Therapeutic drug monitoring of methotrexate in patients with Crohn's disease.

BACKGROUND: Therapeutic drug monitoring (TDM) has the potential to improve efficacy and diminish side effects. Measuring methotrexate-polyglutamate (MTX-PG) in erythrocytes might enable TDM for methotrexate in patients with Crohn's disease (CD). AIM: To investigate the relationship between MTX-PGs and methotrexate drug survival, efficacy and toxicity METHODS: In a multicentre prospective cohort study, patients with CD starting subcutaneous methotrexate without biologics were included and followed for 12 months. Primary outcome was subcutaneous methotrexate discontinuation or requirement for step-up therapy. Secondary outcomes included faecal calprotectin (FCP), Harvey Bradshaw Index (HBI), hepatotoxicity and gastrointestinal intolerance. Erythrocyte MTX-PGs were analysed at weeks 8, 12, 24 and 52 or upon treatment discontinuation. RESULTS: We included 80 patients with CD (mean age 55 ± 13y, 35% male) with a median FCP of 268 µg/g (IQR 73-480). After the 12-month visit, 21 patients (26%) were still on subcutaneous methotrexate monotherapy. Twenty-one patients stopped because of disease activity, 29 because of toxicity, and four for both reasons. Five patients ended study participation or stopped methotrexate for another reason. A higher MTX-PG3 concentration was associated with a higher rate of methotrexate drug survival (HR 0.86, 95% CI 0.75-0.99), lower FCP (ß -3.7, SE 1.3, p < 0.01) and with biochemical response (FCP ≤250 if baseline >250 µg/g; OR 1.1, 95% CI 1.0-1.3). Higher MTX-PGs were associated with less gastrointestinal intolerance. There was no robust association between MTX-PGs and HBI or hepatotoxicity. CONCLUSIONS: Higher MTX-PG3 concentrations are related to better methotrexate drug survival and decreased FCP levels. Therefore, MTX-PG3 could be used for TDM if a target concentration can be established.

Pharmacokinetics of oral and subcutaneous methotrexate in red and white blood cells in patients with early rheumatoid arthritis: the methotrexate monitoring trial.

OBJECTIVE: To investigate the pharmacokinetics of methotrexate polyglutamate (MTX-PG) accumulation in red blood cells (RBCs) and peripheral blood mononuclear cells (PBMCs) in patients with early rheumatoid arthritis (RA) after oral and subcutaneous MTX treatment. METHODS: In a clinical prospective cohort study (Methotrexate Monitoring study), newly diagnosed patients with RA were randomised for oral or subcutaneous MTX. At 1, 2, 3 and 6 months after therapy initiation, blood was collected and RBCs and PBMCs were isolated. MTX-PG1-6 concentrations were determined by mass spectrometry methods using stable isotopes of MTX-PG1-6 as internal standards. RESULTS: 43 patients (mean age: 58.5 years, 77% female) were included. PBMCs and RBCs revealed disparate pharmacokinetic profiles in both absolute MTX-PG accumulation levels and distribution profiles. Intracellular MTX-PG accumulation in PBMCs was significantly (p<0.001) 10-fold to 20-fold higher than RBCs at all time points, regardless of the administration route. MTX-PG distribution in PBMCs was composed of mostly MTX-PG1 (PG1>PG2>PG3). Remarkably, the distribution profile in PBMCs remained constant over 6 months. RBCs accumulated mainly MTX-PG1 and lower levels of MTX-PG2-5 at t=1 month. After 3 months, MTX-PG3 was the main PG-moiety in RBCs, a profile retained after 6 months of MTX therapy. Subcutaneous MTX administration results in higher RBC drug levels than after oral administration, especially shortly after treatment initiation. CONCLUSIONS: This is the first study reporting disparate MTX-PG accumulation profiles in RBCs versus PBMCs in newly diagnosed patients with RA during 6 months oral or subcutaneous MTX administration. This analysis can contribute to improved MTX therapeutic drug monitoring for patients with RA. TRIAL REGISTRATION NUMBER: NTR 7149.

