Methotrexate polyglutamates as a potential marker of adherence to long-term therapy in children with juvenile idiopathic arthritis and juvenile dermatomyositis: an observational, cross-sectional study

Adherence in young people living with juvenile arthritis: A systematic review

Objective

Juvenile idiopathic arthritis (JIA) is one of the leading causes of chronic pain in pediatric patients. Treatment regimens, which are critical to symptom management, can be burdensome, involving medication with potentially aversive side effects and exercise that can cause joint pain. Thus, it is important to examine the barriers and facilitators to adherence in JIA. While systematic reviews exist for rheumatic disease in adults, there has not yet been a synthesis of the literature examining adherence in JIA.

Methods

PsychINFO, PubMed and MEDLINE databases were systematically searched to identify qualitative and quantitative empirical studies that investigate adherence for JIA. Keywords included: patient compliance OR adherence OR persistence; youth OR children OR juvenile OR pediatric OR teen OR child OR adolescent; and rheumatoid arthritis OR idiopathic arthritis OR arthritis. Articles were excluded from the review if they involved non-human or adult samples, were non-experimental (e.g., practice recommendations), were not peer-reviewed, or were not written in English. After abstract selection, 32 articles were included in the analyses.

Results

Adherence to exercise regimens was consistently lower than adherence to medication. Researchers relied heavily on self-report of adherence, which suggests a need for additional research with more objective measures of adherence. Across studies, psychological treatment was not included, so adherence to this treatment component in JIA remains understudied.

Conclusions

Results suggest that future research should target devising and evaluating interventions to improve adherence to exercise and perhaps psychological treatment.

Implications for Impact

To facilitate adherence in JIA, behavioral health providers should focus on building a strong therapeutic alliance between provider and child, fostering positive coping skills in parents and children, and monitoring the parent-child relationship.

Glutathione S-Transferase Gene Polymorphisms as Predictors of Methotrexate Efficacy in Juvenile Idiopathic Arthritis

Because of the unpredictable efficacy of methotrexate (MTX) in the treatment of juvenile idiopathic arthritis (JIA), the possibility of a favourable outcome is reduced in more than 30% of patients. To investigate the possible influence of glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) gene deletion polymorphisms on MTX efficacy in patients with JIA, we determined these polymorphisms in 63 patients with JIA who did not achieve remission and 46 patients with JIA who achieved remission during MTX therapy. No significant differences were observed in the distribution of single GSTM1 or GSTT1 deletion polymorphisms or their combination between the two groups: 58.7% to 63.5%; p = 0.567, 17.4% to 22.2%; p = 0.502, and 13% to 12.7%; p = 0.966, respectively. Our results suggest that GSTM1 and GSTT1 deletion polymorphisms do not influence the efficacy of MTX in patients with JIA. Additional studies are required to determine the possible influence of GST deletion polymorphisms on MTX efficacy in patients with JIA.

Adherence to low-dose methotrexate in children with juvenile idiopathic arthritis using a sensitive methotrexate assay

BACKGROUND

Low-dose weekly methotrexate (MTX) is the mainstay of treatment in juvenile idiopathic arthritis. Unfortunately, a substantial part of patients has insufficient efficacy of MTX. A potential cause of this inadequate response is suboptimal drug adherence. The aim of this study was to assess MTX adherence in juvenile idiopathic arthritis patients by quantification of MTX concentrations in plasma. Secondly, the association between MTX concentrations and either self-reported adherence issues, or concomitant use of biologics was examined.

METHODS

This was a retrospective, observational study using plasma samples from juvenile idiopathic arthritis patients. An ultrasensitive liquid chromatography-tandem mass spectrometry method was developed for quantification of MTX and its metabolite 7-hydroxy-MTX in plasma. The determined MTX plasma concentrations in juvenile idiopathic arthritis patients were compared with corresponding adherence limits, categorising them as either adherent or possibly non-adherent to MTX therapy.

RESULTS

Plasma samples of 43 patients with juvenile idiopathic arthritis were analysed. Adherence to MTX in this population was 88% shortly after initiation of MTX therapy and decreased to 77% after one year of treatment. Teenagers were more at risk for non-adherence (p = 0.002). We could not find an association between MTX adherence with either self-reported adherence issues, nor with the use of concomitant biological treatment (p = 1.00 and p = 0.27, respectively; Fisher's Exact).

CONCLUSIONS

Quantification of MTX in plasma is a feasible and objective method to assess adherence in patients using low-dose weekly MTX. In clinical practice, the use of this method could be a helpful tool for physicians to refute or support suspicion of non-adherence to MTX therapy.

How can we optimize the use of methotrexate to treat pediatric patients with inflammatory skin diseases?

INTRODUCTION

Methotrexate (MTX) is a folic acid antagonist used in clinical practice in oncology and rheumatology, as well as in the treatment of inflammatory skin conditions in children. The low-doses of MTX are commonly used in children for the treatment of many inflammatory and autoimmune conditions, including inflammatory skin diseases, due to its anti-inflammatory and immunomodulatory effects.

