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

Unveiling the heritability of selected unexplored pharmacogenetic markers in the Saudi population

Background

Pharmacogenomic (PGx) variants can significantly impact drug response, but limited data exists on their prevalence in Middle Eastern populations. This study aimed to investigate the inheritance of certain markers in candidate pharmacogenes among healthy Saudis.

Methods

DNA samples from 95 unrelated healthy Saudi participants were genotyped using the Affymetrix Axiom Precision Medicine Diversity Array. Thirty-eight variants in 15 pharmacogenes were analyzed based on their clinical relevance and lack of previous reporting in Saudi populations.

Results

Twenty-six of the 37 tested markers were undetected in the cohort. The selected variants in six genes [DPYD (rs1801268), CACNA1S (rs772226819), EGFR (rs121434568), RYR1 (rs193922816), CYP2B6 (rs3826711), and MT-RNR1 (rs267606617, rs267606618, rs267606619)] were found to be non-existing among Saudis. In contrast, 11 variants and alleles in nine pharmacogenes were detected at varying frequencies. Notable findings included high frequencies of variants in ATIC [rs4673993, minor allele frequency (MAF) = 0.71)] and SLC19A1 (rs1051266, MAF = 0.48) affecting methotrexate efficacy. Three alleles were identified in CYP3A4, including a common (CYP3A4 rs2242480) and two rare alleles (*3 and *22). Another three markers [rs16969968 in CHRNA5, rs11881222 in IFNL3 (IL28B), and SLCO1B1*14] were found to be highly distributed among the participants (MAF = 0.35, 0.30, and 0.14, respectively). Conversely, three rare markers: CYP2A6*2, NAT2*14, and rs115545701 in CFTR, were identified at low-frequency levels (MAF = 0.021, 0.011, 0.005, respectively). Statistically significant differences in allele frequencies were observed for eight variants between Saudi and African populations, five variants compared to East Asians, and two variants compared to Europeans.

Conclusion

This study provides novel insights into the distribution of clinically relevant PGx variants in the Saudi population. The findings have implications for personalizing treatments for various conditions, including rheumatoid arthritis, cystic fibrosis, and hepatitis C. These data contribute to the development of population-specific PGx testing panels and treatment guidelines.

Genetic Variants of the ATIC Gene and Therapeutic Response to Methotrexate in Patients with Rheumatoid Arthritis

Methotrexate (MTX) is the conventional synthetic disease-modifying anti-rheumatic drug (csDMARD) recommended as the first-choice anti-rheumatic drug for rheumatoid arthritis (RA). However, responses to MTX may be influenced by genetic variants. We aim to evaluate the association of the rs2372536, rs4673990, and rs4673993 genetic variants of the ATIC gene with therapeutic failure of MTX in patients with RA. A case-control study was performed. Disease activity was measured using the disease activity score based on erythrocyte sedimentation rate (DAS28-ESR). RA patients were classified into two groups: (a) responders (DAS28-ESR ≤ 3.2), which is the group of patients who did respond to methotrexate, and (b) non-responders (DAS28-ESR > 3.2), which is the group of patients who did not respond to methotrexate. Serum levels of the 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) enzyme and Interleukin-6 (IL-6) were quantified using an enzyme-linked immunosorbent assay (ELISA). Genotyping of ATIC genetic variants was performed with quantitative polymerase chain reaction (qPCR) using TaqMan probes. A total of 260 patients with RA were included. In total, 142 (54.6%) were non-responders to MTX. IL-6 levels were increased in the non-responder group (p = 0.002), while no statistical differences were observed in the AICAR levels. The variables associated with non-response were higher HAQ-Di, weekly MTX dose, glucocorticoid use, erythrocyte sedimentation rate, and carriers of the polymorphic homozygous variant of rs4673993 (OR = 4.5, 95% CI: 1.04-19.34; p = 0.04). The use of sulfazaline offered protective effects. Our findings indicate that the polymorphism rs4673993 gene variant of the AICAR protein may significantly influence MTX resistance. Therefore, these results support the importance of the pathway generating extracellular adenosine and its effects on promoting the immune regulation for the mechanism of MTX therapy of RA.

