Association of the TYMS 3G/3G genotype with poor response and GGH 354GG genotype with the bone marrow toxicity of the methotrexate in RA patients

Impact of TYMS gene polymorphism on the outcome of methotrexate treatment in a sample of Iraqi rheumatoid arthritis patients - identification of novel single nucleotide polymorphism: Cross-sectional study

The current work aims to evaluate the association between genetic mutations in thymidylate synthetase (TYMS gene in exon1 and partial regions of promotor and intron 1 [877 bp, 657,220-658,096 bp]) and the therapeutic outcomes for rheumatoid arthritis (RA) Iraqi patients. An observational cross-sectional study involving 95 RA patients with established RA patients based on their methotrexate treatment responsiveness. Genetic sequencing of the TYMS gene was performed for all patients according to the instruction manuals of the sequencing company (Macrogen Inc. Geumchen, South Korea). Four polymorphisms were identified by sequencing 95 randomly selected patients in the noncoding region of TYMS. Three of these polymorphisms were found in the NCBI database's dbSNP (rs2853741, rs2606241, and rs2853742 SNPs), and one SNP polymorphism is novel (657334). The CTAT (657334, rs2853741, rs2606241, and rs2853742 SNPs) haplotype was significantly associated with responder with odd ratio, 95% confidence interval: 0.506, 0.281-0.912 (P value = .022). In contrast, the other haplotypes were not associated with MTX responsiveness. In the multivariate analysis, after adjusting to the effect of age, sex, smoking, and disease duration, the TCrs2853741 genotype was associated with non-responders (P value = .030). In contrast, the ACrs260641 genotype, after adjusting to the effect of age, sex, and smoking, was associated with non-responders (P value = .035). Genetic polymorphism of the TYMS gene, especially in TCrs2853741 and ACrs260641, predicts non-responder to MTX treatment in RA, while the presence of the CTAT haplotype predicts a good response to MTX treatment.

High Efficacy Combined Microneedles Array with Methotrexate Nanocrystals for Effective Anti-Rheumatoid Arthritis

Introduction

Methotrexate (MTX) is the first-line drug for the treatment of rheumatoid arthritis (RA) in several countries. However, MTX has an extremely low solubility in water, and the side effects caused by its delivery mode restrict its curative effect. In this study, we designed a dissolving microneedles array (DMNA) containing MTX nanocrystals (MTX-NCs) (MTX-NC@DMNA) to improve the treatment of RA. DMNA-based drug delivery combines the advantages of patient compliance with the use of transdermal drug delivery systems and high-efficiency injection administration; thus, it can mitigate the side effects that result from current administration routes. Carrier-free and surfactant-free MTX-NCs were prepared to overcome bioavailability limitations and poor drug loading problems.

Methods

The MTX-NCs prepared by reverse solvent precipitation method was encapsulated in the DMNA. The morphology, mechanical properties, safety, stability and in vivo dissolution were evaluated, and its pharmacodynamic characteristics were assessed in a rat model of RA.

Results

The particle size of the MTX-NCs was 148.1 ± 10.1 nm. The MTX-NC@DMNA were found to be rigid enough to penetrate the skin and deliver the drug successfully. The results indicated effective skin recovery after removal of the DMNA. It was found that the MTX-NC@DMNA significantly reduced foot swelling in the rats and regulated the balance in the levels of related cytokines. It also reduced pathological damage to the synovium, joint, and cartilage, and effectively alleviated organ injury in the rats.

Conclusion

Transdermal administration of MTX-NC@DMNA may be an effective approach for treating RA.

Pharmacogenetics of Drug Therapies in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disorder that can lead to severe joint damage and is often associated with a high morbidity and disability. Disease-modifying anti-rheumatic drugs (DMARDs) are the mainstay of treatment in RA. DMARDs not only relieve the clinical signs and symptoms of RA but also inhibit the radiographic progression of disease and reduce the effects of chronic systemic inflammation. Since the introduction of biologic DMARDs in the late 1990s, the therapeutic range of options for the management of RA has significantly expanded. However, patients' response to these agents is not uniform with considerable variability in both efficacy and toxicity. There are no reliable means of predicting an individual patient's response to a given DMARD prior to initiation of therapy. In this chapter, the current published literature on the pharmacogenetics of traditional DMARDS and the newer biologic DMARDs in RA is highlighted. Pharmacogenetics may help individualize drug therapy in patients with RA by providing reliable biomarkers to predict medication toxicity and efficacy.

Genome-wide association study of liver enzyme elevation in rheumatoid arthritis patients starting methotrexate

Aim: To identify novel genetic variants predisposing to elevation of Alanine aminotransferase (ALT) in rheumatoid arthritis (RA) patients after initiation of methotrexate (MTX) treatment. Patients & methods: We performed genome-wide association studies in 198 RA patients starting MTX. Outcomes were maximum level of ALT and ALT >1.5-times the upper level of normal within the first 6 months of treatment. Results: RAVER2 (rs72675408) was significantly associated with maximum level of ALT (p = 4.36 × 10^-8). This variant is in linkage disequilibrium with rs72675451, which is associated with differential expression of JAK1 and RAVER2. Conclusion: We found an association between ALT elevation and genetic variants that may regulate the expression of JAK1 and RAVER2. JAK1 encodes a janus kinase involved in the pathogenesis of RA.