AREAS COVERED

This review discusses the possibilities for optimizing the use of methotrexate in the treatment of pediatric patients with inflammatory skin diseases. A thorough search through PubMed and Embase databases was performed to identify relevant literature.

EXPERT OPINION

Clinical observations confirm the high efficacy and safety of low-dose MTX in children with inflammatory skin diseases. Unfortunately, to date there are few studies providing guidelines on the optimal dosage of MTX in children with inflammatory skin diseases; routes of administration; principles of monitoring; and the safety of long-term use of this medication in children. There is still a need for specific recommendations on the safest and most effective dosing and monitoring regimen for children treated with methotrexate for inflammatory skin diseases.

Biomimetic Material for Quantification of Methotrexate Using Sensor Based on Molecularly Imprinted Polypyrrole Film and MWCNT/GCE

This study investigates biomimetic sensors for the detection of methotrexate contaminants in environmental samples. Sensors inspired by biological systems are the focus of this biomimetic strategy. Methotrexate is an antimetabolite that is widely used for the treatment of cancer and autoimmune diseases. Due to the widespread use of methotrexate and its rampant disposal into the environment, the residues of this drug are regarded as an emerging contaminant of huge concern, considering that exposure to the contaminant has been found to lead to the inhibition of some essential metabolic processes, posing serious risks to humans and other living beings. In this context, this work aims to quantify methotrexate through the application of a highly efficient biomimetic electrochemical sensor constructed using polypyrrole-based molecularly imprinted polymer (MIP) electrodeposited by cyclic voltammetry on a glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNT). The electrodeposited polymeric films were characterized by infrared spectrometry (FTIR), scanning electron microscopy (SEM), and cyclic voltammetry (CV). The analyses conducted using differential pulse voltammetry (DPV) yielded a detection limit of 2.7 × 10^-9 mol L^-1 for methotrexate, a linear range of 0.01-125 μmol L^-1, and a sensitivity of 0.152 μA L mol^-1. The results obtained from the analysis of the selectivity of the proposed sensor through the incorporation of interferents in the standard solution pointed to an electrochemical signal decay of only 15.4%. The findings of this study show that the proposed sensor is highly promising and suitable for use in the quantification of methotrexate in environmental samples.

Adherence to metformin in adults with type 2 diabetes: a combined method approach

Background

Medication adherence, one of the most important aspects in the process of optimal medicines use, is unfortunately still a major challenge in modern healthcare, and further research is required into how adherence can be assessed and optimised. The aim of this study was to use a combined method approach of self-report and dried blood spot (DBS) sampling coupled with population pharmacokinetic (PopPK) modelling, to assess adherence to metformin in adult patients with type 2 diabetes. Further aims were to assess metformin exposure levels in patients, determine factors associated with non-adherence with prescribed metformin, and to explore the relationship between adherence and therapeutic outcomes.

Methods

A combined method approach was used to evaluate metformin adherence in patients with type 2 diabetes who had been prescribed metformin for a minimum period of 6 months. Patients were recruited from consultant-led diabetic outpatient clinics at three hospitals in Northern Ireland, UK. Data collection involved self-reported questionnaires [Medication Adherence Report Scale (MARS), Beliefs about Medicines Questionnaire and Centre for Epidemiologic Studies Depression Scale], direct measurement of metformin concentration in DBS samples, and researcher-led patient interviews. The DBS sampling approach was coupled with population pharmacokinetic (PopPK) modelling, which took account of patient characteristics, metformin dosage and type of formulation prescribed (immediate or sustained release).

Results

The proportion of patients considered to be adherent to their prescribed metformin, derived from self-reported MARS scores and metformin concentration in DBS samples, was 61.2% (74 out of 121 patients). The majority (n = 103, 85.1%) of recruited patients had metformin exposure levels that fell within the therapeutic range. However, 17 patients (14.1%) had low exposure to metformin and one patient (0.8%) had undetectable metformin level in their blood sample (non-exposure). Metformin self-administration and use of a purchased adherence pill box significantly increased the probability of a patient being classified as adherent based on logistic regression analysis. Both HbA1c and random glucose levels (representing poor glycaemic control) in the present research were, however, not statistically linked to non-adherence to metformin (P > 0.05).

Conclusions

A significant proportion of participating patients were not fully adherent with their therapy. DBS sampling together with the use of a published PopPK model was a useful, novel, direct, objective approach to estimate levels of adherence in adult patients with type 2 diabetes (61.2%).

Supplementary Information

The online version contains supplementary material available at 10.1186/s40545-022-00457-5.

Current status of therapeutic drug monitoring for methotrexate, imatinib, paclitaxel in China

BACKGROUND

Accurate TDMs of plasma methotrexate, imatinib and paclitaxel assist in the development of optimal therapeutic regimes. This study aims to investigate the current status of methotrexate, imatinib and paclitaxel measurements in China and explore the suitable EQA materials for those drugs.

