Methotrexate Polyglutamate Concentrations Research Articles

Methotrexate accumulation in target intestinal mucosa and white blood cells differs from non-target red blood cells of patients with Crohn's disease.

Intracellular methotrexate polyglutamates (MTX-PGs) concentrations are measurable in red blood cells (RBCs) during MTX treatment. MTX-PG3 concentrations correlate with efficacy in patients with Crohn's disease (CD). Since RBCs are not involved in pathogenesis of CD and lack extended MTX metabolism, we determined MTX-PGs accumulation in peripheral blood mononuclear cells (PBMCs: effector cells) and intestinal mucosa (target cells) and compared those with RBCs as a potential more precise biomarker. In a multicentre prospective cohort study, blood samples of patients with CD were collected during the first year of MTX therapy. Mucosal biopsies were obtained from non-inflamed rectum and/or inflamed intestine. MTX-PGs concentrations in mucosa, PBMCs and RBCs were measured by liquid chromatography-tandem mass spectrometry. From 80 patients with CD, a total of 27 mucosal biopsies, 9 PBMC and 212 RBC samples were collected. From 12 weeks of MTX therapy onwards, MTX-PG3 was the most predominant species (33%) in RBCs. In PBMCs, the distribution was skewed towards MTX-PG1 (48%), which accounted for an 18 times higher concentration than in RBCs. Long-chain MTX-PGs were highly present in mucosa: 21% of MTX-PGtotal was MTX-PG5. MTX-PG6 was measurable in all biopsies. MTX-PG patterns differ between mucosa, PBMCs and RBCs of patients with CD.

Pharmacokinetic-pharmacodynamic modelling and simulation of methotrexate dosing in patients with rheumatoid arthritis.

To develop a non-linear mixed-effects population pharmacokinetic and pharmacodynamic (PK-PD) model describing the change in the concentration of methotrexate polyglutamates in erythrocytes (ery-MTX-PGn with "n" number of glutamate, representing PK component) and how this relates to modified 28-joint Disease Activity Score incorporating erythrocyte sedimentation rate (DAS-28-3) for rheumatoid arthritis (RA), representing PD component. An existing PK model was fitted to data from a study consisting of 117 RA patients. The estimation of population PK-PD parameters was performed using stochastic approximation expectation maximisation algorithm in Monolix 2021R2. The model was used to perform Monte Carlo simulations of a loading dose regimen (50mg subcutaneous methotrexate as loading doses, then 20mg weekly oral methotrexate) compared to a standard dosing regimen (10mg weekly oral methotrexate for 2 weeks, then 20mg weekly oral methotrexate). Every 40 nmol/L increase in ery-MTX-PG3-5 total concentration correlated with 1-unit reduction in DAS-28-3. Significant covariate effects on the therapeutic response of methotrexate included the use of prednisolone in the first 4 weeks (positive use correlated with 25% reduction in DAS-28-3 when other variables were constant) and patient age (every 10-year increase in age correlated with 3.4% increase in DAS-28-3 when other variables were constant). 4 methotrexate loading doses led to a higher percentage of patients achieving a good/moderate response compared to the standard regimen (Week 4: 87.6% vs. 39.8%; Week 10: 64.7% vs. 57.0%). A loading dose regimen was more likely to achieve higher ery-MTX-PG concentration and better therapeutic response after 4 weeks of methotrexate treatment.

Methotrexate Polyglutamate Concentrations as a Possible Predictive Marker for Effectiveness of Methotrexate Therapy in Patients with Sarcoidosis: A Pilot Study.

