Erythrocyte Methotrexate Research Articles

Subcutaneous administration, higher age and lower renal function are associated with erythrocyte methotrexate accumulation in Crohn’s disease: a cross-sectional study

BackgroundMethotrexate is an immunomodulatory drug for patients with Crohn’s disease. Erythrocyte MTX-polyglutamates (MTX-PG1-5) may be used for therapeutic drug monitoring (TDM) as MTX-PG is thought to mediate MTX’s efficacy. Information on determinants of the concentration of MTX-PG in patients with Crohn’s disease is lacking. We aim to identify clinical and biochemical determinants of the erythrocyte MTX-PG1-5 and MTX-PGtotal concentration in patients with Crohn’s disease.MethodsAdults with Crohn’s disease on methotrexate treatment who visited the outpatient clinic of Amsterdam UMC were included. Erythrocyte MTX-PGs were measured by tandem mass spectrometry.ResultsNineteen patients were included, with a median duration of MTX use of 77 months (range 7–202). Twelve patients received MTX monotherapy, whereas 7 patients were on concomitant TNF-α inhibitors. The mean dose of MTX was 15.5 mg (SD ± 2.8) and 12 (63%) patients used subcutaneous MTX. MTX-PG1-5 were successfully measured in 18 patients, showing substantial variability in concentrations of MTX-PGtotal and individual species. The median MTX-PGtotal was 117.1 nmol/L (range 46.4–258.7) with preferential accumulation of MTX-PG3 (43.1 nmol/L, range 15.3–96.1). Patients on subcutaneous compared to oral MTX had higher median MTX-PG(4,5) levels (55 versus 9 nmol/L, p = 0.01). Higher age (β = 0.71) and lower estimated glomerular filtration rate (β = − 0.52) were associated with a significantly higher MTX-PGtotal concentration (R2 = 0.60, p = 0.001).ConclusionMTX-PG concentrations display a considerable inter-individual variability. Higher MTX-PG accumulation is associated with subcutaneous administration, higher age, and lower renal function in Crohn’s disease patients.

OA26 Erythrocyte mean corpuscular volume as a surrogate marker for methotrexate polyglutamation during early treatment in rheumatoid arthritis

Abstract Background/Aims The long-term outcomes for patients with rheumatoid arthritis (RA) depend on early and effective disease control. Methotrexate remains the key first-line disease-modifying therapy for the majority of patients. The gradual onset of action of methotrexate has been proposed to be linked to the build-up of intracellular stores of the drug, achieved through the process of polyglutamation. This is a complex and expensive assay. Recent work has shown an association between the increase in mean corpuscular volume (MCV) of erythrocytes and improvements in disease activity. This study seeks to relate intracellular methotrexate and 5-methyl-tetrahydrofolate polyglutamate concentrations with changes in MCV and their association with early ‘steroid free’ remission in RA patients. Methods 68 drug-naïve, newly diagnosed RA patients were recruited form the Newcastle Early Arthritis Clinic (NEAC). These patients were followed up for 6 months with serial blood sampling and quantification of the erythrocyte methotrexate and 5-methyl-tetrahydrofolate polyglutamate levels by liquid chromatography-mass spectrometry (LC-MS). This was then related to the contemporaneous erythrocyte MCV values from the clinical monitoring bloods on those occasions and the treatment outcome at 6 months. The outcome measure used was 4 component DAS28CRP remission (<2.4) with only the baseline intramuscular steroid permitted for the definition of remission. Results The majority of patients displayed a gradual increase in MCV over the first 6 months of treatment (MCV change from patient baseline used to normalise the data). When grouped by the ‘steroid free’ remission outcome, there was a divergence in MCV change with greater MCV increases observed in those achieving remission from 4 months of treatment onward (p < 0.05). In the same patient group, the accumulation of longer chain methotrexate polyglutamates (chain length 3 to 5) was observed to follow a similar trend to MCV with higher polyglutamate concentrations in those achieving the remission outcome from 2 months of treatment (P < 0.05). When the contemporaneous MCV and MTX polyglutamate samples were compared, an association was observed between the longer chain MTX polyglutamates and the change in MCV values (R2 = 0.39, p < 0.001), but not between intracellular 5-methyl-tetrahydrofolate and MCV (R2 = 0.01, p = NS). Conclusion Change in MCV shows an association with early remission induction with MTX therapy in treatment-naïve RA patients. This change in MCV appears to be associated with the accumulation of intracellular MTX metabolites, rather than via depletion of intracellular folates. MCV may therefore represent a tractable proxy measure of methotrexate polyglutamation for application in larger studies or for the purpose of drug monitoring. Disclosure P.M. Brown: None. A.G. Pratt: None. A.E. Anderson: None. A.W. Morgan: None. J.D. Isaacs: None.

