 2.03-69.0). There was no difference in phenotype in endometriosis-ulcerative colitis patients. There were no significant differences in IBD-related medication use or surgeries overall or when stratified by IBD type. Conclusions Patients with CD and endometriosis, which was surgically diagnosed, were more likely to have stricturing CD. Concomitant endometriosis did not impact the natural history of IBD.

Background and aimsPrenatal and early life bacterial colonisation is thought to play a major role in shaping the immune system. Furthermore, accumulating evidence links early life exposures to the risk of developing IBD later in life. We aimed to assess the effect of maternal IBD on the composition of the microbiome during pregnancy and on the offspring’s microbiome.MethodsWe prospectively examined the diversity and taxonomy of the microbiome of pregnant women with and without IBD and their babies at multiple time points. We evaluated the role of maternal IBD diagnosis, the mode of delivery, antibiotic use and feeding behaviour on the microbiome composition during early life. To assess the effects of IBD-associated maternal and infant microbiota on the enteric immune system, we inoculated germ-free mice (GFM) with the respective stool and profiled adaptive and innate immune cell populations in the murine intestines.ResultsPregnant women with IBD and their offspring presented with lower bacterial diversity and altered bacterial composition compared with control women and their babies. Maternal IBD was the main predictor of the microbiota diversity in the infant gut at 7, 14, 30, 60 and 90 days of life. Babies born to mothers with IBD demonstrated enrichment in Gammaproteobacteria and depletion in Bifidobacteria. Finally, GFM inoculated with third trimester IBD mother and 90-day infant stools showed significantly reduced microbial diversity and fewer class-switched memory B cells and regulatory T cells in the colon.ConclusionAberrant gut microbiota composition persists during pregnancy with IBD and alters the bacterial diversity and abundance in the infant stool. The dysbiotic microbiota triggered abnormal imprinting of the intestinal immune system in GFM.

Item does not contain fulltext BACKGROUND: Nodular regenerative hyperplasia (NRH) of the liver is associated with inflammatory-mediated diseases and certain drugs. There is conflicting data on the prevalence of NRH and its clinical implications in inflammatory bowel disease (IBD) patients treated with thioguanine. METHODS: A retrospective cohort study involving 7 Dutch centers comprised all IBD patients who were being treated with thioguanine and underwent a liver biopsy as part of the standard toxicity screening. Liver biopsy specimens were reviewed by 2 experienced liver pathologists. Clinical data as well as liver chemistry, blood counts, and abdominal imaging were collected. RESULTS: One hundred eleven IBD patients who submitted to liver biopsy were treated with thioguanine in a daily dose of 0.3 mg/kg for a median duration of 20 (4-64) months. NRH was detected in 6% of patients (7; 95% confidence interval, 3-14 patients). Older age (P = 0.02), elevated gamma-glutamyl transferase (P = 0.01) and alkaline phosphatase (P = 0.01) levels, a higher mean corpuscular volume (P = 0.02), and a lower platelet or leukocyte count (P < 0.01 and P = 0.02, respectively) were associated with NRH. Three of the 7 patients with NRH did not have any associated clinical symptoms or signs. The other 4 had minor biochemical abnormalities only. Ultrasonography revealed splenomegaly in 3 of the 78 patients (4%; 95% confidence interval, 0%-9%), only one of whom had NRH. There was no clinically overt portal hypertension. CONCLUSIONS: The prevalence of NRH was 6% in liver biopsies obtained from IBD patients treated with thioguanine. Histopathological irregularities including NRH were not associated with clinically significant findings over the period of observation.

