Analytical validation of GMEX rapid point-of-care CYP2C19 genotyping system for the CHANCE-2 trial

Accuracy and technical characteristics of CYP2C19 point of care tests: a systematic review

Aim: To assess the accuracy and technical characteristics of CYP2C19 point of care tests (POCTs).Patients & methods: Systematic review of primary studies, in any population or setting, that evaluated POCTs for detecting CYP2C19 loss of function (LOF) alleles.Results: Eleven studies provided accuracy data (eight Spartan; one Genomadix Cube; one GMEX; one Genedrive). The POCTs had very high sensitivity and specificity for the alleles they tested for. Twenty-two studies reported technical characteristics: POCTs were easy to operate and provided results quickly. Limited data were reported for test failure rate and cost.Conclusion: CYP2C19 POCTs may be a useful alternative to laboratory-based testing to guide antiplatelet therapy. Further data are required on accuracy (GMEX; Genedrive), test failure and cost (all POCT).

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.

LDL-C Levels and Bleeding Risk in Patients Taking DAPT After Minor Ischemic Stroke or TIA

Importance

Evidence on the bleeding risk associated with low-density lipoprotein cholesterol (LDL-C) levels in patients receiving dual antiplatelet therapy (DAPT) remains sparse.

Objective

To investigate the association of LDL-C levels with bleeding risk in patients with minor ischemic stroke (MIS) or high-risk transient ischemic attack (HRTIA) receiving DAPT.

Design, Setting, and Participants

This cohort study was an analysis of pooled data from 2 randomized, double-blind, placebo-controlled clinical trials in China of patients with MIS or HRTIA who were receiving DAPT: the CHANCE (Clopidogrel in High-Risk Patients With Acute Nondisabling Cerebrovascular Events) trial enrolled patients at 114 sites from October 2009 to July 2012, and the CHANCE-2 enrolled patients at 202 centers from September 2019 to March 2021. Both sets of patients were followed up for 90 days. Data analysis was performed from August 2022 to May 2023.

Exposures

Baseline LDL-C levels and receipt of ticagrelor-aspirin and clopidogrel-aspirin DAPT.

Main Outcomes and Measures

The primary outcome was any bleeding, and the secondary outcome was severe or moderate bleeding within 3 months after randomization. The association of LDL-C levels and all outcomes was assessed by using the Cox proportional hazard model. Hazard ratios (HRs) with 95% CIs were calculated on univariable (unadjusted) Cox regression models. Adjusted HRs (aHRs) and their 95% CIs were calculated on multivariable Cox regression models.

Results

In total, 8996 patients with acute MIS or HRTIA who were receiving DAPT were included in the 2 trials, of whom 1066 without serum specimens and 490 patients with missing baseline LDL-C value were excluded. Finally, 7440 patients with DAPT (4486 in the clopidogrel-aspirin group and 2954 in the ticagrelor-aspirin group) were included in this study. The median (IQR) age was 64.32 (56.56-71.30) years, and 2479 patients (33.32%) were women. A total of 270 (3.63%) bleeding events were reported at 3 months, and LDL-C less than 70 mg/dL was associated with an increased risk of both any bleeding (aHR, 1.48; 95% CI, 1.03-2.12), and severe or moderate bleeding (aHR, 2.78; 95% CI, 1.18-6.53). The risk of any bleeding was increased at lower LDL-C levels in the ticagrelor-aspirin group (aHR, 1.71; 95% CI, 1.08-2.72). However, an increased risk of any bleeding was not observed in the clopidogrel-aspirin group (aHR, 1.30; 95% CI, 0.73-2.30). There was no significant association between LDL-C levels and the risk of severe or moderate bleeding in either the ticagrelor-aspirin or clopidogrel-aspirin group.

Conclusions and Relevance

These findings suggest that low LDL-C levels are associated with an increased bleeding risk within 3 months among patients with MIS or HRTIA receiving DAPT, especially those taking ticagrelor-aspirin. Weighing the risks and benefits is crucial when simultaneously considering the selection of LDL-C target strategies and DAPT regimens among these patients.

