Aurea Lima

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.

SLC19A1 80G allele as a biomarker of methotrexate-related gastrointestinal toxicity in Portuguese rheumatoid arthritis patients

AIM The aim of our study was to characterize the association of clinicopathological variables and the SLC19A1/RFC-1 G80A polymorphism in methotrexate (MTX)-related toxicity in Portuguese patients with rheumatoid arthritis. PATIENTS & METHODS The study included 233 consecutively recruited patients with rheumatoid arthritis under MTX treatment. The SLC19A1 G80A polymorphism was evaluated by PCR-RFLP. RESULTS Statistical analysis revealed that SLC19A1 80G carriers had increased risk of gastrointestinal toxicity (odds ratio [OR]: 2.61, p = 0.019) and that regular folic acid supplementation was associated with both overall and gastrointestinal toxicity protection (OR: 0.15, p < 0.001 and OR: 0.19, p < 0.001, respectively). Multivariate analysis confirmed the association of SLC19A1 80G and regular folic acid supplementation to gastrointestinal toxicity (OR: 5.53 and 0.13, respectively). Moreover, a multivariate Cox regression model demonstrated a higher risk of earlier gastrointestinal toxicity in SLC19A1 80G carriers (hazard ratio: 3.63, p = 0.002). CONCLUSION SLC19A1 G80A genotyping may be a useful tool for clinicians to identify patients at higher risk for developing gastrointestinal toxicity related to MTX treatment.

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.

Future perspectives of Smartphone applications for rheumatic diseases self-management

Abstract Rheumatic diseases (RD) self-management interventions are designed to improve health-related quality of life, health care utilization, and perceived self-efficacy. Despite these demonstrated good results, there are several issues that hinder or render less appealing these interventions. One economically and socially viable solution is exploiting the potential of Smartphone technology. This potential comes from Smartphones pervasive presence in actual society, combined with the advantages of being personal, intuitive, and computationally powerful, with capability to support applications and assist its user throughout different activities of daily living and environments persistently. With their global acceptance increasing quickly, there is a great opportunity for mobile health in using Smartphone applications for RD self-management. Besides the potential of such applications, research on the development and evaluation of such applications is in the early stages. Therefore, it is important to foresee its future applicability in order to meet the needs of the twenty-first century.

SLC19A1, SLC46A1 and SLCO1B1 Polymorphisms as Predictors of Methotrexate-Related Toxicity in Portuguese Rheumatoid Arthritis Patients

Methotrexate (MTX) is used for rheumatoid arthritis (RA) treatment showing a wide toxicity profile. This study aimed to evaluate the influence of single nucleotide polymorphisms (SNPs) in genes encoding for MTX transporters with the occurrence of MTX-related toxicity (overall and gastrointestinal). A total of 233 Portuguese RA patients were genotyped for 23 SNPs. Haplotype analyses were performed and a toxicogenetic risk index (TRI) was created for SNPs that revealed to be statistically significant. Regarding MTX overall toxicity, an increased risk was associated to SLC19A1 rs7499 G carriers (p = 0.017), SLC46A1 rs2239907 GG (p = 0.030) and, SLCO1B1 rs4149056 T carriers (p = 0.040) and TT (p = 0.019). TRI revealed that patients with Index 3 were 18-fold more likely to present an adverse drug reaction when compared to those with Index 1 (p = 0.001). For MTX gastrointestinal toxicity, results demonstrated an increased risk associated with SLC19A1 rs7499 G carriers (p = 0.012) and GG (p = 0.045), SLC19A1 rs1051266 G carriers (p = 0.034), SLC19A1 rs2838956 A carriers (p = 0.049) and, SLCO1B1 rs4149056 T carriers (p = 0.042) and TT (p = 0.025). Haplotype analyses showed association between GGAG haplotype for SLC19A1 rs7499, rs1051266, rs2838956 and rs3788200 with MTX gastrointestinal toxicity (p = 0.029). TRI revealed that patients with Index 4 were 9-fold more likely to present a gastrointestinal disorder when compared to those with Index 1 (p = 0.020). This study demonstrated that SLC19A1, SLC46A1 and SLCO1B1 genotypes may help to identify patients with increased risk of MTX-related overall toxicity and that SLC19A1 and SLCO1B1 genotypes, and SLC19A1 haplotypes may help to identify patients with increased risk of MTX-related gastrointestinal toxicity.

Prediction of methotrexate clinical response in Portuguese rheumatoid arthritis patients: implication of MTHFR rs1801133 and ATIC rs4673993 polymorphisms.

Objective. Methotrexate (MTX), the most used drug in rheumatoid arthritis (RA) treatment, showing variability in clinical response, is often associated with genetic polymorphisms. This study aimed to elucidate the role of methylenetetrahydrofolate reductase (MTHFR) C677T and aminoimidazole carboxamide adenosine ribonucleotide transformylase (ATIC) T675C polymorphisms and clinicopathological variables in clinical response to MTX in Portuguese RA patients. Methods. Study included 233 RA patients treated with MTX for at least six months. MTHFR C677T and ATIC T675C polymorphisms were genotyped and clinicopathological variables were collected. Statistical analyses were performed and binary logistic regression method adjusted to possible confounding variables. Results. Multivariate analyses demonstrated that MTHFR 677TT (OR = 4.63; P = 0.013) and ATIC 675T carriers (OR = 5.16; P = 0.013) were associated with over 4-fold increased risk for nonresponse. For clinicopathological variables, noncurrent smokers (OR = 7.98; P = 0.001), patients positive to anti-cyclic citrullinated peptide (OR = 3.53; P = 0.004) and antinuclear antibodies (OR = 2.28; P = 0.045), with higher health assessment questionnaire score (OR = 2.42; P = 0.007), and nonsteroidal anti-inflammatory drug users (OR = 2.77; P = 0.018) were also associated with nonresponse. Contrarily, subcutaneous administration route (OR = 0.11; P < 0.001) was associated with response. Conclusion. Our study suggests that MTHFR C677T and ATIC T675C genotyping combined with clinicopathological data may help to identify patients whom will not benefit from MTX treatment and, therefore, assist clinicians in personalizing RA treatment.