METHODS

4 processed plasma samples including 2 levels of frozen pooled plasma samples and 2 levels of lyophilized pooled plasma samples were measured in different laboratories using different measurement systems. The inter-laboratory %CV and intra-measurement-system %CV of laboratories were calculated to assess the status of methotrexate, imatinib and paclitaxel measurements. The short-term stability and homogeneity of those processed samples were studied and compared. The relative differences (%) between the results of those two kinds of processed samples were also calculated to determine whether there were significant differences in their matrix effects for various measurement systems.

RESULTS

The mean inter-laboratory %CVs ranged from 12.8% to 15.3%, 14.7% to 19.6% and 56.8% to 81.6% for methotrexate, imatinib and paclitaxel, respectively. The intra-measurement %CV of homogeneous commercial measurement systems was better than other measurement systems. The lyophilized samples were more stable than frozen samples and there were no obvious differences in their matrix effects for most measurement systems.

CONCLUSIONS

The agreement among the results of methotrexate, imatinib, and especially paclitaxel from different laboratories was not satisfactory. Currently, the lyophilized samples were the more suitable EQA material for methotrexate, imatinib and paclitaxel than frozen samples.

SLCO1B1 *15 allele is associated with methotrexate-induced nausea in pediatric patients with inflammatory bowel disease

Low-dose methotrexate (MTX) is an immunosuppressant used to treat inflammatory bowel disease (IBD). SLCO1B1 genetic variation has been associated with delayed MTX clearance and increased toxicity. The purpose of this study was to evaluate the association between SLCO1B1 genetic variation and MTX-induced nausea in children with IBD. We performed a single center retrospective chart analysis of 278 patients who were prescribed MTX for IBD. Two hundred two patients had banked DNA and were genotyped for three SLCO1B1 single nucleotide polymorphisms (SNPs; rs4149056, rs2306283, and rs11045819). Diplotypes were determined by combining the SNPs into *1, *4, *5, *14, *15, and *37 alleles. Incidence of nausea was abstracted from clinician notes. Prescriptions and demographics were extracted from the medical record. The cohort was 69.8% boys, 89.1% White, and 87.6% had a diagnosis of Crohn's disease with a mean age of 16.0 (± 3.8) years. MTX-induced nausea was noted in 34% of the cohort. MTX-induced nausea was associated with the number of reduced-function *15 alleles (p = 0.034) and occurred 2.26 times more often in patients with at least one *15 allele who did not initiate MTX treatment with concomitant ondansetron (p = 0.034). MTX-induced nausea was significantly independently associated with SLCO1B1 diplotype (p = 0.006) after controlling for MTX dose group and concomitant ondansetron. Our data demonstrate that the SLCO1B1 *15 allele is associated with MTX-induced nausea in pediatric patients with IBD. Additionally, *15 allele carriers could benefit from a dose reduction of MTX to reduce exposure and treatment initiation with concomitant ondansetron to reduce nausea.

Gathering patients and rheumatologists' perceptions to improve outcomes in idiopathic inflammatory myopathies

OBJECTIVE

Therapeutic targets in Idiopathic Inflammatory Myopathies (IIM) are based on the opinions of physicians/specialists, which may not reflect the main concerns of patients. The authors, therefore, assessed the outcome concerns of patients with IIM and compared them with the concerns of rheumatologists in order to develop an IIM outcome standard set.

METHODS

Ninety-three IIM patients, 51 rheumatologists, and one physiotherapist were invited to participate. An open questionnaire was initially applied. The top 10 answers were selected and applied in a multiple-choice questionnaire, inquiring about the top 3 major concerns. Answers were compared, and the agreement rate was calculated. Concerns were gathered in an IIM outcome standard set with validated measures.

RESULTS

The top three outcome concerns raised by patients were medication side effects/muscle weakness/prevention functionality loss. The top three concerns among rheumatologists were to prevent loss of functionality/to ensure the quality of life/to achieve disease remission. Other's outcomes concerns only pointed out by patients were muscle pain/diffuse pain/skin lesions/fatigue. The agreement rate between both groups was 41%. Assessment of these parameters guided the development of an IIM standard set which included Myositis Disease Activity Assessment Visual Analogue Scale/Manual Muscle Testing/fatigue and pain Global Visual Analogue Scale/Health Assessment Questionnaire/level of physical activity.

CONCLUSION

The authors propose a novel standard set to be pursued in IIM routine follow-up, which includes not only the main patients/rheumatologist outcome concerns but also additional important outcomes only indicated by patients. Future studies are necessary to confirm if this comprehensive approach will result in improved adherence and ultimately in better assistance.