Methotrexate (MTX), a folate antagonist, is often used as second-line treatment in patients with sarcoidosis. Effectiveness of MTX has large inter-patient variability and at present therapeutic drug monitoring (TDM) of MTX is not possible. Upon administration, MTX is actively transported into cells and metabolized to its active forms by adding glutamate residues forming MTXPG(n=1-5) resulting in enhanced cellular retention. In this study we address the question whether different MTXPG(n) concentrations in red blood cells (RBC) of patients with sarcoidosis after 3months of MTX therapy correlate with response to treatment. We retrospectively included patients with sarcoidosis that had started on MTX therapy and from whom blood samples and FDG-PET/CT were available 3 and 6-12months after MTX initiation, respectively. FDG-uptake was measured by SUVmax in the heart, lungs and thoracic lymph nodes. Changes in SUVmax was used to determine anti-inflammatory response after 6-12months of MTX therapy. MTXPG(n) concentrations were measured from whole blood RBC using an LC-MS/MS method. Pearson correlation coefficients were calculated to evaluate the relationship betweenchanges in the SUVmax andMTXPG(n) concentrations. We included 42 sarcoidosis patients treated with MTX (15mg/week); 31 with cardiac sarcoidosis and 11 with pulmonary sarcoidosis. In MTXPG3 and MTXPG4 a significant negative relation between the absolute changes in SUVmax and MTXPG(n) was found r = - 0.312 (n = 42, p = 0.047) for MTXPG3 and r = - 0.336 (n = 42, p = 0.031 for MTXPG4). The other MTXPG(n) did not correlate to changes in SUVmax. These results suggest a relation between MTXPG(n) concentrations and the anti-inflammatory effect in patients with sarcoidosis. Further prospective validation is warranted, but if measuring MTXPG concentrations could predict treatment effect of MTX this would be a step in the direction of personalized medicine.

Methotrexate Polyglutamates Exposure - Response Modeling in a Large Cohort of Rheumatoid Arthritis Patients Starting Methotrexate.

Methotrexate polyglutamates (MTX-PG) concentrations in red blood cells (RBCs) have been suggested as a biomarker of response in patients with rheumatoid arthritis (RA) receiving low-dose MTX therapy. We investigated the association and interpatient variability between RBC-MTX-PG3-5 -exposure and response in patients with RA starting MTX. Data of three prospective cohorts were available. The relationship between exposure and Disease Activity Score in 28 joints (DAS28) was analyzed using a population pharmacokinetic-pharmacodynamic model. Relevant covariates were tested using full covariate modeling and backward elimination. From 395 patients, 3,401 MTX-PG concentrations and 1,337 DAS28 measurements were available between 0 and 300 days after MTX treatment onset. The developed model adequately described the time course of MTX-PG3-5 and DAS28. The median MTX-PG3-5 level at month 1 was 30.9 nmol/L (interquartile range (IQR): 23.6-43.7; n = 41) and at month 3: 69.3 nmol/L (IQR: 17.9-41.2; n = 351). Clearance of MTX-PG3-5 from RBCs was 28% lower (95% confidence interval (CI): 23.6-32.8%) in a woman and 10% lower (95% CI: 7.7-12.4%) in a 65-year-old compared with a 35-year-old patient. MTX-PG3-5 concentrations associated with DAS28: half-maximal effective concentration (EC50 ) was 9.14 nmol/L (95% CI: 4.2 nmol/L-14.1 nmol/L). EF at 80% (EC80 ) above 47 nmol/L was regarded as the optimal response. Independent of the MTX-PG 3-5 - response association, co-administration of disease-modifying antirheumatic drugs and corticosteroids improved response (additive effect on maximum effect (Emax )), whereas smoking, high body mass index and low albumin decreased Emax . In patients with RA starting MTX, RBC-MTX-PG3-5 was associated with clinical response. A dose increase is suggested when MTX-PG3-5 at month 1 is below 9.15 nmol/L, continued with the same dose when the concentration is above 47 nmol/L, and consider other treatment options above 78 nmol/L from 3months onwards.

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

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. 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 (β), correlation coefficient and mean difference (of MTX-PG in responders vs. nonresponders) for IMIDs separately and collectively. Twenty-five studies were included. In RA and JIA, higher MTX-PG was significantly associated with lower disease activity at 3months (β: -0.002; 95% confidence interval [CI]: -0.004 to -0.001) and after 4months of MTX use (β: -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: 5.2nmol/L MTX-PGtotal ; P< .01). 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.

