Treatment persistence of ustekinumab and vedolizumab in IBD patients is independent of prior immunogenicity to anti-TNFs: a retrospective study.

BACKGROUND AND AIMS: Immunological treatment failure of anti-TNF therapy negatively influences treatment persistence of a second anti-TNF in IBD patients. So far it is unknown if this effect is also observed for other monoclonal antibodies. We assessed the influence of immunogenicity to anti-TNFs on treatment persistence of subsequent ustekinumab and vedolizumab therapy. METHODS: IBD patients with and without immunogenicity to anti-TNFs (undetectable trough levels and antibody titers ≥20 ng/mL) and subsequent ustekinumab (UST) and/or vedolizumab (VDZ) therapy were included in this retrospective, single-center study. The Kaplan-Meier method with the log-rank test and Cox proportional hazards were used as statistical methods. RESULTS: One hundred patients (Crohn's disease: 62, Ulcerative colitis: 31, IBD unclassified: 7) with 127 treatment lines (62 with UST, 65 with VDZ) were included in the analysis. Immunogenicity to previous anti-TNFs did not influence treatment persistence of subsequent ustekinumab and vedolizumab therapy (UST: Log rank: p = .95, Immunogenicity: HR for treatment discontinuation: 0.97 [95% CI 0.31-3.04]; VDZ: p = .65, HR: 0.85 [0.41-1.75]; total cohort [UST and VDZ]: p = .62, HR: 0.86 [0.47-1.57]). Azathioprine co-treatment did not lengthen treatment persistence (UST: Log rank: p = .77, azathioprine: HR: 1.20 [0.34-4.27]; VDZ: p = .92, HR: 0.58 [0.17-1.99]; total cohort: p = .79, HR: 1.10 [0.55-2.20]). In this anti-TNF experienced cohort, patients with ustekinumab remained longer on treatment than patients receiving vedolizumab (Log rank: p = .005, UST: HR: 0.43 [0.23-0.79]). CONCLUSIONS: Immunogenicity to anti-TNFs does not influence treatment persistence of subsequent ustekinumab and vedolizumab therapy.

[Ustekinumab - Current position]. / Ustekinumab ­ eine Standortbestimmung.

The present review by the IBD-Dach group provides a comprehensive summary of the mode of action, clinical development, approval, efficacy and safety aspects of the novel anti-p40 antibody Ustekinumab. The review provides current data, including the large clinical trials as well as smaller case series and work outside the field of inflammatory bowel diseases for shedding more light into special situations. Together, the data indicate that Ustekinumab shows clinical efficacy as well as a good safety profile for the treatment of Crohn's disease.

[Second Austrian consensus on the safe use of anti-TNFα-antibodies in patients with inflammatory bowel diseases]. / Zweiter österreichischer Konsensus zur sicheren Anwendung von anti-TNF-α-Antikörpern bei chronisch-entzündlichen Darmerkrankungen.

Anti-TNFα-antibodies have revolutionized the therapy of inflammatory bowel diseases and other immune-mediated inflammatory diseases. Due to the increasing application of these substances, the Working Group of Inflammatory Bowel Diseases of the Austrian Association of Gastroenterology and Hepatology intended to update their consensus report on the safe use of Infliximab (published in 2010) and to enlarge its scope to cover all anti-TNFα-antibodies. The present consensus report summarizes the current evidence on the safe use of anti-TNFα-antibodies and covers the following topics: general risk of infection, bacterial infections (i. e., Clostridium difficile, Tuberculosis, food hygiene), Pneumocystis jiroveci, viral infections (i. e., Hepatitis B, Hepatitis C, HIV, CMV, VZV), vaccination in general and recommendation for vaccines, gastrointestinal aspects (i. e., perianal fistula, abdominal fistula, intestinal strictures, stenosis and bowel obstruction), dermatologic aspects (skin malignancies, eczema-like drug-related skin eruption), infusion reactions and immunogenicity, demyelinating diseases, hepatotoxicity, haematotoxicity, congestive heart failure, risk and history of malignancies, and pregnancy and breast feeding. For practical reasons, the relevant aspects are summarized in a checklist which is divided into two parts: issues to be addressed before therapy and issues to be addressed during therapy.