Hepatotoxic potentials of methotrexate: Understanding the possible toxicological molecular mechanisms

Methotrexate (MTX) is one of the most effective and widely used drugs in the management of autoimmune and dermatological diseases. Rheumatoid arthritis and psoriasis patients who are under long term MTX-therapy are at high risk of developing a liver injury. Accumulation of intracellular MTX-polyglutamate (MTX-PG), a metabolite of MTX triggers oxidative stress, inflammation, steatosis, fibrosis, and apoptosis in hepatocytes. MTX-PG causes oxidative stress in the liver by inducing lipid peroxidation thereby releasing reactive oxygen species and suppressing antioxidant response elements. MTX-PG induces several pro-inflammatory signaling pathways and cytokines such as tumor necrosis factor-α, nuclear factor kappa B and interleukin 6 (IL-6), IL- β1, IL-12. MTX-PG depletes hepatic folate level and decreases RNA and DNA synthesis leading to hepatocyte death. MTX-PG inhibits 5-aminoimidazole-4-carboxamide ribonucleotide transformylase enzyme and thereby causes accumulation of intracellular adenosine, which causes activation of hepatic stellate cells, extracellular matrix accumulation and hepatic fibrosis. MTX-PG induces hepatocytes apoptosis by activation of caspase 3 via the intrinsic pathway. Clinically, aggravation of underlying fatty liver to non-alcoholic steatohepatitis with fibrosis seems to be an important mechanism of liver injury in MTX-treated RA patients. Therefore, there is a need for monitoring liver injury in RA, psoriatic and cancer patients with NAFLD and fibrosis risk factors during MTX treatment. This review summarizes the possible molecular mechanism of MTX-induced hepatotoxicity. It may pave the way for early detection of liver injury and develop novel strategies for treating MTX mediated hepatotoxicity.

Methotrexate Polyglutamates Analysis by Chromatography Methods in Biological Matrices: A Review

Methotrexate (MTX) is used as an immunosuppressant and antineoplastic drug in clinical practice. MTX is a parent drug and converts to MTX polyglutamates (MTXPGs) to exhibit its biological activity. Clinical studies found that MTXPG levels were associated with MTX response and toxicities, especially at low doses. Due to huge variance of MTX response and toxicities between individuals, therapeutic drug monitoring is necessary for its use in individualized therapy. Various chromatography methods coupled with ultraviolet-visible detector, fluorescence detector and mass spectrometry have been reported for MTXPG analysis in various biological matrices. The aim of this paper is to review the chromatographic based methods for the measurement of total and/or individual MTXPGs. We searched Embase, Science Direct and PubMed databases using "methotrexate polyglutamate" and "chromatography" as search terms, and found 745 articles. Of those, 14 articles were extracted for this study. The key steps for method development (sample pretreatment, parameter optimization of liquid chromatography and mass spectrometry, selection of internal standard) and validation (lower limit of quantitation, accuracy, precision, recovery, matrix effect and stability) were analyzed and summarized, which might be helpful for researchers to develop their own methods.

Decision-Analytic Modeling for Time-Effectiveness of the Sequence of Induction Treatments for Moderate to Severe Plaque Psoriasis

Importance

Systemic psoriasis treatments vary in efficacy and cost but also in time until onset of action. Patients with no response to a first induction treatment are typically switched to another, and some patients require several treatments before they see an improvement.

Objective

To determine the most cost-effective sequence of induction treatment through a comparative time-effectiveness analysis of different systemic treatment sequences currently licensed in Germany for moderate to severe plaque psoriasis.

Design, Setting, and Participants

This time-effectiveness analysis used a decision-analytic model set in the German health care system. The population simulated to receive the treatment sequences consisted of adult men and women with psoriasis vulgaris or plaque type psoriasis eligible for systemic treatment. Systematic reviews were performed to generate model input values. Data were collected from November 1 through December 15, 2017, and analyzed from January through August 2018.

Interventions

Five treatment sequences frequently used in Germany, identified through an online expert survey (response rate, 10 of 15 [66.7%]), and 4 theoretical sequences starting with a biological agent. Treatments included methotrexate sodium (MTX), cyclosporine (CSA), fumaric acid esters (FAE), adalimumab (ADA), ixekizumab (IXE), infliximab (INF), and secukinumab (SEC).

Main Outcomes and Measures

Two health states were defined: responder (patients achieving a Psoriasis Area Severity Index [PASI] ≥75) and nonresponder (PASI <75). Probability values were defined as response rates of PASI-75. Treatment effects were determined by the mean change in Dermatology Life Quality Index (DLQI) score. Time until onset of action was assessed as weeks until 25% of patients reach PASI-75. Individual time-effectiveness ratios were calculated per treatment sequence as time until onset of action (in weeks) per minimally important difference (MID) in DLQI and were subsequently ranked.

Results

Treatment sequences starting with a biological agent, including IXE-INF-SEC (1.4 weeks per DLQI-MID), INF-IXE-SEC (2.05 weeks per DLQI-MID), SEC-IXE-ADA (2.1 weeks per DLQI-MID), and ADA-IXE-SEC (2.8 weeks per DLQI-MID) were more time-effective than frequently used treatment sequences, including MTX-SEC-ADA (6.8 weeks per DLQI-MID), MTX-ADA-IXE (7.0 weeks per DLQI-MID), MTX-ADA-SEC (7.2 weeks per DLQI-MID), MTX-FAE-ADA (10.05 weeks per DLQI-MID), and FAE-MTX-CSA (11.5 weeks per DLQI-MID). The results were robust to deterministic sensitivity analyses.

