Pharmacogenomics of Methotrexate Membrane Transport Pathway: Can Clinical Response to Methotrexate in Rheumatoid Arthritis Be Predicted?

Proteomics analyses of human plasma reveal triosephosphate isomerase as a potential blood marker of methotrexate resistance in rheumatoid arthritis

OBJECTIVE

The objective of this study was to assess differentially expressed blood proteins between patients with active RA and patients in remission after MTX treatment, with the aim of identifying a biomarker of MTX resistance (MTXR).

METHODS

Two populations of RA patients treated with a stable dose of s.c. MTX for at least 3 months were constituted according to the DAS28: remission (DAS28 < 2.6; n = 24) and active disease (DAS28 > 3.2; n = 32). The two groups of RA patients were homogeneous regarding their epidemiological characteristics, except for the duration of treatment, which was longer in the remission group. After collection of a blood sample, plasma protein digestion was performed, followed by untargeted proteomics analysis. Then, a targeted analysis was performed to confirm the results of the untargeted approach.

RESULTS

Untargeted proteomics analysis revealed eight plasma proteins that were differentially expressed between the two groups of patients. Among them, triosephosphate isomerase (TPI-1) and glucose-6-phosphate isomerase (GPI), which are main actors in glycolysis, were found down-regulated in the active group. This result was confirmed for TPI-1 in the targeted proteomics analysis.

CONCLUSION

A first step was achieved in the search for biomarkers of MTXR, with the identification of two actors in glycolysis (TPI-1 and GPI). The next step will be to confirm these results in a larger cohort, including samples from treatment-naive patients, to assess the predictive potential of these protein markers.

Comparative efficacy of five approved Janus kinase inhibitors as monotherapy and combination therapy in patients with moderate-to-severe active rheumatoid arthritis: a systematic review and network meta-analysis of randomized controlled trials

Background

The European League of Rheumatology(EULAR)guidelines recommend Janus kinase (JAK) inhibitors for patients with moderate to severe rheumatoid arthritis (RA) who are insensitive or under-responsive to conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs). But there was no recommendation for which one was preferred in five currently approved JAK inhibitors. The objective of this network meta-analysis study was to evaluate the efficacy of five JAK inhibitors as monotherapy and combination therapy in patients with moderate-to-severe active rheumatoid arthritis.

Methods

The randomized controlled trials (RCTs) of tofacitinib, baricitinib, upadacitinib, filgotinib and peficitinib as monotherapy or combined with csDMARD in the treatment of active RA were searched in database of PubMed, Embase, Web of Science and Cochrane Library, up to December 2023. The control group included placebo or csDMARD. Outcome indicators included American College of Rheumatology 20% response (ACR20), ACR50, ACR70 and the percentage of patients achieving 28-joint disease activity score using C-reactive protein (DAS28(CRP))<2.6 at 12 weeks and 24 weeks. The statistical analysis was performed by Stata14 and RevMan5.4. Data processing, network evidence plots, surface under the cumulative ranking curve (SUCRA) ranking, league plots and funnel plots were generated. Risk ratio (RR) and 95% confidence interval (95%CI) as effect sizes to analyze the statistics.

Results

This study included thirty-six RCTs with 16,713 patients. All JAK inhibitors were more effective than placebo in ACR20 (RRs ranging between 1.74 and 3.08), ACR50 (RRs ranging between 2.02 and 7.47), ACR70 (RRs ranging between 2.68 and 18.13), DAS28(CRP) < 2.6 (RRs ranging between 2.70 and 7.09) at 12 weeks. Upadacitinib 30 mg and upadacitinib 15 mg showed relatively good efficacy according to their relative SUCRA ranking. All JAK inhibitors were more effective than csDMARD or placebo in ACR20 (RRs ranging between 1.16 and 1.86), ACR50 (RRs ranging between 1.69 and 2.84), ACR70 (RRs ranging between 1.50 and 4.47), DAS28(CRP) < 2.6 (RRs ranging between 2.28 and 7.56) at 24 weeks. Upadacitinib 15 mg + csDMARD and baricitinib 4 mg + csDMARD showed relatively good efficacy according to their relative SUCRA ranking. The safety analysis results such as serious infection, malignancy, major adverse cardiovascular event (MACE), and venous thromboembolic events (VTE) showed no statistical difference.