BACKGROUND AND PURPOSE Although 6-mercaptopurine and azathioprine are effective treatments in inflammatory bowel disease (IBD), many patients discontinue treatment because of side effects. 6-Thioguanine (6-TG) may be an alternative rescue therapy in these intolerant patients but the pharmacokinetics of 6-TG are not fully described. Here we have measured the pharmacokinetics of the biotransformation of 6-TG into the pharmacologically active metabolites, 6-thioguanine nucleotides (6-TGN), in IBD patients. EXPERIMENTAL APPROACH In 12 patients with IBD, levels of 6-TGN and activities of thiopurine S-methyltransferase, xanthine oxidase and hypoxanthine guanine-phosphoribosyl-transferase were measured in a two-stage (i.v. and p.o. administration of 0.3 mg·kg−1 6-TG), prospective study. Median exposure of 6-TGN in red blood cells (RBC) was expressed as the ratio of the area under the curve (AUC) per mg 6-TG after i.v. dosing and that after p.o. dosing. KEY RESULTS The median AUC per mg 6-TG was 1068 (p.o.) and 7184 (i.v.) pmol·h (8 × 108 RBC)−1. Median exposure of 6-TGN in RBC was 15% (9–28). Hypoxanthine guanine-phosphoribosyl-transferase activity correlated with peak 6-TGN and with AUC per mg (r= 0.7, P= 0.02 and r= 0.6, P= 0.03 respectively). Thiopurine S-methyltransferase activity was inversely related to AUC per mg (r=−0.8, P= 0.001), whereas that of xanthine oxidase was correlated with a lower peak 6-TGN (r=−0.7, P= 0.02). CONCLUSIONS AND IMPLICATIONS The great variability of the AUC per mg for 6-TG observed after p.o. and i.v. administration of 6-TG, was partly explained by variability in activities of metabolizing enzymes. Exposure of 6-TGN was low in all patients.

Background and purpose: 5-aminosalicylate (5-ASA) raises levels of 6-thioguanine nucleotides (6-TGN), the active metabolites of thiopurines such as azathioprine (AZA). Changes in levels of each individual TGN – 6-thioguanosine mono-, di- and triphosphate (6-TGMP, 6-TGDP, 6-TGTP) – and of 6-methylmercaptopurine ribonucleotides (6-MMPR) after 5-ASA are not known. Experimental approach: Effects of increasing 5-ASA doses on AZA metabolites were investigated prospectively in 22 patients with inflammatory bowel disease in 4-week study periods. Patients started with 2 g 5-ASA daily, and then were increased to 4 g daily and followed by a washout period. Thiopurine doses remained unchanged throughout the entire study. Levels of 6-TGMP, 6-TGDP, 6-TGTP and 6-MMPR as well as of 5-ASA and N-acetyl-5-aminosalicylic acid (N-Ac-5-ASA) were determined each study period. Key results: Median baseline levels in 17 patients of 6-TGDP, 6-TGTP and 6-MMPR were 52, 319 and 1676 pmol per 8 × 108 red blood cells respectively. After co-administration of 2 g 5-ASA daily, median 6-TGDP and 6-TGTP levels increased but median 6-MMPR levels were unchanged. Increasing 5-ASA to 4 g daily did not affect median 6-TGDP and 6-TGTP levels, but median 6-MMPR levels decreased. After discontinuation of 5-ASA, both 6-TGDP and 6-TGTP levels decreased and median 6-MMPR levels increased. The 6-TGTP/(6-TGDP+6-TGTP)-ratio did not change during the study, but 6-MMPR/6-TGN ratios decreased. Conclusions and implications: Individual 6-TGN metabolites increased after addition of 5-ASA, but 6-MMPR-levels and the 6-MMPR/6-TGN ratios decreased. Further studies are needed to decide whether this pharmacokinetic interaction would result in improvement of efficacy and/or increased risk of toxicity of AZA.

Acute severe steroid-refractory ulcerative colitis (ASUC) provides challenges for physicians and surgeons who manage these patients. When a patient is diagnosed with ASUC, they should be admitted for inpatient management including intravenous corticosteroids, venous thromboembolism prophylaxis, oral or enteral feeding if tolerated, and exclusion of infection including Clostridium difficile. Failure to improve by day 3 of corticosteroids requires escalation to medical rescue therapies such as infliximab or cyclosporine, or surgical management with colectomy. This chapter will review management of ASUC with a focus on the medical rescue options available.