A meta-analysis of methotrexate polyglutamates in relation to efficacy and toxicity of methotrexate in inflammatory arthritis, colitis and dermatitis.

AIMS: In immune-mediated inflammatory diseases (IMIDs), early symptom control is a key therapeutic goal. Methotrexate (MTX) is the first-line treatment across IMIDs. However, MTX is underutilized and suboptimally dosed, partly due to the inability of making individualized treatment decisions through therapeutic drug monitoring (TDM). To implement TDM in clinical practice, establishing a relationship between drug concentration and disease activity is paramount. In this meta-analysis, we investigated the relationship between concentrations of MTX polyglutamates (MTX-PG) in erythrocytes and efficacy as well as toxicity across IMIDs. METHODS: Studies analysing MTX-PG in relation to disease activity and/or toxicity were included for inflammatory arthritis (rheumatoid [RA] and juvenile idiopathic arthritis [JIA]), inflammatory bowel disease (Crohn's and ulcerative colitis) and dermatitis (psoriasis and atopic dermatitis). Meta-analyses were performed resulting in several summary effect measures: regression coefficient (ß), correlation coefficient and mean difference (of MTX-PG in responders vs. nonresponders) for IMIDs separately and collectively. RESULTS: Twenty-five studies were included. In RA and JIA, higher MTX-PG was significantly associated with lower disease activity at 3 months (ß: -0.002; 95% confidence interval [CI]: -0.004 to -0.001) and after 4 months of MTX use (ß: -0.003; 95% CI: -0.005 to -0.002). Similarly, higher MTX-PG correlated with lower disease activity in psoriasis (R: -0.82; 95% CI: -0.976 to -0.102). Higher MTX-PG was observed in RA, JIA and psoriasis responders (mean difference: 5.2 nmol/L MTX-PGtotal ; P < .01). CONCLUSION: We showed that higher concentrations of erythrocyte MTX-PG were associated with lower disease activity in RA, JIA and psoriasis. These findings are an important step towards implementation of TDM for MTX treatment across IMIDs.

Complex Machine-Learning Algorithms and Multivariable Logistic Regression on Par in the Prediction of Insufficient Clinical Response to Methotrexate in Rheumatoid Arthritis.

The goals of this study were to examine whether machine-learning algorithms outperform multivariable logistic regression in the prediction of insufficient response to methotrexate (MTX); secondly, to examine which features are essential for correct prediction; and finally, to investigate whether the best performing model specifically identifies insufficient responders to MTX (combination) therapy. The prediction of insufficient response (3-month Disease Activity Score 28-Erythrocyte-sedimentation rate (DAS28-ESR) > 3.2) was assessed using logistic regression, least absolute shrinkage and selection operator (LASSO), random forest, and extreme gradient boosting (XGBoost). The baseline features of 355 rheumatoid arthritis (RA) patients from the "treatment in the Rotterdam Early Arthritis CoHort" (tREACH) and the U-Act-Early trial were combined for analyses. The model performances were compared using area under the curve (AUC) of receiver operating characteristic (ROC) curves, 95% confidence intervals (95% CI), and sensitivity and specificity. Finally, the best performing model following feature selection was tested on 101 RA patients starting tocilizumab (TCZ)-monotherapy. Logistic regression (AUC = 0.77 95% CI: 0.68-0.86) performed as well as LASSO (AUC = 0.76, 95% CI: 0.67-0.85), random forest (AUC = 0.71, 95% CI: 0.61 = 0.81), and XGBoost (AUC = 0.70, 95% CI: 0.61-0.81), yet logistic regression reached the highest sensitivity (81%). The most important features were baseline DAS28 (components). For all algorithms, models with six features performed similarly to those with 16. When applied to the TCZ-monotherapy group, logistic regression's sensitivity significantly dropped from 83% to 69% (p = 0.03). In the current dataset, logistic regression performed equally well compared to machine-learning algorithms in the prediction of insufficient response to MTX. Models could be reduced to six features, which are more conducive for clinical implementation. Interestingly, the prediction model was specific to MTX (combination) therapy response.