A Review of Clinical Applications and Side Effects of Methotrexate in Ophthalmology

Methotrexate (MTX) is a folate analog widely used against a range of diseases including malignancies and autoimmune disorders. Its high effectiveness-price ratio also won extensive application in ophthalmology. On the other hand, although MTX has an excellent pharmacological efficacy, MTX associated side effects in clinical use, which vary from patient to patient, are nonnegligible. There is no comparatively systematic review on MTX associated side effects and its risk factors. This review aimed to reveal novel clinical approaches of MTX and its adverse effects in order to provide a reference for ophthalmic scholars in clinical application of MTX.

Characterization of pharmacogenetic markers related to Acute Lymphoblastic Leukemia toxicity in Amazonian native Americans population

Acute Lymphoblastic Leukemia (ALL) is the most common cancer in children. Differences are found among ethnic groups in the results of the treatment of pediatric ALL. In general, children with a high level of native American ancestry tend to respond less positively to ALL treatments, which may be related to specific genomic variants found in native American groups. Despite the evidence, few data are available on the distribution of the pharmacogenomic variants relevant to the treatment of ALL in traditional Amerindian populations, such the those of the Amazon region. Given this, the present study investigated 27 molecular markers related to the treatment of ALL in Amerindians from Brazilian Amazonia and compared the frequencies with those recorded previously on five continents, that are available in the 1,000 Genomes database. The variation in the genotype frequencies among populations was evaluated using Fisher's exact test. The False Discovery Rate method was used to correct the results of the multiple analyses. Significant differences were found in the frequencies of the majority of markers between the Amerindian populations and those of other regions around the world. These findings highlight the unique genetic profile of the indigenous population of Brazilian Amazonia, which may reflect a distinct therapeutic profile for the treatment of ALL in these populations.

MTHFR, TYMS and SLCO1B1 polymorphisms and adverse liver effects of methotrexate in rheumatoid arthritis

Aims: To investigate whether variants of MTHFR, TYMS and SLCO1B1 are associated with ALT elevation in rheumatoid arthritis patients starting methotrexate (MTX). Patients & methods: Clinical and laboratory data were collected from the start of MTX treatment. Genotyping of MTHFR, TYMS and SLCO1B1 was performed. Univariate and multiple logistic regression were used for statistical analysis. Results: 34 out of 369 patients experienced ALT >1.5 × ULN less than 6 months from start. MTHFR A1298C (rs1801131) was nominally associated with an ALT >1.5 × ULN within 6 months after the start of MTX (OR = 1.7 [95% CI: 1.04-2.9]; p = 0.03), but did not pass correction for multiple testing. A multiple model containing MTHFR 1298C and clinical factors predicted the outcome (C-statistic 0.735). TYMS and SLCO1B1 were not associated with the outcome. Conclusions: A model containing MTHFR 1298C and clinical factors might predict risk of early ALT elevation.

Methotrexate pharmacogenetics in the treatment of rheumatoid arthritis

For many decades, methotrexate (MXT) has remained the drug of choice in the treatment of rheumatoid arthritis (RA). Unfortunately, a considerable number of patients do not achieve an appropriate therapeutic response. Pharmacogenetics studies do not give usable results regarding differences in MTX response among RA patients. The mechanism of MTX action in RA is not completely understood. We present and discuss data regarding the molecular basis of folate and adenosine pathways, the most obvious MTX targets, to explain possible causes of therapy failure. The molecular basis of the disease could also have an impact on therapy outcomes and in this review we explore this. Finally, we make a short review of available pharmacogenetics study results.

Pharmacogenetics: A strategy for personalized medicine for autoimmune diseases

For many years, a considerable number of patients with autoimmune diseases (ADs) have suffered from a lack of drug response and drug-related toxicity. Despite the emergence of new therapeutic options such as biological agents, patients continue to struggle with these problems. Unfortunately, new challenges, including the paradoxical effects of biological drugs, have complicated the situation. In recent decades, efforts have been made to predict drug response as well as drug-related side effects. Thanks to the many advances in genetics, evaluation of markers to predict drug response/toxicity before the initiation of treatment may be an avenue toward personalizing treatments. Implementing pharmacogenetics and pharmacogenomics in the clinic could improve clinical care; however, obstacles remain to effective personalized medicine for ADs. The present study attempted to clarify the concept of pharmacogenetics/pharmacogenomics for ADs. After an overview on the pathogenesis of the most common types of treatments, this paper focuses on pharmacogenetic studies related to the selected ADs. Bridging the gap between pharmacogenetics and personalized medicine is also discussed. Moreover, the advantages, disadvantages and recommendations related to making personalized medicine practical for ADs have been addressed.

Polymorphism in Organic Anion-Transporting Polypeptide Gene Related to Methotrexate Response in Rheumatoid Arthritis Treatment

BACKGROUND

Methotrexate (MTX) is still the first-choice drug for the treatment of rheumatoid arthritis (RA). In Japan, MTX doses of up to 16 mg/week were approved in 2011. In this study, we aimed to identify the gene polymorphisms that can predict therapeutic effects of MTX in Japanese patients in current clinical settings.

