Mark M. Broekman

Risk Factors for Rectal Stump Cancer in Inflammatory Bowel Disease

BACKGROUND: Patients with long-standing colitis carry an increased risk of colorectal cancer and are therefore enrolled in colonoscopic surveillance programs. It is presently not known if endoscopic surveillance of patients with colitis with a closed rectal stump after a subtotal colectomy is justified. Neither is it clear which of these patients might be at increased risk for rectal stump cancer. OBJECTIVE: The aim of this study is to identify the risk factors for rectal stump cancer. DESIGN: This investigation is a retrospective descriptive case-control study. SETTINGS: This study was conducted at tertiary referral centers in the Netherlands. PATIENTS: Colorectal cancer cases associated with inflammatory bowel disease diagnosed between 1990 and 2006 were selected in a nationwide pathology archive. Patients with rectal stump cancer were selected from this group. The pathology archive was also used to identify inflammatory bowel disease controls matched for referral center with a closed rectal stump after subtotal colectomy, but without neoplasia. Follow-up started at the date of subtotal colectomy with the formation of a rectal stump. Demographic and disease characteristics were collected at baseline. MAIN OUTCOME MEASUREMENTS: Hazard ratios with 95% confidence intervals were calculated for factors associated with the development of rectal stump cancer with the use of univariate Cox regression analysis. End points were rectal stump cancer, end of follow-up, or death. RESULTS: A total of 12 patients with rectal stump cancer and 18 matching controls without neoplasia were identified. Univariate analysis showed an association between rectal stump cancer and primary sclerosing cholangitis, and disease duration until subtotal colectomy. LIMITATIONS: This study is limited by its retrospective design, and, despite being the largest series to date, it still has a limited number of cases. CONCLUSIONS: Risk factors for rectal stump cancer in a closed rectal stump after subtotal colectomy were primary sclerosing cholangitis and disease duration until subtotal colectomy.

Risk factors for thiopurine-induced myelosuppression and infections in inflammatory bowel disease patients with a normal TPMT genotype

Leucopenia is a common side effect in patients treated with thiopurines. Variants in the thiopurine S‐methyltransferase (TPMT) gene are the best‐known risk factor, but only explain up to 25% of leucopenia cases.

Common single nucleotide polymorphisms in transient receptor potential melastatin type 6 increase the risk for proton pump inhibitor-induced hypomagnesemia: a case–control study

Objective Proton pump inhibitors (PPIs) are effective drugs for the treatment of gastric acid-related disorders. Serious adverse events are rare for PPIs, but recent data suggest that PPIs cause hypomagnesemia. The aim of this study was to estimate the frequency of PPI-induced hypomagnesemia and to define the risk factors for its development. Materials and methods A total of 133 chronic users of PPIs were enrolled and patients were distinguished on the basis of their serum Mg2+ concentrations. Common single nucleotide polymorphisms (SNPs) in the candidate gene, transient receptor potential melastatin type 6 (TRPM6), were screened. Results Seventeen out of 133 patients had PPI-induced hypomagnesemia. The duration of PPI use was longer in those with hypomagnesemia (7.7 vs. 5.2 years). Two common SNPs in TRPM6 (rs3750425 and rs2274924) increased the risk for PPI-induced hypomagnesemia by 5.8-fold. Conclusion We found hypomagnesemia in 13% of PPI users. SNPs in TRPM6 drive the risk of developing hypomagnesemia during chronic PPI use.

GST Theta null genotype is associated with an increased risk for ulcerative colitis: a case-control study and meta-analysis of GST Mu and GST Theta polymorphisms in inflammatory bowel disease

Glutathione S-transferases (GSTs) are important in the detoxification of many compounds, including reactive oxygen species. Polymorphisms in GSTs resulting in a decreased enzyme activity might enhance the risk for inflammatory bowel disease by eliciting a state of oxidative stress. Previous case–control studies showed divergent results and were frequently limited in sample size; therefore we conducted a meta-analysis including results from our case–control study. For the case–control study, we genotyped 552 patients with Crohn’s disease (CD), 223 patients with ulcerative colitis (UC) and 972 healthy controls by PCR for functional deletions in GST Mu and GST Theta. Both were not analyzed in recent genome-wide association studies. For the meta-analysis, PubMed, EMBASE and Web of Science were searched. In this meta-analysis, we show an enhanced susceptibility for UC in individuals with the GSTT1null genotype (odds ratio (OR) 2.27, 95% confidence interval (CI) 1.31–3.92). In our case–control study, a reduced risk for CD was seen with the GSTT1null genotype (OR 0.58, 95% CI 0.43–0.77); however, pooled analysis showed an OR of 1.67, 95% CI 0.81–3.45. In this meta-analysis, we showed an increased risk for UC in individuals with the GSTT1null genotype.