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

AB0263 THE LEVEL OF 7-HYDROXY METHOTREXATE IN BLOOD CELLS IN PATIENTS WITH RHEUMATOID ARTHRITIS DIRECTLY CORRELATES WITH THE LEVEL OF POLYGLUTAMATES OF METHOTREXATE

Background:7-hydroxy Methotrexate (7-hydroxy-MTX) is a phase I metabolite of MTX, which is converted by hepatic aldehyde oxidases. It is known that 7-hydroxy MTX can reduce the effectiveness of methotrexate, which is associated with increased excretion of methotrexate due to a decrease in polyglutamation and binding to enzymes [1].Objectives:To analyze the level of 7-hydroxy-MTX in peripheral blood cells in order to study the correlation of the level of this metabolite with the level of polyglutamates of methotrexate (MTXPGs).Methods:The prospective study included 65 patients aged 53±11 years, 50 women, 13 men, diagnosed with RA, according to the ACR/EULAR 2020 criteria, methotrexate (MTX) naiive. The duration of the disease was 7,5[4;24] months. All patients were administrated MTX subcutaneously at a dose of 10-15 mg/m2. The visits were carried out at weeks 0, 4, 12, 24 and 36, at all visits samples were taken for the content of MTXPGs with 1,2,3 and 4 glutamate residues and 7-hydroxy MTX separately in red blood cells mass (RBC) and mononuclear cells (MO). The mononuclear fraction was isolated by layering on verografin-ficoll. All patients received folic acid at a standard dose of 5 mg 24 hours after parenteral MTX administration. Samples were collected no earlier than 36 hours after MTX administration. All patients had normal renal function. Disease activity was assessed using the DAS28 index calculated by C-reactive protein.Results:The average concentration of 7-hydroxy MTX is shown in Table 1.Table 1.Level of 7-hydroxy MTX in erythrocytes and mononuclear cells, nmol/L, Median [25; 75 quartiles]7-hydroxy MTX level in:4 weeks12 weeks24 weeks36 weeksRBC18,5[3,1;61,5]10,2[3,6;50,8]10,3[1,7;36,8]7,2[0,1;25,3]MO0,8[0,1;15,2]4,0[0,1;42,2]3,5[0,1;8,1]0,4[0,1;8,9]The level of 7-hydroxy-MTX directly correlated with the level of MTXPGs 1-4, and summary MTXPG in both RBC and MO. Analysis of pairwise correlations according to Pearson showed that: after 4, 12 and 36 weeks, the level of 7-hydroxy-MTX did not correlate with the value of DAS28. After 24 weeks of therapy, the level of 7-hydroxy-MTX in RBC was inversely correlated with DAS28 of the disease (p=0.043).Conclusion:The preliminary results indicate a positive correlation between the level of 7-hydroxy-MTX and MTXPGs in RBC and MO. In this regard, the concentration of 7-hydroxy-MTX can be used as a prognostic marker for MTX therapy in the absence of opportunities in clinical centers to measure the entire line of MTXPGs in RBC and MO. Since the data obtained are somewhat at odds with the few literary sources, it is necessary to conduct further research on this fact.