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

Background: Methotrexate (MTX) is widely used for rheumatoid arthritis (RA) treatment. Single nucleotide polymorphisms (SNPs) could be used as predictors of patients’ therapeutic outcome variability. Therefore, this study aims to evaluate the influence of SNPs in genes encoding for MTX membrane transport proteins in order to predict clinical response to MTX. Methods: Clinicopathological data from 233 RA patients treated with MTX were collected, clinical response defined, and patients genotyped for 23 SNPs. Genotype and haplotype analyses were performed using multivariate methods and a genetic risk index (GRI) for non-response was created. Results: Increased risk for non-response was associated to SLC22A11 rs11231809 T carriers; ABCC1 rs246240 G carriers; ABCC1 rs3784864 G carriers; CGG haplotype for ABCC1 rs35592, rs2074087 and rs3784864; and CGG haplotype for ABCC1 rs35592, rs246240 and rs3784864. GRI demonstrated that patients with Index 3 were 16-fold more likely to be non-responders than those with Index 1. Conclusions: This study revealed that SLC22A11 and ABCC1 may be important to identify those patients who will not benefit from MTX treatment, highlighting the relevance in translating these results to clinical practice. However, further validation by independent studies is needed to develop the field of personalized medicine to predict clinical response to MTX treatment.

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.

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.

SAT0064 Moving Towards Personalized Medicine in Rheumatoid Arthritis: Atic Polymorphisms as Pharmacogenetic Predictors of Methotrexate Therapeutic Outcome

Background Identifying genetic predictors of methotrexate (MTX) therapeutic outcome in patients with rheumatoid arthritis (RA) may have great importance for a swift moving towards personalized medicine1,2. Objectives To investigate whether selected polymorphisms in genes relevant for MTX action mechanism (de novo purine synthesis pathway) modulate MTX therapeutic outcome in Portuguese RA patients. Methods In a group of 233 Caucasian RA patients treated with MTX, clinicopathological data were collected and outcomes defined. Patients were genotyped for 8 single nucleotide polymorphisms (SNPs): 1) aminoimidazole-4-carboxiamide ribonucleotide transformylase (ATIC) rs2372536 C>G, rs3821353 G>T, rs4673993 T>C, rs7563206 T>C, rs12995526 T>C and rs16853834 C>T; 2) glycineamide ribonucleotide formyl transferase (GART) rs8971 A>G; and, 3) phosphoribosyl pyrophosphate amidotransferase (PPAT) rs3796548 C>T. Univariate analyses and binary logistic regressions (BLR) adjusted to possible confounder variables were performed by using genotype and haplotype-based approaches. Genetic (GRI) and toxicogenetic (TRI) risk indexes were created. Results Four SNPs in ATIC were associated with about 3-fold increased risk for a non-response profile to MTX: rs2372536 G carriers, rs4673993 T carriers, rs7563206 T carriers and rs12995526 T carriers. After adjusting in a BLR, genotypes remained significant. All SNPs in ATIC were in linkage disequilibrium except for rs3821353 and rs16853834 and analyses were performed considering the following combinations: 1. rs2372536, rs3821353, rs4673993, rs7563206 and rs12995526; and 2. rs2372536, rs4673993, rs7563206, rs12995526 and rs16853834. Haplotypes CGTTT for combination 1. and CTTTC for combination 2. were associated with a non-response profile. The BLR was only significant for CGTTT haplotype when compared to CTCCC. The GRI revealed that patients with 4 risk variants, i.e. with the 4 genotypes in ATIC that were statistically significant in BLR, had a 2-fold increased risk for a non-response profile. When adjusted in BLR, results were not confirmed. Two SNPs in ATIC were associated with about 2-fold risk for MTX-related toxicity: rs7563206 CC and rs12995526 CC. After adjusting in a BLR, the genotypes remained significant and 2 others demonstrated a borderline association with MTX-related toxicity (rs2372536 G carriers and rs3821353 T carriers). Haplotype CTTCC for combination 1. was associated with MTX-related toxicity only when adjusted in BLR. The TRI revealed that patients with 4 risk variants, i.e. with the 4 genotypes in ATIC that were significant in BLR, had a 16-fold increased risk for MTX-related toxicity. This risk remained even when adjusted in BLR. Conclusions The studied SNPs in ATIC can be considered as pharmacogenetic markers of MTX therapeutic outcome in RA patients, although further studies will be required to validate these findings. References Romao VC, et al. Three decades of low-dose methotrexate in rheumatoid arthritis: Can we predict toxicity? Immunol Res 2014;60(2-3):289-310. Lima A, et al. Genetic polymorphisms in low-dose methotrexate transporters: current relevance as methotrexate therapeutic outcome biomarkers. Pharmacogenomics 2014;15(12):1611-35. Disclosure of Interest None declared