Farmacogenética do CYP2C19 em pacientes usuários do clopidogrel: estudo piloto

Abstract

After Percutaneous Coronary Intervention (PCI), patients should make daily use of antiplatelet agents, such as clopidogrel. Clopidogrel is a prodrug that requires hepatic activation by the enzyme Cytochrome P450 (CYP) 2C19. Changes in the CYP2C19 gene can compromise clopidogrel activation, resulting in treatment failure or adverse effects. The general objective of this pilot study was to verify the feasibility of implementing pharmacogenetics tests of the CYP2C19 gene in patients using clopidogrel. And the specific ones were: to implement bench work protocols for the first time at the Human Genetics Laboratory (LGH) of the Federal University of Triângulo Mineiro (UFTM), to genotype the star alleles of pharmacogenetic importance of the CYP2C19 gene; and to verify whether there is a relationship between the genotyping results and the aggregometry results. To achieve these objectives, the research project was submitted to and approved by the Ethics Committee for Research with Human Beings of UFTM, under number 6.233.152. Post-PCI patients were invited to participate in the study at the cardiology service of the Hospital de Clínicas of the Federal University of Triângulo Mineiro (HC-UFTM). During patient recruitment, the Informed Consent Form was obtained and biological samples (up to 6.0 mL of blood) were collected in a tube with Ethylenediamine Tetraacetic Acid and another with citrate. Laboratory assays (extraction, purification and quantification of genomic DNA; genotyping of Single Nucleotide Variants of the CYP2C19 gene; and aggregometry) were performed at the LGH of UFTM. The data were reported descriptively, expressed in graphs and tables. The standardization of patient recruitment protocols was carried out following the parameters recommended by Collegiate Board Resolution No. 466/2012, and the standardization of bench experiments was carried out in order to comply with biosafety standards and good laboratory practices. A total of 146 patients were genotyped, and of these, 51 were also submitted to the aggregometry test. The most prevalent genotype was *1/*1 (46.6%) (normal metabolizer), followed by *1/*17 (24.7%) (rapid metabolizer) and *1/*2 (intermediate metabolizer). No individuals were found with *3 and no individuals with the *2/*2 genotype (slow metabolizer) were found. The allelic frequency of rs4244285 (*2) was 0.12; and of rs12248560 (*17) was 0.19. The highest frequency (n=26 patients) of aggregometry was observed in values between 104 and 208 PRU, followed by 10 patients who presented PRU values between 52 and 104. Of the total analyzed, 14 (25.5%) patients were considered resistant (PRU > 208) and 37 (74.5%) were nonresistant (PRU < 208). Most of the genotypes evaluated have PRU values < 208, with the exception of genotype *1/*17. It is concluded that it is possible to perform a pharmacogenetic study to investigate polymorphisms in the gene CYP2C19 of pharmacogenetic interest in patients using clopidogrel at HC-UFTM, without having any work of the same type previously performed. It is expected that the study will continue and that the number of patients will increase to increase the pharmacogenetic evidence on the gene CYP2C19 in clopidogrel users in the Brazilian population.