Conclusions and Relevance

When allocating monetary resources, policy makers and regulators may want to consider time until patients experience an MID in their quality of life as an additional outcome measure.

Trial Registration

PROSPERO Identifier: CRD42017074218.

Methotrexate Triglutamate as a Determinant of Clinical Response in Mexican Patients With Rheumatoid Arthritis: Pharmacokinetics and Dose Recommendation

Methotrexate is the gold standard treatment in rheumatoid arthritis. Once absorbed, it is internalized in cells, where glutamate residues are added to produce polyglutamated forms, which are responsible for the effect of methotrexate. The aim of the current study is to determine the relationship between methotrexate triglutamate concentrations and the clinical evolution in rheumatoid arthritis patients, as well as to characterize the variability in both features to propose strategies for low-dose methotrexate optimization. The quantification of methotrexate triglutamate concentration in red blood cells was performed through ultra-performance liquid chromatography coupled with mass spectrometry. Polymorphisms of genes involved in the formation of polyglutamates were determined by real-time polymerase chain reaction. A multivariate regression was performed to determine the covariates involved in the variability of methotrexate triglutamate concentrations and a population pharmacokinetics model was developed through nonlinear mixed-effects modeling. Disease activity score changed according to methotrexate triglutamate concentrations; patients with good response to treatment had higher concentrations than moderate or nonresponding patients. The methotrexate triglutamate concentrations were related to time under treatment, dose, red blood cells, and body mass index. A 1-compartment open model was selected to estimate the pharmacokinetic parameters; the typical total clearance (L/day) was determined as 1.45 * (body mass index/28 kg/m² ) * (red blood cells/4.6 × 10⁶ cells/μL) and the volume of distribution was 52.4 L, with an absorption rate of 0.0346/day and a fraction metabolized of 1.03%. Through the application of the model, the initial dose of methotrexate is proposed on the basis of stochastic simulations and considering methotrexate triglutamate concentrations found in responders patients.

Simultaneous determination of erythrocyte methotrexate polyglutamates by a novel and simple HPLC-MS/MS method with stable isotope-labeled internal standards

Low-dose methotrexate is the first-line therapy for juvenile idiopathic arthritis. In vivo, methotrexate is converted into a series of methotrexate polyglutamates whose intracellular levels contribute significantly to its efficacy and toxicity. In this study, a novel high-performance liquid chromatography-tandem mass spectrometry method was developed and validated to simultaneously determine erythrocyte methotrexate polyglutamates using stable isotope-labeled internal standards. Erythrocyte samples were precipitated by perchloric acid and then determined on an XBridge BEH C18 column with an XP vanguard precolumn in 12 min. The mobile phase consisted of 10 nM ammonium acetate (pH 10) and methanol under gradient elution. The detection was carried out in multiple reaction monitoring mode via an electrospray ionization source in positive ionization mode. The calibration curve for each metabolite was linear from 2.0 to 500.0 nmol/L (r²  > 0.99). The intraday and interday accuracies were between 93.0 and 107.0%, and the corresponding precisions were between 0.8 and 5.2%. The relative recovery ranged from 82.7 to 105.1%, and the relative matrix effect varied from 96.5 to 104.4%. The erythrocyte metabolites were stable for 30 days at -80°C. This simple and accurate method is applicable to routine monitoring of the concentration of erythrocyte methotrexate polyglutamates in patients to achieve individualized treatment.

New Horizons in Hydrogels for Methotrexate Delivery

Since its first clinical application, methotrexate (MTX) has been widely used for the treatment of human diseases. Despite great advantages, some properties such as poor absorption, short plasma half-life and unpredictable bioavailability have led researchers to seek novel delivery systems to improve its characteristics for parenteral and oral administration. Recently, great attention has been directed to hydrogels for the preparation of MTX formulations. This review describes the potential of hydrogels for the formulation of MTX to treat cancer, rheumatoid arthritis, psoriasis and central nervous system diseases. We will delineate the state-of-the-art and promising potential of hydrogels for systemic MTX delivery as well as transdermal delivery of the drug-using hydrogel-based formulations.

Molecular mechanism of action and pharmacokinetic properties of methotrexate

Since its discovery in 1945, methotrexate has become a standard therapy for number of diseases, including oncological, inflammatory and pulmonary ones. Major physiological interactions of methotrexate include folate pathway, adenosine, prostaglandins, leukotrienes and cytokines. Methotrexate is used in treatment of pulmonary sarcoidosis as a second line therapy and is drug of choice in patients who are not candidates for corticosteroid therapy, with recommended starting weekly dose of 5-15 mg. Number of studies dealt with methotrexate use in rheumatoid arthritis and oncological patients. Authors are conducting research on oral methotrexate use and pharmacokinetics in chronic sarcoidosis patients and have performed literature research to better understand molecular mechanisms of methotrexate action as well as high level pharmacokinetic considerations. Polyglutamation of methotrexate affects its pharmacokinetic and pharmacodynamic properties and prolongs its effect. Bile excretion plays significant role due to extensive enterohepatic recirculation, although majority of methotrexate is excreted through urine. Better understanding of its pharmacokinetic properties in sarcoidosis patients warrant optimizing therapy when corticosteroids are contraindicated in these patients.