Genome-wide investigation of persistence with methotrexate treatment in early rheumatoid arthritis

OBJECTIVES

To investigate the influence of genetic factors on persistence with treatment of early RA with MTX monotherapy.

METHODS

We conducted a genome-wide association study (GWAS) in a sample of 3902 Swedish early-RA patients initiating MTX in DMARD monotherapy as their first-ever DMARD. The outcome, short- and long-term MTX treatment persistence, was defined as remaining on MTX at 1 and at 3 years, respectively, with no additional DMARDs added. As genetic predictors, we investigated individual SNPs, and then calculated a polygenic risk score (PRS) based on SNPs associated with RA risk. The SNP-based heritability of persistence was estimated overall and by RA serostatus.

RESULTS

No individual SNP reached genome-wide significance (P < 5 × 10-8), either for persistence at 1 year or at 3 years. The RA PRS was not significantly associated with MTX treatment persistence at 1 year [relative risk (RR) = 0.98 (0.96-1.01)] or at 3 years [RR = 0.96 (0.93-1.00)]. The heritability of MTX treatment persistence was estimated to be 0.45 (0.15-0.75) at 1 year and 0.14 (0-0.40) at 3 years. The results in seropositive RA were comparable with those in the analysis of RA overall, while heritability estimates and PRS RRs were attenuated towards the null in seronegative RA.

CONCLUSION

Despite being the largest GWAS on an MTX treatment outcome to date, no genome-wide significant associations were detected. The modest heritability observed, coupled with the broad spread of suggestively associated loci, indicate that genetic influence is of polygenic nature. Nevertheless, MTX monotherapy persistence was lower in patients with a greater genetic disposition, per the PRS, towards RA.

Pharmacogenetic and pharmacogenomic treatment of rheumatoid arthritis: a review of Pharmacogenomics Knowledge Base scientific evidence

Tweetable abstract Update on the genetic variants with the highest level of Pharmacogenomics Knowledge Base evidence for their association with toxicity and efficacy in response to the most commonly used disease-modifying antirheumatic drugs for the treatment of rheumatoid arthritis.

Pharmacogenetic Sex-Specific Effects of Methotrexate Response in Patients with Rheumatoid Arthritis

Methotrexate (MTX) is a commonly used drug for the treatment of rheumatoid arthritis (RA), but its effectiveness can vary greatly among patients. Pharmacogenetics, the study of how genetic variations can affect drug response, has the potential to improve the personalized treatment of RA by identifying genetic markers that can predict a patient's response to MTX. However, the field of MTX pharmacogenetics is still in its early stages and there is a lack of consistency among studies. This study aimed to identify genetic markers associated with MTX efficacy and toxicity in a large sample of RA patients, and to investigate the role of clinical covariates and sex-specific effects. Our results have identified an association of ITPA rs1127354 and ABCB1 rs1045642 with response to MTX, polymorphisms of FPGS rs1544105, GGH rs1800909, and MTHFR genes with disease remission, GGH rs1800909 and MTHFR rs1801131 polymorphisms with all adverse events, and ADA rs244076 and MTHFR rs1801131 and rs1801133, However, clinical covariates were more important factors to consider when building predictive models. These findings highlight the potential of pharmacogenetics to improve personalized treatment of RA, but also emphasize the need for further research to fully understand the complex mechanisms involved.

Polygenic Pharmacogenomic Markers as Predictors of Toxicity Phenotypes in the Treatment of Acute Lymphoblastic Leukemia: A Single-Center Study

PURPOSE

Acute lymphoblastic leukemia (ALL) is the most prevalent cause of childhood cancer and requires a long course of therapy consisting of three primary phases with interval intensification blocks. Although these phases are necessary to achieve remission, the primary chemotherapeutic agents have potentially serious toxicities, which may lead to delays or discontinuations of therapy. The purpose of this study was to perform a comprehensive pharmacogenomic evaluation of common antileukemic agents and develop a polygenic toxicity risk score predictive of the most common toxicities observed during ALL treatment.

METHODS

This cross-sectional study included 75 patients with pediatric ALL treated between 2012 and 2020 at the University of Florida. Toxicity data were collected within 100 days of initiation of therapy using CTCAE v4.0 for toxicity grading. For pharmacogenomic evaluation, single-nucleotide polymorphisms (SNPs) and genes were selected from previous reports or PharmGKB database. 116 unique SNPs were evaluated for incidence of various toxicities. A multivariable multi-SNP modeling for up to 3-SNP combination was performed to develop a polygenic toxicity risk score of prognostic value.