Antibiotic-Associated Apoptotic Enterocolitis in the Absence of a Defined Pathogen: The Role of Intestinal Microbiota Depletion.

OBJECTIVE: Antibiotic therapy is a major risk factor for the development of diarrhea and colitis with varying severity. Often the origin of antibiotic-associated gastrointestinal deterioration remains elusive and no specific infectious agents could be discerned. PATIENTS: We represent three cases of intractable high-volume diarrhea associated with combined antibiotic and steroid therapy in critically ill patients not fitting into established disease entities. Cases presented with severe apoptotic enterocolitis resembling acute intestinal graft-versus-host-disease. Microbiologic workup precluded known enteropathogens, but microbiota analysis revealed a severely depleted gut microbiota with concomitant opportunistic pathogen overgrowth. INTERVENTIONS: Fecal microbiota transplantation, performed in one patient, was associated with correction of dysbiosis, rapid clinical improvement, and healing of enterocolitis. CONCLUSIONS: Our series represents a severe form of antibiotic-associated colitis in critically ill patients signified by microbiota depletion, and reestablishment of a physiologic gastrointestinal microbiota might be beneficial for this condition.

Opposing roles of prostaglandin D2 receptors in ulcerative colitis.

Proresolution functions were reported for PGD2 in colitis, but the role of its two receptors, D-type prostanoid (DP) and, in particular, chemoattractant receptor homologous molecule expressed on Th2 cells (CRTH2), is less well defined. We investigated DP and CRTH2 expression and function during human and murine ulcerative colitis (UC). Expression of receptors was measured by flow cytometry on peripheral blood leukocytes and by immunohistochemistry and immunoblotting in colon biopsies of patients with active UC and healthy individuals. Receptor involvement in UC was evaluated in a mouse model of dextran sulfate sodium colitis. DP and CRTH2 expression changed in leukocytes of patients with active UC in a differential manner. In UC patients, DP showed higher expression in neutrophils but lower in monocytes as compared with control subjects. In contrast, CRTH2 was decreased in eosinophils, NK, and CD3(+) T cells but not in monocytes and CD3(+)/CD4(+) T cells. The decrease of CRTH2 on blood eosinophils clearly correlated with disease activity. DP correlated positively with disease activity in eosinophils but inversely in neutrophils. CRTH2 internalized upon treatment with PGD2 and 11-dehydro TXB2 in eosinophils of controls. Biopsies of UC patients revealed an increase of CRTH2-positive cells in the colonic mucosa and high CRTH2 protein content. The CRTH2 antagonist CAY10595 improved, whereas the DP antagonist MK0524 worsened inflammation in murine colitis. DP and CRTH2 play differential roles in UC. Although expression of CRTH2 on blood leukocytes is downregulated in UC, CRTH2 is present in colon tissue, where it may contribute to inflammation, whereas DP most likely promotes anti-inflammatory actions.

Withdrawal of long-term maintenance treatment with azathioprine tends to increase relapse risk in patients with Crohn's disease.

