Background Identifying genetic predictors of methotrexate (MTX) therapy response in patients with rheumatoid arthritis (RA) may have importance for clinical benefit optimalization. MTX therapeutic effect is achieved by inhibiting enzymes of the folate and adenosine pathways. MTX response is mainly influenced by 5,10-methylenetetrahydrofolate reductase (MTHFR) enzyme activity.

Objectives The aim of the study was to determine whether single nucleotide polymorphisms (SNPs) in the MTHFR gene are predictive of MTX response according to the change of DAS28 after a 6-month MTX treatment in RA patient cohort of the East Bohemian population. The two SNPs 677C>T (rs1801133) and 1298A>C (rs1801131) of the MTHFR gene have been genotyped.

Methods Monocentric, regional, retrospective and prospective, cross-sectional study. The 118 patients (mean age 57 years, SD ±12.7, age of 27- 83 years, and 31 male – 26%) were enrolled in study, all of whom fulfilled the American College of Rheumatology (ACR) 1987 criteria, and currently or previously taking MTX oral treatment, either as monotherapy (n=16) or in combination with DMRDs or corticoids (n=102). The concomitant treatment were sulfasalazin (n=18), leflunomide (n=10), hydrochloroquin (n=18), cyclosporine (n=8), biologics (n=7) and glucocorticoids (n=86). Treatment outcome was evaluated using DAS28 score and based on EULAR criteria at the beginning of MTX treatment, prospectively at entry into study or retrospectively from patients' file (in case of patients with history of MTX treatment) and after a 6-month therapy. Genotyping assays: Leukocyte genomic DNA will be extracted from whole blood using a QIAamp DNA Blood Mini Kit (Quiagen). Genotyping was performed by qPCR allelic discrimination using commercial TaqMan (allele-specific) assays (LifeTechnologies) or sequencing. Statistical analysis was carried out in PASW® 18 software. Statistical dependences were tested by GLM (Generalized Linear Models), with bootstrap procedure.

Results Results of the study thus show that higher dose of MTX lead to better response of DAS28, i.e. 1.19 DAS28/10mg MTX (p=0.02). In case of polymorphism 677C>T, mean response on MTX treatment (expressed by decrease of DAS 28 after a 6-months treatment) in CC homozygotes was found 1.59 DAS/10mg MTX (median of MTX dose); CI 95% = (0.12, 3.06); p=0.034, in CT heterozygotes 0.70 DAS28/10mg; CI 95% = (-0.82, 2.22); p=0.36, and in homozygotes TT 1.83 DAS 28/10mg; CI 95% = (-1.70, 5.37); p=0.31. Regarding 1298A>C polymorphism, in AA homozygotes DAS 28 changed by 1.92 DAS28/10mg; CI 95% =(0.43, 3.41); p=0.012, in AC heterozygotes 0.43 DAS28/10mg; CI 95% = (-1.08, 1.94); p=0.57, and in CC homozygotes 1.33 DAS 28/10mg; CI 95% = (-1.59, 4.24); p=0.37.

Conclusions Our data shows that significant response to MTX treatment was found only in case of 677CC and 1298AA homozygous patients. Significant decrease of DAS 28 was associated with MTX dose in 677CC and 1298AA homozygotes. These results indicate the association of MTHFR polymorphisms with MTX response.

Acknowledgements Supported by MH CZ - DRO (UHHK, 00179906)

Disclosure of Interest : None declared

DOI 10.1136/annrheumdis-2014-eular.4365