Conclusion

This NMA study indicated that all JAK inhibitors performed better than placebo. Based on the results of this study, upadacitinib 30 mg, upadacitinib 15 mg, upadacitinib 15 mg + csDMARD and baricitinib 4 mg + csDMARD were recommended treatment options with relatively good efficacy and safety. However, attention should be paid to monitoring the occurrence of adverse events in high-risk RA patients with medication. Combination therapy with csDMARD might be more suitable for the maintenance of long-term efficacy. However, in clinical practice, it is still necessary to select the appropriate therapeutic regimen based on the actual clinical situation.

IFABP2 as a new prognostic biomarker for secondary non-response in rheumatoid arthritis

BACKGROUND

Increased intestinal permeability promotes the translocation of bacterial products from the local microbiome to the circulation, inducing inflammation and increasing clinical activity in rheumatoid arthritis (RA). This study evaluates whether intestinal fatty acid binding protein 2 (IFABP2) serum levels are prognostic biomarkers of non-response to conventional synthetic disease-modifying antirheumatic drug therapy (csDMARDs) in RA.

METHODS

The therapeutic schemes administered to 60 women with RA for at least 18 months were assessed retrospectively, and the treatment response was classified according to the change in DAS28-ESR over time. Serum levels of IFABP2 and TNF-α were determined by ELISA. Receiver operating characteristics (ROC) curve analysis and logistic regression models were used to assess the predictive value and the association of IFABP2 with the non-responder phenotype in RA patients.

RESULTS

Eleven women had a responder phenotype, 23 had a primary non-responder phenotype, and 26 had a secondary non-responder phenotype. Secondary non-responders showed higher DAS28-ESR (P = 0.009) and higher IFABP2 serum levels compared to the responder group (P = 0.023) and the primary non-responder group (P = 0.018). IFABP2 serum levels were positively correlated with chloroquine dose (r = 0.581, P = 0.007) and negatively correlated with total cholesterol (r = -0.456, P = 0.019) in secondary non-responders. The area under the curve (AUC) value of IFABP2 for predicting secondary non-response was 0.736, and IFABP2 serum levels > 9.311 ng/mL were associated with secondary non-response to csDMARDs (OR = 6.00, P = 0.003).

CONCLUSION

IFABP2 serum levels are potentially a new biomarker predictive of secondary non-response to csDMARDs in RA, although our findings should be validated externally and in a larger cohort.

Specific enterotype of gut microbiota predicted clinical effect of methotrexate in patients with rheumatoid arthritis

OBJECTIVE

The most used drug for the treatment of rheumatoid arthritis (RA) remains methotrexate (MTX). Unfortunately, up to 50% of patients do not achieve a clinically adequate outcome. Here we study whether the gut microbiota patterns can aid in the prediction of MTX efficacy for RA.

METHOD

To dissect gut microbiome profiles of RA patients (n = 145), 16S rRNA gene sequencing was performed. Dirichlet multinomial mixture (DMM) clustering was used to identify enterotypes at genus level. The relationships between enterotypes and clinical measures (such as lymphocyte subsets and cytokines detected by flow cytometry) were explored. Then, enterotype stability was evaluated by the stratification of the RA patient cohort (n = 66) in Shanghai, China, using the same method. Finally, the enterotype-based gut microbial human index classifier was applied to another independent RA patient cohort (n = 27) to identify the factors associated with MTX clinical response.

