Erythrocyte Methotrexate–Polyglutamate Concentrations in Pediatric Inflammatory Bowel Disease

P050 METHOTREXATE POLYGLUTAMATES AS BIOMARKERS OF TREATMENT RESPONSE IN PEDIATRIC INFLAMMATORY BOWEL DISEASE

Inside cells, the immunomodulator methotrexate (MTX) undergoes the addition of glutamates to form methotrexate polyglutamates (MTX-Glu)—promising biomarkers of systemic exposure and treatment response to MTX in rheumatology. MTX-Glu are underexplored in Inflammatory Bowel Disease (IBD), with no data in pediatrics. In this cross-sectional secondary analysis, we assessed the relationships between MTX-Glu and MTX dose and treatment response in pediatric IBD. Twenty-one children with IBD, receiving maintenance therapy with infliximab (IFX) and MTX, had MTX-Glu1–6 concentrations and IFX troughs/antibodies measured and disease activity assessed for comparison in remission vs. active IBD using non-parametric tests, with associations explored using Spearman’s correlation (ρ) and regression analyses; SASv9.4 (α = 0.05). Total and long-chain MTX-Glu correlated with MTX dose (ρ = 0.51 and 0.56, respectively; p ≤ 0.02). In children with Crohn’s disease (n = 19), short-chain MTX-Glu1–2 were 2.5-fold higher in remission vs. active disease, approaching statistical significance (p = 0.066), with no statistical differences in IFX trough (p = 0.549) between groups. Our study highlights a potential role for long-chain MTX-Glu in the therapeutic drug monitoring of MTX in IBD. It is the first study in pediatric IBD and, although statistical significance was not reached, our findings also suggest that higher short-chain MTX-Glu levels may be associated with IBD treatment response to MTX in children.

Background Methotrexate (MTX) is increasingly prescribed in paediatric inflammatory bowel disease (IBD), but therapeutic drug monitoring (TDM) is currently not feasible due to its characteristic pharmacokinetics and short half-life in plasma, which amounts to approximately 2.5-6.5 hours. Because of this, plasma MTX is no longer detectable shortly after administration. However, MTX-polyglutamates (PG1-5) are formed intracellularly and accumulate over time. Recently, we developed a technique for targeted erythrocyte MTX-PG analysis with the potential for TDM. Data in paediatric IBD with this technique are lacking so far. Here, we aimed to identify the potential of erythrocyte MTX-PG analysis to measure MTX levels in paediatric IBD. Methods In this observational cross-sectional study, we determined MTX-PG concentrations in erythrocytes retrieved from blood samples of paediatric IBD patients on low-dose MTX maintenance therapy, defined as exposure to a stable dose of MTX for at least twelve consecutive weeks. MTX-PG concentrations were determined by stable-isotope dilution liquid chromatography mass-spectrometry. Furthermore, we evaluated the effects of route of administration (oral versus subcutaneous), MTX dosage, and anthropometric data on MTX-PG concentrations. Results Fifty-two paediatric IBD patients on MTX maintenance therapy were included. The predominant subspecies was MTX-PG3 (mean 30.5 nmol/L, SD ± 20.0) and the mean MTX-PGtotal concentration was 88.6 nmol/L (SD ± 52.6). A higher dose was linearly associated with significantly higher MTX-PG3 (r = 0.56), MTX-PG4 (r = 0.52), MTX-PG5 (r = 0.48) and MTX-PGtotal (r = 0.49) levels. When adjusted for body surface area, MTX dose was also linearly associated with significantly higher MTX-PG3 (r = 0.51), MTX-PG4 (r= 0.39), and MTX-PGtotal (r= 0.40) concentrations. A reliable comparison regarding route of administration was not possible in this cohort, due to the small number of patients receiving subcutaneous MTX (n=3). Conclusion We observed high inter-individual variability in the reached erythrocyte MTX-PG concentrations. Body surface adjusted or unadjusted MTX dosage showed a positive linear correlation with erythrocyte MTX-PG concentrations in children with IBD. This is a prerequisite for TDM and provides a strong basis for further research into the relation between TDM of MTX, effectivity and toxicity.

Inflammatory bowel disease in children and adolescents: Working Group Report of the First World Congress of Pediatric Gastroenterology, Hepatology, and Nutrition.