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

DOI: 10.1002/jssc.202001081 The cover picture shows a new HPLC strategy for quantitative analysis of multiple components via a single marker (QAMS) to determine nine nucleosides (cytidine, uridine, 2'‒deoxyuridine, inosine, guanosine, 2'‒deoxyguanosine, thymidine, adenosine and 2'‒deoxyadenosine) in Rhizoma Paridis for the first time. The results of methodology validation showed that there was no significant difference between QAMS method and the external standard method, indicating that QAMS method can applied to solve the problem of a shortage of reference materials and high cost in multicomponent analysis. Our work provide an efficient and feasible quality assessment method for other natural products containing nucleosides.

Effect of total glucosides of paeony and Tripterygium wilfordii polyglycosides on erythrocyte methotrexate polyglutamates in rats, analysed using ultra-high-performance liquid chromatography-tandem mass spectrometry.

The aim of the study was to explore the effect of total glucosides of paeony (TGP) and Tripterygium wilfordii polyglycosides (TWP) on erythrocyte methotrexate polyglutamates (MTXPGs), the metabolites of methotrexate (MTX). An ultra-high-performance liquid chromatography (UPLC)-tandem mass spectrometry (MS/MS) method was developed to determine MTXPGs. The effects of MTXPGs were analysed using 24 male Sprague-Dawley rats that were randomly divided into the MTX alone, MTX-TGP combined, and MTX-TWP combined groups. Rats were administered MTX at a dose of 0.9 mg/kg once a week, TGP at 0.054 g/kg and TWP at 1.8 mg/kg three times a day. Venous blood (1.0 ml) was collected at weeks 2, 4, 6, 9, 12 and 15 and then analysed using the developed UPLC-MS/MS method. Specificity, linear range, inter-and intra-day precision, recovery, matrix effect and stability of MTXPGs met the standard regulations. This method was successfully used for the detection of MTXPGs. After administration of MTX alone, erythrocyte MTXPGs increased and accumulated in a time- and dose-dependent manner. Compared to MTX alone, the combination with TGP significantly decreased the content of total MTXPGs and short-chain MTXPGs (Methotrexate [MTX/MTXPG1] and 4-amino-10-methylpteroyldiglutamic acid [MTXPG2], P < 0.05), but had no significant effect on long-chain MTXPGs (4-amino-10-methylpteroyltriglutamic acid [MTXPG3], P > 0.05) and very long-chain MTXPGs (4-amino-10-methylpteroyltetraglutamic acid [MTXPG4] and 4-amino-10-methylpteroylpentaglutamic acid [MTXPG5], P > 0.05) at week 15. The combination of MTX with TWP had no significant effect on the content of total MTXPGs, short-chain MTXPGs and long-chain MTXPGs (P > 0.05), but it significantly decreased the content of very long-chain MTXPGs (P < 0.05) at week 15. The UPLC-MS/MS method was successfully used to determine MTXPGs in rat erythrocytes. TGP and TWP in combination with MTX affected the production of MTXPGs of different chain lengths in erythrocytes.

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 10nM 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 500.0nmol/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.

Methotrexate pharmacokinetic is influenced by co-administration of cyclosporin in rheumatoid arthritis patients. Results from a randomized clinical trial