RESULTS

Our analysis revealed that the RA patients always displayed two different dysbiotic microbiota patterns: RA E1 comprised predominantly Prevotella and RA E2 comprised predominantly Bacteroides. Among all of the lymphocyte subsets and cytokines, only the number of CD8+ T cells showed a significant difference between RA E1 and RA E2. These results were validated in the RA patient cohort in Shanghai, China. Significant associations of RA E1 with clinical response to subsequent MTX treatment were confirmed by another independent RA patient cohort.

CONCLUSION

Together, the enterotype-based gut microbial human index (EGMI) classifier was useful to precisely and effectively identify enterotypes of individual RA patients, which could effectively evaluate MTX clinical responses.

MTHFR c.665C>T and c.1298A>C Polymorphisms in Tailoring Personalized Anti-TNF-α Therapy for Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease with a prevalence of 1%. Currently, RA treatment aims to achieve low disease activity or remission. Failure to achieve this goal causes disease progression with a poor prognosis. When treatment with first-line drugs fails, treatment with tumor necrosis factor-α (TNF-α) inhibitors may be prescribed to which many patients do not respond adequately, making the identification of response markers urgent. This study investigated the association of two RA-related genetic polymorphisms, c.665C>T (historically referred to as C677T) and c.1298A>C, in the MTHFR gene as response markers to an anti-TNF-α therapy. A total of 81 patients were enrolled, 60% of whom responded to the therapy. Analyses showed that both polymorphisms were associated with a response to therapy in an allele dose-dependent manner. The association for c.665C>T was significant for a rare genotype (p = 0.01). However, the observed opposite trend of association for c.1298A>C was not significant. An analysis revealed that c.1298A>C, unlike c.665C>T, was also significantly associated with the drug type (p = 0.032). Our preliminary results showed that the genetic polymorphisms in the MTHFR gene were associated with a response to anti-TNF-α therapy, with a potential significance for the anti-TNF-α drug type. This evidence suggests a role for one-carbon metabolism in anti-TNF-α drug efficacy and contributes to further personalized RA interventions.

Identification of SNPs associated with methotrexate treatment outcomes in patients with early rheumatoid arthritis

Methotrexate is one of the cornerstones of rheumatoid arthritis (RA) therapy. Genetic factors or single nucleotide polymorphisms (SNPs) are responsible for 15%–30% of the variation in drug response. Identification of clinically effective SNP biomarkers for predicting methotrexate (MTX) sensitivity has been a challenge. The aim of this study was to explore the association between the disease related outcome of MTX treatment and 23 SNPs in 8 genes of the MTX pathway, as well as one pro-inflammatory related gene in RA patients naïve to MTX. Categorical outcomes such as Disease Activity Score (DAS)-based European Alliance of Associations for Rheumatology (EULAR) non-response at 4 months, The American College of Rheumatology and EULAR (ACR/EULAR) non-remission at 6 months, and failure to sustain MTX monotherapy from 12 to 24 months were assessed, together with continuous outcomes of disease activity, joint pain and fatigue. We found that the SNPs rs1801394 in the MTRR gene, rs408626 in DHFR gene, and rs2259571 in AIF-1 gene were significantly associated with disease activity relevant continuous outcomes. Additionally, SNP rs1801133 in the MTHFR gene was identified to be associated with improved fatigue. Moreover, associations with p values at uncorrected significance level were found in SNPs and different categorical outcomes: 1) rs1476413 in the MTHFR gene and rs3784864 in ABCC1 gene are associated with ACR/EULAR non-remission; 2) rs1801133 in the MTHFR gene is associated with EULAR response; 3) rs246240 in the ABCC1 gene, rs2259571 in the AIF-1 gene, rs2274808 in the SLC19A1 gene and rs1476413 in the MTHFR gene are associated with failure to MTX monotherapy after 12–24 months. The results suggest that SNPs in genes associated with MTX activity may be used to predict MTX relevant-clinical outcomes in patients with RA.

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.