OBJECTIVES: Literature describing the risk factors predisposing inflammatory bowel disease (IBD) patients to anal squamous neoplasia is very scarce. Case reports and small case series have implicated perianal Crohn's disease (CD), long-standing IBD, human papillomavirus (HPV) infection, and immunosuppressive treatment. In this study, we retrospectively examined the association between HPV infection and anal squamous neoplastic lesions among IBD patients from our center. METHODS: We reviewed the pathology records and slides of IBD patients diagnosed with anal squamous cell carcinomas (SCCs), high-grade squamous intraepithelial lesions (HSILs), and low-grade squamous intraepithelial lesions (LSILs) who presented at our center between 1 March 1994 and 9 September 2014. The HPV status of the neoplasms was assessed histologically, by immunohistochemical staining for p16 overexpression, and by global and type-specific HPV PCR. RESULTS: SCCs, HSILs, LSILs, and small cell carcinoma were identified, respectively, in six, nine, two, and one IBD patients. All six patients with SCC had CD with perianal involvement. HPV-related neoplasia was identified in 3/6 cases of SCC (all HPV-16), 1/1 small cell carcinoma (HPV-18), and 9/9 HSIL (7 HPV-16, 2 not typed); 2/2 LSILs were negative for high-risk HPV. CONCLUSIONS: In our experience, anal squamous neoplastic lesions in IBD are associated with HPV infection and SCC seem to be associated with perianal CD. Prospective studies are needed to confirm these results.

Tumor necrosis factor-α (TNFα) antagonists have advanced the management of inflammatory bowel diseases patients leading to an improvement of patient's quality of life with the reduction of number of surgeries and hospitalizations. Despite these advances, many patients do not respond to the induction therapy (primary non-response—PNR) or lose response during the treatment (secondary loss of response—LOR). In this paper we will provide an overview of the definition, epidemiology and risk factors for PNR and LOR, as well as discuss the therapeutic options for managing LOR.

SIRS, We read with great interest the review of literature and proposed management-algorithm concerning the often challenging questions on fertility and pregnancy in inflammatory bowel disease (IBD) patients. The risks and benefits of continuation of azathioprine (AZA) or mercaptopurine (MP) therapy should indeed be balanced in each pregnant IBD patient. In general, maintenance thiopurine therapy throughout pregnancy is considered safe and there is no necessity for cessation of administration. The authors state that the foetus is protected from potential teratogenic effects of thiopurines, as it lacks the enzyme inosinate phosphorylase, which is required to convert AZA or MP to its active metabolites. We feel that this statement needs some refinement. The unborn child is only marginally exposed to the parent compounds AZA or MP themselves, as these drugs are rapidly absorbed and metabolised intracellularly by enterocytes and hepatocytes into several metabolites. Therefore, it is to be expected that there will be no, or limited, metabolism of AZA or MP in the foetus itself. Recently, we demonstrated that the human foetus is exposed to the pharmacologically active metabolite 6-tioguanine nucleotides generated from maternal AZA use. Surprisingly, in the vast majority of newborns, the thiopurine metabolite 6methylmercaptopurine could not be detected in red blood cells directly drawn from the umbilical cord after delivery. Based on these observations, it appears that the placenta plays a critical role in the transfer of maternal thiopurine metabolites. To our knowledge, the enzyme inosinate phosphorylase does not play a role in the metabolism of thiopurines. Therefore, the statement that the foetus is protected from teratogenic effects as it lacks the enzyme inosinate phosphorylase cannot hold true. Perhaps the manuscript should have stated that maintenance thiopurine therapy during pregnancy is considered safe, despite intrauterine exposure to thiopurine metabolite 6-tioguanine nucleotides.