The aim was to investigate if the pharmacokinetics of methotrexate (MTX) are affected by the addition of cyclosporin (CsA). Forty patients diagnosed with early rheumatoid arthritis (RA) were included in this open prospective study: 20 patients were treated with a dose of 7.5 mg MTX and a dose of 2.5 mg/kg CsA, 20 patients were treated with a dose of 7.5 mg MTX and placebo. Baseline measurements of plasma MTX and erythrocyte MTX were made. Area under the plasma concentration versus time curve (AUC) and other pharmacokinetic variables were estimated by means of a population based software model. Clinical improvement of 20–50–70% according to the American College of Rheumatology (ACR) and adverse events were evaluated ongoing for 52 weeks. We found that mean peak plasma MTX concentration was significantly higher in the MTX + CsA combination treatment group (p = .003). No differences in AUC, erythrocyte MTX or other pharmacokinetic parameters were found between the two treatment groups. Estimated Glomerular Filtration Rate (eGFR) decreased significantly in the MTX + CsA treatment group (p < .001), but no serious adverse events occurred in either of the two groups. In conclusion, CsA added to methotrexate treatment in early RA significantly increased peak-plasma MTX concentration, but other pharmacokinetic parameters and measurements of MTX were unchanged.

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.

High Methotrexate Triglutamate Level Is an Independent Predictor of Adverse Effects in Asian Indian Rheumatoid Arthritis Patients-A Preliminary Study.

It is unclear whether erythrocyte methotrexate polyglutamate levels (MTX-glun) are associated with response or adverse effects to methotrexate in rheumatoid arthritis. This preliminary study evaluated their utility in Asian Indian patients over 24 weeks. Rheumatoid arthritis patients were started on oral methotrexate at a dose of 15 mg/wk, which was escalated to 25 mg by 12 weeks and continued till 24 weeks. Erythrocyte (RBC) MTX-glu1 to MTX-glu5 levels (nmol/L RBC) were determined at 4, 8, 16, and 24 weeks by using reverse-phase high-performance liquid chromatography. Area under the concentration curve (AUC) of MTX-glu1-5, MTX-glu3-5, and MTX-glu3 levels was compared between groups with regards to response and adverse effects. This study included 117 patients with mean (SD) age of 42.7 (±11.9) years and disease duration of 2.0 (1.7) years. Mean (SD) RBC MTX-glu1-5 levels at 4, 8, 16, and 24 weeks were 93 (±29), 129 (±46), 143 (±49), and 159 (±65) nmol/L RBC; the highest individual polyglutamate was MTX-glu3 (40%). There was significant correlation between MTX-glu1-5 (r = 0.38, P < 0.001) and MTX-glu3 (r = 0.49, P < 0.001) with methotrexate dose. There was no significant difference of AUC MTX-glun between responders and nonresponders. However, AUC MTX-glu3 was significantly (P = 0.03) higher in patients with adverse effects. On logistic regression, AUC of MTX-glu3 [odds ratio = 1.004 (95% confidence interval 1.002-1.007)] and methotrexate dose at 24 weeks were independent predictors of adverse effects. In this preliminary study, higher levels of RBC MTX-glu3 were found to be the independent predictors for adverse effects in rheumatoid arthritis patients.

Measures of 6-mercaptopurine and methotrexate maintenance therapy intensity in childhood acute lymphoblastic leukemia.

Normal white blood cell counts (WBC) are unknown in children with acute lymphoblastic leukemia (ALL). Accordingly, 6-mercaptopurine (6MP) and methotrexate (MTX) maintenance therapy is adjusted by a common WBC target of 1.5-3.0×109/L. Consequently, the absolute degree of myelosuppression is unknown for the individual child and we wanted to evaluate this. A median of 22 (range 8-27) 6MP/MTX metabolite samples and 100 (range 25-130) blood counts during therapy and 10 (range 2-15) offtherapy were collected in 50 children with ALL. Differences between off-therapy and on-therapy WBCs [including absolute neutrophil (ANC) and lymphocyte counts (ALC)] were used to retrospectively approximate the absolute myelosuppression (="delta-") and association with age, sex and 6MP/MTX doses explored. We applied linear mixed models to estimate on-therapy counts by 6MP/MTX metabolites: DNA-incorporated thioguanine nucleotides (DNA-TGN), erythrocyte thioguanine nucleotides (ery-TGN), erythrocyte-methylated 6MP metabolites (ery-MeMP) and erythrocyte MTX polyglutamates with 2-6 glutamate residues (ery-MTXpg2-6). On-therapy WBC was correlated with ANC and ALC (r s =0.84 and r s =0.33, p values <0.001), whereas ANC was weakly correlated with ALC (r s =-0.11, p<0.001), and neither significantly correlated with age. Off-therapy ALC, but not ANC, was strongly correlated with age (r s =-0.68 and -0.18, p<0.001 and p=0.22). Delta-ALC decreased with increasing age (r s =-0.69, p<0.001). Incorporation of DNA-TGN was positively associated with ery-TGN (p<0.001), ery-MeMP (p<0.001) and ery-MTXpg2-6 (p=0.047). On-therapy ALC decreased with increasing DNA-TGN level (p<0.001, model adjusted for off-therapy ALC), whereas on-therapy ANC could not be modeled reliably. Measurements of 6MP/MTX metabolites could supplement blood counts in assessing therapy intensity, but require prospective validation.