High dose methotrexate in adult Egyptian patients with hematological malignancies: impact of ABCB1 3435C > T rs1045642 and MTHFR 677C > T rs1801133 polymorphisms on toxicities and delayed elimination

High dose methotrexate (HDMTX) is an essential agent in chemotherapeutic regimens used in various hematological malignancies in Egyptian adults. The research for the impact of gene polymorphism on HDMTX induced toxicities and delayed elimination is an important ongoing objective in many studies, variable and conflicting results produced in the past years to clarify that impact. This study aimed to investigate the role of ABCB1 3435 C > T rs1045642 and MTHFR 677 C > T rs1801133 polymorphisms on HDMTX induced toxicity outcomes and delayed elimination in Egyptian adult patients with hematological malignancies. A prospective, observational cohort study was conducted on a total of 62 Egyptian adult patients with hematological malignancies age ≥ 18-years-old. All demographic, medical, and laboratory data were continuously collected from the patients' medical files in an up-to-date follow-up in selected clinics during the period from April 2018 to March 2020. Venous blood samples were collected for the purpose of genotyping, DNA extraction, and measurement of MTX levels. All the relevant data were statistically analyzed. The studied patients' median age was 25 years old with a range of (18-62) years. Forty-six patients were males with about 74%, and 16 were females with about 26%. Eighty-nine percent of the patients diagnosed with acute lymphoblastic leukemia 'ALL', 5% of the patients had B cell non-hodgkin lymphoma 'B-NHL' and 3% diagnosed with primary central nervous system lymphoma 'PCNSL' and Burkitt's lymphoma 'BL' Hematological, hepatic, renal and gastrointestinal toxicities observed post-HDMTX were recorded with the hematological toxicities toping on all the others, also patients with delayed elimination at 72 hours post the HDMTX dose were determined. Statistical analysis revealed a significant association between ABCB1 3435 C > T rs1045642 and HDMTX delayed elimination with about 10 times higher risk among the minor allele 'T' carriers (p-value = 0.006) (odds ratio [OR]: 10.470; 95% CI: 1.961-55.904). No significant association observed between the studied gene polymorphisms: MTHFR 677 C > T rs1801133, ABCB1 3435 C > T rs1045642, and different toxicity outcomes. According to our best knowledge, this study is the first to conclude a significant association between ABCB1 3435 C > T rs1045642 gene polymorphism and HDMTX delayed elimination at 72 hours post HDMTX infusion; also, it is the first study to analyze the association between ABCB1 3435 C > T rs1045642 polymorphism with HDMTX toxicity and delayed elimination in adult Egyptian patients with hematological malignancies.

Pharmacogenetics-Based Preliminary Algorithm to Predict the Incidence of Infection in Patients Receiving Cytotoxic Chemotherapy for Hematological Malignancies: A Discovery Cohort

Introduction: Infections in hematological cancer patients are common and usually life-threatening; avoiding them could decrease morbidity, mortality, and cost. Genes associated with antineoplastics’ pharmacokinetics or with the immune/inflammatory response could explain variability in infection occurrence.

Objective: To build a pharmacogenetic-based algorithm to predict the incidence of infections in patients undergoing cytotoxic chemotherapy.

Methods: Prospective cohort study in adult patients receiving cytotoxic chemotherapy to treat leukemia, lymphoma, or myeloma in two hospitals in Santiago, Chile. We constructed the predictive model using logistic regression. We assessed thirteen genetic polymorphisms (including nine pharmacokinetic—related genes and four inflammatory response-related genes) and sociodemographic/clinical variables to be incorporated into the model. The model’s calibration and discrimination were used to compare models; they were assessed by the Hosmer-Lemeshow goodness-of-fit test and area under the ROC curve, respectively, in association with Pseudo-R².

Results: We analyzed 203 chemotherapy cycles in 50 patients (47.8 ± 16.1 years; 56% women), including 13 (26%) with acute lymphoblastic and 12 (24%) with myeloblastic leukemia.