Background Methotrexate (MTX) is frequently prescribed in paediatric inflammatory bowel disease (IBD), with laboratory monitoring routinely performed to detect adverse events (AEs) such as hepatotoxicity and myelotoxicity. However, data on the incidence of these AEs in paediatric IBD remain limited. This study aims to assess the incidence of MTX-induced AEs in paediatric IBD, and to identify factors associated with AEs. Methods We conducted a retrospective monocentre cohort study, including all paediatric IBD patients initiating MTX at the Amsterdam UMC between 2010 and 2023. We collected demographic data, disease characteristics, and laboratory results. We specifically evaluated the occurrence of hepatotoxicity, myelotoxicity, and gastrointestinal (GI) side effects (nausea and vomiting). The severity of AEs was assessed according to the Common Terminology Criteria for Adverse Events. Shortly, grade 1 hepatotoxicity was defined as upper limit of normal (ULN)-2.5 times ULN, grade 2 as 2.5-5 times ULN, and grade 3 as 5-20 times ULN. Myelotoxicity was defined as leukopenia, neutropenia and/or thrombocytopenia. Incidence rates were calculated, and regression analyses were performed to assess potential predictors of MTX-induced AEs. Results A total of 208 paediatric IBD patients (179 CD, 18 UC, 10 IBD-U) starting MTX therapy were identified, 111 of whom used MTX as immunomodulator alongside a biological. Mean dose at initiation was 13 mg/week (±3.21SD), and 66.5% received MTX orally, versus 33.5% subcutaneous administration. All used folic acid. Hepatotoxicity was observed in 85 patients (40.1%), of which the majority (n=52, 63.4%) classified as grade 1, while 10 patients (12.2%) showed grade 3 toxicity. Myelotoxicity occurred in 43 cases (20.7%), most of which presented as mild toxicity (n=35, 83.3%), with no cases of severe toxicity. GI side effects were reported in 95 patients (45.7%). MTX was permanently discontinued in 24 patients (11.5%) due to hepatotoxicity, in 2 patients (1.0%) due to myelotoxicity, and in 35 patients (16.8%) due to GI side effects. The incidence density of AEs was 0.25 per person-year, with a total of 480 events across 1908 person-years. Female sex (RR 1.4, 95% CI [1.12–1.78], p=0.004) and MTX dose (RR 0.9, 95% CI [0.89– 0.97], p=0.002) were significant predictors of hepato- and/or myelotoxicity. Female sex (RR 1.5, 95% CI [1.17–1.97], p=0.002) and subcutaneous administration of MTX (RR 0.5, 95% CI [0.41–0.73], p<0.01) were significant predictors of GI AEs. Conclusion Our findings indicate that severe MTX-induced AEs in paediatric IBD are uncommon, and that MTX-related AEs rarely necessitate therapy cessation. Female sex, MTX dosage, and subcutaneous administration were significant predictors of MTX-induced AEs.

BACKGROUND: The prognosis of pediatric onset inflammatory bowel disease (IBD) remains uncertain. We examined the overall and site-specific cancer risk among pediatric onset IBD patients as compared to non-IBD individuals from the general population. METHODS: Based on diagnoses from the Danish National Patient Register, we established a nationwide cohort (1977–2014) including all individuals with an IBD diagnosis before the age of 18 (n = 4,221) and 42,210 randomly selected age and sex matched individuals from the general population. The risk of cancer was determined by using Cox proportional hazard regression. RESULTS: During 59,563 person-years of follow-up, 126 of 4,221 pediatric onset IBD patients developed cancer (2.1 cases per 1,000 person-years) as compared to 554 of 42,210 non-IBD individuals (1.0 case per 1,000 person-years). Accordingly, the hazard ratio (HR) of any cancer was 2.16 (95% CI, 1.77–2.62). When examining site-specific cancers, the risk was significantly increased for non-melanoma skin: HR, 2.21 (95% CI, 1.41–3.46), liver: HR, 32.83 (95% CI, 9.23–116.78), small bowel, mouth, upper gastrointestinal: HR, 8.4 (95% CI, 2.70–26.14) and colorectal cancer: HR, 18.26 (95% CI, 9.16–36.39). Males with pediatric onset IBD had a significantly higher risk of cancer than females: HR, 3.17 (95% CI, 2.33–4.29) vs 1.71 (95% CI, 1.32–2.21). A slightly higher risk of cancer was observed for Crohn's disease patients than for ulcerative colitis patients: HR, 2.45 (95% CI, 1.82–3.30) vs 1.96 (95% CI, 1.51–2.55). CONCLUSION(S): In this nationwide cohort study, individuals with pediatric IBD had significantly increased risk of cancer, especially liver, small bowel, mouth, upper gastrointestinal, and colorectal cancer, but absolute numbers were low. The impact of chronic inflammation, respectively, IBD treatments on cancer risk in early onset IBD merits further investigation.

