title: Measurement of erythrocyte methotrexate polyglutamate levels: ready for clinical use in rheumatoid arthritis?
abstract: Methotrexate (MTX) is one of the most commonly prescribed and most effective drugs for the treatment of rheumatoid arthritis (RA). Given the partial response of many patients and the side effect profile of the drug, there is considerable interest in identifying biomarkers to guide MTX therapy in RA. Upon entering cells, MTX is polyglutamated. Measuring MTX polyglutamate (MTX PG) levels in circulating red blood cells has been proposed as an objective measure to help optimize MTX therapy in RA. Data are conflicting with regard to the clinical utility of MTX PG measurements as a predictor of the efficacy or toxicity of low-dose MTX effects in RA. Should large, randomized clinical trials of this assay show consistent, reproducible, long-term correlations between MTX PG levels and efficacy or toxicity, this test could become a prominent tool for clinicians to optimize the use of MTX in treating RA.
authors.affiliation: Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, 1530 3rd Avenue South, 178 SHEL, Birmingham, AL 35294-2182, USA.
authors.forename: Maria I
authors.initials: MI
authors.lastname: Danila
authors.forename: Laura B
authors.initials: LB
authors.lastname: Hughes
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Brown
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Morgan
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Baggott
authors.forename: Donna K
authors.initials: DK
authors.lastname: Arnett
authors.forename: S Louis
authors.initials: SL
authors.lastname: Bridges
mesh_terms: D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D008727:Methotrexate / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D016896:Treatment Outcome
chemical_list: D011099:Polyglutamic Acid; C014085:methotrexate polyglutamate; D008727:Methotrexate