Candidate gene and pathway analyses identifying genetic variations associated with prasugrel pharmacokinetics and pharmacodynamics

Prasugrel Intermediate Metabolite Modulates Platelet Inhibition by Negatively Interfering With an Active Metabolite: An Ex Vivo, In Vitro, and In Silico Study

BACKGROUND

Prasugrel is converted into prasugrel active metabolite (PAM; R-138727) through the cytochrome P450-mediated conversion of an intermediate metabolite (PIM; R-95913). It is unknown whether PIM exerts any biological function. The FABOLUS-FASTER trial (Facilitation Through Aggrastat or Cangrelor Bolus and Infusion Over Prasugrel: A Multicenter Randomized Open-Label Trial in Patients With ST-Elevation Myocardial Infarction Referred for Primary Percutaneous Intervention) showed that chewed prasugrel does not improve bioactivity, in spite of accelerated PAM kinetics.

METHODS

PIM and PAM pharmacokinetics were assessed by mass spectrometry in blood samples collected from ST-segment-elevation myocardial infarction patients randomized to chewed (n=17) or integral (n=15) 60 mg prasugrel. The ex vivo and in vitro effects of PAM and PIM were assessed on ADP-induced platelet activation. The binding sites of PIM and PAM were investigated by molecular dynamics simulation.

RESULTS

Chewed prasugrel was associated with higher PIM levels compared with integral prasugrel: PIM median area under the curve (25-75 p): 73 (41.5-92.0) versus 33 (0.0-50.0) ng·h/mL (P<0.05). PIM plasma concentrations negatively correlated with inhibition of ADP-induced platelet aggregation, which strongly correlated to the PAM/PIM ratio (ρ=0.782; P<0.001; n=30) than PAM, suggesting an antagonistic role of PIM on PAM-induced P2Y12 inhibition. Subsequent in vitro tests confirmed the dose-dependent, reversible antagonistic effect of PIM on PAM inhibition of aggregation (maximum effect, -49.5% [95% CI, -54.4% to -44.6%]; P<0.001), confirmed by P-selectin expression and vasodilator-stimulated phosphoprotein phosphorylation as readouts at the signaling level. At molecular dynamics simulations of the drug-receptor systems, PIM accommodates through noncovalent reversible binding in the same PAM-binding site, distinct from that of 2-methylthio-adenosine-5'-diphosphate.

CONCLUSIONS

PIM negatively interferes with PAM, thereby reducing its inhibitory activity, likely competing at the P2Y12 receptor-binding site.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02978040. URL: https://www.clinicaltrialsregister.eu; Unique identifier: EudraCT 2017-001065-24.

CYP2C19 Genetic Testing for Oral P2Y12 Inhibitor Therapy: A Scientific Statement From the American Heart Association

There is significant variability in the efficacy and safety of oral P2Y12 inhibitors, which are used to prevent ischemic outcomes in common diseases such as coronary and peripheral arterial disease and stroke. Clopidogrel, a prodrug, is the most used oral P2Y12 inhibitor and is activated primarily after being metabolized by a highly polymorphic hepatic cytochrome CYP2C219 enzyme. Loss-of-function genetic variants in CYP2C219 are common, can result in decreased active metabolite levels and increased on-treatment platelet aggregation, and are associated with increased ischemic events on clopidogrel therapy. Such patients can be identified by CYP2C19 genetic testing and can be treated with alternative therapy. Conversely, universal use of potent oral P2Y12 inhibitors such as ticagrelor or prasugrel, which are not dependent on CYP2C19 for activation, has been recommended but can result in increased bleeding. Recent clinical trials and meta-analyses have demonstrated that a precision medicine approach in which loss-of-function carriers are prescribed ticagrelor or prasugrel and noncarriers are prescribed clopidogrel results in reducing ischemic events without increasing bleeding risk. The evidence to date supports CYP2C19 genetic testing before oral P2Y12 inhibitors are prescribed in patients with acute coronary syndromes or percutaneous coronary intervention. Clinical implementation of such genetic testing will depend on among multiple factors: rapid availability of results or adoption of the concept of performing preemptive genetic testing, provision of easy-to-understand results with therapeutic recommendations, and seamless integration in the electronic health record.