Effect of Methotrexate Use and Erythrocyte Methotrexate Polyglutamate on Glycosylated Hemoglobin in Rheumatoid Arthritis

To investigate whether methotrexate (MTX) use, as compared to other therapies, and erythrocyte methotrexate polyglutamate (MTXGlu) concentrations are associated with changes in glycosylated hemoglobin (HbA1c ) levels in rheumatoid arthritis (RA) patients. The derivation cohort consisted of patients selected from the Treatment in the Rotterdam Early Arthritis Cohort who fulfilled the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria for RA. Patients were randomized to 6 treatment arms: triple disease-modifying antirheumatic drug (DMARD) therapy (consisting of MTX, sulfasalazine, and hydroxychloroquine [HCQ]) + intramuscular (IM) glucocorticoids, triple DMARD therapy + oral glucocorticoids, MTX + oral glucocorticoid therapy, MTX therapy, oral glucocorticoid therapy, and HCQ therapy. HbA1c levels were determined at baseline and at 3 months. Concentrations of erythrocyte MTXGlu1-5 were measured after 3 months of treatment. Within treatment arms, changes in the level of HbA1c were compared by paired t-test. Associations of MTXGlu concentrations with changes in the level of HbA1c were tested using multiple linear regression analysis, adjusted for age, sex, body mass index, and comedication. Significant associations were validated using data on RA patients taking MTX who were enrolled in the Methotrexate in Rotterdam cohort. In the derivation cohort, the mean change in HbA1c level after 3 months of treatment was -1.9 mmoles/mole (-0.18%) (P = 0.001). Levels of HbA1c decreased in 4 of the individual treatment groups, as follows: for the triple DMARD therapy + IM glucocorticoids treatment arm, -5.5 mmoles/mole (-0.50%) (P < 0.001), for the triple DMARD therapy + oral glucocorticoids treatment arm, -3.7 mmoles/mole (-0.34%) (P < 0.001), for the MTX treatment arm, -0.8 mmoles/mole (-0.08%) (P = 0.018), and for the HCQ treatment arm, -2.0 mmoles/mole (-0.19%) (P = 0.175). Increased levels of MTXGlu2 (β = -0.20, P = 0.005), MTXGlu3 (β = -0.31, P < 0.001), MTXGlu4 (β = -0.33, P < 0.001) after treatment, MTXGlu5 (β = -0.39, P < 0.001), and total MTXGlu (β = -0.29, P < 0.001) were associated with decreased levels of HBA1c . In the validation cohort, levels of HbA1c were decreased by 2.6 mmoles/mole (0.23%) (P < 0.001) after treatment, and MTXGlu3 was associated with decreased levels of HbA1c (β = -0.26, P = 0.018). MTX use and higher concentrations of erythrocyte MTXGlu are associated with decreased levels of HbA1c in RA patients. Triple DMARD therapy and HCQ treatment resulted in reduced HbA1c levels, and glucocorticoid treatment resulted in increased levels of HbA1c .