P312 Erythrocyte methotrexate polyglutamate concentrations in patients with Crohn’s Disease: towards a new therapeutic drug monitoring tool

Abstract Background Methotrexate (MTX) is an immunomodulatory drug for patients with Crohn’s Disease (CD), used as first-line therapy, as a second-line in case of failure to thiopurine, and concomitantly with anti-TNFα agents to decrease production of anti-drug antibodies. Nevertheless, MTX is underutilised in the treatment of CD, despite its proven efficacy and good safety profile. This is for a large part due to the lack of therapeutic drug monitoring (TDM) of MTX because no stable plasma MTX levels are reached. Intracellular MTX-polyglutamates (MTX-PGs), formed after folylpolyglutamate synthetase attaches glutamate residues to MTX, could be used as a TDM tool as MTX-PG is thought to mediate MTX’s efficacy. We present the results of our cross-sectional study in CD patients, aiming to gain insight into erythrocyte MTX-PG levels. Methods CD adults on MTX treatment who visited the outpatient clinic of Amsterdam UMC between May 2019 and February 2020 were included consecutively. An established LC-ESI-MS/MS method1 was used to measure erythrocyte MTX-PGs. Results Nineteen patients were included. Mean disease duration was 17 years (SD±13.7). Montreal disease location and behaviour were as follows (n=): L1 = 2, L2 = 4, L3 = 13; B1 = 11, B2 = 5, B3 = 3. Only 4 patients had a flare according to Physician Global Assessment. Twelve patients received MTX monotherapy, whereas 7 patients were on concomitant anti-TNFα agents. The mean dose of MTX was 15.5 mg (SD±2.8) and 12 (63%) patients had subcutaneous (sc.) MTX. We successfully measured MTX-PG2-5 in 18 patients, showing substantial variability in measured concentrations of total MTX-PG(tot) and the individual species. The median MTX-PGtot was 117.1 nmol/L [min:46.4-max:358.7] with preferential accumulation of MTX-PG3 (43.1 [15.3-96.1]); the least predominant species being MTX-PG5 (9.4 [1.1-24.1]). Patients on sc. compared to oral MTX had higher MTX-PGtot levels (177.8 [58.8-358.7] vs. 93.2 [46.4-120.8] nmol/L, p=0.067) and significantly higher long-chain MTX-PG4-5 levels (55 [3.7-84.3] vs. 8.9 [2.4-15.0] nmol/L, p=0.010); see figure. Conclusion We showed that erythrocyte MTX-PGs can be measured in CD patients by tandem MS. Large variability in concentrations was demonstrated, similar to our previously published results in rheumatoid and juvenile arthritis2,3 which is a pre-requisite for MTX-PG use as a TDM tool. We showed for the first time that MTX-PG accumulation was higher in sc. MTX vs. oral MTX treatment. This work provides the first step towards establishing TDM for MTX in CD, a goal we aim to realize in our upcoming longitudinal study. References

Therapeutic drug monitoring of methotrexate and its metabolites in the red blood cells and mononuclear cells of patients with rheumatoid arthritis

Objective: to assess the time course of changes in the concentration of methotrexate (MTX) and its main metabolites in the red blood cells (RBC) and mononuclear cells (MNC) of patients with rheumatoid arthritis (RA), by taking into account individual characteristics (age, statin therapy, and smoking).Patients and methods. The investigation enrolled 33 MTX-treated patients (mean age 53.2±11.7 years) with RA, who underwent therapeutic drug monitoring to measure the RBC and MNC concentrations of free MTX and MTX polyglutamates (MTXPGs) with 2, 3, and 4 glutamate residues (MTXPG 2–4) in using tandem chromatomass spectrometry after 4, 12, and 24 weeks of therapy.Results and discussion. Following 12 weeks, the concentration of MTXPG4 in the MNC was higher in patients taking statins, while that of MTX and MTXPG2 in the RBC were significantly lower than in smokers. At 24 weeks, older patients were observed to have a higher MTX level and a lower MTXPG4 concentration in the RBC.Conclusion. After 24 weeks of therapy, the RBC concentration of MTPG4 was lower and that of MTX was higher in older patients than in others, which confirms data on a slower MTX metabolism in the elderly. The use of statins is likely to have a positive impact on the accumulation of MTXPG. There is a statistically significantly lower RBC concentration of MTXPG in at 12 weeks of therapy.

