CYP2C19 Loss-of-function Alleles Research Articles

Leflunomide for Inflammatory Arthritis in End-Stage Renal Disease on Peritoneal Dialysis: A Pharmacokinetic and Pharmacogenetic Study

To study the pharmacokinetics and pharmacogenetics of leflunomide and document its efficacy and safety in the treatment of inflammatory arthritis in a patient with end-stage renal disease (ESRD) who was on peritoneal dialysis. Therapy for a 78-year-old man with ESRD who required peritoneal dialysis was started with leflunomide 10 mg/day for psoriatic arthritis. The dosage was increased to 20 mg/day after 3 months. Monitoring was continued until the patient's unexpected death from myocardial infarction at 8 months. Total and unbound teriflunomide (the active metabolite of leflunomide) concentrations were measured by liquid-chromatography-tandem mass spectrometry. Genotyping for CYP2C19 and ABCG2 polymorphisms, both known to influence teriflunomide pharmacokinetics, was also performed. Total concentrations of teriflunomide varied between 5.2 and 23.2 mg/L, while unbound concentrations varied between 0.0306 and 0.1468 mg/L. The unbound fraction varied between 0.367% and 0.71%. Teriflunomide was found in the dialysate at a concentration of 0.0981 mg/L. A single CYP2C19 loss of function allele was present, as was wild-type ABCG2. Leflunomide appeared to be therapeutically effective, as evidenced by a reduction in daily prednisolone dosage from 20 mg to 6mg; the Disease Activity Score in 28 joints (DAS28) was 5.46 at enrollment and 4.03 after 7 months. Health Assessment Questionnaire-Disability Index improved from 0.5 to 0.125 at 7 months. Numerous significant adverse events that were considered unrelated to leflunomide occurred. Dose adjustment for leflunomide does not appear to be required in the context of ESRD requiring peritoneal dialysis. We present novel evidence that a small amount of teriflunomide is removed by peritoneal dialysis. This case suggests that leflunomide is safe to use as therapy for inflammatory arthritis despite the presence of ESRD requiring peritoneal dialysis.

Interaction analysis between genetic polymorphisms and pharmacodynamic effect in patients treated with adjunctive cilostazol to dual antiplatelet therapy: results of the ACCEL‐TRIPLE (Accelerated Platelet Inhibition by Triple Antiplatelet Therapy According to Gene Polymorphism) study