METHODS

This study involved 171 patients with RA (all Japanese nationals, age 63.5±10.0 years) who had been administered MTX. The analyzed polymorphisms included 82 single nucleotide polymorphisms (SNPs) involved in the MTX pharmacological pathway or in the pathogenesis of RA. Responders were patients who showed high sustained remission or low disease activity with MTX or conventional disease-modifying anti-rheumatic drugs (DMARDs) treatment beyond 6 months. Non-responders were patients who showed moderate or high disease activity, who were prescribed biological DMARDs. A logistic model was constructed with Responder/Non-responder as the target variable, and minor allele frequency was set as an explanatory variable.

RESULTS

None of the 82 SNPs targeted for analysis met the Bonferroni significance threshold of 6.098×10^-4. However, we identified SLCO1B1 rs11045879 as an SNP that might yield significant results if the number of patients were to be increased (P=0.015).

CONCLUSIONS

The rs11045879 minor allele in the SLCO1B1 gene is a potential predictor of non-responders to MTX treatment among Japanese RA patients. In future collaborative research, we will investigate whether the association with SLCO1B1 polymorphism is significant by performing statistical analysis with a larger study population.

Genetic Polymorphisms of TYMS, MTHFR, ATIC, MTR, and MTRR Are Related to the Outcome of Methotrexate Therapy for Rheumatoid Arthritis in a Chinese Population

Objective: Analysis of the relationship between single nucleotide polymorphisms (SNPs) and outcomes of methotrexate (MTX) therapy for rheumatoid arthritis (RA) in China.

Materials and Methods: TYMS 28 bp VNTR (rs34743033), MTHFR [677C>T (rs1801133) and 1298A>C (rs1801131)], ATIC 347C>G (rs2372536), MTR A2756G (rs1805087), and MTRR 66A>G (rs1801394) enzyme proteins may be related to the outcomes of MTX therapy, according to our previous meta-analysis. A total of 162 patients with RA were included in our study. SNPs were evaluated using polymerase chain reaction (PCR). Disease Activity Score 28 (DAS28) was used to evaluate the clinical response, and adverse drug reactions (ADRs) were collected after physical examinations of the patients.

Results: The MTHFR 677C>T gene showed a relationship with the ADRs of MTX in the Recessive model [TT vs. (CC+CT)] (p = 0.04, OR = 2.20, 95% CI: 1.01, 4.77). In the Codominant model [CT vs. (CC+TT)], the MTHFR 677C>T gene also showed a trend of association with ADRs (p = 0.08, OR = 0.52, 95% CI: 0.25, 1.08). No significant difference was found between TYMS, MTHFR, ATIC, MTR, and MTRR gene polymorphisms and the RA response or ADRs related to MTX in our study.

Conclusion: Our results showed that the MTHFR [677C>T (rs1801133)] TT genotype is associated with ADRs to MTX in Chinese RA patients. Other SNPs, including TYMS 28bp VNTR (rs34743033), MTHFR [677C>T (rs1801133) and 1298A>C (rs1801131)], ATIC 347C>G (rs2372536), MTR A2756G (rs1805087), and MTRR 66A>G (rs1801394) gene polymorphisms, were not associated with MTX treatment outcomes. Further studies are required to validate these findings.

Genome-wide association study of response to methotrexate in early rheumatoid arthritis patients

Methotrexate (MTX) monotherapy is a common first treatment for rheumatoid arthritis (RA), but many patients do not respond adequately. In order to identify genetic predictors of response, we have combined data from two consortia to carry out a genome-wide study of response to MTX in 1424 early RA patients of European ancestry. Clinical endpoints were change from baseline to 6 months after starting treatment in swollen 28-joint count, tender 28-joint count, C-reactive protein and the overall 3-component disease activity score (DAS28). No single nucleotide polymorphism (SNP) reached genome-wide statistical significance for any outcome measure. The strongest evidence for association was with rs168201 in NRG3 (p = 10^-7 for change in DAS28). Some support was also seen for association with ZMIZ1, previously highlighted in a study of response to MTX in juvenile idiopathic arthritis. Follow-up in two smaller cohorts of 429 and 177 RA patients did not support these findings, although these cohorts were more heterogeneous.

Clinical Pharmacogenetic Models of Treatment Response to Methotrexate Monotherapy in Slovenian and Serbian Rheumatoid Arthritis Patients: Differences in Patient's Management May Preclude Generalization of the Models

Objectives: Methotrexate (MTX) is the first line treatment for rheumatoid arthritis (RA), but nevertheless 30% of patients experience MTX inefficacy. Our aim was to develop a clinical pharmacogenetic model to predict which RA patients will not respond to MTX monotherapy. We also assessed whether this model can be generalized to other populations by validating it on a group of Serbian RA patients.

Methods: In 110 RA Slovenian patients, data on clinical factors and 34 polymorphisms in MTX pathway were analyzed by Least Absolute Shrinkage and Selection Operator (LASSO) penalized regression to select variables associated with the disease activity as measured by Disease Activity Score (DAS28) score after 6 months of MTX monotherapy. A clinical pharmacogenetic index was constructed from penalized regression coefficients with absolute value above 0.05. This index was cross-validated and also independently validated on 133 Serbian RA patients.