The relationship between the efficacy of methotrexate in rheumatoid arthritis and the achieved level of its polyglutamates in erythrocytes (pilot study)

Therapeutic control of the methotrexate (MT) polyglutamates (MTPG) level in erythrocytes can be an objective marker of the effective dose of MT prescribed for rheumatoid arthritis (RA).Objective: to assess the relationship between the level of MTPG in red blood cells and efficacy of the MT dose used by RA patients.Subjects and methods. The study included 60 patients with RA (44 women and 16 men over 18 years) who met the criteria of the American College of Rheumatology and the European League Against Rheumatism (ACR/EULAR) 2010 and received MT ≥20 mg/week subcutaneously for ≥12 weeks. The patients were divided into two groups of comparable age, sex, alcohol intake, number of smokers, body mass index (BMI), depending on the presence (group 1; n=30) or absence (group 2; n=30) of the effect of MT, according to the EULAR efficacy criteria (DAS28). The concentration of MTPG (total MTPG and metabolites of MTPG 1, 2, 3, 4, 5) was determined in erythrocytes by high-performance liquid chromatography with mass spectrometric detection.Results and discussion. It was found that the levels of total MTPG and MTPG1, 2, 3, 5 in erythrocytes did not differ in groups of responders and nonresponders, and the dose of MT was comparable in both groups. At the same time, the level of MTPG4 in the first group was significantly higher (26.4±6.1 nmol/l; p=0.023) than in the second one (22.1±6.8 nmol/l). Analysis of the ROC curve showed that the values of MTPG4 &lt;22.5 nmol/l corresponded to the absence of effect of MT. The area under the curve was 0.672 (95% confidence interval 0.536–0.808 (p=0.022), sensitivity 77%, specificity 53.3%.Conclusion. For effective treatment of patients with RA MT dose should provide MTPG4 level in red blood cells ≥22.5 nmol/l.

Genetic polymorphism of the methotrexate transporter ABCG2, blood pressure and markers of arterial function in patients with rheumatoid arthritis: repeated cross-sectional study.

PurposeMethotrexate (MTX) treatment is associated with lower blood pressure (BP) and arterial stiffness in rheumatoid arthritis (RA). We investigated associations between single-nucleotide polymorphism (SNP) of the ATP-binding cassette efflux transporter gene ABCG2 (rs2231142), BP, and arterial stiffness in RA patients treated with MTX.Patients and methodsClinical and 24-hour peripheral and central BP, arterial wave reflection (Augmentation Index, AIx), arterial stiffness (Pulse Wave Velocity, PWV), and intracellular MTX polyglutamate (MTXPGs) concentrations were assessed in 56 RA patients on stable treatment with MTX using a repeated cross-sectional study design with measurements at baseline and after 8 months.ResultsMajority of the RA patients were homozygotes for the normal allele (CC, n=46) whereas 10 were rs2231142 heterozygotes (AC, n=10). MTXPGs concentrations were non-significantly higher in AC when compared to CC (144.3 vs 116.3 nmol/L packed RBCs, P=0.10). At baseline, the AC group had significantly lower age-adjusted clinical systolic BP (SBP) (P=0.01), 24-hour peripheral SBP (P=0.003), and central SBP (P=0.02) when compared to the CC group. However, AIx and PWV values were not significantly different between the two groups. When data from both visits were combined in a single analysis, and additionally adjusted for visit, gender, body mass index, and Disease Activity Score 28, the trend in SBP differences between-groups persisted but was no longer significant.ConclusionFuture studies are required to test the hypothesis that this genetic polymorphism is associated with lower BP, arterial stiffness, and possibly, cardiovascular risk, in RA patients treated with MTX.

Association of erythrocyte methotrexate-polyglutamate levels with the efficacy and hepatotoxicity of methotrexate in patients with rheumatoid arthritis: a 76-week prospective study

ObjectiveTo assess the utility of erythrocyte methotrexate-polyglutamate (MTX-PG) concentrations in determining the safety and efficacy of MTX in patients with rheumatoid arthritis (RA).Methods79 MTX-naïve patients with RA were enrolled in...

Folylpolyglutamate synthase is a major determinant of intracellular methotrexate polyglutamates in patients with rheumatoid arthritis.

