Relationship between genetic variants in the adenosine pathway and outcome of methotrexate treatment in patients with recent-onset rheumatoid arthritis.
OBJECTIVE
Among patients with rheumatoid arthritis (RA), there is a high degree of interindividual variability in the degree of response to methotrexate (MTX) treatment. This study was undertaken to explore polymorphisms in genes contributing to antiinflammatory adenosine release as novel predictors of MTX treatment outcome.


METHODS
In 205 patients with newly diagnosed RA, 5 polymorphisms in 5 genes coding for enzymes related to the release of adenosine were analyzed. All patients received standardized MTX treatment (up to 25 mg per week orally), combined with folic acid. MTX efficacy was evaluated by the Disease Activity Score (DAS) and compared among genotypes. The association between MTX-related adverse events and genotype was also assessed. The following polymorphisms were determined: AMPD1 34C>T, ATIC 347C>G, ITPA 94C>A, MTR 2756A>G, and MTRR 66A>G. When significant differences were found by chi-square analysis, odds ratios (ORs) and 95% confidence intervals were calculated.


RESULTS
Patients carrying the AMPD1 34T allele, ATIC 347CC, or ITPA 94CC were more likely to have a good clinical response, as defined by a DAS of < or =2.4 (OR [95% confidence interval] 2.1 [1.0-4.5], 2.5 [1.3-4.7], and 2.7 [1.1-8.1], respectively). The likelihood of a good clinical response was increased if patients possessed all 3 favorable genotypes (OR 27.8 [95% confidence interval 3.2-250]). Regarding toxicity, only ATIC G allele carriers experienced a greater frequency of adverse events (OR 2.0 [95% confidence interval 1.1-3.7]).


CONCLUSIONS
Polymorphisms in the AMPD1, ATIC, and ITPA genes are associated with good clinical response to MTX treatment. These findings indicate that genotyping may help in the identification of patients who will benefit most from MTX treatment and may assist clinicians in making treatment decisions regarding patients with recent-onset RA.
Wessels
Judith A M
JA
Leiden University Medical Center, Leiden, The Netherlands.
Kooloos
Wouter M
WM
De Jonge
Robert
R
De Vries-Bouwstra
Jeska K
JK
Allaart
Cornelia F
CF
Linssen
Annelies
A
Collee
Gerard
G
De Sonnaville
Peter
P
Lindemans
Jan
J
Huizinga
Tom W J
TW
Guchelaar
Henk-Jan
HJ
D000659:AMP Deaminase / Q000235:genetics*; D000241:Adenosine / Q000378:metabolism*; D000328:Adult; D000368:Aged; D018501:Antirheumatic Agents / Q000627:therapeutic use; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000235:genetics*; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D014644:Genetic Variation; D006801:Humans; D008297:Male; D008727:Methotrexate / Q000627:therapeutic use*; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D016037:Single-Blind Method
D018501:Antirheumatic Agents; D004247:DNA; D000659:AMP Deaminase; C514117:AMPD1 protein, human; D000241:Adenosine; D008727:Methotrexate