Results: A clinical pharmacogenetic index for prediction of DAS28 after 6 months of MTX monotherapy in Slovenian RA patients consisted of DAS28 score at diagnosis, presence of erosions, MTX dose, Solute Carrier Family 19 Member 1 (SLC19A1) rs1051266, Solute Carrier Organic Anion Transporter Family Member 1B1 (SLCO1B1) rs2306283, Thymidylate Synthase (TYMS), and Adenosine Monophosphate Deaminase 1 (AMPD1) rs17602729. It correctly classified 69% of Slovenian patients as responders or nonresponders and explained 30% of variability in DAS28 after 6 months of MTX monotherapy. Testing for validity in another population showed that it classified correctly only 22.5% of Serbian RA patients.

Conclusions: We developed a clinical pharmacogenetic model for DAS28 after 6 months of MTX monotherapy in Slovenian RA patients by combining clinical and genetic variables. The clinical pharmacogenetic index developed for Slovenian patients did not perform well on Serbian patients, presumably due to the differences in patients' characteristics and clinical management between the two groups.

SLCO1B1 rs4149056 genetic polymorphism predicting methotrexate toxicity in Chinese patients with non-Hodgkin lymphoma

AIM

To investigate the impact of polymorphisms in the FPGS, GGH and SLCO1B1 genes on high dose methotrexate (HD-MTX) related toxicity in Chinese patients with non-Hodgkin lymphoma (NHL).

MATERIALS & METHODS

We analyzed FPGS (rs10106), GGH (rs719235, rs10464903, rs12681874), SLCO1B1 (rs4149056) genetic polymorphisms in 105 Chinese patients with NHL treated with HD-MTX.

RESULTS

There was a statistically significant impact of the SLCO1B1 rs4149056 polymorphism on hepatotoxicity. Patients with TC and CC genotype had more hepatotoxicity than TT genotype (60 vs 32.94%, p = 0.025). After adjusting for disease stage, dosage, infusion time and therapy method, SLCO1B1 rs4149056 genotype remained significantly associated with hepatotoxicity (p = 0.028).

CONCLUSION

SLCO1B1 rs4149056 genetic variants can affect the HD-MTX-related toxicity in Chinese patients with NHL.

Polymorphisms and Pharmacogenomics for the Clinical Efficacy of Methotrexate in Patients with Rheumatoid Arthritis: A Systematic Review and Meta-analysis

Methotrexate (MTX) is widely used and considered a first-line disease modifying anti-rheumatic drug (DMARD) for the treatment of rheumatoid arthritis (RA). Many of the relevant genes have been investigated to estimate the association between gene polymorphisms and MTX effectiveness in RA patients, although inconsistent results have been reported. A systematic review and meta-analysis were performed to identify genetic variants associated with MTX efficacy. A total of 30 publications that included 34 genes and 125 SNPs associated with the transporters, enzymes, and metabolites of MTX or the progression of RA were included in the systematic review (SR), and 21 studies were included in 9 meta-analyses. Associations between MTX response in RA patients in MTHFR 1298A > C (rs1801131), ATIC 347C > G (rs2372536), RFC-1 80G > A (rs1051266), SLC19A1 A > G (rs2838956) and SLC19A1 G > A (rs7499) genetic polymorphisms were found, but not observed between the MTHFR 677C > T (rs1801133), TYMS 28 bp VNTR (rs34743033), MTRR 66A > G (rs1801394), and ABCB1 3435C > T (rs1045642). However, for the polymorphisms not being associated following meta-analysis could still be associated if larger cohorts were used, and studies of other polymorphisms are necessary in large cohorts and a rigorous way, which may provide more accurate results for the effect of the gene polymorphisms on the MTX response.

Polymorphisms and pharmacogenomics for the toxicity of methotrexate monotherapy in patients with rheumatoid arthritis: A systematic review and meta-analysis

BACKGROUND

Methotrexate (MTX) is widely used and considered a first-line disease modifying antirheumatic drug (DMARD) for the treatment of rheumatoid arthritis (RA). However, 10% to 30% of patients discontinue therapy within a year of starting the treatment, usually because of undesirable side effects. Many of the relevant genes have been investigated to estimate the association between gene polymorphisms and MTX toxicity in RA patients, although inconsistent results have been reported.

METHODS

We searched EMBASE and PubMed in February 2016 for polymorphisms and pharmacogenomics study of the toxicity of MTX monotherapy in RA patients. The meta-analysis was stratified by whether genetic variants associated with MTX toxicity.

RESULTS

A total of 42 publications that included 28 genes with 88 gene SNPs associated with the transporters, enzymes, and metabolites of MTX or the progression of RA were included in the SR, and 31 studies were included in 7 meta-analyses. The meta-analysis showed a significant association between the toxicity of MTX and the RFC-1 80G > A (rs1051266) polymorphism in the European RA patients.

CONCLUSION

RFC-1 80G > A (rs1051266) polymorphism was associated with MTX toxicity, and larger and more stringent study designs may provide more accurate results for the effect of these SNPs on the MTX toxicity.