RESULTS

We identified several SNPs predictive of toxicity phenotypes in univariate analysis. Further multivariable SNP-SNP combination analysis suggest that susceptibility to chemotherapy-induced toxicities is likely multigenic in nature. For 3-SNPscore models, patients with high scores experienced increased risk of GI (P = 2.07E-05, 3 SNPs: TYMS-rs151264360/FPGS-rs1544105/GSTM1-GSTM5-rs3754446), neurologic (P = .0005, 3 SNPs: DCTD-rs6829021/SLC28A3-rs17343066/CTPS1-rs12067645), endocrine (P = 4.77E-08, 3 SNPs: AKR1C3-rs1937840/TYMS-rs2853539/CTH-rs648743), and heme toxicities (P = .053, 3 SNPs: CYP3A5-rs776746/ABCB1-rs4148737/CTPS1-rs12067645).

CONCLUSION

Our results imply that instead of a single-SNP approach, SNP-SNP combinations in multiple genes in drug pathways increases the robustness of prediction of toxicity. These results further provide promising SNP models that can help establish clinically relevant biomarkers allowing for greater individualization of cancer therapy to maximize efficacy and minimize toxicity for each patient.

Genetic variations in methotrexate metabolic pathway genes influence methotrexate responses in rheumatoid arthritis patients in Malaysia

Methotrexate (MTX) is the most widely used disease-modifying anti-rheumatic drug (DMARD) for rheumatoid arthritis (RA). Many studies have attempted to understand the genetic risk factors that affect the therapeutic outcomes in RA patients treated with MTX. Unlike other studies that focus on the populations of Caucasians, Indian and east Asian countries, this study investigated the impacts of six single nucleotide polymorphisms (SNPs) that are hypothesized to affect the outcomes of MTX treatment in Malaysian RA patients. A total of 647 RA patients from three ethnicities (N_Malay = 153; N_Chinese = 326; N_Indian = 168) who received MTX monotherapy (minimum 15 mg per week) were sampled from three hospitals in Malaysia. SNPs were genotyped in patients using TaqMan real-time PCR assay. Data obtained were statistically analysed for the association between SNPs and MTX efficacy and toxicity. Analysis of all 647 RA patients indicated that none of the SNPs has influence on either MTX efficacy or MTX toxicity according to the Chi-square test and binary logistic regression. However, stratification by self-identified ancestries revealed that two out of six SNPs, ATIC C347G (rs2372536) (OR 0.5478, 95% CI 0.3396–0.8835, p = 0.01321) and ATIC T675C (rs4673993) (OR 0.5247, 95% CI 0.3248–0.8478, p = 0.008111), were significantly associated with MTX adequate response in RA patients with Malay ancestry (p < 0.05). As for the MTX toxicity, no significant association was identified for any SNPs selected in this study. Taken all together, ATIC C347G and ATIC T675C can be further evaluated on their impact in MTX efficacy using larger ancestry-specific cohort, and also incorporating high-order gene–gene and gene–environment interactions.

Associations Between Genetic Polymorphisms Within Transporter Genes and Clinical Response to Methotrexate in Chinese Rheumatoid Arthritis Patients: A Pilot Study

Purpose

To investigate the associations between genetic polymorphisms within transporter genes and clinical response to methotrexate (MTX) in Chinese rheumatoid arthritis (RA) patients.

Patients and Methods

A total of 100 RA patients receiving MTX were prospectively followed up for approximately 3 months to determine the clinical response based on several criteria, including European League Against Rheumatism (EULAR) good and moderate response, disease activity score in 28 joint counts – erythrocyte sedimentation rate (DAS28-ESR) low disease activity (LDA), change in DAS28-ESR (ΔDAS28-ESR) and ΔDAS28-ESR >0.6. Fifty-four single nucleotide polymorphisms (SNPs) within seven transporter genes, including SLC19A1, ABCB1, ABCC1~4 and ABCG2, were genotyped.