Pediatric inflammatory bowel disease (PIBD) has traditionally been prevalent in Western regions, but its incidence is rising globally, particularly in pediatric cases. Our study, conducted in Sri Lanka, a developing...

Inflammatory bowel disease (IBD) manifests as a complex disease resulting from gene–environment interactions or as a monogenic disease resulting from deleterious mutations. While monogenic IBD is predominantly pediatric, only one-quarter of complex IBD is pediatric. In this study, we were the first to systematically compare genetic architecture between monogenic and complex pediatric and adult IBD on genetic and molecular pathway levels. Genes reported as causal for monogenic pediatric IBD and related syndromes and as risk factors for pediatric and adult complex IBD were analyzed using CytoScape and ClueGO software tools to elucidate significantly enriched Gene Ontology (GO) terms. Despite the small overlap (seven genes) between monogenic IBD genes (85) and complex IBD loci (240), GO analysis revealed several enriched GO terms shared between subgroups (13.9%). Terms Th17 cell differentiation and Jak/STAT signaling were enriched in both monogenic and complex IBD subgroups. However, primary immunodeficiency and B-cell receptor signaling pathway were specifically enriched only for pediatric subgroups, confirming existing clinical observations and experimental evidence of primary immunodeficiency in pediatric IBD patients. In addition, comparative analysis identified patients below 6 years of age to significantly differ from complex pediatric and adult IBD and could be considered a separate entity.

Methotrexate injection site reactions: Case report and literature review

Methotrexate (MTX) intolerance is defined as gastrointestinal and behavioral symptoms occurring before or after MTX administration that may lead to treatment discontinuation. The aim of this study was to determine prevalence of MTX intolerance in pediatric inflammatory bowel disease (IBD) using the Methotrexate Intolerance Severity Score developed in rheumatology and to identify risk factors for MTX intolerance. Patients with pediatric IBD followed in the IBD clinic of Sainte Justine Hospital who had received MTX for IBD between 2004 and 2016 and were still actively on MTX were invited to fill out the Methotrexate Intolerance Severity Score questionnaire. A cutoff score of ≥6 points was used to define MTX intolerance, with at least one point for anticipatory, associative or behavioral items. Among 102 pediatric patients with IBD, 32 (31%) patients reported symptoms of MTX intolerance. Using a multivariable logistic regression model, factors that were associated with having symptoms of MTX intolerance were female sex (odds ratio 4.31 [95% confidence interval, 1.37-13.60], P = 0.01), receiving a dose of MTX higher than 20 mg/wk at the time of the questionnaire (odds ratio 4.06 [95% confidence interval, 1.30-12.70], P = 0.02), and having active disease according to Physician's Global Assessment (odds ratio 3.44 [95% confidence interval, 1.15-10.26], P = 0.03). Prophylactic prescription of antiemetics and folic acid did not prevent symptoms of MTX intolerance. Symptoms of MTX intolerance are frequent in pediatric IBD. The Methotrexate Intolerance Severity Score questionnaire could help better recognition of these symptoms. Identification of risk factors could have important implications for the success of treatment.