Are gene polymorphisms related to treatment outcomes of methotrexate in patients with rheumatoid arthritis? A systematic review and meta-analysis

Aim: Identifying the predictors of responsiveness and adverse events in methotrexate (MTX) treated patients with rheumatoid arthritis (RA) has been the focus of most concern, but still without consistent consensus. Methods: PubMed and OVID EMBASE were searched to collect relevant studies that addressed correlations between gene polymorphisms and efficacy and/or toxicity in MTX-treated RA patients. Allelic, recessive, dominant and over-dominant model were applied. Results: A total of 68 studies were included. For associations with efficacy, AMPD1 34C>T polymorphism was related to responsiveness in dominant model (odds ratio [OR]: 1.77; 95% CI: 1.19–2.63) and over-dominant model (OR: 1.59; 95% CI: 1.04–2.45). ATIC T675C polymorphism had association with responsiveness in recessive model (OR: 2.54; 95% CI: 1.23–5.26). For associations with toxicity, polymorphisms in TYMS 1494 del6 and FPGS rs10106 were correlated to absenting overall adverse events in recessive model (OR: 0.68; 95% CI: 0.49–0.95) and dominant model (OR: 0.54; 95% CI: 0.35–0.83) respectively while MTHFR C677T was associated with presenting overall adverse events in allelic model (OR: 1.29; 95% CI: 1.02–1.63), recessive model (OR: 1.38; 95% CI: 1.00–1.89) and dominant model (OR: 1.41; 95% CI: 1.02–1.94). Conclusion: Polymorphisms in AMPD1 34C>T and ATIC T675C predict responsiveness. The absence of TYMS 1494 del6 and FPGS rs10106 and presence of MTHFR C677T predict adverse events in RA patients treated with MTX. Moreover, variations of the associations were found between Caucasians and non-Caucasians.

Genetic polymorphisms of enzyme proteins and transporters related to methotrexate response and pharmacokinetics in a Japanese population

Background

Methotrexate (MTX) is currently the anchor drug widely used worldwide in the treatment of rheumatoid arthritis (RA). However, the therapeutic response to MTX has been shown to vary widely among individuals, genders and ethnic groups. The reason for this has been not clarified but it is considered to be partially due to several mechanisms in the cellular pathway of MTX including single-nucleotide polymorphisms (SNPs). The purpose of this study was to investigate the allelic frequencies in different ethnic and/or population groups in the 10 polymorphisms of enzyme proteins and transporters related to the MTX response and pharmacokinetics including MTHFR, TYMS, RFC1, FPGS, GGH, ABCB1, ABCC2 and ABCG2 in unrelated healthy Japanese adults and patients with RA.

Methods

Ten polymorphisms, methylenetetrahydrofolate reductase (MTHFR) 1298, thymidylate synthase (TYMS) 3'-UTR, reduced folate carrier 1 (RFC1) 80 and−43, folypolyglutamyl synthase (FPGS) 1994, γ-glutamyl hydrolase (GGH) 452 and−401, the ABC transporters (ABCB1 3435, ABCC2 IVS23 + 56, ABCG2 914) of enzyme proteins and transporters related to MTX response and pharmacokinetics in 299 unrelated healthy Japanese adults and 159 Japanese patients with RA were investigated to clarify their contributions to individual variations in response and safety to MTX and establish personalized MTX therapy. SNPs were evaluated using real-time polymerase chain reaction (PCR).

Results

Comparison of allelic frequencies in our study with other ethnic/population groups of healthy adults and RA patients showed significant differences in 10 polymorphisms among healthy adults and 7 among RA patients. Allelic frequencies of MTHFR 1298 C, FPGS 1994A and ABCB1 3435 T were lower in Japanese than in Caucasian populations and those of ABCC2 IVS23 + 56 C and ABCG2 914A were higher in Japanese than in Caucasian/European populations in both healthy adults and RA patients. Allelic frequencies of MTHFR 1298 C, GGH−401 T, ABCB1 3435 T, and ABCG2 914A were higher in healthy Japanese adults than in an African population, and those of RFC1 80A, RFC1−43C and ABCC2 IVS23 + 56 C in healthy Japanese adults were lower than in Africans. However, no significant differences were seen in the distribution of allelic frequencies between healthy Japanese adults and RA patients.

Conclusion

The variations in allelic frequencies in different ethnic and/or population groups in healthy adults and RA patients may contribute to individual variations in MTX response and toxicity.

Genetics as a molecular window into recovery, its treatment, and stress responses after stroke

Stroke remains a major source of adult disability in the USA and worldwide. Most patients show some recovery during the weeks to months following a stroke, but this is generally incomplete. An emerging branch of therapeutics targets the processes underlying this behavioral recovery from stroke toward the goal of reducing long-term disability. A key factor hampering these efforts is the very large degree of variability between stroke survivors. Available data suggest that genetic differences could explain an important fraction of the differences between subjects. The current review considers this from several angles, including genetic differences in relation to drugs that promote recovery. Genetic factors related to physiological and psychological stress responses may also be critically important to understanding recovery after stroke and its treatment. The studies reviewed provide insights into recovery and suggest directions for further research to improve clinical decision-making in this setting. Genetic differences between patients might be used to help clinical trials select specific patient subgroups, on a biological basis, in order to sharpen the precision with which new treatments are evaluated. Pharmacogenomic factors might also provide insights into inter-subject differences in treatment side effects for pharmacological prescriptions, and behavioral interventions, and others. These efforts must be conducted with the strictest ethical standards given the highly sensitive nature of genetic data. Understanding the effect of selected genetic measures could improve a clinician's ability to predict the risk and efficacy of a restorative therapy and to make maximally informed decisions, and in so doing, facilitate individual patient care.

