Laura Kassoumeri

Association of the 5-aminoimidazole-4-carboxamide ribonucleotide transformylase gene with response to methotrexate in juvenile idiopathic arthritis

Objectives Methotrexate (MTX) is the mainstay treatment for juvenile idiopathic arthritis (JIA), however approximately 30% of children will fail to respond to the drug. Identification of genetic predictors of response to MTX would be invaluable in developing optimal treatment strategies for JIA. Using a candidate gene approach, single nucleotide polymorphisms (SNPs) within genes in the metabolic pathway of MTX, were investigated for association with response to treatment in JIA cases. Methods Tagging SNPs were selected across 13 MTX metabolic pathway genes and were genotyped using Sequenom genotyping technology in subjects recruited from the Sparks Childhood Arthritis Response to Medication Study. Response to MTX was defined using the American College of Rheumatology (ACR) paediatric response criteria and SNP genotype frequencies were compared between the worst and best responders (ACR-Ped70) to MTX. An independent cohort of US JIA cases was available for validation of initial findings. Results One SNP within the inosine triphosphate pyrophosphatase gene (ITPA) and two SNPs within 5-aminoimidazole-4-carboxamide ribonucleotide transformylase gene (ATIC) were significantly associated with a poor response to MTX. One of the ATIC SNPs showed a trend towards association with MTX response in an independent cohort of US JIA cases. Meta-analysis of the two studies strengthened this association (combined p value=0.002). Conclusions This study presents association of a SNP in the ATIC gene with response to MTX in JIA. There is now growing evidence to support a role of the ATIC gene with response to MTX treatment. These results could contribute towards a better understanding of and ability to predict MTX response in JIA.

A subgroup of juvenile idiopathic arthritis patients who respond well to methotrexate are identified by the serum biomarker MRP8/14 protein

OBJECTIVES In JIA there is an unmet need for biomarkers with which to identify patients who will respond well to MTX. The aim of this study was to define the prognostic value of baseline serum proteins and clinical variables in response to MTX to help inform the clinician at time of diagnosis whether the patient is likely to respond well to MTX. METHODS JIA patients were recruited into the Childhood Arthritis Response to Medication Study (CHARMS). Clinical data and venous blood were collected before administration of MTX and at follow-up. MRP8/14 and inflammatory cytokines were measured by ELISA and multiplex immunoassay, respectively. CRP and ESR were measured as part of routine clinical assessment. To explore which baseline factors might predict successful treatment, binary logistic regression models were fitted for outcome. RESULTS High disease activity (high serum MRP8/14, active joint count or physicians score) pre-MTX was observed in a subgroup of patients with a better response to therapy. In a multivariable analysis, after accounting for MRP8/14 at baseline, no other factors were independently significantly associated with outcome. Patients with baseline MRP8/14 >3000 ng/ml were more likely to respond to MTX at ACR50 or better: odds ratio 16.07 (95% CI 2.00, 129.3). CONCLUSION We have demonstrated that high levels of baseline serum MRP8/14 have prognostic value in predicting a subgroup of patients whose arthritis will improve on MTX. Routine collection of serum prior to the start of medication would be a valuable step in collaborative validation of such biomarkers.

Generation of novel pharmacogenomic candidates in response to methotrexate in juvenile idiopathic arthritis: correlation between gene expression and genotype.

Objectives Little is known about the mechanisms of efficacy of methotrexate (MTX) in childhood arthritis, or genetic influences upon response to MTX. The aims of this study were to use gene expression profiling to identify novel pathways/genes altered by MTX and then investigate these genes for genotype associations with response to MTX treatment. Methods Gene expression profiling before and after MTX treatment was performed on 11 children with juvenile idiopathic arthritis (JIA) treated with MTX, in whom response at 6 months of treatment was defined. Genes showing the most differential gene expression after the treatment were selected for single nucleotide polymorphism (SNP) genotyping. Genotype frequencies were compared between nonresponders and responders (ACR-Ped70). An independent cohort was available for validation. Results Gene expression profiling before and after MTX treatment revealed 1222 differentially expressed probes sets (fold change >1.7, P<0.05) and 1065 when restricted to full responder cases only. Six highly differentially expressed genes were analyzed for genetic association in response to MTX. Three SNPs in the SLC16A7 gene showed significant association with MTX response. One SNP showed validated association in an independent cohort. Conclusion This study is the first, to our knowledge, to evaluate gene expression profiles in children with JIA before and after MTX, and to analyze genetic variation in differentially expressed genes. We have identified a gene, which may contribute to genetic variability in MTX response in JIA, and established as proof of principle that genes that are differentially expressed at mRNA level after drug administration may also be good candidates for genetic analysis.

Genome-wide data reveal novel genes for methotrexate response in a large cohort of juvenile idiopathic arthritis cases.