Hyphenated mass spectrometry techniques for assessing medication adherence: advantages, challenges, clinical applications and future perspectives

Nonadherence to prescribed pharmacotherapy is an understated public health problem globally and is costing many patients their chance to return to good health and healthcare systems billions. Clinicians need an accurate assessment of adherence to medications to aid the clinical decision-making process in the event of poor patient progress and to maximise the patient health outcomes from the drug therapies prescribed. An overview of indirect and direct methods used to measure medication adherence is presented, highlighting the potential for accurate measuring of drugs in biological samples using hyphenated mass spectrometry (MS) techniques to provide healthcare professionals with a reliable evidence base for clinical decision making. In this review we summarise published applications of hyphenated MS techniques for a diverse range of clinical areas demonstrating the rise in the use of such direct methods for assessing medication adherence. Although liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods using plasma, serum and urine samples are the most popular, in recent years increased attention has been given to liquid chromatography high-resolution mass spectrometry (LC-HRMS) methods and alternative biosample matrices including hair, saliva and blood microsamples. The advantages and challenges of using hyphenated MS techniques to address this healthcare problem are also discussed alongside future perspectives.

Analytical methodologies for determination of methotrexate and its metabolites in pharmaceutical, biological and environmental samples

Methotrexate (MTX) is a folate antagonist drug used for several diseases, such as cancers, various malignancies, rheumatoid arthritis (RA) and inflammatory bowel disease. Due to its structural features, including the presence of two carboxylic acid groups and its low native fluorescence, there are some challenges to develop analytical methods for its determination. MTX is metabolized to 7-hydroxymethotrexate (7-OH-MTX), 2,4-diamino-N10-methylpteroic acid (DAMPA), and the active MTX polyglutamates (MTXPGs) in the liver, intestine, and red blood cells (RBCs), respectively. Additionally, the drug has a narrow therapeutic range; hence, its therapeutic drug monitoring (TDM) is necessary to regulate the pharmacokinetics of the drug and to decrease the risk of toxicity. Due to environmental toxicity of MTX; its sensitive, fast and low cost determination in workplace environments is of great interest. A large number of methodologies including high performance liquid chromatography equipped with UV-visible, fluorescence, or electrochemical detection, liquid chromatography-mass spectroscopy, capillary electrophoresis, UV-visible spectrophotometry, and electrochemical methods have been developed for the quantitation of MTX and its metabolites in pharmaceutical, biological, and environmental samples. This paper will attempt to review several published methodologies and the instrumental conditions, which have been applied to measure MTX and its metabolites within the last decade.

Methotrexate Polyglutamate Values in Children and Adolescents With Acute Lymphoblastic Leukemia During Maintenance Therapy

Inadequate adherence to maintenance therapy is a major cause of relapse in patients with acute lymphoblastic leukemia (ALL). Therapeutic monitoring of mercaptopurine (thiopurine) red cell metabolites to assess adherence has been available for many years. Recently a clinical laboratory improvement amendments of 1988-approved test for methotrexate with three polyglutamate residues (MTXPG3) measured in peripheral blood red cells was approved. MTXPG3 is the primary intracellular metabolite of methotrexate, and like thiopurine metabolites, is retained for the life of the red cell giving an estimate of drug exposure over time. Normative values for MTXPG3 are available for adults and children with rheumatoid arthritis on methotrexate monotherapy, which are not applicable for patients with ALL on maintenance. Older literature on the MTXPG3 fraction in children with ALL is limited. We examined the MTXPG3 levels from 123 samples in 76 patients with ALL on maintenance oral methotrexate and mercaptopurine that were collected for clinical care. Male individuals had significantly higher MTXPG3 levels than female individuals which was unrelated to absolute neutrophil count, age, serum creatinine, and average doses of methotrexate or mercaptopurine. The MTXPG3 5th, 10th, 90th, and 95th percentile values are 0, 8.4, 53, and 64, respectively with a median of 24.7 nmol/L. The low 5th percentile MTXPG3 reflects 6 samples from 3 patients, age 16 to 21 years that were considered poorly adherent before collecting the specimen. As with red cell thiopurine (mercaptopurine) metabolites, MTXPG3 normative values may provide useful information to monitor for poor patient adherence or methotrexate toxicity during maintenance chemotherapy in ALL.