Methotrexate selectively targets human proinflammatory macrophages through a thymidylate synthase/p53 axis

OBJECTIVES

Methotrexate (MTX) functions as an antiproliferative agent in cancer and an anti-inflammatory drug in rheumatoid arthritis (RA). Although macrophages critically contribute to RA pathology, their response to MTX remains unknown. As a means to identify MTX response markers, we have explored its transcriptional effect on macrophages polarised by GM-CSF (GM-MØ) or M-CSF (M-MØ), which resemble proinflammatory and anti-inflammatory macrophages found in RA and normal joints, respectively.

METHODS

The transcriptomic profile of both human macrophage subtypes exposed to 50 nM of MTX under long-term and short-term schedules were determined using gene expression microarrays, and validated through quantitative real time PCR and ELISA. The molecular pathway involved in macrophage MTX-responsiveness was determined through pharmacological, siRNA-mediated knockdown approaches, metabolomics for polyglutamylated-MTX detection, western blot, and immunofluorescence on RA and normal joints.

RESULTS

MTX exclusively modulated gene expression in proinflammatory GM-MØ, where it influenced the expression of 757 genes and induced CCL20 and LIF at the mRNA and protein levels. Pharmacological and siRNA-mediated approaches indicated that macrophage subset-specific MTX responsiveness correlates with thymidylate synthase (TS) expression, as proinflammatory TS⁺ GM-MØ are susceptible to MTX, whereas anti-inflammatory TS^low/- M-MØ and monocytes are refractory to MTX. Furthermore, p53 activity was found to mediate the TS-dependent MTX-responsiveness of proinflammatory TS⁺ GM-MØ. Importantly, TS and p53 were found to be expressed by CD163⁺/TNFα⁺ GM-CSF-polarised macrophages from RA joints but not from normal synovium.

CONCLUSIONS

Macrophage response to MTX is polarisation-dependent and determined by the TS-p53 axis. CCL20 and LIF constitute novel macrophage markers for MTX responsiveness in vitro.

Methotrexate pharmacokinetic genetic variants are associated with outcome in rheumatoid arthritis patients

BACKGROUND

Methotrexate (MTX) is the most used drug for the treatment of rheumatoid arthritis (RA) although outcome differs among patients.

AIM

To evaluate whether polymorphisms in pharmacokinetic genes are associated with outcome in RA patients receiving MTX.

PATIENTS & METHODS

We analyzed 28 SNPs in SLC19A1/RFC1, ABCB1, FPGS and GGH genes.

RESULTS

We studied 194 RA patients receiving MTX monotherapy. Two FPGS SNPs, rs10987742 and rs10106, were associated with response (p = 0.033 and p = 0.041, respectively). The FPGS rs10106 variant was also associated with MTX survival (p = 0.005) and toxicity (p = 0.021). Three ABCB1 SNPs, rs868755, rs10280623 and rs1858923, were associated with toxicity (p = 0.025, p = 0.048 and p = 0.031, respectively).

CONCLUSION

FPGS and ABCB1 genetic variants can influence the outcome in RA patients receiving MTX monotherapy.

The effect of gene polymorphisms on patient responses to rheumatoid arthritis therapy

INTRODUCTION

Rheumatoid arthritis (RA) is a systemic disease leading to joint destruction. The therapy of RA is mainly based on disease-modifying anti-rheumatic drugs (DMARDs) and biological drugs. The response to treatment is different among patients. Therefore, we have searched for factors that may predict the efficacy and toxicity during therapy in individual patients.

AREAS COVERED

This review presents the role of genetic polymorphisms as predictors of the efficacy and toxicity during the therapy of RA patients with DMARDs (methotrexate, leflunomide, sulfasalazine) and biological drugs (anti-TNF-alpha antagonists, Tocilizumab, Rituximab).

EXPERT OPINION

Despite studies having shown an association between genetic polymorphisms and response to therapy in RA patients, the majority of these findings are still inconclusive and inconsistent. We are still far from applying pharmacogenetic tests in routine clinical practice that can predict the outcome of treatment. Several factors, such as small sample size with low statistical power, variability in the outcome definitions and the heterogeneity of the cohorts, limited number of tested single nucleotide polymorphisms (SNPs), small effect for the selected variant, and a lack of consideration of epigenetic factors, may contribute to the inconsistency observed and may lead to limited success in personalizing therapy.

Folate metabolic pathway single nucleotide polymorphisms: a predictive pharmacogenetic marker of methotrexate response in Indian (Asian) patients with rheumatoid arthritis

AIM

We evaluated the pharmacogenetic influence of genetic polymorphisms in folate pathway genes in Indian rheumatoid arthritis patients receiving methotrexate (MTX).

PATIENTS & METHODS

Twelve polymorphisms within nine folate pathway genes were analyzed for association with MTX response in 322 Indian rheumatoid arthritis (RA) patients and MTX pharmacokinetics in 94 RA patients.

RESULTS

Polymorphisms in GGH, SHMT1 and TS were associated with MTX-related adverse events while SNPs in MTHFR and RFC1/SLC19A1 were associated with MTX efficacy. TS5'UTR and SHMT1 polymorphisms were associated with higher plasma levels of MTX.

CONCLUSION

Polymorphisms in folate-MTX pathway genes contribute to MTX response and affect MTX concentrations in Indian RA patients. A toxicogenetic index could identify patients who develop adverse events to MTX.

Three decades of low-dose methotrexate in rheumatoid arthritis: can we predict toxicity?