Compared with standard dual antiplatelet therapy, adjunctive cilostazol to dual antiplatelet therapy ('triple antiplatelet therapy') has a potential to reduce ischemic event occurrence after percutaneous coronary intervention. The pharmacokinetic and pharmacodynamic effects of clopidogrel have been significantly influenced by the enzyme activity of the ABCB1 C3435T and the CYP2C19 system. • For the pharmacokinetics of cilostazol, genetic polymorphisms of the CYP3A5 and CYP2C19 have been associated with the substantial interindividual variability in healthy volunteers. Loss-of-function polymorphism of the CYP2C19 gene, but not the ABCB1 C3435T and CYP3A5*3 genes, affects the antiplatelet effect of triple antiplatelet therapy. Most of extensive and intermediate East Asian metabolizers (0 or 1 CYP2C19 loss-of-function allele) show adequate platelet inhibition when treated with triple antiplatelet therapy after percutaneous coronary intervention. However, carriage of 2 CYP2C19 loss-of-function alleles is still associated with the risk of high platelet reactivity (defined by by 5 µM ADP-induced maximal platelet aggregation >46%), which clinical impact needs to be validated in future clinical trials. AIMS Although adjunctive cilostazol to dual antiplatelet therapy can reduce the risks of clinical events after percutaneous coronary intervention (PCI), whether genetic polymorphism can influence the pharmacodynamics of this regimen has not been evaluated. One hundred and twenty-seven patients treated with PCI and taking triple antiplatelet therapy (≥1 month) were enrolled. Platelet reactivity was assessed by conventional aggregometry and the VerifyNow P2Y12 assay. High on-treatment platelet reactivity (HPR) was defined as 5 µm ADP-induced maximal platelet reactivity (Agg(max) ) >46%. CYP3A5*3, CYP2C19*2/*3 and ABCB1 3435C > T were genotyped. CYP3A5*3 and ABCB1 3435C > T variants did not affect the antiplatelet effect of triple antiplatelet therapy. For non-carriers, one and two carriers of the CYP2C19 loss-of-function (LOF) allele, Agg(max) consecutively increased after the addition of 5 µm[mean (95% confidence intervals): 24.6% (20.8 to 28.5%) vs. 28.7% (25.4 to 32.0%) vs. 32.3% (25.8 to 38.7%), P = 0.062, respectively] and 20 µm ADP [34.2% (29.3 to 39.0%) vs. 41.7% (37.8 to 45.6%) vs. 44.9% (37.9 to 51.9%), P = 0.007, respectively]. Likewise, late platelet reactivity and P2Y12 reaction units proportionally changed according to the number of CYP2C19 LOF alleles. HPRs were observed in 9.2% of subjects: 6.3%, 7.4% and 20.0% with 0, 1 and 2 carriers of CYP2C19 LOF allele(s) (P = 0.099). In multivariate analysis, carriage of two CYP2C19 LOF alleles was a significant predictor for the prevalence of HPR (odds ratio 5.78, 95% CI 1.21, 27.78, P = 0.028). Among PCI-treated patients, the effect of triple antiplatelet therapy is influenced by the CYP2C19 LOF allele. Its clinical benefit needs to be validated according to the CYP2C19 metabolic phenotype in future clinical trials. [Adjunctive Cilostazol Versus High Maintenance dose ClopidogrEL in Acute Myocardial Infarction Patients According to CYP2C19 Polymorphism (ACCEL-AMI-2C19), NCT00915733 and Adjunctive Cilostazol Versus High Maintenance-dose Clopidogrel According to Cytochrome 2C19 Polymorphism (ACCEL-2C19), NCT01012193].

Association of CYP2C19 Genotype With Periprocedural Myocardial Infarction After Uneventful Stent Implantation in Chinese Patients Receiving Clopidogrel Pretreatment

High platelet reactivity (HPR) after clopidogrel treatment is linked to an increased risk of periprocedural myocardial infarction (PMI). The occurrence of PMI that could be associated with CYP2C19 genotype status was our hypothesis. A total of 233 patients with non-ST elevation acute coronary syndromes (NSTACS) undergoing uneventful elective percutaneous coronary intervention were included. Platelet reactivity was assessed by thrombelastograph at 24 h after 300 mg clopidogrel loading. HPR was defined as ≥70% adenosine diphosphate-induced platelet aggregation. The CYP2C19*2 and *3 loss-of-function (LOF) alleles were determined using DNA microarray method. Patients with PMI had significantly higher on-clopidogrel platelet reactivity compared to those without PMI (60.0±24.4% vs. 43.0±24.0%, P<0.001). HPR was more frequently observed in patients with PMI and was the strongest risk factor of PMI in multivariate analysis (OR(adj)=4.348, 95% CI: 1.846-10.241, P=0.001). Furthermore, the incidence of HPR was significantly associated with the carriage of 2 CYP2C19 LOF alleles. Compared with non-carriers, patients carrying 2 CYP2C19 LOF alleles had a 3.000-fold increased risk (95% CI: 1.071-8.400, P=0.037) for PMI in multivariate analysis. However, inclusion of HPR as a covariate in the regression model changed the significant relationship between the carriage of 2 CYP2C19 LOF alleles and PMI. Among Chinese patients with NSTACS, carriers with 2 CYP2C19 LOF alleles are more prone to HPR, which is associated with an increased risk for PMI.

Impact of CYP2C19 variant genotypes on clinical efficacy of antiplatelet treatment with clopidogrel: systematic review and meta-analysis

Objective To evaluate the accumulated information from genetic association studies investigating the impact of variants of the cytochrome P450 (CYP) 2C19 genotype on the clinical efficacy of clopidogrel.Design Systematic review...