BACKGROUND AND AIM: Many patients with quiescent Crohn's disease are maintained on long-term treatment with azathioprine (AZA), but controlled data are limited. We aimed to evaluate the efficacy of AZA therapy for more than 4 years to maintain clinical remission. METHODS: We performed a randomized double-blind placebo-controlled AZA withdrawal trial with a follow-up period of 24 months. Patients had to have continuous AZA therapy ≥ 4 years without exacerbation of disease during the 12 months before enrollment, and a Crohn's disease activity index < 150 at baseline. Patients were randomized to continue on AZA or switch to placebo. The primary endpoint was time to clinical relapse during follow-up. RESULTS: After inclusion of 52 patients, the trial was stopped prematurely due to slow recruitment. During the 2-year follow-up, clinical relapse occurred in 4 of 26 (15 %) patients on continued AZA and in 8 of 26 (31 %) patients on placebo. Time to clinical relapse averaged 22.3 months (95 % CI 20.6-24.0) on AZA and 19.2 months (95 % CI 16.4-22.1) on placebo (p = 0.20). According to life-table analysis, the proportion of patients in remission after 12 and 24 months was 96 ± 4 and 86 ± 7 % in patients receiving AZA versus 76 ± 8 and 68 ± 9 % in patients receiving placebo (month 12, p = 0.035; month 24, p = 0.30). A higher AZA dose at enrollment was an independent predictor for relapse (p < 0.05). CONCLUSIONS: AZA withdrawal resulted in a significantly increased relapse risk after 1 year and a nonstatistically significant trend for relapse after 2 years. Our results are in line with previous observations.

The Toxin-Producing Pathobiont Klebsiella oxytoca Is Not Associated with Flares of Inflammatory Bowel Diseases.

BACKGROUND: Alterations in the intestinal microbiota are thought to be involved in the pathogenesis of inflammatory bowel diseases (IBD). Klebsiella oxytoca is an intestinal pathobiont that can produce a cytotoxin (tillivaline). AIM: We aimed to elucidate the pathogenetic relevance of toxin-producing K. oxytoca in patients with IBD flares and investigated the clonal relationship of K. oxytoca isolates from IBD patients using multilocus sequence typing (MLST). METHODS: Fecal samples of 235 adult IBD patients were collected from January 2008 to May 2009 and were tested for K. oxytoca, C. difficile toxin, and other pathogens by standard microbiological methods. Clinical data and disease activity scores were collected. K. oxytoca isolates were tested for toxin production using cell culture assays. A total of 45 K. oxytoca isolates from IBD patients, healthy, asymptomatic carriers and from patients with antibiotic-associated hemorrhagic colitis in part from our strain collection were tested for their clonal relationship using MLST. RESULTS: The prevalence of K. oxytoca in IBD overall was 4.7%. Eleven K. oxytoca isolates were detected. Two of 11 isolates were tested positive for toxin production. There was no significant difference in the distribution of K. oxytoca isolates between the groups (active vs. remission in UC and CD). MLST yielded 33 sequence types. K. oxytoca isolates from IBD did not cluster separately from isolates from asymptomatic carriers. CONCLUSIONS: Our data demonstrate that toxin (tilivalline)-producing K. oxytoca is not associated with IBD flares.

Tofacitinib in the treatment of ulcerative colitis : A position paper issued by the Inflammatory Bowel Disease Working Group of the Austrian Society of Gastroenterology and Hepatology (ÖGGH).

Ulcerative colitis (UC) is one of the main forms of inflammatory bowel disease (IBD). Despite the widening range of drug treatment options, primary nonresponse, secondary loss of response as well as adverse events call for additional treatment alternatives.Tofacitinib is an oral small-molecule drug of the class of Janus kinase inhibitors which, in the European Union, was approved for the treatment of moderate to severe active UC in August 2018. This position paper, drawn up by the IBD Working Group of the Austrian Society of Gastroenterology and Hepatology, summarizes the mechanism of action, clinical development, marketing authorization status, efficacy and safety of tofacitinib. Also, by providing a synopsis of available data from both pivotal and post-marketing studies, clinical aspects of specific interest are highlighted and discussed.The available body of evidence indicates that tofacitinib is an additional effective medication for the treatment of UC that exhibits a good safety profile. This position paper aims at optimizing the safe and effective use of tofacitinib in daily clinical practice.

Inflammatory bowel disease is a risk factor for recurrent venous thromboembolism.