THU0122 Effect of Two MTX Dosing Regimens on Intracellular MTX Accumulation in Rheumatoid Arthritis Patients

BackgroundLow-dose methotrexate (MTX) is gold standard in the treatment of rheumatoid arthritis (RA). Response to MTX is very variable and is related to the intracellular MTX-polyglutamate (MTX-PG) levels.1,2 Similar to...

Methotrexate polyglutamates in erythrocytes are associated with lower disease activity in juvenile idiopathic arthritis patients

ObjectiveTo determine association of erythrocyte methotrexate polyglutamates (MTX-PG) with disease activity and adverse effects in a prospective juvenile idiopathic arthritis (JIA) cohort.MethodsOne hundred and thirteen JIA patients were followed from...

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.

Short-chain methotrexate polyglutamate MTXPG2 as outcome parameter in rheumatoid arthritis

Background Due to its positive benefit-risk-ratio, methotrexate (MTX) is a first-line therapy in the treatment of rheumatoid arthritis (RA). Although MTX is very effective, the large interpatient variability in drug response is a major drawback in clinical practice. Erythrocyte methotrexate polyglutamates (MTXPG1–7) — intracellular storage products of methotrexate — are supposed to correlate with clinical efficacy. In particular, long-chain polyglutamates (MTXPG4–5) are strongly retained in the cells and are therefore discussed to be potential markers for clinical response in rheumatoid arthritis. We hypothesized that concentrations of methotrexate polyglutamates could correlate with clinical response parameters in rheumatoid arthritis.

Effect of methotrexate polyglutamates on thioguanine nucleotide concentrations during continuation therapy of acute lymphoblastic leukemia with mercaptopurine.

Methotrexate is widely administered with mercaptopurine, a prodrug requiring activation into thioguanine nucleotides (TGN) to exert antileukemic effects. In vitro, methotrexate enhances TGN formation, but in vivo, such enhancement has yet to be demonstrated. We investigated whether TGN concentrations were related to methotrexate concentrations in children with acute lymphoblastic leukemia who received a weekly intravenous methotrexate (40 mg/m(2)) dose combined with daily mercaptopurine (75 mg/m(2)). A total of 141 erythrocyte TGN concentrations were measured with erythrocyte methotrexate polyglutamates (MTX-PG) concentrations in 87 patients. Average TGN concentrations ranged from 137 to 958 pmol/8 x 10(8) cells (median 389), average total MTX-PG concentrations (MTX- PG(1-7)) from 0.60 to 97.7 pmol/10(9)cells (median 29), and average long chain polyglutamate concentrations (MTX-PG(5-7)) from 0 to 8.35 pmol/10(9) cells (median 2.43). Higher TGN concentrations correlated with higher MTX-PG(5-7) concentrations (P = 0.002). These data support the practice of administering methotrexate with mercaptopurine during continuation therapy of acute lymphoblastic leukemia.

Continuing therapy for childhood acute lymphoblastic leukaemia: clinical and cellular pharmacology of methotrexate, 6-mercaptopurine and 6-thioguanine

Across the world, therapy with 6-mercaptopurine (6-MP) and methotrexate (MTX) forms the basis of the continuing therapy of childhood acute lymphoblastic leukaemia (ALL). In this review, the pharmacological determinants of the sensitivity of human leukaemia cell lines and lymphoblasts derived from children with ALL will be discussed. In addition, clinical pharmacological studies of 6-MP and MTX in relation to the continuing therapy with childhood ALL will be reviewed. For 6-MP in vitro, prolonged exposure times to relatively high extracellular drug concentrations are necessary for cytotoxicity, and these concentrations are much higher than those achieved during continuing therapy for childhood ALL. For MTX, plasma concentrations are achieved during continuing therapy that would be cytotoxic to human leukaemia cells during prolonged exposures in vitro. For both MTX and 6-MP, wide inter- and intrapatient variation in plasma pharmacokinetic parameters has been described. For 6-MP and MTX, cellular pharmacological studies have been largely restricted to erythrocytes as a surrogate of the possible effects in leukaemic blasts. Although measures of the pharmacology of 6-MP and MTX in erythrocytes has been related to prognosis in many studies, 6-MP systemic exposure and the dose intensity of 6-MP and MTX actually received by children during this phase of therapy seems to be the most important determinant of efficacy. Further studies will be needed to determine the importance of pharmacokinetic variability during continuing therapy as a determinant of outcome for children with ALL. In this respect, minimal residual disease status during this phase of treatment may prove to be a useful pharmacodynamic endpoint.