Pharmacokinetics-related polymorphisms incorporated into the model were CYP3A4 rs2242480C>T and OAT4 rs11231809T>A. Immune/inflammatory response-related polymorphisms were TLR2 rs4696480T>A and IL-6 rs1800796C>G. Clinical/demographic variables incorporated into the model were chemotherapy type and cycle, diagnosis, days in neutropenia, age, and sex. The Pseudo-R² was 0.56, the p-value of the Hosmer-Lemeshow test was 0.98, showing good goodness-of-fit, and the area under the ROC curve was 0.93, showing good diagnostic accuracy.

Conclusions: Genetics can help to predict infections in patients undergoing chemotherapy. This algorithm should be validated and could be used to save lives, decrease economic costs, and optimize limited health resources.

ABCB1 and SLCO1B1 gene polymorphisms predict methotrexate-resistant for low-risk gestational trophoblastic neoplasia

Aim: The aim of this study was to explore the effects of ABCB1 and SLCO1B1 gene polymorphisms and the methotrexate (MTX) treatment response in patients with low-risk gestational trophoblastic neoplasia (GTN). Materials & methods: Low-risk GTN patients who received MTX as a first-line single agent were enrolled. DNA was extracted from peripheral blood samples from 18 patients and assessed for ABCB1 C3435T and SLCO1B1 T521C. Results: ABCB1 C3435T and SLCO1B1 T521C polymorphisms were not associated with the MTX response or toxicity in Thai patients Conclusion: The selected ABCB1 and SLCO1B1 polymorphism do not predict the risk of MTX resistance in low-risk GTN.

ABCB1, ABCG2, ABCC1, ABCC2, and ABCC3 drug transporter polymorphisms and their impact on drug bioavailability: what is our current understanding?

INTRODUCTION

Interindividual differences in drug response are a frequent clinical challenge partly due to variation in pharmacokinetics. ATP-binding cassette (ABC) transporters are crucial determinants of drug disposition. They are subject of gene regulation and drug-interaction; however, it is still under debate to which extend genetic variants in these transporters contribute to interindividual variability of a wide range of drugs.

AREAS COVERED

This review discusses the current literature on the impact of genetic variants in ABCB1, ABCG2 as well as ABCC1, ABCC2, and ABCC3 on pharmacokinetics and drug response. The aim was to evaluate if results from recent studies would increase the evidence for potential clinically relevant pharmacogenetic effects.

EXPERT OPINION

Although enormous efforts have been made to investigate effects of ABC transporter genotypes on drug pharmacokinetics and response, the majority of studies showed only weak if any associations. Despite few unique results, studies mostly failed to confirm earlier findings or still remained inconsistent. The impact of genetic variants on drug bioavailability is only minor and other factors regulating the transporter expression and function seem to be more critical. In our opinion, the findings on the so far investigated genetic variants in ABC efflux transporters are not suitable as predictive biomarkers.

Drug-resistance in rheumatoid arthritis: the role of p53 gene mutations, ABC family transporters and personal factors

Rheumatoid arthritis (RA) is an autoimmune disease that is associated with chronic inflammation in joints, which contribute to synovial membrane hyperplasia and cartilage damage. Conventional disease-modifying antirheumatic drugs (DMARDs), such as methotrexate (MTX) and leflunomide (LEF), are the common RA therapy to reduce inflammation and disease progression. Recently, drug-resistance in RA with conventional treatment has become an issue. Mutations in p53 tumor suppressor gene and overexpression of ABCB1/MDR-1/P-gp transporters may contribute to antirheumatic drug-resistance in RA. Biologic DMARDs (bDMARDs) are often prescribed, when conventional DMARDs fail to treat RA, by targeting proinflammatory mediators such as tumor necrosis factor-α (TNF-α) and interleukin (IL)-6. The efficacy of bDMARDs is affected by personal factors, for example, age, smoking, body mass index (BMI), immunogenicity, and genetic polymorphisms. This review highlights the role of p53 gene mutations, ABC family transporters and personal factors in antirheumatic drug-resistance, which may lead to new personalized therapies against RA with an increased drug-sensitivity.