BACKGROUND & AIMS: Patients with inflammatory bowel disease (IBD) are at increased risk of a first venous thromboembolism (VTE), yet their risk of recurrent VTE is unknown. We performed a cohort study to determine the risk for recurrent VTE among patients with IBD compared with subjects without IBD. METHODS: We assessed 2811 patients with IBD for a history of VTE, recruited from outpatient clinics at 14 referral centers (June 2006-December 2008). Patients with VTE before a diagnosis of IBD or those not confirmed to have VTE, cancer, or a VTE other than deep vein thrombosis or pulmonary embolism, were excluded. Recurrence rates were compared with 1255 prospectively followed patients without IBD that had a first unprovoked VTE (not triggered by trauma, surgery, or pregnancy). The primary end point was symptomatic, objectively confirmed, recurrent VTE after discontinuation of anticoagulation therapy after a first VTE. RESULTS: Overall, of 116 IBD patients who had a history of first VTE, 86 were unprovoked. The probability of recurrence 5 years after discontinuation of anticoagulation therapy was higher among patients with IBD than patients without IBD (33.4%; 95% confidence interval [CI]: 21.8-45.0 vs 21.7%; 95% CI: 18.8-24.6; P = .01). After adjustment for potential confounders, IBD was an independent risk factor of recurrence (hazard ratio = 2.5; 95% CI: 1.4-4.2; P = .001). CONCLUSIONS: Patients with IBD are at an increased risk of recurrent VTE compared to patients without IBD.

Azathioprine versus mesalazine for prevention of postoperative clinical recurrence in patients with Crohn's disease with endoscopic recurrence: efficacy and safety results of a randomised, double-blind, double-dummy, multicentre trial.

OBJECTIVE: The aim of the study was to compare azathioprine versus mesalazine tablets for the prevention of clinical recurrence in patients with postoperative Crohn's disease (CD) with moderate or severe endoscopic recurrence. METHODS: This was a 1 year, double-blind, double-dummy, randomised study which took place in 21 gastroenterology centres in Austria, the Czech Republic, Germany and Israel. The study participants were 78 adults with CD who had undergone resection with ileocolonic anastomosis in the preceding 6-24 months without subsequent clinical recurrence and with a Crohn's disease activity index (CDAI) score <200, but with moderate or severe endoscopic recurrence. The study drugs were azathioprine 2.0-2.5 mg/kg/day or mesalazine 4 g/day over 1 year. The primary end point was therapeutic failure during 1 year, defined as a CDAI score > or = 200 and an increase of > or = 60 points from baseline, or study drug discontinuation due to lack of efficacy or intolerable adverse drug reaction. RESULTS: Treatment failure occurred in 22.0% (9/41) of azathioprine-treated patients and 10.8% (4/37) of mesalazine-treated patients, a difference of 11.1% (95% CI -5.0% to 27.3%, p=0.19). Clinical recurrence was significantly less frequent with azathioprine versus mesalazine (0/41 (0%) vs 4/37 (10.8%), p=0.031), whereas study drug discontinuation due to adverse drug reactions only occurred in azathioprine-treated patients (9/41 (22.0%) vs 0%, p=0.002). The proportion of patients showing > or = 1 point reduction in Rutgeerts score between baseline and month 12 was 63.3% (19/30) and 34.4% (11/32) in the azathioprine and mesalazine groups, respectively (p=0.023). CONCLUSIONS: In this population of patients with postoperative CD at high risk of clinical recurrence, superiority for azathioprine versus mesalazine could not be demonstrated for therapeutic failure.

Low prevalence of gastroesophageal reflux symptoms in vegetarians.