Results

Multivariable analysis revealed that SLC19A1 rs12659 and rs3788200, ABCC2 rs3740066, rs4148396 and rs717620 were significantly associated with EULAR good and moderate response, and ABCC2 rs3740066 and rs717620 were significantly associated with DAS28-ESR LDA, and ABCB1 rs1128503, rs4148737 and ABCC3 rs2277624, rs4148416 were significantly associated with ΔDAS28-ESR. Moreover, 12 genetic polymorphisms were found to be significantly associated with ΔDAS28-ESR >0.6. With adjustment for corresponding confounders, SLC19A1 TGAA haplotype consisting of rs1051266, rs1131596, rs12659 and rs3788200 was significantly associated with EULAR good and moderate response and ΔDAS28-ESR >0.6 compared with the most common haplotype CAGG. The ABCC2 haplotype TTT composed of rs717620, rs4148396 and rs3740066 was significantly associated with EULAR good and moderate response and ΔDAS28-ESR >0.6 compared with the most common haplotype CCC.

Conclusion

Our results highlight the potential of genetic polymorphisms within transporter genes, particularly SLC19A1 and ABCC2, as predictors of clinical response to MTX in Chinese RA patients.

Cell-Free DNA in Rheumatoid Arthritis

Endogenous DNA derived from the nuclei or mitochondria is released into the bloodstream following cell damage or death. Extracellular DNA, called cell-free DNA (cfDNA), is associated with various pathological conditions. Recently, multiple aspects of cfDNA have been assessed, including cfDNA levels, integrity, methylation, and mutations. Rheumatoid arthritis (RA) is the most common form of autoimmune arthritis, and treatment of RA has highly varied outcomes. cfDNA in patients with RA is elevated in peripheral blood and synovial fluid and is associated with disease activity. Profiling of cfDNA in patients with RA may then be utilized in various aspects of clinical practice, such as the prediction of prognosis and treatment responses; monitoring disease state; and as a diagnostic marker. In this review, we discuss cfDNA in patients with RA, particularly the sources of cfDNA and the correlation of cfDNA with RA pathogenesis. We also highlight the potential of analyzing cfDNA profiles to guide individualized treatment approaches for RA.

The genetics of rheumatoid arthritis

RA is a chronic systemic inflammatory disease that primarily affects the small joints of the hands and feet, and results in a mean reduction in life expectancy of 3-10 years. RA is a multigene disorder with a substantial genetic component and a heritability estimate of 60%. Large-scale Genome-Wide Association Studies (GWAS) and meta-analyses have revealed common disease-associated variants in the population that may contribute cumulatively to RA pathogenesis. This review identifies the most significant genetic variants associated with RA susceptibility to date, with particular focus on the contribution of the HLA class II genes across different ethnic groups. Also discussed are the potential applications of pharmacogenomics to RA management by identifying polymorphisms associated with variation in treatment response or toxicity. The use of genetic variants to guide treatment strategy has the potential to not only reduce National Health Service costs, but also drastically improve patient experience and quality of life.

Genetic Polymorphisms Associated with Rheumatoid Arthritis Development and Antirheumatic Therapy Response

Rheumatoid arthritis (RA) is the most common inflammatory arthropathy worldwide. Possible manifestations of RA can be represented by a wide variability of symptoms, clinical forms, and course options. This multifactorial disease is triggered by a genetic predisposition and environmental factors. Both clinical and genealogical studies have demonstrated disease case accumulation in families. Revealing the impact of candidate gene missense variants on the disease course elucidates understanding of RA molecular pathogenesis. A multivariate genomewide association study (GWAS) based analysis identified the genes and signalling pathways involved in the pathogenesis of the disease. However, these identified RA candidate gene variants only explain 30% of familial disease cases. The genetic causes for a significant proportion of familial RA have not been determined until now. Therefore, it is important to identify RA risk groups in different populations, as well as the possible prognostic value of some genetic variants for disease development, progression, and treatment. Our review has two purposes. First, to summarise the data on RA candidate genes and the increased disease risk associated with these alleles in various populations. Second, to describe how the genetic variants can be used in the selection of drugs for the treatment of RA.