Clinical response to methotrexate (MTX) treatment for children with juvenile idiopathic arthritis (JIA) displays considerable heterogeneity. Currently, there are no reliable predictors to identify non-responders: earlier identification could lead to a targeted treatment. We genotyped 759 JIA cases from the UK, the Netherlands and Czech Republic. Clinical variables were measured at baseline and 6 months after start of the treatment. In Phase I analysis, samples were analysed for the association with MTX response using ordinal regression of ACR-pedi categories and linear regression of change in clinical variables, and identified 31 genetic regions (P<0.001). Phase II analysis increased SNP density in the most strongly associated regions, identifying 14 regions (P<1 × 10−5): three contain genes of particular biological interest (ZMIZ1, TGIF1 and CFTR). These data suggest a role for novel pathways in MTX response and further investigations within associated regions will help to reach our goal of predicting response to MTX in JIA.

Mothers’ reports of the difficulties that their children experience in taking methotrexate for Juvenile Idiopathic Arthritis and how these impact on quality of life

BackgroundChildren who take methotrexate for juvenile idiopathic arthritis may experience side effects, including nausea and vomiting, leading to anticipatory nausea in some children, and fear of injections or blood tests. The aim of this study was to examine the prevalence and extent of these difficulties and their impact on quality of life.MethodsParticipants were mothers of children with JIA who were currently taking methotrexate (MTX). Mothers completed a questionnaire about MTX that was developed for the study, two questions from the treatment subscale of the Pediatric Quality of Life Inventory (PedsQL) Rheumatology scale to assess needle-related problems and the Child Health Questionnaire 50-item parent version (CHQ-PF50) to assess health-related quality of life (HRQoL).Results171 mothers participated in the study. More than half of children were reported to have experienced one or more of: nausea or vomiting after taking MTX, anticipatory nausea, fear of blood tests or fear of injections. There was no significant difference in reported rates of sickness or needle-related problems between MTX responders (ACR70 or above), partial responders (ACR30 or ACR50) and non-responders. In multivariate analyses, variables that were significant independent predictors of one or more MTX-related difficulties included younger age, taking MTX subcutaneously and having a larger number of currently active joints. Feeling sick after taking MTX was a significant independent predictor of poorer scores on the physical summary scale of the CHQ-PF50. Anxiety about injections and feeling sick after taking MTX were significant independent predictors of poorer scores on the psychosocial summary scale.ConclusionsDifficulties in taking MTX are experienced by a significant proportion of children with JIA and these may have an adverse impact on HRQoL. Approaches to help minimize these difficulties are required.

Methotrexate in childhood arthritis: effects on gene expression

Background Methotrexate (MTX) is the standard disease modifying therapy for children with juvenile idiopathic arthritis (JIA), inducing remission in ~65% of cases. There are currently no known predictors which classify who will successfully respond to MTX therapy nor those who will remain well following MTX withdrawal. Mechanisms of MTX action in JIA are at present unclear: genetic and gene expression profiling would provide novel insights into the biology of this therapy.

Can inflammatory markers predict response to methotrexate in JIA? Results from the CHARM study

Background Juvenile idiopathic arthritis (JIA) is the most common childhood rheumatological disease with an incidence of 1 in 1000. Methotrexate is the primary DMARD given to patients with JIA but approximately 30% of children fail to respond. The SPARKS CHARM study enrolls patients with JIA about to start MTX with the aim to discover predictors of response to MTX, to distinguish patients who will respond well to MTX from non-responders.

Are parents' views about their child's treatment for juvenile idiopathic arthritis (JIA) related to evaluations of their child's quality of life (QoL)? – SPARKS CHARM study

Methods Mothers or fathers of 143 children aged ≥ 5 with JIA, completed questionnaires about general beliefs regarding treatment (Treatment Representations Inventory, subscales – treatment value, concerns, cure and decision satisfaction) and specific beliefs regarding benefits and difficulties in taking MTX. Core outcome variables (COV), except ESR, were used to provide information on disease severity. Data were analysed by correlations followed by multiple linear regression with QoL, assessed by the Child Health Questionnaire (CHQ), as the dependent variable.

Characterising inflammatory markers in two childhood autoimmune diseases (JIA and JDM) pre and post methotrexate

Background Methotrexate (MTX) is the first line of therapy for patients with juvenile idiopathic arthritis (JIA) and juvenile dermatomyositis (JDM). The mechanisms of action of MTX in childhood autoimmunity are not fully elucidated. The primary target sites of inflammation of JIA and JDM i.e. joint and muscle, respectively do not represent sites from which samples can be easily obtained to monitor inflammatory markers. In contrast peripheral blood is accessible and can be obtained at time of routine clinical screen. We hypothesized that changes in peripheral blood of patients would be informative in monitoring disease and understanding inflammatory pathways that are modulated by MTX.

Investigating which variables from the core outcome variables in juvenile idiopathic arthritis (JIA) are the best predictors of classification as a responder to treatment with methotrexate (MTX)

Methods Using a dataset of 410 JIA patients treated with MTX, (provided by PRINTO) 3 sets of logistic regression analyses were conducted, one at each classification level, to determine the likelihood of a classification of improvement. For each level a series of univariate logistic analyses were conducted to identify, from the six COV, individually significant (p < 0.05) predictors of improvement. These variables were entered into a stepwise multivariate logistic analysis to identify independent predictors of classification (p < 0.01) at each level.