BACKGROUND: Dietary modification could reduce the risk of gastroesophageal reflux disease. Circumstantial evidence suggests that gastroesophageal reflux is less prevalent in people adhering to a vegetarian diet. We aimed to study the relationship between vegetarianism and the occurrence of gastroesophageal reflux symptoms (GERS). METHODS: This study compares the prevalence of GERS in vegetarians with non-vegetarian controls from the general population. Frequency and severity of GERS (heartburn and/or acid regurgitation) were assessed with a self-administrated questionnaire. RESULTS: Within 1 year, any GERS were experienced by 19 of 100 (19%) vegetarians and by 98 of 250 (39.2%) non-vegetarian controls (p < 0.001). Frequent GERS, defined as GERS on at least 1 day per week, were noted in 3% of vegetarians and in 12.8% of controls (p = 0.006). Reflux symptoms were significantly less severe in vegetarians than in non-vegetarians (p < 0.001). According to multivariable analysis, independent predictors of GERS included male sex, current smoking, BMI ≥ 25 (odds ratio [OR] = 1.94; 95% confidence interval [CI], 1.14-3.31), and a non-vegetarian diet (OR = 2.19; 95% CI, 1.20-3.97); non-vegetarian diet independently predicted frequent GERS (OR 4.03; 95% CI, 1.17-13.9). An increased risk of GERS (OR = 2.17; 95% CI, 1.09-4.29) and frequent GERS (OR 4.00; 95% CI, 1.13-14.18) in non-vegetarians were also demonstrated by logistic regression of matched data. In non-vegetarians, the risk of reflux symptoms was not significantly related to meat intake. CONCLUSIONS: The prevalence and severity of GERS are lower in vegetarians than in non-vegetarians from the general population. The results are in line with a mitigating effect of vegetarianism on GERS. Data must be interpreted with caution given the retrospective study design and the small sample size.

Limited long-term treatment persistence of first anti-TNF therapy in 538 patients with inflammatory bowel diseases: a 20-year real-world study.

BACKGROUND: Anti-TNF antibodies were the first biologic treatment option for patients with inflammatory bowel diseases. AIMS: To assess length of treatment persistence of first anti-TNF therapy and influencing factors used in the standard care of patients with inflammatory bowel diseases. METHODS: Single-centre, retrospective study from a register including patients who received anti-TNF therapy in the last 20 years at the study centre. Kaplan-Meier analysis with log-rank test was used to describe treatment persistence. With multivariable Cox regression analysis, risk factors for treatment failure were investigated. RESULTS: Five hundred thirty-eight patients (CD, Crohn's disease: 367, UC, ulcerative colitis: 147, inflammatory bowel disease unclassified: 24) with a median follow-up of 8.1 years were included. Median (95% confidence interval) treatment persistence in the total cohort was 2.3 years (28 [22, 38] months), and nearly half of patients withdrew from treatment within 2 years. Male patients were treated longer than females (male: 37 [25, 48] months, female: 23 [14, 33] months, P = 0.002). Treatment persistence was longer in CD compared to UC (CD: 39 [30, 50] months, UC: 13 [9, 19] months, P < 0.001), and patients with CD remained longer on adalimumab than on infliximab treatment (adalimumab: 67 [55, 95] months, infliximab: 19 [14, 31] months, P < 0.001). Treatment failure (52%) and side effects (25%) were the most common reasons for withdrawal from therapy; 14% withdrew due to remission. Female sex was identified as independent predictor for treatment failure in UC (hazard ratio [CI]: 1.73 [1.02-2.92], P = 0.04). CONCLUSION: Long-term treatment persistence of first anti-TNF therapy was limited in patients with inflammatory bowel diseases, primarily due to treatment failure and side effects.

A systematic survey evaluating 6-thioguanine-related hepatotoxicity in patients with inflammatory bowel disease.