The impacts of gene polymorphisms on methotrexate in Chinese psoriatic patients

BACKGROUND

Methotrexate (MTX) is the first-line treatment for psoriasis in China. The metabolic processes of MTX include various proteins and genes. Previous studies have shown that gene polymorphisms had significant impacts on the efficacy of MTX. However, the influence of gene polymorphisms has not been reported in the Chinese psoriatic patients.

OBJECTIVE

The aim of this study was to verify the impacts of candidate genes polymorphisms on the effectiveness of MTX in a Chinese psoriatic population.

METHODS

In this study, we enrolled 259 psoriasis patients from two clinical centres. Each of them received MTX treatment at 7.5-15 mg/week for at least 8 weeks. Patients were stratified as responders and non-responders according to whether the Psoriasis Area and Severity Index score declined more than 75% (PASI75). According to previous reports, 16 single nucleotide polymorphisms (SNPs) were selected and genotyped for each patient using the Sequenom platform. Fisher's exact test, the chi-square test, Mann-Whitney tests and ANOVA analyses were used for statistical analysis.

RESULTS

Among 259 patients, there were 182 males and 77 females, 63 patients with psoriatic arthritis and 196 patients without arthritis phenotype, and the age of all patients ranged from 19 to 70 years (49.7 ± 13.6). The baseline PASI value of patients was 13.8 ± 8.5, and 33.2% of patients achieved a PASI75 response after MTX treatment. Patients carrying the ATP-binding cassette subfamily B member 1 gene (ABCB1) rs1045642 TT genotype were associated with more severe psoriasis skin lesion (P = 0.032). Furthermore, the ABCB1 rs1045642 TT genotype was found to be more frequent in non-responders (P = 0.017), especially in moderate-to-severe patients (P = 0.002) and patients without psoriatic arthritis (P = 0.026) after MTX treatment.

CONCLUSION

We have demonstrated for the first time that polymorphism of the ABCB1 rs1045642 TT genotype is predictive of a worse clinical response of skin lesions to MTX therapy in a Chinese psoriatic population.

Analysis of association of ADORA2A and ADORA3 polymorphisms genotypes/haplotypes with efficacy and toxicity of methotrexate in patients with Rheumatoid arthritis

Adenosine receptors ADORA₂A and ADORA₃ are part of the adenosine-mediated antiinflammatory pathway and are overexpressed in patients with Rheumatoid arthritis (RA). Methotrexate (MTX) antiinflammatory effects are partially mediated via increased release of adenosine into extracellular space. Polymorphisms in ADORA₂A and ADORA₃ genes may have an impact on the efficacy and toxicity of MTX in RA patients. The study included 127 RA patients. Treatment efficacy was estimated using the changes in Disease activity score (DAS28) after 6 months of MTX monotherapy, according to EULAR response criteria. Patients with good and moderate response were classified as "responders", and with a poor response as "nonresponders". Adverse effects were collected during the follow-up period. Genotyping for polymorphisms within ADORA₂A gene (rs2298383, rs2236624, rs5751876, rs17004921) and ADORA₃ gene (rs2298191, rs1544223, rs3393) was performed using the KASPar assays. Among patients 112 (88.19%) were responders (18.8% good, 81.2% moderate). We observed no association between analyzed genotypes or alleles and MTX response by EULAR criteria but carriers of ADORA₂A rs17004921 T allele (CT + TT) had a higher DAS28 decrease after 6 months of treatment than patients with CC genotype (p = 0.013). Adverse effects were reported in 31 patients (24.41%). Bone erosions were present in 82 (64.6%) patients. Haplotype block was observed among all 3 analyzed polymorphisms within ADORA₃ gene and TAA haplotype was associated with bone erosions (29% vs 15.6%, p = 0.023) and hepatotoxicity (51.3% vs 21.6%, p = 0.013). According to our study, ADORA₃ TAA haplotype may be associated with bone erosions and hepatotoxicity in RA patients treated with MTX.

Are gene polymorphisms related to adverse events of methotrexate in patients with rheumatoid arthritis? A retrospective cohort study based on an updated meta-analysis

Aims:

We performed an updated meta-analysis to verify correlations between gene polymorphisms and adverse events in methotrexate (MTX)-treated rheumatoid arthritis (RA) patients. Then, we conducted a retrospective cohort study of Han Chinese in China.