Methotrexate (MTX) is the anchor disease-modifying antirheumatic drug (DMARD) in rheumatoid arthritis (RA) treatment. It is used in monotherapy and/or in combination with other synthetic or biological DMARDs, and is known to have the best cost-effectiveness and efficacy/toxicity ratios. However, toxicity is still a concern, with a significant proportion of patients interrupting long-term treatment due to the occurrence of MTX-related adverse drug reactions (ADRs), which are the main cause of drug withdrawal. Despite the extensive accumulated experience in the last three decades, it is still impossible in routine clinical practice to identify patients prone to develop MTX toxicity. While clinical and biological variables, including folate supplementation, partially help to minimize MTX-related ADRs, the advent of pharmacogenomics could provide further insight into risk stratification and help to optimize drug monitoring and long-term retention. In this paper, we aimed to review and summarize current data on low-dose MTX-associated toxicity, its prevention and predictors, keeping in mind practical RA clinical care.

Genetic polymorphisms affect efficacy and adverse drug reactions of DMARDs in rheumatoid arthritis

Disease-modifying antirheumatic drugs (DMARDs) and biological agents are critical in preventing the severe complications of rheumatoid arthritis (RA). However, the outcome of treatment with these drugs in RA patients is quite variable and unpredictable. Drug-metabolizing enzymes (dihydrofolate reductase, cytochrome P450 enzymes, N-acetyltransferases, etc.), drug transporters (ATP-binding cassette transporters), and drug targets (tumor necrosis factor-α receptors) are coded for by variant alleles. These gene polymorphisms may influence the pharmacokinetics, pharmacodynamics, and side effects of medicines. The cause for differences in efficacy and adverse drug reactions may be genetic variation in drug metabolism among individuals. Polymorphisms in drug transporter genes may change the distribution and excretion of medicines, and the sensitivity of the targets to drugs is strongly influenced by genetic variations. In this article, we review the genetic polymorphisms that affect the efficacy of DMARDs or the occurrence of adverse drug reactions associated with DMARDs in RA.

γ-Glutamyl hydrolase modulation significantly influences global and gene-specific DNA methylation and gene expression in human colon and breast cancer cells

γ-Glutamyl hydrolase (GGH) plays an important role in folate homeostasis by catalyzing hydrolysis of polyglutamylated folate into monoglutamates. Polyglutamylated folates are better substrates for several enzymes involved in the generation of S-adenosylmethionine, the primary methyl group donor, and hence, GGH modulation may affect DNA methylation. DNA methylation is an important epigenetic determinant in gene expression, in the maintenance of DNA integrity and stability, and in chromatin modifications, and aberrant or dysregulation of DNA methylation has been mechanistically linked to the development of human diseases including cancer. Using a recently developed in vitro model of GGH modulation in HCT116 colon and MDA-MB-435 breast cancer cells, we investigated whether GGH modulation would affect global and gene-specific DNA methylation and whether these alterations were associated with significant gene expression changes. In both cell lines, GGH overexpression decreased global DNA methylation and DNA methyltransferase (DNMT) activity, while GGH inhibition increased global DNA methylation and DNMT activity. Epigenomic and gene expression analyses revealed that GGH modulation influenced CpG promoter DNA methylation and gene expression involved in important biological pathways including cell cycle, cellular development, and cellular growth and proliferation. Some of the observed altered gene expression appeared to be regulated by changes in CpG promoter DNA methylation. Our data suggest that the GGH modulation-induced changes in total intracellular folate concentrations and content of long-chain folylpolyglutamates are associated with functionally significant DNA methylation alterations in several important biological pathways.

Role of key TYMS polymorphisms on methotrexate therapeutic outcome in portuguese rheumatoid arthritis patients

BACKGROUND

Therapeutic outcome of rheumatoid arthritis (RA) patients treated with methotrexate (MTX) can be modulated by thymidylate synthase (TS) levels, which may be altered by genetic polymorphisms in TS gene (TYMS). This study aims to elucidate the influence of TYMS polymorphisms in MTX therapeutic outcome (regarding both clinical response and toxicity) in Portuguese RA patients.

METHODS

Clinicopathological data from 233 Caucasian RA patients treated with MTX were collected, outcomes were defined and patients were genotyped for the following TYMS polymorphisms: 1) 28 base pairs (bp) variable number tandem repeat (rs34743033); 2) single nucleotide polymorphism C>G (rs2853542); and 3) 6 bp sequence deletion (1494del6, rs34489327). Chi-square and binary logistic regression analyses were performed, using genotype and haplotype-based approaches.

RESULTS

Considering TYMS genotypes, 3R3R (p = 0.005, OR = 2.34), 3RC3RG (p = 0.016, OR = 3.52) and 6bp- carriers (p = 0.011, OR = 1.96) were associated with non-response to MTX. Multivariate analysis confirmed the increased risk for non-response to MTX in 6bp- carriers (p = 0.016, OR = 2.74). Data demonstrated that TYMS polymorphisms were in linkage disequilibrium (p<0.00001). Haplotype multivariate analysis revealed that haplotypes harboring both 3R and 6bp- alleles were associated with non-response to MTX. Regarding MTX-related toxicity, no statistically significant differences were observed in relation to TYMS genotypes and haplotypes.

CONCLUSION

Our study reveals that TYMS polymorphisms could be important to help predicting clinical response to MTX in RA patients. Despite the potential of these findings, translation into clinical practice needs larger studies to confirm these evidences.