OBJECTIVE: Drug-induced liver injury was recently reported as a major complication leading to hepatic nodular regenerative hyperplasia (NRH) in patients with inflammatory bowel disease (IBD) and 6-thioguanine (6-TG) therapy. The aim of the study was to evaluate the prevalence of 6-TG-related hepatotoxicity in a large multi-centered IBD population by means of a systematic online survey. METHODS: Clinical and laboratory data, imaging techniques (sonography, CT, MRI) and histology of liver biopsies were surveyed in IBD patients treated with 6-TG. The decision on whether liver imaging and/or liver biopsy were performed was exclusively at the discretion of the investigator. RESULTS: 6-TG use was fully documented in 296 patients (median treatment duration 56 weeks, range < 1-207). Laboratory signs of drug-induced liver injury were found in 43 patients (14.5%). Liver imaging revealed pathologic results in 68/176 patients (38.6%). Liver biopsy was performed in a subset of 60 patients; using silver-reticulin staining (n = 59), NRH was considered in 16 patients (27.1%). Age was the only independent, albeit weak, risk factor for development of NRH. CONCLUSION: This large online survey confirms the strong association between 6-TG treatment and the significant risk of development of NRH in patients with IBD. The definitive diagnosis of NRH depends solely upon liver biopsy.

Diet therapy for inflammatory bowel diseases: The established and the new.

Although patients with inflammatory bowel diseases (IBD) have a strong interest in dietary modifications as part of their therapeutic management, dietary advice plays only a minor part in published guidelines. The scientific literature shows that dietary factors might influence the risk of developing IBD, that dysbiosis induced by nutrition contributes to the pathogenesis of IBD, and that diet may serve as a symptomatic treatment for irritable bowel syndrome-like symptoms in IBD. The role of nutrition in IBD is underscored by the effect of various dietary therapies. In paediatric patients with Crohn's disease (CD) enteral nutrition (EN) reaches remission rates similar to steroids. In adult patients, however, EN is inferior to corticosteroids. EN is not effective in ulcerative colitis (UC). Total parenteral nutrition in IBD is not superior to steroids or EN. The use of specific probiotics in patients with IBD can be recommended only in special clinical situations. There is no evidence for efficacy of probiotics in CD. By contrast, studies in UC have shown a beneficial effect in selected patients. For patients with pouchitis, antibiotic treatment followed by probiotics, like VSL#3 or Lactobacillus GG, is effective. When probiotics are used, the risk of bacterial translocation and subsequent bacteremia has to be considered. More understanding of the normal intestinal microflora, and better characterization of probiotic strains at the phenotypic and genomic levels is needed as well as clarification of the mechanisms of action in different clinical settings. A FODMAP reduced diet may improve symptoms in IBD.

Surgical Management of Duodenal Gastrointestinal Stromal Tumors: A Case Report.

Gastrointestinal stromal tumors (GISTs) represent the most common mesenchymal tumor entity of the gastrointestinal tract. In fewer than 5% of cases, primary GISTs are located in the duodenum. Surgery represents the treatment of choice for localized tumor disease and remains challenging in GISTs located at the duodenum. The optimal surgical approach is currently discussed controversially in the literature due to the fact that extended resections in terms of pancreaticoduodenectomy may cause significant postoperative morbidity and mortality compared to limited resection. We report on a rare case of GIST located in the upper part of the duodenum treated by limited surgical resection. Avoidance of postoperative complications may lead to optimal oncological outcome in selected patients.

Austrian infliximab experience in Crohn's disease: a nationwide cooperative study with long-term follow-up.