In recent years, microbes and their metabolites are increasingly recognised as key players in the pathogenesis of a wide range of gastrointestinal disorders, such as inflammatory bowel disease (IBD), colorectal cancer, irritable bowel syndrome, and coeliac disease, but also diseases outside the gastrointestinal tract.1, 2 A relatively novel topic in the field of gut metabolomics is the study of faecal volatile organic compounds (VOCs). VOCs are carbon-based molecules and their chemical composition allows for vaporisation at room temperature. They are therefore released as gases from various matrices, such as blood, urine, or faeces, and are responsible for the odour of a substance. In the gut, these compounds primarily result from the metabolic activities of gut microbiota and the intestinal mucosa.3 Alterations in VOC profiles have been described as indicative of various intestinal diseases, including IBD, where specific changes in microbiota composition and diversity, reflected by changes in VOC-profiles, correlate with disease activity.4 Belnour et al. recently conducted a study in a population consisting of 132 case/control pairs of children with IBD and children with gastrointestinal symptoms without IBD.5 Their aim was to compare faecal VOC profiles between both groups, and to assess the relation of faecal VOCs with disease phenotype, localisation, severity, and response to treatment. VOCs were analysed through gas chromatography-mass spectrometry (GC-MS). They observed significantly decreased mean abundance of 43.6% of 62 measured faecal VOCs in IBD patients compared to controls, which is in accordance with the microbial dysbiosis linked with IBD in literature. Propan-1-ol, phenol, and oct-1-en-3-ol, all being alcohols, were the most distinctive VOCs in children with IBD compared to controls. The first two are products of amino acid degradation (threonine, and tyrosine and tryptophan, respectively) by Enterobacteriaceae and Clostridium species, which are often more abundant in IBD.6 The associated amino acids themselves are also linked to gut inflammation.7 The gut microbiome and metabolome have gained scientific interest due to the ongoing quest for new non-invasive biomarkers. Currently, the most used non-invasive biomarker for the detection and monitoring of IBD is faecal calprotectin (FCP), which is characterised by a high sensitivity for identifying disease activity and luminal inflammation, but suffers from low specificity. The reliance on FCP in clinical practice often leads to unnecessary endoscopies which are especially burdensome for children. Consequently, there is a need for novel more accurate non-invasive biomarkers. Belnour et al.'s finding that faecal VOCs could differentiate children with IBD from those with gastrointestinal symptoms without IBD, is significant and aligns with recent literature.8 However, as the authors note, these findings merely provide insights into the pathogenesis of paediatric IBD, and further research is warranted to develop a clinical biomarker. Another critical issue in managing IBD is predicting disease severity and response to therapy. In paediatric IBD, therapeutic guidelines regularly recommend a step-up approach. At baseline, predicting which patients will develop severe disease in the disease course and could benefit from early treatment escalation is challenging. The observation of Belnour et al. of differences in faecal VOC profiles between various states of disease severity and treatment responses is of importance. It highlights the complex pathogenesis of IBD and underscores the need for personalised medical approaches due to the disease's heterogeneity. Advantages of VOC analysis include its speed and relatively low costs. However, challenges include the influence of environmental factors, especially dietary intake, the lack of standardised sampling, storage and handling protocols, and the variety in used analytical techniques.9 GC-MS is considered the gold standard for VOC analysis,10 which separates complex compounds in a GC column, ionises and further separates in the MS column based on mass and transportation time. GC-MS is highly accurate and can identify specific VOCs on molecular level, but is the most expensive, high-maintenance and needs trained personnel to use. Electronic noses (eNoses) are more accessible in terms of costs and time. This technique is based on pattern-recognition of VOC mixtures, allowing for identification of disease-specific VOC patterns, but cannot measure individual VOCs. Though the clinical implementation of faecal VOC analysis is still distant, it holds promise as a potential novel non-invasive biomarker in (paediatric) IBD. Endoscopies will as yet remain necessary for diagnosing IBD to obtain information on disease phenotype, localisation and severity, but faecal VOCs could possibly support to select which patients presenting with gastrointestinal symptoms require endoscopy for suspected IBD diagnosis, given the limited specificity of FCP. Future research should focus on identifying specific VOCs and validating previous results in larger cohorts. The first step however is standardising and refining measurement methodologies to overcome variability in sampling and analysis. The authors have no conflicts of interest to declare. Data sharing is not applicable to this article as no new data were created or analyzed in this study.