Pharmacogenetics of neural injury recovery

Relatively few pharmacological agents are part of routine care for neural injury, although several are used or under consideration in acute stroke, chronic stroke, traumatic brain injury and secondary stroke prevention. Tissue plasminogen activator is approved for the treatment of acute ischemic stroke, and genetic variants may impact the efficacy and safety of this drug. In the chronic phase of stroke, several drugs such as L-dopa, fluoxetine and donepezil are under investigation for enhancing rehabilitation therapy, with varying levels of evidence. One potential reason for the mixed efficacy displayed by these drugs may be the influence of genetic factors that were not considered in prior studies. An understanding of the genetics impacting the efficacy of dopaminergic, serotonergic and cholinergic drugs may allow clinicians to target these potential therapies to those patients most likely to benefit. In the setting of stroke prevention, which is directly linked to neural injury recovery, the most highly studied pharmacogenomic interactions pertain to clopidogrel and warfarin. Incorporating pharmacogenomics into neural injury recovery has the potential to maximize the benefit of several current and potential pharmacological therapies and to refine the choice of pharmacological agent that may be used to enhance benefits from rehabilitation therapy.

Pharmacogenetics and pharmacogenomics for rheumatoid arthritis responsiveness to methotrexate treatment: the 2013 update

Rheumatoid arthritis (RA) is a complex, systemic autoimmune disease characterized by chronic inflammation of multiple peripheral joints, which leads to serious destruction of cartilage and bone, progressive deformity and severe disability. Methotrexate (MTX) is one of the first-line drugs commonly used in RA therapy owing to its excellent long-term efficacy and cheapness. However, the efficacy and toxicity of MTX treatment have significant interpatient variability. Genetic factors contribute to this variability. In this review, we have summarized and updated the progress of RA response to MTX treatment since 2009 by focusing on the fields of pharmacogenetics and pharmacogenomics. Identification of genetic factors involved in MTX treatment response will increase the understanding of RA pathology and the development of new personalized treatments.

Pharmacogenetics in rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic inflammatory arthritis leading to severe joint damage and associated with high morbidity and mortality. Disease-modifying antirheumatic drugs (DMARDs) are the mainstay of treatment in RA. DMARDs not only relieve the clinical signs and symptoms of RA but also inhibit the radiographic progression of disease. In the last decade, a new class of disease-modifying medications, the biologic agents, has been added to the existing spectrum of DMARDs in RA. However, patients' response to these agents is not uniform with considerable variability in both efficacy and toxicity. There are no reliable means of predicting an individual patient's response to a given DMARD prior to initiation of therapy. In this chapter, the current published literature on the pharmacogenetics of traditional DMARDS and the newer biologic DMARDs in RA is highlighted. Pharmacogenetics may help individualize drug therapy in patients with RA in the near future.

γ-Glutamyl hydrolase modulation and folate influence chemosensitivity of cancer cells to 5-fluorouracil and methotrexate

BACKGROUND

γ-Glutamyl hydrolase (GGH) regulates intracellular folate and antifolates for optimal nucleotide biosynthesis and antifolate-induced cytotoxicity, respectively. The modulation of GGH may therefore affect chemosensitivity of cancer cells, and exogenous folate levels may further modify this effect.

METHODS

We generated a novel model of GGH modulation in human HCT116 and MDA-MB-435 cancer cells and investigated the effect of GGH modulation on chemosensitivity to 5-fluorouracil (5FU) and methotrexate (MTX) at different folate concentrations in vitro and in vivo.

RESULTS

Overexpression of GGH significantly decreased chemosensitivity of MDA-MB-435 cells to 5FU and MTX at all folate concentrations as expected. In contrast, in HCT116 cells this predicted effect was observed only at very high folate concentration, and as the folate concentration decreased this effect became null or paradoxically increased. This in vitro observation was confirmed in vivo. Inhibition of GGH significantly increased chemosensitivity of both cancer cells to 5FU at all folate concentrations. Unexpectedly, GGH inhibition significantly decreased chemosensitivity of both cancer cells to MTX at all folate concentrations. In both GGH modulation systems and cell lines, the magnitude of chemosensitivity effect incrementally increased as folate concentration increased.

CONCLUSION

Modulation of GGH affects chemosensitivity of cancer cells to 5FU and MTX, and exogenous folate levels can further modify the effects.

Current approaches for TYMS polymorphisms and their importance in molecular epidemiology and pharmacogenetics

TS is critical for providing the requisite nucleotide precursors in order to maintain DNA synthesis and repair. Furthermore, it is an important target for several drugs such as 5-fluorouracil and methotrexate. However, several mechanisms of resistance to TS inhibitors have been explained as linked to TYMS overexpression. Some authors have described the relationship between genetic polymorphisms on TYMS, in particular rs34743033, rs2853542 and rs34489327, with the development of several diseases and with the clinical response to drug therapy and/or survival. Nevertheless, the obtained results described in the literature are controversial, which has lead to a search strategy to understand the impact of these polymorphisms on molecular epidemiology and pharmacogenetics. With the progress of these scientific areas, early identification of individuals at risk of disease along with improvement in the prediction of patients’ outcome will offer a powerful tool for the translation of TYMS polymorphisms into clinical practice and individualization of treatments.