OBJECTIVE: To determine the nationwide experience with infliximab for the treatment of Crohn's disease in Austria. DESIGN: National multicentre retrospective postal questionnaire survey. SETTING AND PARTICIPANTS: All institutions using infliximab for Crohn's disease in the years 1999 and 2000 were identified by the registry of the local provider of this drug. OUTCOME MEASURES: Response after first treatment course according to physician global assessment, number of subsequent infliximab infusions, disease activity at end of follow-up, avoidance of steroids, frequency of surgery for Crohn's disease, and adverse events. RESULTS: Questionnaires were returned by 32/35 (91%) centres approached. A total of 748 infusions were administered to 153 patients. After the first treatment course an excellent or good response occurred in 48/58 (83%) patients with luminal disease, and in 67/95 (71%) patients with fistulous disease (P < 0.05). After the first treatment course 108 (71%) patients received further infliximab therapy. At a mean follow-up of 29 months, 50% of patients had improved since baseline without requiring surgery for Crohn's disease. Steroid withdrawal was achieved in 25% of patients. Surgery had been performed in one-third of patients and was associated with lacking response to the first treatment course (P < 0.001) and with fistulous disease (P = 0.012). Co-medication with azathioprine favoured the initial response and steroid withdrawal (P < 0.05). One patient died from myocarditis; other adverse events were consistent with that seen in other studies of infliximab. CONCLUSIONS: The Austrian experience with infliximab for Crohn's disease is in general accordance with results from clinical trials and post-marketing studies from single centres. A substantial subgroup of patients appear to have a prolonged benefit from infliximab therapy.

A case of opportunistic skin infection with Mycobacterium marinum during adalimumab treatment in a patient with Crohn's disease.

Opportunistic infections, especially reactivation with M. tuberculosis, are major complications during treatment with anti-TNF agents. Infections with atypical mycobacteria like Mycobacterium marinum are rare and tend to turn into a difficult and prolonged course due to delayed diagnosis. This is the first case of M. marinum infection during adalimumab therapy in a patient with Crohn's disease. The most important diagnostic step was a detailed medical history as PCR tested for M. tuberculosis and for atypical subspecies was false negative. Up to now a discontinuation of anti-TNF therapy has been recommended, however, there is no consensus about the reintroduction of biologicals after sufficient anti-infective therapy. In this patient anti-TNF therapy had to be reintroduced because of increasing activity with no relapse of M. marinum after a follow-up of 12 months.

Mucosal improvement in patients with moderate to severe postoperative endoscopic recurrence of Crohn's disease and azathioprine metabolite levels.

BACKGROUND: The value of azathioprine metabolites (6-thioguanine nucleotides [6-TGN]) in monitoring clinical treatment response is still controversially discussed. Data regarding thiopurine metabolite levels and endoscopic improvement are lacking. METHODS: Data were analyzed post hoc from a 1-year, multicenter, double-blind, double-dummy, randomized trial comparing azathioprine 2.0 to 2.5 mg/kg per day versus mesalamine 4 g/d in a subset of 23 postoperative patients with Crohn's disease (CD) treated with azathioprine and having moderate-to-severe endoscopic recurrence according to a modified 6-grade score. Red blood cell (RBC) concentrations of 6-TGN, 6-methyl-mercaptopurine ribonucleotides (6-MMPR), and 6-methyl-thioguanine nucleotides (6-MTGN) were indicated as follows: area under the concentration-time curve, average concentration (C av), and concentration at the final study visit. RESULTS: Overall, 74% of patients showed an improvement in the modified endoscopic score (P = 0.022). Median endoscopic score reduced from 4 at the baseline to 2 at the final visit. Patients with a high C av for 6-TGN (≥ 193 pmol/8 × 10(8) RBC; P = 0.017) or 6-MTGN (≥ 79.2 pmol/8 × 10(8) RBC; P = 0.035) significantly improved in endoscopic score, and the improvement in endoscopic score correlated with C av for 6-TGN (r = -0.51; P = 0.013). For concentration at the final visit, higher values for 6-TGN (≥ 142 pmol/8 × 10(8) RBC; P = 0.017) were associated with a better postoperative score. Sensitivity analysis revealed a significant correlation between 6-TGN (area under the concentration-time curve) and postoperative endoscopic improvement. CONCLUSIONS: Our post hoc analysis from a double-blind, randomized trial suggests that higher RBC 6-TGN levels are associated with endoscopic improvement in patients with severe postoperative endoscopic recurrence of CD. Thus, our study provides first evidence on the utility of monitoring of thiopurine metabolites to achieve mucosal response in CD.