Pediatric-onset inflammatory bowel disease (IBD) is characterized by distinct phenotypic differences compared to adult-onset IBD. This raises the question whether early (pediatric) onset IBD represents the same disease process occurring in adults but merely at an earlier age or does IBD in children have a very different etiology and pathogenesis but with the same clinical presentation as adults. The use of techniques such as whole genome association studies to perform broad, unbiased screening for the contributions of common genetic variations to complex disease has rapidly assisted in the identification of several novel susceptibility loci associated with pediatric-onset Crohn's disease such as IL23R and ATG16L1. These genes join the already confirmed IBD susceptibility genes such as NOD2/CARD15, IBD5, and DLG5. Therefore, there is hope that advances in the field of clinical and molecular genetics will assist in answering the fundamental question of whether pediatric IBD has a different etiology and pathogenesis compared to adult IBD. This review examines the current status of clinical and molecular genetics of pediatric IBD, and highlights the differences between pediatric and adult IBD in disease phenotypes and genotypes. Finally, the future directions of genetic investigations in pediatric IBD are discussed.

The significance of hypergammaglobulinemia as a phenotypic feature of inflammatory bowel disease is unknown. Thus, we aimed to analyze the magnitude and significance of hypergammaglobulinemia in newly diagnosed pediatric inflammatory bowel disease patients. The medical records of 296 pediatric onset inflammatory bowel disease patients who were evaluated from 2002 to 2015 were retrospectively reviewed. Patients with recorded immunoglobulin G (IgG) levels were categorized as either normal or high IgG levels at diagnosis. Baseline characteristics included age at onset, sex, severity indices, laboratory data, extraintestinal manifestations, endoscopic findings, and anthropometric measurements. Of 184 subjects [mean age, 13.2±2.8 years; 105 (60%) males] with recorded IgG levels, 129 (70%) had Crohn disease, 46 (25%) had ulcerative colitis, and 9 (5%) had unclassified inflammatory bowel disease. Overall, 46 patients (25%) had hypergammaglobulinemia, including 30 (23%) with Crohn disease, 14 (30%) with ulcerative colitis, and 2 (22%) with unclassified disease. Hypergammaglobulinemia was associated with the female sex (55% vs. 35%; p=0.03) and extraintestinal manifestations (70% vs. 10%; p<0.0001), including arthritis, skin disorders, and primary sclerosing cholangitis but not with arthralgia. It was also associated with corticosteroid induction (68% vs. 45%; p=0.02) and maintenance with an immunomodulator (61% vs. 21%; p=0.0001) after diagnosis. In ulcerative colitis patients, hypergammaglobulinemia was associated with a high pancolitis prevalence (p=0.002). Hypergammaglobulinemia is a marker of extraintestinal manifestations in pediatric inflammatory bowel disease and may assist in distinguishing arthritis from arthralgia.

THU0161 ORAL VERSUS SUBCUTANEOUS METHOTREXATE IN RECENTLYDIAGNOSED RHEUMATOID ARTHRITIS: DO WE GET THE SAME RESULTS?

: The objective of the present study was to quantify the national pediatric inpatient inflammatory bowel disease (IBD) burden in terms of the number of IBD-related hospitalizations, the number of days spent in the hospital, and hospitalization costs. : Hospitalizations for children and adolescents 20 years and younger with a primary diagnosis of either Crohn disease (CD) or ulcerative colitis (UC) were selected from the 2006 Kids' Inpatient Database (KID). Length of the hospital stay in days (LOS) and charges for the hospitalization were found directly in the Kids' Inpatient Database, and cost was calculated using the hospital's cost-to-charge ratio. Predictor variables included patient characteristics, such as age and severity of illness, and hospital characteristics. Ordinary-least-squares regressions were developed and estimated to explain hospitalization costs. : In 2006, there were 10,777 IBD-related hospitalizations. The total and mean costs for CD were $66.3 million and $10,176 (95% confidence interval [CI] $9647-$10,705), and for UC were $48.6 million and $11,836 (95% CI $10,760-$12,912). For CD, 0- to 5-year-old patients had the highest mean LOS (8.10, 95% CI 5.53-10.67, days) and mean cost ($13,894, 95% CI $9053-$18,735), whereas, for UC, 11- to 15-year-old patients had the highest mean LOS (7.49, 95% CI 6.88-8.10, 95% CI 5.53-10.67, days) and mean cost ($13,407, 95% CI $11,704-$15,110). : For a pediatric disease with a rather low prevalence rate, the estimated annual inpatient pediatric burden of IBD is a sizeable $152.4 million (2010 US$) and 64,985 days spent in the hospital. As medications and outpatient treatments improve for the treatment of IBD, there is an opportunity for significant reduction in inpatient burden.