Pharmacogenetic considerations in therapy with novel antiplatelet and anticoagulant agents

Antiplatelets and anticoagulants are extensively used in cardiovascular medicine for the prevention and treatment of thrombosis in the venous and arterial circulations. Wide inter-individual variability has been observed in response to antiplatelets and anticoagulants, which triggered researchers to investigate the genetic basis of this variability. Data from extensive pharmacogenetic studies pointed to strong evidence of association between polymorphisms in candidate genes and the pharmacokinetics and pharmacodynamic action and clinical response of the antiplatelets clopidogrel and the anticoagulant warfarin. In this review, we conducted an extensive search on Medline for the time period of 2009-2023. We also searched the PharmGKB website for levels of evidence of variant-drug combinations and for drug labels and clinical guidelines. We focus on the pharmacogenetics of novel antiplatelets and anticoagulants while excluding acetylsalicylic acid, warfarin and heparins, and discuss the current knowledge with emphasis on the level of evidence.

Cardiovascular Pharmacogenomics: An Update on Clinical Studies of Antithrombotic Drugs in Brazilian Patients

Anticoagulant and antiplatelet drugs effectively prevent thrombotic events in patients with cardiovascular diseases, ischemic stroke, peripheral vascular diseases, and other thromboembolic diseases. However, genetic and non-genetic factors affect the response to antithrombotic therapy and can increase the risk of adverse events. This narrative review discusses pharmacogenomic studies on antithrombotic drugs commonly prescribed in Brazil. Multiple Brazilian studies assessed the impact of pharmacokinetic (PK) and pharmacodynamic (PD) gene variants on warfarin response. The reduced function alleles CYP2C9*2 and CYP2C9*3, and VKORC1 rs9923231 (c.-1639G>A) are associated with increased sensitivity to warfarin and a low dose requirement to prevent bleeding episodes, whereas CYP4F2 rs2108622 (p.Val433Met) carriers have higher dose requirements (warfarin resistance). These deleterious variants and non-genetic factors (age, gender, body weight, co-administered drugs, food interactions, and others) account for up to 63% of the warfarin dose variability. Few pharmacogenomics studies have explored antiplatelet drugs in Brazilian cohorts, finding associations between CYP2C19*2, PON1 rs662 and ABCC3 rs757421 genotypes and platelet responsiveness or clopidogrel PK in subjects with coronary artery disease (CAD) or acute coronary syndrome (ACS), whereas ITGB3 contributes to aspirin PK but not platelet responsiveness in diabetic patients. Brazilian guidelines on anticoagulants and antiplatelets recommend the use of a platelet aggregation test or genotyping only in selected cases of ACS subjects without ST-segment elevation taking clopidogrel, and also suggest CYP2C9 and VKORC1 genotyping before starting warfarin therapy to assess the risk of bleeding episodes or warfarin resistance.

Glucocorticoid Receptor Polymorphisms in Children Undergoing Congenital Heart Surgery with Cardiopulmonary Bypass

We conducted a candidate gene association study to test the hypothesis that different gene polymorphisms will be associated with corticosteroid responsiveness and study outcomes among children undergoing congenital heart surgery. This is a prospective observational cohort study at a large, tertiary pediatric cardiac center on children undergoing corrective or palliative congenital heart surgery. A total of 83 children were enrolled. DNA was isolated for three polymorphisms of interest namely N363 (rs56149945) and 9β (rs6198) associated with increased sensitivity to corticosteroids and Bcl I (rs41423247) associated with decreased sensitivity to corticosteroids. Duration of inotropic use, low cardiac output scores (LCOS), and vasoactive inotrope scores were examined in relation to these three polymorphisms. Using Kaplan-Meier analysis, heterozygous individuals showed longer transcriptional intermediary factor (TIF) compared with wild type for N363 polymorphism ( p  = 0.05). In multivariable Cox regression, heterozygous alleles for 9β polymorphism showed significantly shorter TIF compared with wild type (hazard ratio = 2.04 [1.08-3.87], p  = 0.03). The relationship between lower LCOS scores and alleles groups was significant for 9β heterozygous polymorphism only (1.5 [1-2.2], p  = 0.01) in comparison to wild type and homozygous. The presence of heterozygote alleles for the increased corticosteroid sensitivity is associated with longer TIF compared with wild type. Conversely, the presence of heterozygous alleles for the decreased sensitivity to corticosteroids is associated with shorter TIF compared with wild type.