Methotrexate disposition, anti-folate activity and efficacy in the collagen-induced arthritis mouse model

Methotrexate (MTX) efficacy in autoimmune arthritis is variable and unpredictable resulting in the need for the identification of biomarkers to guide drug therapy. This study utilizes the collagen-induced arthritis mouse model to investigate erythrocyte MTX disposition and anti-folate activity as biochemical markers of efficacy in autoimmune arthritis. Following induction of arthritis, DBA/1J mice were treated with once-weekly subcutaneous MTX at varying doses over a period of 40 days. At the completion of the study tissue samples were analyzed for MTX and folate content and assessed for their relationship with MTX efficacy. MTX treatment resulted in a reduction in disease activity that was variable and dose-dependent. Erythrocyte accumulation of MTX and its polyglutamate metabolites were dose proportionate, however, polyglutamate metabolites represented a mean ± S.E.M. of 8.9 ± 0.4% of total erythrocyte MTX, which is markedly lower than previously observed in humans and failed to display any significant association with MTX efficacy. MTX treatment resulted in reductions in erythrocyte 5-methyl-tetrahydrofolate (5mTHF) levels that were similar to those previously observed in human studies. Disease induction was associated with a decrease in liver 5mTHF and increased formyl-tetrahydrofolate (fTHF) that was normalized in MTX treated mice. MTX efficacy was associated with reductions in erythrocyte 5mTHF (P = 0.04) and increases in liver 5mTHF (P = 0.0001). Together, these findings demonstrate a relationship between alterations in tissue folate levels and MTX efficacy, and supports erythrocyte levels of 5mTHF as a marker of MTX efficacy in autoimmune arthritis.

Emerging role of metabolomics in rheumatology

The pursuit for understanding disease pathogenesis, in this age of rapid laboratory diagnostics and fast-paced research, has led scientists worldwide to take recourse in hypothesis-free approaches for molecular diagnosis. Metabolomics is one such powerful tool that explores comprehensibly the metabolic alternations in human diseases. It involves study of small molecules of less than 1 kD in size by either LSMS or nuclear magnetic resonance. Unlike genomics, which tells us what may have happened, metabolomics reflects what did happen. The NMR technique has an advantage of analyzing metabolites without sample preparation, thereby diminishing artifacts, is less cumbersome and with the latest database on Metabolome; about 30 000 metabolites can be identified. The study of metabolomics for several rheumatic diseases, including rheumatoid arthritis, lupus, osteoarthritis and vasculitis, has revealed distinctive metabolic signatures. Thus, metabolomics is a technique that promises precision medicine with better biomarkers, robust predictors of drug response and of disease outcome, discovery of newer metabolites and pathways in disease pathogenesis, and finally, targeted drug development. This review intends to decipher its relevance in common rheumatic diseases.

Useful pharmacodynamic endpoints in children: selection, measurement, and next steps

Pharmacodynamic (PD) endpoints are essential for establishing the benefit-to-risk ratio for therapeutic interventions in children and neonates. This article discusses the selection of an appropriate measure of response, the PD endpoint, which is a critical methodological step in designing pediatric efficacy and safety studies. We provide an overview of existing guidance on the choice of PD endpoints in pediatric clinical research. We identified several considerations relevant to the selection and measurement of PD endpoints in pediatric clinical trials, including the use of biomarkers, modeling, compliance, scoring systems, and validated measurement tools. To be useful, PD endpoints in children need to be clinically relevant, responsive to both treatment and/or disease progression, reproducible, and reliable. In most pediatric disease areas, this requires significant validation efforts. We propose a minimal set of criteria for useful PD endpoint selection and measurement. We conclude that, given the current heterogeneity of pediatric PD endpoint definitions and measurements, both across and within defined disease areas, there is an acute need for internationally agreed, validated, and condition-specific pediatric PD endpoints that consider the needs of all stakeholders, including healthcare providers, policy makers, patients, and families.

Development of a nomogram for the estimation of long-term adherence to clozapine therapy using neutrophil fluorescence

AIMS

Previously, we have reported an association between clozapine use and elevated FL3 neutrophil fluorescence, a flow-cytometric parameter for cell viability. Here, we developed and evaluated a pharmacokinetic-pharmacodynamic model relating FL3-fluorescence to clozapine exposure and derived a nomogram for estimation of long-term adherence.

METHODS

Data from 27 patients initiating clozapine were analysed using nonlinear mixed effects modelling. A previously described pharmacokinetic model for clozapine was coupled to a FL3 fluorescence model. For this, an effect compartment with clozapine concentrations as input and a first order decay rate as output was linked with an E_max model to FL3-fluorescence. FL3-fluorescence was simulated for clozapine doses of 50, 150 and 400 mg daily (n = 10 000) to establish the nomogram. Finally, true simulated adherence (% of daily doses taken over 100 days) was compared to nomogram-estimated adherence to evaluate the performance of the nomogram.

RESULTS

The half-life of FL3-fluorescence was estimated at 228 h (coefficient of variation 35%). Median absolute prediction errors of the nomogram in case of fully random adherence for 50, 150 and 400 mg ranged from -0.193% to -0.525%. The nomogram performed slightly worse in case of nonrandom adherence (median prediction error up to 5.19%), but was still clinically acceptable. Compliance patterns containing longer drug holidays revealed that the nomogram adequately estimates compliance over approximately the last 3 weeks prior to FL3-measurement.

CONCLUSION

Our nomogram could provide information regarding long-term adherence based on prescribed clozapine dose and FL3-fluorescence. Future studies should further explore the clinical value of this biomarker and nomogram.