Feasibility of Community Pharmacist-Initiated and Point-of-Care CYP2C19 Genotype-Guided De-Escalation of Oral P2Y12 Inhibitors

Tailoring antiplatelet therapy based on CYP2C19 pharmacogenetic (PGx) testing can improve cardiovascular outcomes and potentially reduce healthcare costs in patients on a P2Y12-inhibitor regime with prasugrel or ticagrelor. However, ubiquitous adoption—particularly in an outpatient setting—remains limited. We conducted a proof-of-concept study to evaluate the feasibility of CYP2C19-guided de-escalation of prasugrel/ticagrelor to clopidogrel through point-of-care (POC) PGx testing in the community pharmacy. Multiple feasibility outcomes were assessed. Overall, 144 patients underwent CYP2C19 PGx testing in 27 community pharmacies. Successful test results were obtained in 142 patients (98.6%). De-escalation to clopidogrel occurred in 19 patients (20%) out of 95 (67%) eligible for therapy de-escalation, which was mainly due to PGx testing not being included in cardiology guidelines. Out of the 119 patients (84%) and 14 pharmacists (100%) surveyed, 109 patients (92%) found the community pharmacy a suitable location for PGx testing, and the majority of pharmacists (86%) thought it has added value. Net costs due to PGx testing were estimated at €43 per patient, which could be reduced by earlier testing and could turn into savings if de-escalation would double to 40%. Although the observed de-escalation rate was low, POC CYP2C19-guided de-escalation to clopidogrel appears feasible in a community pharmacy setting.

Time Course for Benefit and Risk With Ticagrelor and Aspirin in Individuals With Acute Ischemic Stroke or Transient Ischemic Attack Who Carry CYP2C19 Loss-of-Function Alleles: A Secondary Analysis of the CHANCE-2 Randomized Clinical Trial

Importance

Dual antiplatelet therapy (DAPT) with ticagrelor and aspirin has been found to be effective for secondary prevention after minor ischemic stroke or transient ischemic attack (TIA) in individuals who carry CYP2C19 loss-of-function (LOF) alleles; however, uncertainties remain about the time course of benefit and risk with ticagrelor and aspirin in these patients.

Objective

To obtain time-course estimates of efficacy and risk with ticagrelor and aspirin after minor stroke or TIA in individuals with CYP2C19 LOF alleles.

Design, Setting, and Participants

The Ticagrelor or Clopidogrel With Aspirin in High-risk Patients With Acute Nondisabling Cerebrovascular Events II (CHANCE-2) randomized clinical trial enrolled patients 40 years and older from 202 hospitals in China with acute minor stroke or TIA who carried CYP2C19 LOF alleles between September 23, 2019, and March 22, 2021, and were followed up for 90 days. All 6412 patients enrolled in the CHANCE-2 trial were included in this secondary analysis. Data were analyzed in October 2021.

Interventions

Ticagrelor (180 mg on day 1 followed by 90 mg twice daily on days 2-90) or clopidogrel (300 mg on day 1 followed by 75 mg daily on days 2-90). All patients received aspirin (75-300 mg on day 1 followed by 75 mg daily for 21 days).

Main Outcomes and Measures

The efficacy outcome was major ischemic event, defined as the composite of ischemic stroke or nonhemorrhagic death. Safety outcomes included moderate to severe bleeding and any bleeding.

Results

A total of 6412 patients were included (3205 in the ticagrelor and aspirin group and 3207 in the clopidogrel and aspirin group). The median (IQR) age was 65 (57-71) years, and 4242 patients (66%) were men. The reduction of major ischemic events with ticagrelor and aspirin predominately occurred in the first week (absolute risk reduction, 1.34%; 95% CI, 0.29 to 2.39) and attenuated but remained in the next 3 weeks (absolute risk reduction in the second week, 0.11%; 95% CI, -0.24 to 0.45; absolute risk reduction in the third week, 0.14%; 95% CI, -0.11 to 0.38; absolute risk reduction in the fourth week, 0.04%; 95% CI, -0.18 to 0.25). The risk of moderate to severe bleeding was consistently low in the ticagrelor and aspirin group. The absolute increase in any bleeding seen in the first week (0.87%; 95% CI, 0.25 to 1.50) remained in the next 3 weeks (absolute increase in the second week, 1.21%; 95% CI, 0.75 to 1.68; absolute increase in the third week, 0.33%; 95% CI, -0.05 to 0.72; absolute increase in the fourth week, 0.23%; 95% CI, -0.03 to 0.49).