Methods:

Relevant studies were collected from the PubMed database and the EMBASE database until December 2017. Pre-allele, dominant, recessive, codominant, and homozygotic models were applied. In addition, a retrospective cohort study enrolling 162 RA patients treated with MTX was conducted. Single nucleotide polymorphism (SNP) genotyping was analyzed by PCR and product sequencing.

Results:

A total of 39 studies were included in 20 meta-analyses; meta-analysis showed a significant association between MTX-related toxicity and 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C>T(rs1801133) polymorphism in East Asian RA patients, and significant associations were observed between MTX-related toxicity and 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase (ATIC) 347C>G (rs2372536), reduced folate carrier 1 (RFC-1) 80G>A (rs1051266), and adenosine triphosphate-binding cassette B1 (ABCB1) 3435C>T(rs1045642) polymorphisms in European RA patients but not in East Asian RA patients. Moreover, in our retrospective cohort study, ATIC 347C>G(rs2372536) and ABCB1 3435C>T(rs1045642) polymorphisms were not associated with MTX-related toxicity. However, a significant association was observed between MTX-related toxicity and RFC-1 80G>A (rs1051266) polymorphism in Chinese Han RA patients.

Conclusion:

Evidence-based results suggest that the MTHFR 677C>T(rs1801133), ATIC 347C>G(rs2372536), RFC-1 80G>A (rs1051266), ABCB1 3435C>T(rs1045642) polymorphisms are associated with MTX-related toxicity. Larger and more stringent study designs may provide more accurate findings for the effects of these SNPs on MTX-related toxicity, and larger sample-size studies of the Chinese Han population should be conducted for further validation.

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.

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.

Cytopenia induced by low-dose methotrexate: An analysis of 433 cases from the French pharmacovigilance database

INTRODUCTION

Up to 5% of individuals exposed to low-dose methotrexate (MTX) (i.e., ≤30 mg/week) may develop cytopenia. However, MTX-induced cytopenia have been poorly described.

MATERIAL AND METHODS

All cases of cytopenia (i.e., anaemia, leukopenia, thrombocytopenia, bi- or pancytopenia) in patients receiving low-dose MTX reported to the French pharmacovigilance database during 2006-2016 were analysed. Three groups were defined: cytopenia due to MTX medication errors (e.g., daily rather than weekly administration), cytopenia in people receiving several medications including MTX, cytopenia in people receiving only MTX.

RESULTS

433 cases were analysed. Eighty-four cases (19.4%) were due to medication errors, 180 (41.6%) occurred in individuals exposed both to MTX and other drugs, and 169 (39.0%) occurred in individuals only exposed to MTX. By comparison to other patients, those with cytopenia due to medication errors were older (74 ± 13 vs 69 ± 15 years, p = 0.002), received more frequently MTX orally (92.9% vs 65.3%, p<0.001) and had more frequently pancytopenia (71.4% vs 54.4%, p = 0.005). By comparison to individuals exposed to multiple drugs (n = 180), those exposed only to MTX (n = 169) were older (71 ± 15 vs 67 ± 14, p = 0.02), and had more often pancytopenia (62.7% vs 46.7%, p = 0.001). Among those only exposed to MTX, most cases (n = 140, 82.8%) were considered as toxic rather than idiosyncratic reactions and a trigger (e.g. diarrhoea) was found in 59.3% of those cases. Overall 30 (6.9%) deaths occurred, including 8 in the "medication error" group and 8 in the "MTX only" group.

CONCLUSION

These data may be useful for defining optimal biological monitoring of patients prescribed low-dose MTX.

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.

Replication study of polymorphisms associated with response to methotrexate in patients with rheumatoid arthritis

About 70 genetic studies have already addressed the need of biomarkers to predict the response of patients with rheumatoid arthritis (RA) to methotrexate (MTX) treatment. However, no genetic biomarker has yet been sufficiently validated. Here, we aimed to replicate a selection of 25 SNPs in the largest collection of patients up to date, which consisted of 915 patients treated with MTX. The change in disease activity (measured as ΔDAS28) from baseline was considered the primary outcome. In addition, response according to widely used criteria (EULAR) was taken as secondary outcome. We considered consistency between outcomes, P values accounting for the number of SNPs, and independence from potential confounders for interpretation of the results. Only the rs1801394 SNP in MTRR fulfilled the high association standards. Its minor allele was associated with less improvement than the major allele according to ΔDAS28 (p = 0.0016), and EULAR response (p = 0.004), with independence of sex, age, baseline DAS28, smoking, seropositivity, concomitant corticosteroid use or previous treatments. In addition, previous evidence suggests the association of this SNP with response to MTX in another autoimmune disease, juvenile idiopathic arthritis, and with high intracellular folate levels, which could contribute to poor response.