More Dose-dependent Side Effects with Mercaptopurine over Azathioprine in IBD Treatment Due to Relatively Higher Dosing

Background: There are substantial global differences in the preference for mercaptopurine (MP) or its prodrug azathioprine (AZA) as first-choice thiopurine to treat inflammatory bowel diseases. Studies comparing both agents are scarce. Our aim was to compare AZA and MP in thiopurine-naive patients with inflammatory bowel disease for the frequency of side effects and efficacy. Methods: Post hoc analysis of the “Thiopurine response Optimization by Pharmacogenetic testing in Inflammatory bowel disease Clinics” (TOPIC) trial, in which thiopurine-naive patients with inflammatory bowel disease with an indication for a thiopurine were randomized for a genotype-based dose versus standard of care. For this study, Cox proportional hazard ratios (HRs) were calculated to compare AZA and MP for discontinuation rates within 5 months, incidence of hepatotoxicity, leukopenia, and gastrointestinal side effects. Treatment efficacy was compared by logistic regression. Results: Patient characteristics were similar for patients treated with AZA (n = 494, 64.4%) and MP (n = 273, 35.6%), yet patients with MP were relatively higher dosed compared with those on AZA. Discontinuation rates within 5 months were not different, 39.3% (AZA) and 38.1% (MP), HR 0.92 (95% confidence interval, 0.72–1.17; P = 0.50); however, patients on MP were more often subjected to dose reductions (30% versus 14%, P < 0.01). Higher rates of hepatotoxicity, HR 1.93 (95% confidence interval, 1.35–2.76; P < 0.01) and leukopenia, HR 2.55 (95% confidence interval, 1.51–4.30; P < 0.01) were observed with MP, which annulled in a secondary analysis with adjustment for the higher dose and metabolite levels. Conclusions: Patients treated with MP were relatively higher dosed, which resulted in more dose-dependent side effects and a higher rate of dose reductions.

The glutathione transferase Mu null genotype leads to lower 6-MMPR levels in patients treated with azathioprine but not with mercaptopurine

The conversion of azathioprine (AZA) to mercaptopurine (MP) is mediated by glutathione transferase Mu1 (GSTM1), alpha1 (GSTA1) and alpha2 (GSTA2). We designed a case-control study with data from the TOPIC trial to explore the effects of genetic variation on steady state 6-methylmercaptopurine ribonucleotide (6-MMPR) and 6-thioguanine nucleotide (6-TGN) metabolite levels. We included 199 patients with inflammatory bowel disease (126 on AZA and 73 on MP). GSTM1-null genotype carriers on AZA had two-fold lower 6-MMPR levels than AZA users carrying one or two copies of GSTM1 (2239 (1006–4587) versus 4371 (1897–7369) pmol/8 × 108 RBCs; P<0.01). In patients on MP (control group) 6-MMPR levels were comparable (6195 (1551–10712) versus 6544 (1717–11600) pmol/8 × 108 RBCs; P=0.84). The 6-TGN levels were not affected by the GSTM1 genotype. The presence of genetic variants in GSTA1 and GSTA2 was not related to the 6-MMPR and 6-TGN levels.

Patients' beliefs about medicine are associated with early thiopurine discontinuation in patients with inflammatory bowel diseases

Background Patients’ beliefs about medicine may either reflect the necessity for treatment or concerns regarding the treatment. We explored the extent to which these beliefs have an effect on thiopurine metabolite levels and premature discontinuation in patients with inflammatory bowel disease (IBD). Patients and methods Patients enrolled in the ‘Thiopurine response Optimization by Pharmacogenetic testing in Inflammatory Bowel Disease Clinics’ (TOPIC) trial were asked to complete the Beliefs about Medicine Questionnaire (BMQ) 4 weeks after thiopurine initiation. The BMQ measures perceptions about treatment necessity and concerns. On the basis of the necessity and concern scores, patients can be categorized as accepting, ambivalent, indifferent, or skeptical. The thiopurine discontinuation rates for these belief subgroups were compared by Kaplan–Meier curves. Furthermore, clinical response and metabolite levels were compared between the belief subgroups. Results A total of 767 patients with IBD started thiopurine treatment, of whom 576 (75%) completed the BMQ. Patients could be classified as accepting (34%), indifferent (17%), ambivalent (34%), or skeptical (15%). Compared with patients in the accepting group (discontinuation rate 22%), patients with an indifferent (35%; P=0.02), ambivalent (37%; P<0.01), or skeptical belief (54%; P<0.01) had higher thiopurine discontinuation rates. No differences were observed in the steady-state thiopurine metabolite levels between the different belief subgroups. Conclusion Patients with a low perceived treatment necessity or high concerns toward IBD treatment were more likely to discontinue thiopurine treatment prematurely. Extra attention toward these patients might prevent premature discontinuation.

