Project description:Juvenile idiopathic arthritis (JIAs) is the most common chronic rheumatic disease of childhood and is an important cause of disability. The folic acid analog methotrexate is the first choice disease-modifying anti-rheumatic drug in this disease, however, 35-45% of patients fail to respond. Molecular elements, such as variants in genes of pharmacological relevance, influencing response to methotrexate in JIA, would be important to individualize treatment strategies. Several studies have evaluated the effects of candidate genetic variants in the complex pathway of genes involved in methotrexate pharmacodynamics and pharmacokinetics, however, results are still contrasting and no definitive genetic marker of methotrexate response useful for the clinician to tailor therapy of children with JIA has been identified. Recently, genome-wide approaches have been applied, identifying new potential biological processes involved in methotrexate response in JIA such as TGF-beta signaling and calcium channels. If these genomic results are properly validated and integrated with innovative analyses comprising deep sequencing, epigenetics, and pharmacokinetics, they will greatly contribute to personalize therapy with methotrexate in children with JIA.
Project description:This analysis aims to calculate MTX monotherapy persistence and describe the occurrence of and factors associated with the occurrence of adverse drug reactions (ADRs) with MTX. Patients with JIA starting MTX monotherapy from two UK studies were included. Patient characteristics, treatment details and ADR occurrence were collected at treatment start, 6 months, 1 year and annually. The following groups of ADRs were included: gastrointestinal, elevated liver enzymes, leukopenia, drug hypersensitivity, rash, needle phobia and any events leading to permanent MTX discontinuation. Treatment exposure was calculated from MTX start until MTX monotherapy cessation, last follow-up or 31 December 2017 (cut-off), whichever came first. Survival analysis assessed the time on MTX monotherapy and the time to the first ADR on MTX monotherapy within 2 years. Multivariable logistic regression assessed characteristics associated with any ADR and gastrointestinal ADRs. A total of 577 patients started MTX. At 2 years, 310 (54%) were no longer on MTX monotherapy. Reasons included ineffectiveness (60%; 161/185 started a biologic), adverse event (25%), remission (8%) and patient/family decision (3%). Over this time, 212 (37%) patients experienced one or more ADR; commonly gastrointestinal (68%) or elevated liver enzymes (26%). Lower physician global assessment and older age predicted any ADR and gastrointestinal ADR, respectively. Patients with polyarticular RF and JIA had reduced odds of both any ADR and a gastrointestinal ADR. After 2 years, more than half the patients were no longer on MTX monotherapy, while more than one-third experienced one or more ADR, most commonly gastrointestinal. Research focusing on identifying which children will respond and/or experience ADRs is crucial to inform treatment decisions and management planning.
Project description:Folates exist as a fluctuating pool of polyglutamated metabolites that may serve as a clinical marker of methotrexate (MTX) activity. This study was undertaken to evaluate circulating folate content and folate polyglutamate distribution in juvenile idiopathic arthritis (JIA) patients and in a cell culture model based on MTX exposure and folate supply.Blood, plasma, and red blood cell (RBC) measurements of MTX and folates were obtained from previously published data sets and an additional analysis of JIA patients receiving MTX (n = 98) and those not receiving MTX (n = 78). Erythroblastoid cells maintained in culture were exposed to MTX and grown under varying levels of folic acid supplementation. Samples were analyzed for cellular folate and MTX content.Circulating folate levels were lower in JIA patients receiving MTX, with reduced levels of blood, plasma, and RBC 5-methyl-tetrahydrofolate (5mTHF) (P < 0.0001). Average polyglutamate chain length (Gluavg ) of RBC 5mTHF was elevated in JIA patients receiving MTX (median ± interquartile range 5.63 ± 0.15 versus 5.54 ± 0.11 in those not receiving MTX; P < 0.001) and correlated with both RBC MTX accumulation (P = 0.02) and reduced plasma 5mTHF levels (P = 0.008). MTX exposure and folate deprivation in erythroblastoid cells resulted in a depletion of bioactive folate species that was associated with a shift to higher Gluavg values for several species, most notably tetrahydrofolate (THF) and 5,10-methylene-tetrahydrofolate (CH2 THF). Increased Gluavg resulted from the depletion of short-chain and the accumulation of long-chain glutamate species.Our findings indicate that folate content and polyglutamate distribution are responsive markers of MTX activity and folate supply in vivo and in vitro, and may provide novel clinical markers of pharmacologic activity of MTX.