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.

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.

Inhibition of miR-16 enhances the sensitivity of fibroblast-like synovial cells to methotrexate by restraining MDR1/P-gp expression via NF-κB pathway

MicroRNAs (miRNAs) are demonstrated to contribute to the regulation of drug resistance in a number of diseases. Nevertheless, little is known about the role and the underlying mechanism of miR-16 in rheumatoid arthritis (RA) methotrexate resistance. In this study, we firstly examined the miR-16 expression in the serum and synovial fluid from RA patients who were unresponsive to methotrexate monotherapy (UR-MTX patients) and responsive RA patients (R-MTX patients). Secondly, the miR-16 expression was measured in both fibroblast-like synovial cells (FLS) and methotrexate resistance RA-FLS cells (FLS-MTX). FLS cells used in this study were isolated from synovial tissue specimens obtained from patients with RA who underwent total joint replacement. FLS-MTX cells were conducted by gradually increasing the concentration of methotrexate in the medium. The construction of FLS-MTX cells was confirmed by 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay. Thirdly, in order to further investigate the role of miR-16 in FLS-MTX cells, we introduced miR-16 inhibitor into FLS-MTX cells to knockdown the expression of miR-16, used fluorescence quantitative PCR to detect the inhibition efficiency. The effects of miR-16 inhibition on cell viability, cell cycle arrest and apoptosis in FLS-MTX cells were monitored with MTT and flow cytometry analysis, respectively. And the regulation of miR-16 on P-glycoprotein (P-gp) was performed using qRT-PCR, western blotting, and immunofluorescence staining. Fourthly, ammonium pyrrolidinedithiocarbamate (PDTC), a NF-κB pathway inhibitor, was applied to verify the mechanism by which miR-16 involved in to regulate the P-gp expression, and thus contributing to the methotrexate resistance in FLS-MTX cells. MiR-16 was upregulated in the in serum and synovial fluid from UR-MTX patients as well as in FLS-MTX cells. Inhibition of miR-16 re-sensitized the FLS-MTX cells to methotrexate by suppressing the cell viability, cell promoting cycle arrest at G0/G1 phase and enhancing apoptosis. Knockdown of miR-16 significantly reduced MDR1 mRNA expression and P-gp protein expression in FLS-MTX cells. Furthermore, inhibition of NF-κB pathway by PDTC reinforced the effect of miR-16 knockdown on P-gp expression, cell viability, cell cycle arrest and apoptosis. In conclusion, our study illustrated that inhibition of miR-16 in FLS-MTX cells alleviated methotrexate resistance by inhibiting MDR1/P-gp expression through inactivation of the NF-κB pathway.

MicroRNAs (miRNAs) are demonstrated to contribute to the regulation of drug resistance in a number of diseases.

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.

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.

The role of solute carrier (SLC) transporters in actinomycin D pharmacokinetics in paediatric cancer patients

BACKGROUND

Actinomycin D is used for treatment of paediatric cancers; however, a large inter-patient pharmacokinetic (PK) variability and hepatotoxicity are significant limitations to its use and warrant further investigation. Elimination of actinomycin D may be mediated by transporters, as the drug does not seem to undergo significant metabolism. We investigated the role of solute carrier (SLC) transporters in actinomycin D PK.

METHODS

Fourteen key SLCs were screened through probe substrate uptake inhibition by actinomycin D in HEK293 cells. Uptake of actinomycin D was further studied in candidate SLCs by measuring intracellular actinomycin D using a validated LCMS assay. Pharmacogenetic analysis was conducted for 60 patients (Clinical trial: NCT00900354), who were genotyped for SNPs for OAT4 and PEPT2.