Validation of a Prognostic Multivariable Prediction Model for Insufficient Clinical Response to Methotrexate in Early Rheumatoid Arthritis and Its Clinical Application in Evidencio.

INTRODUCTION: Methotrexate (MTX) constitutes the first-line therapy in rheumatoid arthritis (RA), yet approximately 30% of the patients do not benefit from MTX. Recently, we reported a prognostic multivariable prediction model for insufficient clinical response to MTX at 3 months of treatment in the treatment in the Rotterdam Early Arthritis Cohort (tREACH), including baseline predictors: Disease activity score 28 (DAS28), Health Assessment Questionnaire (HAQ), erythrocyte folate, single-nucleotide polymorphisms (SNPs; ABCB1, ABCC3), smoking, and BMI. The purpose of the current study was (1) to externally validate the model and (2) to enhance the model's clinical applicability. METHODS: Erythrocyte folate and SNPs were assessed in 91 early disease-modifying antirheumatic drug (DMARD)-naïve RA patients starting MTX in the external validation cohort (U-Act-Early). Insufficient response (DAS28 > 3.2) was determined after 3 months and non-response after 6 months of therapy. The previously developed prediction model was considered successfully validated in the U-Act-Early (validation cohort) if the area under the curve (AUC) of the receiver operating characteristic (ROC) was not significantly lower than in the tREACH (derivation cohort). RESULTS: The AUCs in U-Act-Early at three and 6 months were 0.75 (95% CI 0.64-0.85) and 0.71 (95% CI 0.60-0.82) respectively, similar to the tREACH. Baseline DAS28 > 5.1 and HAQ > 0.6 were the strongest predictors. The model was simplified by excluding the SNPs, while still classifying 73% correctly. Furthermore, interaction terms between BMI and HAQ and BMI and erythrocyte folate significantly improved the model increasing correct classification to 75%. Results were successfully implemented in Evidencio online platform assisting clinicians in shared decision-making to intensify treatment when appropriate. CONCLUSIONS: We successfully externally validated our recently reported prediction model for MTX non-response and enhanced its clinical application thus enabling its evaluation in a clinical trial. TRIAL REGISTRATION: The U-Act-Early is registered at ClinicalTrials.gov. number: NCT01034137. tREACH is registered retrospectively at ISRCTN registry, number: ISRCTN26791028 at 23 August 2007.

Development and validation of a prognostic multivariable model to predict insufficient clinical response to methotrexate in rheumatoid arthritis.

OBJECTIVE: The objective was to predict insufficient response to 3 months methotrexate (MTX) in DMARD naïve rheumatoid arthritis patients. METHODS: A Multivariable logistic regression model of rheumatoid arthritis patients starting MTX was developed in a derivation cohort with 285 patients starting MTX in a clinical multicentre, stratified single-blinded trial, performed in seven secondary care clinics and a tertiary care clinic. The model was validated in a validation cohort with 102 patients starting MTX at a tertiary care clinic. Outcome was insufficient response (disease activity score (DAS)28 >3.2) after 3 months of MTX treatment. Clinical characteristics, lifestyle variables, genetic and metabolic biomarkers were determined at baseline in both cohorts. These variables were dichotomized and used to construct a multivariable prediction model with backward logistic regression analysis. RESULTS: The prediction model for insufficient response in the derivation cohort, included: DAS28>5.1, Health Assessment Questionnaire>0.6, current smoking, BMI>25 kg/m2, ABCB1 rs1045642 genotype, ABCC3 rs4793665 genotype, and erythrocyte-folate<750 nmol/L. In the derivation cohort, AUC of ROC curve was 0.80 (95%CI: 0.73-0.86), and 0.80 (95%CI: 0.69-0.91) in the validation cohort. Betas of the prediction model were transformed into total risk score (range 0-8). At cutoff of ≥4, probability for insufficient response was 44%. Sensitivity was 71%, specificity 72%, with positive and negative predictive value of 72% and 71%. CONCLUSIONS: A prognostics prediction model for insufficient response to MTX in 2 prospective RA cohorts by combining genetic, metabolic, clinical and lifestyle variables was developed and validated. This model satisfactorily identified RA patients with high risk of insufficient response to MTX.