Background Oral thiopurines are effective and widely used in treatment of inflammatory bowel disease (IBD) in humans, although their use is limited due the development of adverse events. Here, we examine the efficacy and toxicity of oral treatment with 6-tioguanine (6-TG) and azathioprine (AZA) in a murine model of IBD. Methods We induced acute or chronic colitis in BALB/c mice by one or four cycles of 3% dextran sulphate sodium (DSS), respectively. Mice were treated by daily gavages of various dosages of 6-tioguanine, azathioprine, or by phosphate buffered saline (PBS) starting the first day of DSS or after two cycles of DSS, respectively. We monitored the efficacy and toxicity by measuring the weight change and serum alanine aminotransferase (ALT) activity and by disease severity and histology, at the end of the experiment. Moreover, we measured cytokine production after colon fragment cultivation by enzyme-linked immunoabsorbent assay and numbers of apoptotic cells in the spleen by flow cytometry. Results 6-TG is effective in the treatment of acute DSS-induced colitis in a dose-dependent manner and 40 μg of 6-TG is significantly more effective in the treatment of acute colitis than both AZA and PBS. This effect is accompanied by decrease of IL-6 and IFN-γ production in colon. We did not observe histological abnormalities in liver samples from control (PBS) or 6-TG treated mice. However, liver samples from most mice treated with AZA showed mild, yet distinct signs of hepatotoxicity. In chronic colitis, all thiopurine derivatives improved colitis, 20 μg of 6-TG per dose was superior. High doses of 6-TG led to significant weight loss at the end of the therapy, but none of the thiopurine derivatives increased levels of serum ALT. Both thiopurine derivatives reduced the proportion of apoptotic T helper cells, but a high production of both IL-6 and TGF-β was observed only in colon of AZA-treated mice. Conclusions Use of 6-TG in the treatment of experimental colitis in mice appears superior to AZA administration and placebo. In contrast to 6-TG, the use of AZA resulted in histological liver abnormalities.

Background: Thiopurines have proven efficacy in long-term maintenance therapy of inflammatory bowel disease (IBD). Limited data are available with regard to factors predicting effectiveness and failure of long-term thiopurine use in IBD patients. Methods: The data in this retrospective study are based on an 8-year intercept cohort of previous or present thiopurine-using IBD patients. Both cohorts are assessed by descriptive and statistical analysis aimed at determining thiopurine effectiveness and the variables that are predictive for failure of thiopurine therapy. Results: In all, 363 IBD patients were included (60% female), 63% with Crohn's disease and 33% with ulcerative colitis. Overall, thiopurines were continued in 145/363 (40%) and discontinued in 208/363 (57%) patients. The proportion of patients still using thiopurines at 3, 6, 12, 24, and 60 months was 73%, 69%, 63%, 51%, and 42%, respectively. Patients discontinued thiopurines due to adverse events (39%), refractoriness (16%), and ongoing remission / patient's request (4%). 6-methylmercaptopurine (6-MMP) concentration and 6-MMP/6-thioguanine nucleotides (6-TGN) ratio were significant higher in the failure group. Prolonged continuation of thiopurines was associated with a decreased risk of discontinuation. Conclusions: Azathioprine and 6-mercaptopurine were considered effective in ≈40% of IBD patients after 5 years of treatment. A quarter of the patients discontinued thiopurines within 3 months, mostly due to adverse events. A high 6-MMP concentration or 6-MMP/6-TGN ratio was associated with therapeutic failure. If thiopurine use was successfully initiated in the first months, its use was usually extended over many years, as long-term use was associated with continuation of therapy. (Inflamm Bowel Dis 2010)