We investigated major determinants of the intracellular concentrations of methotrexate polyglutamates (MTXPGs) in patients with rheumatoid arthritis (RA). In 271 RA patients on stable oral low dose weekly pulse MTX therapy, the concentrations of MTXPGs in red blood cells (RBCs) were measured by liquid chromatography-electrospray ionization-tandem mass spectrometry. Polymerase chain reaction-restriction fragment length polymorphism analysis was performed to determine the genotypes of solute carrier family 19 member 1 (SLC19A1), folylpolyglutamate synthase (FPGS), and gamma-glutamyl hydrolase (GGH). The mean total MTXPG concentration and the concentrations of individual MTXPGs increased dose-dependently, but reached a plateau at MTX doses >10 mg weekly. The MTXPG3-5/1-2 ratio was lower in patients with adverse events related to MTX than in patients without adverse events. Three polymorphisms of FPGS significantly influenced the MTXPG3-5/1-2 ratio in RBCs, while polymorphisms of SLC19A1 and GGH had no impact. The minor allele frequencies of 2 FPGS genotypes were significantly increased in our patients compared with a Caucasian population. FPGS may have a major role in regulating intracellular polyglutamation of MTX in RA patients receiving low-dose weekly MTX therapy.

Prediction of the therapeutic response to methotrexate at 24 weeks by methotrexate–polyglutamates concentration in erythrocytes at 8 weeks in patients with rheumatoid arthritis

Objectives: The objective of this study is to evaluate the pharmacokinetics and pharmacodynamics of methotrexate–polyglutamates (MTX-PGs) in erythrocytes in patients with rheumatoid arthritis and correlate them with the efficacy.Methods: MTX-PG concentrations in erythrocytes were measured in 42 MTX-naïve patients repeatedly for 24 weeks by high-performance liquid chromatography. In 56 patients receiving stable MTX doses for at least 12 weeks, the correlation between MTX doses and MTX-PG concentrations was examined. The efficacy was measured by the change of DAS28CRP (ΔDAS28CRP).Results: There were moderate correlations between MTX dose and MTX-PG 3, 4, and 5. At 24 weeks, MTX-PG2, 3, 4, and 1–5 were higher in patients with ΔDAS28CRP >1.2 than in those with ≤1.2. The cutoff value of MTX-PG1-5 to discriminate ΔDAS28CRP >1.2 from ≤1.2 at 24 weeks was 68.7 nM. Among 20 patients with MTX-PG1-5 > 50.6 nM at 8 weeks, seven already improved at 8 weeks and additional 11 improved at 24 weeks (p < 0.001). On the contrary, among the nine patients with MTX-PG1-5 ≤ 50.6 nM at 8 weeks, none improved at 8 weeks and only one improved at 24 weeks (p = 0.500).Conclusions: Erythrocyte MTX-PGs might be a potential indicator and predictor of MTX efficacy.

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.

IntroductionMethotrexate (MTX) is a cornerstone of treatment in a wide variety of inflammatory conditions, including juvenile idiopathic arthritis (JIA) and juvenile dermatomyositis (JDM). However, owing to its narrow therapeutic index and the considerable interpatient variability in clinical response, monitoring of adherence to MTX is important. The present study demonstrates the feasibility of using methotrexate polyglutamates (MTXPGs) as a biomarker to measure adherence to MTX treatment in children with JIA and JDM.MethodsData were collected prospectively from a cohort of 48 children (median age 11.5 years) who received oral or subcutaneous (SC) MTX therapy for JIA or JDM. Dried blood spot samples were obtained from children by finger pick at the clinic or via self- or parent-led sampling at home, and they were analysed to determine the variability in MTXPG concentrations and assess adherence to MTX therapy.ResultsWide fluctuations in MTXPG total concentrations (>2.0-fold variations) were found in 17 patients receiving stable weekly doses of MTX, which is indicative of nonadherence or partial adherence to MTX therapy. Age (P = 0.026) and route of administration (P = 0.005) were the most important predictors of nonadherence to MTX treatment. In addition, the study showed that MTX dose and route of administration were significantly associated with variations in the distribution of MTXPG subtypes. Higher doses and SC administration of MTX produced higher levels of total MTXPGs and selective accumulation of longer-chain MTXPGs (P < 0.001 and P < 0.0001, respectively).ConclusionsNonadherence to MTX therapy is a significant problem in children with JIA and JDM. The present study suggests that patients with inadequate adherence and/or intolerance to oral MTX may benefit from SC administration of the drug. The clinical utility of MTXPG levels to monitor and optimise adherence to MTX in children has been demonstrated.Trial registrationISRCTN Registry identifier: ISRCTN93945409. Registered 2 December 2011.