Liquid chromatographic methods for the therapeutic drug monitoring of methotrexate as clinical decision support for personalized medicine: A brief review

Methotrexate (MTX) is an antifolate drug used for several diseases. Depending on the disease, MTX can be administered at low dose (LDMTX) in some autoimmune diseases, like rheumatoid arthritis, or at high dose (HDMTX) in some cancers, such as acute lymphoblastic leukemia. After absorption, MTX is metabolized in the liver to 7-hydroxymethotrexate and in the intestine to 2,4-diamino-N10-methylpteroic acid (DAMPA). Moreover, inside red blood cells, MTX is converted to active metabolites, MTX polyglutamates (MTXPGs), contributing to its pharmacodynamics. Owing to its narrow therapeutic range, and inter- and intra-patient variability, either noneffectiveness and/or toxicity may occur. Because of the existence of a relationship between drug therapeutic outcome and its systemic concentration, therapeutic drug monitoring (TDM) may ensure the effectiveness and safety of MTX use. In order to monitor the optimization of patient clinical response profile, several analytical methods have been described for TDM in biological samples. These include liquid chromatography (LC) coupled with ultraviolet detection, fluorescence detection or mass spectrometry, each one presenting advantages and drawbacks. This paper reviews the most commonly used techniques for sample preparation and critically discusses the current LC methods applied for the TDM of MTX in biological samples, at LDMTX and HDMTX.

In the Pursuit of Methotrexate Treatment Response Biomarker in Juvenile Idiopathic Arthritis-Are We Getting Closer to Personalised Medicine?

PURPOSE OF REVIEW

Methotrexate (MTX) is the most widely used disease-modifying antirheumatic drug (DMARD) in paediatric rheumatology and the mainstay in the therapy of juvenile idiopathic arthritis (JIA). Despite its common use, about 30% of children fail to respond to this medicine that results in potentially irreversible joint damage.

RECENT FINDINGS

No clinical biomarker that would predict the outcome of MTX therapy exists. Results of several studies focused on gene polymorphisms and outcome of this DMARD therapy have been published, but no reliable genetic marker useful to tailor the therapy has been discovered so far. The results of the first genome-wide association study in this field have recently revealed new genetic candidates from outside the metabolic pathway of MTX that may be associated with the efficacy of treatment. However promising, those outcomes need validation in independent prospective cohorts before we can claim that clinically useful biomarker predicting MTX treatment response is discovered.

An intensified dosing schedule of subcutaneous methotrexate in patients with moderate to severe plaque-type psoriasis (METOP): a 52 week, multicentre, randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Methotrexate is one of the most commonly used systemic drugs for the treatment of moderate to severe psoriasis; however, high-quality evidence for its use is sparse and limited to use of oral dosing. We aimed to assess the effect of an intensified dosing schedule of subcutaneous methotrexate in patients with moderate to severe plaque-type psoriasis.

METHODS

We did this prospective, multicentre, randomised, double-blind, placebo-controlled, phase 3 trial (METOP) at 16 sites in Germany, France, the Netherlands, and the UK. Eligible patients were aged 18 years or older, had a diagnosis of chronic plaque psoriasis for at least 6 months before baseline, had currently moderate to severe disease, and were methotrexate treatment-naive. Participants were randomly assigned (3:1), via a computer-generated random number sequence integrated into an electronic data capture system, to receive either methotrexate at a starting dose of 17·5 mg/week or placebo for the first 16 weeks, followed by methotrexate treatment of all patients up to 52 weeks (methotrexate-methotrexate vs placebo-methotrexate groups). Dose escalation to 22·5 mg/week was allowed after 8 weeks of methotrexate treatment if patients had not achieved at least a 50% reduction in baseline Psoriasis Area and Severity Index score (PASI), with corresponding volume increases in placebo injections. Treatment was combined with folic acid 5 mg/week. Group allocation was concealed from participants and investigators from the time of randomisation until an interim database lock at week 16, and was open label from week 16 onwards, with no masking of participants or investigators. The primary efficacy endpoint was a 75% reduction in PASI score (PASI 75) from baseline to week 16. We did analysis by modified intention to treat, with non-responder imputation. This study is registered with EudraCT, number 2012-002716-10.

FINDINGS

Between Feb 22, 2013, and May 13, 2015, we randomly assigned 120 patients to receive methotrexate (n=91) or placebo (n=29). At week 16, a PASI 75 response was achieved in 37 (41%) patients in the methotrexate group compared with three (10%) patients in the placebo group (relative risk 3·93, 95% CI 1·31-11·81; p=0·0026). Subcutaneous methotrexate was generally well tolerated; no patients died or had serious infections, malignancies, or major adverse cardiovascular events. Serious adverse events were recorded in three (3%) patients who received methotrexate for the full 52 week treatment period.

INTERPRETATION

Our findings show a favourable 52 week risk-benefit profile of subcutaneous methotrexate in patients with psoriasis. The route of administration and the intensified dosing schedule should be considered when methotrexate is used in this patient group.

FUNDING

Medac.