Methotrexate intolerance in oral and subcutaneous administration in patients with juvenile idiopathic arthritis: a cross-sectional, observational study.

OBJECTIVES: Methotrexate (MTX) is the cornerstone disease-modifying anti-rheumatic drug (DMARD) in juvenile idiopathic arthritis (JIA). In Dutch patients, MTX intolerance occurred frequently and was associated with subcutaneous (SC) administration. The aim of this study was to assess the prevalence of MTX intolerance and its association with the route of administration in a German cohort of JIA patients. METHODS: A cross-sectional study of JIA patients on MTX was performed. Primary outcome was MTX intolerance, which was determined using the validated Methotrexate Intolerance Severity Score (MISS) questionnaire. The prevalence of gastrointestinal adverse effects and MTX intolerance was compared between patients on MTX SC and MTX administered orally (PO). RESULTS: Of 179 JIA patients on MTX, 73 (40.8%) were intolerant. The odds of MTX intolerance were higher in patients using MTX exclusively SC compared to exclusively PO (adjusted odds ratio 3.37 [95% confidence interval 1.19-10.0]). There was strong evidence that the former experienced more behavioural complaints (76.1% vs. 47.4%, p=0.001) and weak evidence that they experienced more abdominal pain after MTX intake (43.5% vs. 27.4%, p=0.056). CONCLUSIONS: The prevalence of MTX intolerance was high and exclusively SC administration of MTX was associated with MTX intolerance and behavioural adverse effects. The prevalence of gastrointestinal adverse effects was at least as high as in patients on MTX PO. The frequently held assumption that SC causes fewer side effects than PO seems unwarranted. Definite answers about the differences between SC and PO administration with respect to safety and efficacy should be obtained by randomised trials.

Methotrexate treatment affects effector but not regulatory T cells in juvenile idiopathic arthritis.

OBJECTIVE: The balance between Treg and effector T cells (Teff) is crucial for immune regulation in JIA. How MTX, the cornerstone treatment in JIA, influences this balance in vivo is poorly elucidated. The aim of this study was to investigate quantitative and qualitative effects of MTX on Treg and Teff in JIA patients during MTX treatment. METHODS: Peripheral blood samples were obtained from JIA patients at the start of MTX and 3 and 6 months thereafter. Treg numbers and phenotypes were determined by flow cytometry and suppressive function in allogeneic suppression assays. Teff proliferation upon stimulation with anti-CD3, activation status and intracellular cytokine production were determined by flow cytometry. Effector cell responsiveness to suppression was investigated in autologous suppression assays. Effector cell cytokines in supernatants of proliferation and suppression assays and in plasma were measured by cytokine multiplex assay. RESULTS: MTX treatment in JIA did not affect Treg phenotype and function. Instead, MTX treatment enhanced, rather than diminished, CD4(+) and CD8(+) T cell proliferation of JIA patients after 6 months of therapy, independent of clinical response. Effector cells during MTX treatment were equally responsive to Treg-mediated suppression. MTX treatment did not attenuate Teff activation status and their capacity to produce IL-13, IL-17, TNF-α and IFN-γ. Similarly to Teff proliferation, plasma IFN-γ concentrations after 6 months were increased. CONCLUSION: This study provides the novel insight that MTX treatment in JIA does not attenuate Teff function but, conversely, enhances T cell proliferation and IFN-γ plasma concentrations in JIA patients.