Methotrexate resistance in relation to treatment outcome in childhood acute lymphoblastic leukemia.

BackgroundMethotrexate (MTX) eradicates leukemic cells by disrupting de novo nucleotide biosynthesis and DNA replication, resulting in cell death. Since its introduction in 1947, MTX-containing chemotherapeutic regimens have proven instrumental in achieving curative effects in acute lymphoblastic leukemia (ALL). However, drug resistance phenomena pose major obstacles to efficacious ALL chemotherapy. Moreover, clinically relevant molecular mechanisms underlying chemoresistance remain largely obscure. Several alterations in MTX metabolism, leading to impaired accumulation of this cytotoxic agent in tumor cells, have been classified as determinants of MTX resistance. However, the relation between MTX resistance and long-term clinical outcome of ALL has not been shown previously.MethodsWe have collected clinical data for 235 childhood ALL patients, for whom samples taken at the time of diagnosis were also broadly characterized with respect to MTX resistance. This included measurement of concentrations of MTX polyglutamates in leukemic cells, mRNA expression of enzymes involved in MTX metabolism (FPGS, FPGH, RFC, DHFR, and TS), MTX sensitivity as determined by the TS inhibition assay, and FPGS activity.ResultsHerein we demonstrate that higher accumulation of long-chain polyglutamates of MTX is strongly associated with better overall (10-year OS: 90.6 vs 64.1 %, P = 0.008) and event-free survival (10-year EFS: 81.2 vs 57.6 %, P = 0.029) of ALL patients. In addition, we assessed both the association of several MTX resistance-related parameters determined in vitro with treatment outcome as well as clinical characteristics of pediatric ALL patients treated with MTX-containing combination chemotherapy. High MTX sensitivity was associated with DNA hyperdiploid ALL (P < 0.001), which was linked with increased MTX accumulation (P = 0.03) and elevated reduced folate carrier (RFC) expression (P = 0.049) in this subset of ALL patients. TEL-AML1 fusion was associated with increased MTX resistance (P = 0.023). Moreover, a low accumulation of MTX polyglutamates was observed in MLL-rearranged and TEL-AML1 rearranged ALL (P < 0.05).ConclusionsThese findings emphasize the central role of MTX in ALL treatment thereby expanding our understanding of the molecular basis of clinical differences in treatment response between ALL individuals. In particular, the identification of patients that are potentially resistant to MTX at diagnosis may allow for tailoring novel treatment strategies to individual leukemia patients.Electronic supplementary materialThe online version of this article (doi:10.1186/s13045-015-0158-9) contains supplementary material, which is available to authorized users.

The role and utility of measuring red blood cell methotrexate polyglutamate concentrations in inflammatory arthropathies—a systematic review

Evidence regarding the relationship between red blood cell methotrexate polyglutamate concentration and response to treatment and adverse drug reactions in patients using methotrexate for inflammatory arthropathies is complex and in some respects appears conflicting. Accordingly, we undertook a systematic analysis of available evidence to determine the clinical utility of dosing methotrexate to a target red blood cell methotrexate polyglutamate concentration. A systematic literature review was conducted to identify all studies that had reported an association between red blood cell methotrexate polyglutamate concentration and disease activity or adverse drug reactions in users of methotrexate for the treatment of rheumatoid arthritis, juvenile idiopathic arthritis or psoriatic arthritis. No randomised controlled trials were identified. Thirteen studies (ten in patients with rheumatoid arthritis and three in patients with juvenile idiopathic arthritis) were identified. All studies evaluated an association between red blood cell methotrexate polyglutamate concentration and response to treatment, and eight evaluated an association with toxicity. Eight studies identified lower disease activity with at least one higher red blood cell methotrexate polyglutamate concentration, although there was at least moderate potential for bias in all of these studies. Relatively large increases in concentration appeared to be required to produce a meaningful reduction in disease activity. Only one study identified an association between red blood cell methotrexate polyglutamate concentration and methotrexate-induced side effects, although studies were likely underpowered to detect this type of association. The manner in which data were presented in the included studies had many limitations that hampered its conclusive assessment, but red blood cell methotrexate polyglutamate concentrations appear to be a potentially useful guide to treatment in patients with inflammatory arthropathies, but the specific polyglutamate that should be monitored and how monitoring could be integrated into treat-to-target approaches should be clarified before it can be routinely implemented.