Conclusion and Relevance

Among patients with minor stroke or TIA who carried CYP2C19 LOF alleles, benefit with ticagrelor and aspirin was present predominately in the first week, with additional small benefit accruing in the next 2 weeks.

Ticagrelor versus Clopidogrel in CYP2C19 Loss-of-Function Carriers with Stroke or TIA

BACKGROUND

Comparisons between ticagrelor and clopidogrel for the secondary prevention of stroke in CYP2C19 loss-of-function carriers have not been extensively performed.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial at 202 centers in China involving patients with a minor ischemic stroke or transient ischemic attack (TIA) who carried CYP2C19 loss-of-function alleles. Patients were assigned within 24 hours after symptom onset, in a 1:1 ratio, to receive ticagrelor (180 mg on day 1 followed by 90 mg twice daily on days 2 through 90) and placebo clopidogrel or to receive clopidogrel (300 mg on day 1 followed by 75 mg once daily on days 2 through 90) and placebo ticagrelor; both groups received aspirin for 21 days. The primary efficacy outcome was new stroke, and the primary safety outcome was severe or moderate bleeding, both within 90 days.

RESULTS

A total of 11,255 patients were screened and 6412 patients were enrolled, with 3205 assigned to the ticagrelor group and 3207 to the clopidogrel group. The median age of the patients was 64.8 years, and 33.8% were women; 98.0% belonged to the Han Chinese ethnic group. Stroke occurred within 90 days in 191 patients (6.0%) in the ticagrelor group and 243 patients (7.6%) in the clopidogrel group (hazard ratio, 0.77; 95% confidence interval, 0.64 to 0.94; P = 0.008). Secondary outcomes were generally in the same direction as the primary outcome. Severe or moderate bleeding occurred in 9 patients (0.3%) in the ticagrelor group and in 11 patients (0.3%) in the clopidogrel group; any bleeding occurred in 170 patients (5.3%) and 80 patients (2.5%), respectively.

CONCLUSIONS

Among Chinese patients with minor ischemic stroke or TIA who were carriers of CYP2C19 loss-of-function alleles, the risk of stroke at 90 days was modestly lower with ticagrelor than with clopidogrel. The risk of severe or moderate bleeding did not differ between the two treatment groups, but ticagrelor was associated with more total bleeding events than clopidogrel. (Funded by the Ministry of Science and Technology of the People's Republic of China and others; CHANCE-2 ClinicalTrials.gov number, NCT04078737.).

Clopidogrel with aspirin in High-risk patients with Acute Non-disabling Cerebrovascular Events II (CHANCE-2): rationale and design of a multicentre randomised trial

Background

In patients with a minor ischaemic stroke or transient ischaemic attack (TIA), separate trials have shown that dual antiplatelet therapy with clopidogrel plus aspirin (clopidogrel–aspirin) or ticagrelor plus aspirin (ticagrelor–aspirin) are more effective than aspirin alone in stroke secondary prevention. However, these two sets of combination have not been directly compared. Since clopidogrel was less effective in stroke patients who were CYP2C19 loss-of-function (LOF) allele carriers, whether ticagrelor–aspirin is clinically superior to clopidogrel–aspirin in this subgroup of patients with stroke is unclear.

Aim

To describe the rationale and design considerations of the Clopidogrel in High-risk patients with Acute Non-disabling Cerebrovascular Events (CHANCE-2) trial.

Design

CHANCE-2 is a randomised, double-blind, double-dummy, placebo-controlled, multicentre trial that compares two dual antiplatelet strategies for minor stroke or TIA patients who are CYP2C19 LOF allele carriers: ticagrelor (180 mg loading dose on day 1 followed by 90 mg twice daily on days 2–90) or clopidogrel (300 mg loading dose on day 1 followed by 75 mg daily on days 2–90), plus open-label aspirin with a dose of 75–300 mg on day 1 followed by 75 mg daily on day 2–21. All will be followed for 1 year.

Study outcomes

The primary efficacy outcome is any stroke (ischaemic or haemorrhagic) within 3 months and the primary safety outcome is any severe or moderate bleeding event within 3 months.

Discussion

The CHANCE-2 trial will evaluate whether ticagrelor–aspirin is superior to clopidogrel–aspirin for minor stroke or TIA patients who are CYP2C19 LOF allele carriers.

Trial registration number

NCT04078737.