Clinical Outcome and Pharmacokinetics After Addition of Low-Dose Cyclosporine to Methotrexate: A Case Study of Five Patients with Treatment-Resistant Inflammatory Bowel Disease

This study reports the clinical outcome, toxicity, and methotrexate pharmacokinetics after the addition of low-dose cyclosporine to methotrexate in patients with ulcerative colitis or Crohn's disease. Three patients with steroid-refractory ulcerative colitis and two patients with steroid refractory Crohn's disease who failed monotherapy with subcutaneous methotrexate 25 mg/week for 16 weeks were treated with the combination of methotrexate and low-dose oral cyclosporine (3 mg/kg/day) for an additional 16 weeks. Clinical response was measured with the Inflammatory Bowel Disease Questionnaire (IBDQ) score. Concentrations of erythrocyte methotrexate, plasma methotrexate, and plasma 7-hydroxymethotrexate were also determined. Both patients with Crohn's disease withdrew from the study for toxicity (headaches, seizure). The three patients with ulcerative colitis experienced clinical improvement with a mean increase in the IBDQ score from 164 to 190 points, p = 0.01. The mean serum creatinine in the three patients who completed the study increased from 0.9 mg/dL at baseline to 1.2 mg/dL at week 16, p = 0.04. One patient developed hypertension. There was no significant change from baseline in the concentrations of erythrocyte methotrexate, plasma methotrexate, and plasma 7-hy-droxymethotrexate. Combination therapy with methotrexate and low-dose oral cyclosporine did not alter methotrexate pharmacokinetics and resulted in high rates of cyclosporine-associated toxicity.

Clinical outcome and pharmacokinetics after addition of low-dose cyclosporine to methotrexate: a case study of five patients with treatment-resistant inflammatory bowel disease.

This study reports the clinical outcome, toxicity, and methotrexate pharmacokinetics after the addition of low-dose cyclosporine to methotrexate in patients with ulcerative colitis or Crohn's disease. Three patients with steroid-refractory ulcerative colitis and two patients with steroid refractory Crohn's disease who failed monotherapy with subcutaneous methotrexate 25 mg/week for 16 weeks were treated with the combination of methotrexate and low-dose oral cyclosporine (3 mg/kg/day) for an additional 16 weeks. Clinical response was measured with the Inflammatory Bowel Disease Questionnaire (IBDQ) score. Concentrations of erythrocyte methotrexate, plasma methotrexate, and plasma 7-hydroxymethotrexate were also determined. Both patients with Crohn's disease withdrew from the study for toxicity (headaches, seizure). The three patients with ulcerative colitis experienced clinical improvement with a mean increase in the IBDQ score from 164 to 190 points, p = 0.01. The mean serum creatinine in the three patients who completed the study increased from 0.9 mg/dL at baseline to 1.2 mg/dL at week 16. p = 0.04. One patient developed hypertension. There was no significant change from baseline in the concentrations of erythrocyte methotrexate, plasma methotrexate, and plasma 7-hydroxymethotrexate. Combination therapy with methotrexate and low-dose oral cyclosporine did not alter methotrexate pharmacokinetics and resulted in high rates of cyclosporine-associated toxicity.