Genetic markers of treatment response in rheumatoid arthritis

Association between ABCB1 C3435T polymorphism and methotrexate treatment outcomes in rheumatoid arthritis patients: a meta-analysis

Aim: This study was conducted to investigate the relationship between ABCB1 gene C3435T polymorphism and methotrexate treatment outcomes in rheumatoid arthritis patients. Methods: Seven electronic databases (PubMed, EMBASE, Web of Science, Cochrane, OVID, Chinese biomedical literature [CBM], China National Knowledge Infrastructure [CNKI] and Wanfang databases) were searched to select eligible publications until 18 July 2018. The references of relevant articles were also manually searched. The quality evaluation of the included studies was carried out according to the guidelines of the Newcastle–Ottawa Scale. Data were analyzed with Review Manager 5.3 and Stata 13.0 software. In total, 12 articles involving 2014 patients were included. Conclusion: Our results demonstrated that the ABCB1 gene C3435T polymorphism might be a reliable predictor of response to methotrexate in rheumatoid arthritis patients. However, well-designed, multicenter and large-scale prospective studies are required to further confirm the validity of our results.

Nonassociation of homocysteine gene polymorphisms with treatment outcome in South Indian Tamil Rheumatoid Arthritis patients

The aim of the study was to look for any association of MTR 2756A>G and MTRR 66A>G gene polymorphisms with clinical phenotype, methotrexate (MTX) treatment response, and MTX-induced adverse events in South Indian Tamil patients with rheumatoid arthritis (RA). A total of 335 patients with RA were investigated. MTR 2756A>G gene polymorphism was analyzed by PCR-RFLP, and MTRR 66A>G SNP was analyzed by TaqMan 5' nuclease assay. The allele frequencies were compared with HapMap groups. MTR 2756G allele was found to be associated with risk of developing RA. The allele frequencies of MTR 2756A>G and MTRR 66A>G SNPs in controls differed significantly when compared with HapMap groups. Neither of the SNPs influenced the MTX treatment outcome and adverse effects. Neither of the SNPs seems to be associated with MTX treatment outcome and adverse events in South Indian Tamil patients with RA.

Genetic risk factors for drug-induced liver injury in rheumatoid arthritis patients using low-dose methotrexate

Low-dose methotrexate (MTX) is part of the mainstay of rheumatoid arthritis treatment. Hepatotoxicity is among the most feared side effects of low-dose MTX and is associated with increased morbidity. At present, histological evaluation of liver biopsies is the gold standard to retrospectively diagnose MTX-induced liver damage. Genetic markers present an interesting opportunity to preemptively identify patients at risk for MTX-induced hepatotoxicity. Here, we will review the literature on candidate genetic markers for the risk of MTX-induced hepatotoxicity. These candidate genetic markers include polymorphisms in the gene encoding the enzyme MTHFR.

Old drugs, old problems: where do we stand in prediction of rheumatoid arthritis responsiveness to methotrexate and other synthetic DMARDs?

Methotrexate (MTX) is the central drug in the management of rheumatoid arthritis (RA) and other immune mediated inflammatory diseases. It is widely used either in monotherapy or in association with other synthetic and biologic disease modifying anti-rheumatic drugs (DMARDs). Although comprehensive clinical experience exists for MTX and synthetic DMARDs, to date it has not been possible to preview correctly whether or not a patient will respond to treatment with these drugs. Predicting response to MTX and other DMARDs would allow the selection of patients based on their likelihood of response, thus enabling individualized therapy and avoiding unnecessary adverse effects and elevated costs. However, studies analyzing this issue have struggled to obtain consistent, replicable results and no factor has yet been recognized to individually distinguish responders from nonresponders at treatment start. Variables possibly influencing drug effectiveness may be disease-, patient- or treatment-related, clinical or biological (genetic and nongenetic). In this review we summarize current evidence on predictors of response to MTX and other synthetic DMARDs, discuss possible causes for the heterogeneity observed and address its translation into daily clinical practice.

Biologics - beyond the joints

Biologics including tumor necrosis factor α (TNF-α), interleukin-6 receptor (IL-6R), T and B cell inhibitors are very effective therapeutic agents for the treatment of arthritides. These compounds effectively improve articular symptoms and inhibit joint damage. In this respect, there are no major differences in the efficacy of the available biologics. However, many arthritis patients also exert extra-articular features, systemic manifestations of the disease. These associated conditions include uveitis, inflammatory bowel disease, psoriasis, secondary bone loss and cardiovascular disease. There have been data suggesting that there may be differences in the effects of various TNF inhibitors, rituximab and tocilizumab on the systemic manifestations described above. At present, we do not always have sufficient evidence to confirm these differences, therefore, more information should be obtained from large trials and long-term observational studies.

Functional polymorphisms and methotrexate treatment outcome in recent-onset rheumatoid arthritis

AIMS

Clinical response to methotrexate (MTX) treatment differs among rheumatoid arthritis patients. Genetic variation can partly account for this phenomenon. In this study, functional polymorphisms in genes related to the mechanism of action of MTX or immunopathogenesis of rheumatoid arthritis were studied for association with treatment outcome in a Dutch cohort of patients with early rheumatoid arthritis. Furthermore, tests for replication of previous research on these genetic variants were performed according to reported end points.

MATERIALS & METHODS

Seven polymorphisms in seven genes were analyzed in 205 genotyped patients with active rheumatoid arthritis. All patients received standardized MTX treatment (< or =25 mg per week orally) combined with folic acid. MTX treatment outcome was evaluated by disease activity score criteria and adverse drug events. The following genetic variants were analyzed and correlated: ABCB1 3435C>T, ITPA IVS2 +21A>C, HLA-G (-14 bp >+14 bp), TGFB1 +869T>C and TLR4 +896A>G. In case of significant differences, regression analyses were applied. Since carriers of the minor alleles of the SNPs DHFR 829C>T and IMPDH2 +787C>T were not observed, no statistical analyses could be performed.

RESULTS

No significant associations or replications of these genetic variants with MTX efficacy were demonstrated. Regarding toxicity, patients carrying the ABCB1 3435T-allele and TLR4 +896G-allele were 2.5-times more likely to develop adverse drug events at 6 months (odds ratio: 2.6; 95% CI: 1.1-6.2, and odds ratio: 2.5; 95% CI: 1.1-6.1, respectively). Additionally, this chance increased almost fourfold in patients with the two unfavorable genotypes (odds ratio: 3.9; 95% CI: 1.5-10.3). However, none of these associations remained significant after correction for multiple testing (p < 0.004).

CONCLUSION

Our data indicate that MTX toxicity was potentially associated with ABCB1 3435C>T and TLR4 +896A>G. However, after correction, none of these associations remained significant. Furthermore, no significant associations or replications of these functional variants with efficacy were found.