Prediction of methotrexate intolerance in juvenile idiopathic arthritis: a prospective, observational cohort study.

BACKGROUND: Methotrexate (MTX) is an effective and safe drug in the treatment of juvenile idiopathic arthritis (JIA). Despite its safety, MTX-related gastrointestinal adverse effects before and after MTX administration, termed MTX intolerance, occur frequently, leading to non-compliance and potentially premature MTX termination. The aim of this study was to construct a risk model to predict MTX intolerance. METHODS: In a prospective JIA cohort, clinical variables and single nucleotide polymorphisms were determined at MTX start. The Methotrexate Intolerance Severity Score was employed to measure MTX intolerance in the first year of treatment. MTX intolerance was most prevalent at 6 or 12 months after MTX start, which was defined as the outcome for the prediction model. The model was developed in 152 patients using multivariable logistic regression analysis and subsequently internally validated using bootstrapping. RESULTS: The prediction model included the following predictors: JIA category, antinuclear antibody, parent/patient assessment of pain, Juvenile Arthritis Disease Activity Score-27, thrombocytes, alanine aminotransferase and creatinine. The model classified 77.5% of patients correctly, and 66.7% of patients after internal validation by bootstrapping. The lowest predicted risk of MTX intolerance was 18.9% and the highest predicted risk was 85.9%. The prediction model was transformed into a risk score (range 0-17). At a cut-off of ≥6, sensitivity was 82.0%, specificity 56.1%, positive predictive value was 58.7% and negative predictive value 80.4%. CONCLUSIONS: This clinical prediction model showed moderate predictive power to detect MTX intolerance. To develop into a clinically usable tool, it should be validated in an independent cohort and updated with new predictors. Such an easy-to-use tool could then assist clinicians in identifying patients at risk to develop MTX intolerance, and in turn to monitor them closely and intervene timely in order to prevent the development of MTX intolerance. TRIAL REGISTRATION: ISRCTN register, www.isrctn.com, ISRCTN13524271.

Interpretation of the Juvenile Arthritis Disease Activity Score: responsiveness, clinically important differences and levels of disease activity in prospective cohorts of patients with juvenile idiopathic arthritis.

OBJECTIVES: The objectives of this study were to assess 27-joint Juvenile Arthritis Disease Activity Score (JADAS-27) responsiveness, JADAS-27 changes corresponding to clinically important differences and cut-off scores for low and high disease activity in a large prospective JIA cohort. METHODS: JADAS-27 responsiveness, using effect size and standardized response mean (SRM), and changes in the JADAS-27 corresponding to clinically important differences were determined for clinical improvement (ACRpedi30) and worsening (flare). To assess whether various degrees of change in the JADAS-27 could be used to demonstrate improvement or worsening in individual patients, diagnostic parameters were computed for cut-off score changes. Finally, cut-off scores for low and high disease activity and their diagnostic parameters were determined. RESULTS: In 228 patients with 529 consecutive visits, ACRpedi30 was detected in 109 and flare in 111 visits. Regarding responsiveness, the effect size was 0.93 and SRM was 1.26 for clinical improvement, while for clinical worsening the effect size was 0.65 and SRM was 0.60. Changes in the JADAS-27 corresponding to clinically important difference were -5.5 for improvement and +1.7 for worsening. Cut-off score changes in the JADAS-27 had 65-90% sensitivity and 67-86% specificity for improvement, and 31-64% sensitivity and 89-97% specificity for worsening. The JADAS-27 cut-off score for low disease activity was ≤2.7 with 76% sensitivity and 62% specificity, and the cut-off score for high disease activity was ≥6 with 77% sensitivity and 77% specificity. CONCLUSION: The JADAS-27 had moderate to good responsiveness and was changed by clinically important differences. The JADAS-27 cut-off scores differentiated between low and high disease activity. These JADAS-27 interpretations could be potentially applicable in clinical care and trials.