FRI0080 Glucocorticoids and methotrexate have a synergistic working on decrease of rheumatoid arhtritis disease activity

BackgroundRecent research has shown that response to glucocorticoids (GC) predicts the effectiveness of DMARD induction therapy including methotrexate (MTX).[1] Moreover, GC use has been associated with higher intracellular concentrations of...

AB0183 Methotrexate induced apoptosis in synoviocyte of rheumatoid arthritis

BackgroundMethotrexate (MTX) was the corner stone treatment of rheumatoid arhtirits. So for long time, MTX was used in rheumatoid arhtirits treatment with other Immunosuppressive drug. There were many hypothesis in...

AB0593 Subcutaneous methotrexate is more efficacious and better tolerated than oral methotrexate: The experience of a large group of patients in the rheumatology department of a district general hospital

BackgroundWith the emphasis in the management of inflammatory arthritis on early disease modification it is vital that prescribed treatments are tolerated and adhered to. Methotrexate can prove difficult for patients...

Determination of erythrocyte methotrexate polyglutamates by liquid chromatography/tandem mass spectrometry after low-dose methotrexate therapy in Chinese patients with rheumatoid arthritis

Methotrexate (MTX) is currently one of the most widely used drugs for treatment of rheumatoid arthritis (RA) through polyglutamation of methotrexate polyglutamates (MTXPGs), a process attaching sequential γ-linked glutamic residues to MTX. A new and sensitive LC/MS/MS method was developed and validated for determination of whole-blood MTX and total MTX (MTX+MTXPGs), and then concentration of MTXPGs was calculated. To determine whole-blood MTX, whole blood was precipitated with 50% trifluoroacetic acid, and extraction was performed using ethyl acetoacetate. Analytes were subjected to LC/MS/MS analysis using positive electrospray ionization. To determine whole-blood total MTX, whole blood was incubated with ascorbic acid (200mM) at 37°C for 3h to enzymatically convert the MTXPGs to MTX, and then processed with the same method mentioned above. Recoveries of spiked MTX at ppb (ng/mL) level were between 26.2% and 37.8% with intra- and inter-day precision less than 15.8% and 11.8%, respectively. The lower limit of detection (LLOD) and lower limit of quantitation (LLOQ) were 0.5ng/mL and 1ng/mL, respectively. The sensitive LC/MS/MS method was fully validated with high selectivity and acceptable accuracy and precision, which was successfully applied to determine the erythrocyte methotrexate polyglutamates in patients with RA.

Effects of Changing from Oral to Subcutaneous Methotrexate on Red Blood Cell Methotrexate Polyglutamate Concentrations and Disease Activity in Patients with Rheumatoid Arthritis

To determine the effects of changing from oral to subcutaneous (SC) methotrexate (MTX) in patients with rheumatoid arthritis (RA) on red blood cell MTX polyglutamate (RBC MTXGlu(n)) concentrations, disease activity, and adverse effects. Thirty patients were changed from oral to SC MTX. Trough RBC MTXGlu(n) concentrations were measured for 24 weeks and concentrations fitted to a first-order accumulation model. Disease activity was assessed by 28-joint Disease Activity Score (DAS28). MTXGlu(3), MTXGlu(4), and MTXGlu(5) concentrations, but not MTXGlu(1) and MTXGlu(2), increased significantly over 24 weeks, reaching 90% of new steady-state concentrations by about 40 weeks. A decrease in DAS28 was associated with increased RBC MTXGlu(5) (p = 0.035) and RBC MTXGlu(3-5) (p = 0.032). No change in adverse effect frequency occurred. Changing to SC MTX results in increased long-chain MTXGlu(n). However, it takes at least 6 months for RBC steady-state concentrations to be achieved. Increased long-chain MTXGlu(n) concentrations were significantly associated with reduced disease activity.