Methotrexate (MTX), a structurally related substance to folic acid, is an important chemotherapeutic agent used for decades in the treatment of pediatric acute lymphoblastic leukemia (ALL) and other types of cancer as non-Hodgkin lymphomas and osteosarcomas. Despite the successful outcomes observed, the primary drawback is the variability in the pharmacokinetics and pharmacodynamics between patients. The main adverse events related to its use are nephrotoxicity, mucositis, and myelosuppression, especially when used in high doses. The potential adverse reactions and toxicities associated with MTX are a cause for concern and may lead to dose reduction or treatment interruption. Genetic variants in MTX transport genes have been linked to toxicity. Pharmacogenetic studies conducted in the past focused on single nucleotide polymorphisms (SNPs) in the coding and 5′-regulatory regions of genes. Recent studies have demonstrated a significant role of microRNAs (miRNAs) in the transport and metabolism of drugs and in the regulation of target genes. In the last few years, the number of annotated miRNAs has continually risen, in addition to the studies of miRNA polymorphisms and MTX toxicity. Therefore, the objective of the present study is to investigate the role of miRNA variants related to MTX adverse effects.

Methotrexate (MTX) is an anti-folate chemotherapeutic agent that is considered to be a gold standard in Acute Lymphoblastic Leukemia (ALL) therapy. Nevertheless, toxicities induced mainly due to high doses of MTX are still a challenge for clinical practice. MTX pharmacogenetics implicate various genes as predictors of MTX toxicity, especially those that participate in MTX intake like solute carrier family 19 member 1 (SLC19A1). The aim of the present study was to evaluate the association between SLC19A1 polymorphisms and its regulatory miRNAs with MTX toxicity in children with ALL. A total of 86 children with ALL were included in this study and were all genotyped for rs2838958, rs1051266 and rs1131596 SLC19A1 polymorphisms as well as the rs56292801 polymorphism of miR-5189. Patients were followed up (48, 72 and 96 h) after treatment with MTX in order to evaluate the presence of MTX-associated adverse events. Our results indicate that there is a statistically significant correlation between the rs1131596 SLC19A1 polymorphism and the development of MTX-induced hepatotoxicity (p = 0.03), but there is no significant association between any of the studied polymorphisms and mucositis or other side effects, such as nausea, emesis, diarrhea, neutropenia, skin rash and infections. In addition, when genotype TT of rs1131596 and genotype AA of rs56292801 are both present in a patient then there is a higher risk of developing severe hepatotoxicity (p = 0.0104).

Methotrexate (MTX), a structurally related substance to folic acid, is an important chemotherapeutic agent used for decades in the treatment of pediatric acute lymphoblastic leukemia (ALL) and other types of cancer as non Hodgkin lymphomas and osteosarcomas. Despite the successful outcomes observed, the primary drawback is the variability in the pharmacokinetics and pharmacodynamics between patients. The main adverse events related to its use are mainly nephrotoxicity, mucositis and myelosuppression especially when used in high doses. The potential adverse reactions and toxicities associated with MTX are a cause for concern and may lead to dose reduction or treatment interruption. Genetic variants in MTX transport genes have been linked to toxicity. Pharmacogenetic studies conducted in the past focused on single nucleotide polymorphisms (SNPs) in the coding and 5′-regulatory regions of genes. Recent studies have demonstrated a significant role of miRNAs in the transport and metabolism of drugs, and in the regulation of target genes. The last few years, the number of annotated miRNAs is continually rising, as well as the studies of miRNA polymorphisms and MTX toxicity. Therefore, the objective of the present study is to investigate the role of miRNA variants related to MTX adverse effects.