Inulin significantly improves serum magnesium levels in proton pump inhibitor‐induced hypomagnesaemia

Proton pump inhibitors (PPI) are among the most widely prescribed drugs to treat gastric acid‐related disorders. PPI‐induced hypomagnesaemia, a defect in intestinal absorption of Mg2+, can be a severe side effect of chronic PPI use.

LPS-Stimulated Whole Blood Cytokine Production Is Not Related to Disease Behavior in Patients with Quiescent Crohn's Disease.

Introduction Crohn’s disease (CD) is a chronic inflammatory disease in which cytokines play a pivotal role in the induction and maintenance of inflammation. Innate cytokine production is genetically determined and varies largely between individuals; this might impact the severity of inflammation. We aimed to assess whether ex-vivo endotoxin-stimulated levels of cytokines could be associated with disease phenotype. Methods Patients with quiescent CD (Harvey-Bradshaw Index ≤ 4 and negative inflammation markers) who were not using immunomodulating drugs or biologicals were eligible. Historical disease characteristics (localization, behavior, number of bowel resections, drug history, extra-intestinal symptoms) were extracted from medical records. We measured cytokine levels (tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-10) in supernatants of lipopolysaccharide (LPS) -stimulated whole blood cultures and correlated these with disease characteristics and age- and sex-matched healthy controls. In addition, we analyzed whether single nucleotide polymorphisms (SNPs) in the promoter region of the TNF-α gene were related to TNF-α levels. Results We included 75 patients with CD and 24 healthy controls. Six patients were excluded because of increased inflammation markers resulting in a total of 69 patients. The mean age (SD) of patients with CD was 51.2 (12.3) years with a mean (SD) disease duration of 24.1 (11.5) years. Disease localization, peri-anal involvement and behavior were not related to LPS-stimulated TNF-α, IL-1β, IL-6 or IL-10 levels. In addition, combination of localization with behavior to differentiate mild from severe disease type showed no significant differences. TNF-α levels were higher in patients with CD (428 pg/ml IQR [267-468]) compared to healthy controls (459 pg/ml IQR [364-570], p=0.02). We found no associations between SNPs in the promoter region and TNF-α levels. Conclusion In this study, innate cytokine production of TNF-α, IL-1β, IL-6 and IL-10 was not related to historical disease characteristics or disease severity in patients with quiescent CD. These findings suggest that genetically determined levels of these cytokines obtained from LPS-stimulated whole blood cultures are not linked with disease behavior or severity.

Mo1739 LPS Stimulated Whole Blood Cytokine Production and the Association With Disease Characteristics in Patients With Quiescent Crohn's Disease

Introduction: Individual cytokine production is for 60-70% under genetic control, but levels of secreted cytokines after stimulation with lipopolysaccharide (LPS) vary widely between individuals. In various fields of inflammatory diseases the variation in LPS stimulated cytokine production has been linked with disease behavior. So far, studies in patients with Crohns disease (CD) used single nucleotide polymorphisms (SNPs) as surrogate marker to identify patients with a high innate cytokine production, but it may be more accurate to measure cytokine production itself for this purpose. Our aim was to measure levels of tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, IL-6 and IL-10 after whole blood stimulation with LPS and correlate this with historical disease characteristics of patients with CD who are currently in remission. Methods: Only CD patients in remission and not on immunosuppressants or biologicals, were eligible for participation as drugs or disease activity can modulate cytokine production. Remission was defined as Harvey-Bradshaw Index <5, with normal C-reactive protein (<10 mg/L) and leukocyte levels. Whole blood samples were incubated with E.coli O55:B5 LPS (1 ng/ml) for 4 hours (TNF-α) or 24 hours (IL-1β, IL6 and IL-10). Cytokine levels were determined in supernatants with specific enzyme-linked immunosorbent assays (ELISAs). Non-parametric statistics were used to test correlations between cytokine levels and historical disease characteristics. Results: Sixty-nine patients (50 female / 19 male) were included. Mean disease duration at inclusion was 24.1 (SD= 11.5) years and the average age was 51.2 (SD=12.3) years. No relation was found between disease localization (ileal vs. colon vs. ileocolonic) or disease behavior (presence of fistulas or strictures) and levels of TNF-α, IL-1β, IL-6 and IL-10. Additional analyses were performed to compare mild and severe disease based on phenotype (ileal disease without fistulas versus ileocolonic disease with fistulas), number of bowel resections and percentage of years in which the patient received immunosuppressants or biologicals. A significant difference (p= 0.04) for IL-6 was found between patients with a single (median 2258 pg/ml, interquartile range [1630-2726]) and those with multiple resections (2816 pg/ml [1851-3531]) (see Table). Conclusion: In conclusion, our results show a relation between IL-6 levels and the number of bowel resections. Altogether, the use of LPS stimulated cytokine production as a biomarker to predict disease behavior in CD seems limited. Relation between cytokine production and disease severity.