RESULTS

OAT4, OCT2, OCT3 and PEPT2 showed significantly lower probe substrate uptake (mean ± SD 75.0 ± 3.5% (p < 0.0001), 74.8 ± 11.2% (p = 0.001), 81.2 ± 14.0% (p = 0.0083) and 70.7 ± 5.7% (p = 0.0188)) compared to that of control. Intracellular accumulation of actinomycin D was greater compared to vector control in OAT4-transfected cells by 1.5- and 1.4-fold at 10 min (p = 0.01) and 20 min (p = 0.03), and in PEPT2-transfected cells by 1.5- and 1.7-fold at 10 min (p = 0.047) and 20 min (p = 0.043), respectively. Subsequent clinical study did not find a significant association between OAT4 rs11231809 and PEPT2 rs2257212 genotypes, and actinomycin D PK parameters such as clearance (CL) and volume of distribution (V_d).

CONCLUSION

Transport of actinomycin D was mediated by OAT4 and PEPT2 in vitro. There was a lack of clinical significance of OAT4 and PEPT2 genotypes as predictors of actinomycin D disposition in paediatric cancer patients.

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.

Clinical and Functional Relevance of the Monocarboxylate Transporter Family in Disease Pathophysiology and Drug Therapy

The solute carrier (SLC) SLC16 gene family comprises 14 members and encodes for monocarboxylate transporters (MCTs), which mediate the absorption and distribution of monocarboxylic compounds across plasma membranes. As the knowledge about their physiological function, activity, and regulation increases, their involvement and contribution to cancer and other diseases become increasingly evident. Moreover, promising opportunities for therapeutic interventions by directly targeting their endogenous functions or by exploiting their ability to deliver drugs to specific organ sites emerge.

Are haplotypes in a single methotrexate pathway more predictive for response in rheumatoid arthritis than in different pathways?

Letter to the editor with respect to: Lima A, Bernardes M, Azevedo R, Seabra V and Medeiros R. Moving toward personalized medicine in rheumatoid arthritis: SNPs in methotrexate intracellular pathways are associated with methotrexate therapeutic outcome. Pharmacogenomics 17(15), 1649-1674 (2016).

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.

Moving toward personalized medicine in rheumatoid arthritis: SNPs in methotrexate intracellular pathways are associated with methotrexate therapeutic outcome

AIM

Evaluate the potential of selected SNPs as predictors of methotrexate (MTX) therapeutic outcome.

PATIENTS & METHODS

In total, 35 SNPs in 14 genes involved in MTX intracellular pathways and Phase II reactions were genotyped in 233 rheumatoid arthritis (RA) patients treated with MTX. Binary logistic regressions were performed by genotype/haplotype-based approaches. Non-Response- and Toxicity-Genetic Risk Indexes (Non-RespGRI and ToxGRI) were created.

RESULTS

MTX nonresponse was associated to eight genotypes and three haplotypes: MTHFR rs1801131 AA and rs1801133 TT; MS rs1805087 AA; MTRR rs1801394 A carriers; ATIC rs2372536 C carriers, rs4673993 T carriers, rs7563206 T carriers and rs12995526 T carriers; CC for GGH rs3758149 and rs12681874; CGTTT for ATIC combination 1; and CTTTC for ATIC combination 2. From overall Non-RespGRI patients with indexes 6-8 had more than sixfold increased risk for MTX nonresponse than those patients with indexes 0-5. MTX-related toxicity was associated to five genotypes and two haplotypes: ATIC rs2372536 G carriers, rs3821353 T carriers, rs7563206 CC and rs12995526 CC; ADORA2A rs2267076 T; CTTCC for ATIC combination 1; and TC for ADORA2A rs2267076 and rs2298383. From overall ToxGRI, patients with indexes 3-4 had more than sevenfold increased risk for MTX-related toxicity than those patients with indexes 1-2.

CONCLUSION

Genotyping may be helpful to identify which RA patients will not benefit from MTX treatment and, consequently, important to personalized medicine in RA. Nevertheless, further studies are required to validate these findings.