Background Monitoring of thiopurine metabolites 6-thioguanine nucleotides (6-TGN) and 6-methylmercaptopurine (6-MMP) is used to assess compliance and explain adverse reactions in IBD-patients. Correlations between dosage, metabolite concentrations and therapeutic efficacy or toxicity are contradictive. Research is complicated by analytical problems as matrices analyzed and analytical procedures vary widely. Moreover, stability of thiopurine metabolites is not well documented, yet pivotal for interpretation of analytical outcomes. Therefore, we prospectively investigated metabolite stability in blood samples under standard storage conditions. Methods Stability at room temperature and refrigeration (22 °C, 4 °C) was investigated during 1 week and frozen samples (−20 °C, −80 °C) were analyzed during 6 months storage. Ten patient samples were analyzed for each study period. Results Median 6-TGN concentrations on day 7 decreased significantly to 53% and 90% during storage at ambient temperature or refrigeration. Median 6-MMP concentrations on day 7 decreased significantly to 55% and 86%, respectively. Samples stored at −20 °C also showed significant decreases in both 6-TGN and 6-MMP in comparison with baseline values. At −80 °C, only 6-MMP showed a significant decrease in values compared to baseline. Conclusion The stability of thiopurine metabolites is clearly a limiting factor in studies investigating utilisation of TDM and correlations with therapeutic outcome in IBD-patients. This has to be accounted for in clinical practice and (multi-center) trials investigating thiopurine drugs.

Background Thioguanine has been used for the treatment of inflammatory bowel disease, in particular for patients who failed conventional thiopurine therapy. To date, thioguanine has been infrequently studied in ulcerative colitis. Aim To evaluate the tolerability, safety and efficacy of thioguanine in the treatment of ulcerative colitis. Methods A database analysis was performed on inflammatory bowel disease patients who had failed conventional thiopurine therapy and were treated with thioguanine. Rates and reasons for treatment failure were assessed. Laboratory values, abdominal ultrasonography, liver biopsy and endoscopic remission rates were evaluated. Results Forty-six patients were included and median treatment duration was 22 months (range 0.3–72.0). Nine patients failed thioguanine therapy: six due to adverse events, three due to therapy resistance. Concomitant treatment with aminosalicylates protected against thioguanine failure (hazard ratio (HR) 0.11, 95% CI 0.03–0.48). When performed, ultrasonography (n = 21) revealed no suspected therapy-related pathology in all but one patient, in whom hepatomegaly was observed. Liver histology (n = 12) predominantly revealed no abnormalities (n = 4) or non-specific regeneration (n = 4); none showed nodular regenerative hyperplasia. At follow-up, 40% of colonoscopies revealed endoscopic remission as compared with 10% at baseline (P = 0.180). Conclusions Long-term use of thioguanine appears to be well tolerated and relatively safe in ulcerative colitis patients who failed conventional thiopurine therapy.

In a report recently published in this journal (1), Reinshagen et al., who investigated 6-thioguanine nucleotide (6-TGN) concentrations in patients with inflammatory bowel disease (IBD), concluded that standard and adapted dosing of azathioprine led to identical 6-TGN concentrations and remission rates and that therapeutic drug monitoring of thiopurine therapy was of no clinical benefit in patients with a wild-type thiopurine S-methyltransferase ( TPMT ) genotype. As Reinshagen et al. point out, monitoring thiopurine metabolites is a more or less accepted method for assessing pharmacotherapeutic compliance. The use of monitoring to assess the achievement of therapeutic goals is still a matter of ongoing discussion, however, and the study conducted by Reinshagen et al. provides valuable data to inform this debate. Unfortunately, critical analytical problems still plague thiopurine research. Important differences exist in analytical procedures and reference values (2), and the stability of the thiopurine metabolites themselves is an issue as well. Few …