Project description:Methotrexate is the most commonly used disease modifying antirheumatic drug in the treatment of juvenile idiopathic arthritis and can be effective in controlling disease in many patients.A significant proportion of patients experience nausea and vomiting induced by methotrexate therapy, which can lead to decreased quality of life and discontinuation of treatment with methotrexate. Many strategies have been employed in attempts to reduce methotrexate-induced nausea, including folate supplementation, switching from oral to subcutaneous methotrexate, anti-emetic therapy, behavioral therapy, and others. Anticipatory nausea can be difficult to treat, making primary prevention of nausea with anti-emetics an attractive approach.Understanding the prevalence and impact of methotrexate-induced nausea, as well as potentially effective interventions, may help maximize the therapeutic benefits of methotrexate.
Project description:BackgroundContext: Methotrexate (MTX) is a cornerstone in the treatment of juvenile idiopathic arthritis (JIA). MTX treatment is commonly associated with nausea. Large inter-individual variation exists in the level of MTX-induced nausea, possibly due to genetic factors.PurposeTo investigate whether MTX-induced nausea was associated with single nucleotide polymorphisms (SNPs) in genes encoding MTX-transporter proteins, a MTX metabolizing enzyme and a nausea receptor.FindingsMethods: Children aged ≥9 years treated with MTX for JIA were eligible. MTX-induced nausea was registered by the children's completion of a nausea diary (min. 7 days) and the parents' completion of the MTX intolerance severity score (MISS). The selected SNPs were: SLCO1B1 (rs4149056; rs4149081), SLCO1B3 (rs2117032), SLC19A1 (rs1051266), ABCC2 (rs2273697; rs3740066; rs717620), ABCB1 (rs2032582; rs1045642), MTHFR (rs1801131, rs1801133), HTR3A (rs1062613; rs1985242; rs1176713) and HTR3B (rs1176744).ResultEnrolled were 121 JIA patients (82 girls: 39 boys) with a median age of 13.3 years (IQR: 11.3-15.1). The median MTX dose was 9.7 mg/m2/week (IQR: 9.0-10.9). The median MTX treatment duration prior to enrolment was 340 days (IQR: 142-766). The SNP analysis was available for 119 patients. MTX intolerance was associated with the genotype distribution of rs1801133 (MTHFR) (p = 0.02). There was no additive effect of the minor alleles for any of the selected SNPs, nor any significant haplotype associations.ConclusionSummary: MTX-induced nausea may be influenced by genetic polymorphisms in a MTX metabolizing enzyme (rs1801133; MTHFR).ImplicationsFurther analyses involving inclusion of larger cohorts are needed to understand the impact of SNPs on MTX-induced nausea in JIA.
Project description:Variability in response to methotrexate (MTX) in the treatment of juvenile idiopathic arthritis (JIA) remains unpredictable and poorly understood. Based on previous studies implicating an interaction between nicotinamide phosphoribosyltransferase (NAMPT) expression and MTX therapy in inflammatory arthritis, we hypothesized that increased NAMPT expression would be associated with reduced therapeutic response to MTX in patients with JIA. A significant association was found between increased plasma concentrations of NAMPT and reduced therapeutic response in patients with JIA treated with MTX. Inhibition of NAMPT in cell culture by either siRNA-based gene silencing or pharmacological inhibition with FK-866 was found to result in a fourfold increase in the pharmacological activity of MTX. Collectively, these findings provide evidence that NAMPT inhibits the pharmacological activity of MTX and may represent a predictive biomarker of response, as well as a therapeutic target, in the treatment of JIA with MTX.