Cilostazol attenuates on-treatment platelet reactivity in patients with CYP2C19 loss of function alleles receiving dual antiplatelet therapy: a genetic substudy of the CILON-T randomised controlled trial

ObjectiveTo evaluate whether the addition of cilostazol to dual antiplatelet therapy (DAT, aspirin plus clopidogrel) can attenuate clopidogrel on-treatment platelet reactivity (OPR) in patients with the CYP2C19 loss-of-function (LOF) allele.MethodsIn...

Pilot Study of the Antiplatelet Effect of Increased Clopidogrel Maintenance Dosing and Its Relationship to CYP2C19 Genotype in Patients With High On-Treatment Reactivity

The objective of this study was to evaluate the antiplatelet effect of clopidogrel 150 mg/day in patients with high on-treatment reactivity (OTR) and to further assess this effect according to CYP2C19 genotype. High OTR is associated with ischemic events in clopidogrel-treated patients after percutaneous coronary intervention. Alternative dosing regimens might enhance platelet inhibition. Patients with high OTR receiving a standard clopidogrel regimen were identified with the VerifyNow P2Y12 assay and administered clopidogrel 150 mg daily for 7 days, after which OTR was reassessed. Comprehensive CYP2C19 genotyping was performed with the BeadXpress platform (Illumina, San Diego, California) for the *2, *3, *4, *5, *6, *7, *8, and *17 variants. A total of 41 subjects were enrolled, 20 of whom were carriers of a CYP2C19 loss-of-function (LoF) allele. High-dose clopidogrel significantly reduced OTR from 285 ± 47 P2Y(12) reaction units (PRU) to 220 ± 91 PRU (p < 0.001). There were no significant differences in antiplatelet effect according to CYP2C19 status, although the reduction in reactivity was minimal in the small number of patients homozygous for LoF alleles (n = 3, 28 ± 31 PRU, p = NS). Increasing body mass index was independently and negatively associated with the reduction in OTR (p = 0.009). In patients with high OTR, clopidogrel 150 mg/day results in a significant reduction in platelet reactivity. Carriage of an LoF CYP2C19 polymorphism does not seem to have a major influence on dose effect. The observed lack of effect in patients with 2 copies of a CYP2C19 LoF allele must be confirmed by larger studies.

Genotyping, Clopidogrel Metabolism, and the Search for the Therapeutic Window of Thienopyridines

It is somewhat remarkable to note that not until recently, nearly 12 years and tens of millions of treated patients after its initial approval, has the metabolism of clopidogrel, an inactive prodrug, begun to be more fully understood. Although this lack of knowledge may not be unique among common cardiovascular drugs, there are 4 characteristics of clopidogrel therapy that make this gap in understanding disconcerting: The potential for life-threatening complications (bleeding or thrombosis) at both ends of its therapeutic spectrum; the fact that 1 dose is supposed to fit all; the lack of a measureable, proven end point (such as blood pressure for antihypertensive drugs) that allows for titration to a target response; and the nearly mandatory need by many patients for clopidogrel, with no acceptable alternative until recently. Article see p 512 Historically, understanding the metabolism of a drug has been critical in identifying those patients most likely to benefit from and, more important, potentially be harmed by that drug. This is especially true for drugs with relatively narrow therapeutic windows, such as phenytoin, warfarin, and others. Although it seems safe to assume, on the basis of our extensive clinical experience, that the therapeutic window of clopidogrel is unlikely to be narrow, this certainly does not represent the depth of knowledge we would hope for after so much clinical experience and research. What we do know is that P2Y12 inhibition with thienopyridines is beneficial in preventing arterial thrombotic events, presumably requiring the achievement of some minimal level of receptor inhibition that may or may not vary on the basis of the patient and clinical scenario. We also know that it is associated with a significant increase in serious bleeding events, with higher levels of inhibition associated with greater bleeding. In the present and future practice environment, with a growing …