Thiopurines are frequently used for the treatment of IBD. The complex pharmacology, metabolism, mechanism of action and toxicity profile of these immunosuppressive drugs have now been partly elucidated. The activity of thiopurines is partly mediated by the metabolite 6-thioguanosine 5′-triphosphate, which inhibits the function of the small GTPase Rac1, leading to apoptosis of activated T cells, and influences the conjugation of T cells with antigen-presenting cells. The activity of the enzyme thiopurine S-methyltransferase has a major influence on the bioavailability and toxicity of thiopurines, and several thiopurine metabolites might have adverse effects in patients. Myelotoxicity can be caused by grossly elevated levels of 6-thioguanine nucleotides, and elevated levels of 6-methylmercaptopurine ribonucleotides have been associated with hepatotoxicity. The sensitivity and specificity of these methylated metabolites for predicting thiopurine-induced liver enzyme abnormalities are, however, poor. 6-Thioguanine has been suggested as an alternative to the classical thiopurines azathioprine and 6-mercaptopurine for the treatment of IBD, but there are concerns about its toxicity profile, especially with regard to the induction of nodular regenerative hyperplasia of the liver. Data now suggest that the induction of nodular regenerative hyperplasia of the liver during 6-thioguanine therapy might be dose-dependent or dependent on the level of 6-thioguanine nucleotides.

INTRODUCTION: Studies indicated that 5-aminosalicylates (5-ASA) may influence the metabolism of thiopurines; however, conclusions were restricted as a result of number of patients or study design. AIM: To determine the influence of 5-ASA on thiopurine metabolism, we performed a prospective multicenter pharmacokinetic interaction study of two different 5-ASA dosages (2 g daily followed by 4 g daily) in 26 inflammatory bowel disease (IBD) patients during steady-state AZA or 6-MP therapy. RESULTS: The 4-wk coadministration of 2 g 5-ASA daily, followed by a 4-wk period of 4 g 5-ASA daily, led to a statistical significant increase of 40% (absolute 84 pmol/8 × 108 RBC) and 70% (absolute 154 pmol/8 × 108 RBC) in 6-thioguaninenucleotide levels (6-TGN), respectively. A rise in 6-TGN levels was observed in 100% of patients after a 4-wk period of 4 g 5-ASA daily. The 6-methylmercaptopurine- ribonucleotide levels did not change. Signs of myelotoxicity were observed in 7.7% of patients (N = 2). CONCLUSIONS: The level of the pharmacologically active 6-TGN significantly increases in a dose-dependent manner during 5-ASA coadministration. IBD patients who are unresponsive or refractory to standard thiopurine therapy may benefit from the coadministration of 5-ASA, leading to an increase in 6-TGN levels.

Background and Aims: Nodular regenerative hyperplasia (NRH) of the liver is associated with several diseases and drugs. Clinical symptoms of NRH may vary from absence of symptoms to full-blown (noncirrhotic) portal hypertension. However, diagnosing NRH is challenging. The objective of this study was to determine inter- and intraobserver agreement on the histopathologic diagnosis of NRH. Methods: Liver specimens (n=48) previously diagnosed as NRH, were reviewed for the presence of NRH by seven pathologists without prior knowledge of the original diagnosis or clinical background. The majority of the liver specimens were from thiopurine using inflammatory bowel disease patients. Histopathologic features contributing to NRH were also assessed. Criteria for NRH were modified by consensus and subsequently validated. Interobserver agreement was evaluated by using the standard kappa index. Results: After review, definite NRH, inconclusive NRH and no NRH were found in 35% (23-40%), 21% (13-27%) and 44% (38-56%), respectively (median, IQR). The median interobserver agreement for NRH was poor (κ = 0.20, IQR 0.14-0.28). The intraobserver variability on NRH ranged between 14% and 71%. After modification of the criteria and exclusion of biopsies with technical shortcomings, the interobserver agreement on the diagnosis NRH was fair (κ = 0.45). Conclusions: The interobserver agreement on the histopathologic diagnosis of NRH was poor, even when assessed by well-experienced liver pathologists. Modification of the criteria of NRH based on consensus effort and exclusion of biopsies of poor quality led to a fairly increased interobserver agreement. The main conclusion of this study is that NRH is a clinicopathologic diagnosis that cannot reliably be based on histopathology alone.