SLC04A1, SLC22A2 and SLC28A2 variants not related to methotrexate efficacy or toxicity in rheumatoid arthritis patients

AIM

A third of rheumatoid arthritis patients discontinue methotrexate treatment due to inefficacy or toxic side effects. Recently, an association between SLC04A1 rs2236553, SLC22A2 rs624249 and rs316019, and SLC28A2 rs10519020 and rs1060896 with the efficacy and toxicity of methotrexate was reported. This study aims to replicate these findings in an independent cohort (n = 324).

METHODS

Regression analyses tested the associations between genotype and methotrexate response or toxicity.

RESULTS

In the discovery study, there was a significant association between toxicity and rs624249, and rs1060896. These associations were not replicated in the independent cohort. Neither study observed an association between methotrexate efficacy and SLC04A1, SLC22A2 or SLC28A2 variants.

CONCLUSION

Current evidence does not support associations between variants in SLC04A1, SLC22A2 and SLC28A2 with methotrexate efficacy or toxicity.

Associations between gene polymorphisms and treatment outcomes of methotrexate in patients with juvenile idiopathic arthritis

Aim: Performance of a meta-analysis with respect to the genetic predictors of methotrexate (MTX) treatment outcomes, efficacy and toxicity, in patients with juvenile idiopathic arthritis (JIA). Methods: Databases of OVID MEDLINE and OVID EMBASE were searched to collect the studies addressing correlations between gene polymorphisms and efficacy and/or toxicity in MTX-treated JIA patients. Pooled odds ratios (ORs) with 95% CIs were estimated in allelic, recessive and/or dominant models. Results: With regards to efficacy, the C677T (rs1801133) polymorphism in MTHFR was associated with nonresponse to MTX treatment in a recessive model (OR: 0.40; 95% CI: 0.19–0.84). For associations with toxicity, the MTHFR C677T (rs1801133) polymorphism was associated with presenting overall adverse events in an allelic model (OR: 1.54; 95% CI: 1.07–2.22) and a dominant model (OR: 1.70; 95% CI: 1.08–2.68). Conclusion: C677T (rs1801133) polymorphism in MTHFR predicts nonresponse and/or adverse effects of MTX treatment in JIA patients.

Evaluation of a clinical pharmacogenetics model to predict methotrexate response in patients with rheumatoid arthritis

Variability of response to treatment hinders successful management of rheumatoid arthritis (RA). Consequently, a clinical pharmacogenetics model for predicting response to methotrexate (CP-MTX) has been previously proposed that includes four clinical variables (disease activity, sex, the presence of rheumatoid factor and smoking status) and four SNPs (rs2236225, rs17602729, rs1127354, and rs2372536) in genes of the folate pathway. It showed good performance, but failed to attract attention, likely, in relation with lack of clear clinical benefit. Here, we have revised the value of the CP-MTX model directly addressing its clinical benefit by focusing on the expected benefit-cost of the predictions. In addition, our study included a much larger number of RA patients (n = 720) in MTX monotherapy than previous studies. Benefit of CP-MTX prediction was defined as the patients that would have received combination therapy as first treatment because they were correctly predicted as non-responders to MTX monotherapy. In contrast, cost of CP-MTX prediction was defined as the responder patients that were wrongly predicted as non-responders. Application of CP-MTX predictions to our patients showed a good benefit-cost relationship, with half of the 66.7% non-responders to MTX monotherapy rightly directed to alternative treatments (a benefit of 33.3%) at the cost of 8.5% wrongly predicted non-responders. These benefits-costs were consistent with reanalysis of the previously published studies. Therefore, predictions of CP-MTX showed a good benefit-cost relationship for informing MTX prescription.