The Study of CYP2C19 Genotype-Guided Clopidogrel Treatment Models

The study purposed to learn how clopidogrel-based antiplatelet treatment for preventing adverse cardiovascular events after ePCI works in chronic coronary artery disease when guided by personal genetic characteristics for drug metabolism.

The study aimed to answer two research questions:

* Does CYP2C19 genotype-guided clopidogrel treatment provide better clinical outcomes when compared with conventional treatment selection led without CYP2C19 genotyping?
* Can CYP2C19 genotype-guided antiplatelet treatment be beneficially applied in real-world clinical practice?

After obtaining the informed consent eligible study participants screened by inclusion and exclusion criteria were randomized and allocated into two groups:

* for whom the CYP2C19 genotype-guided clopidogrel treatment has been applied - the experimental group,
* for whom conventional clopidogrel has been applied without CYP2C19 genotyping - the control group.

The experimental group participants underwent CYP2C19 genotyping. Study participants with CYP2C19 normal function alleles (NFA) \*2, \*3 genotypes constituted the separate experimental arm and received clopidogrel-based preventive antiplatelet treatment.

Participants with CYP2C19 \*2 and \*3 loss of function (LoF) alleles were allocated to the separate experimental group and received preventive antiplatelet treatment alternative to clopidogrel.

Study participants who had not undergone CYP2C19 genotyping and received conventional preventive antiplatelet treatment with clopidogrel were assigned as active comparators.

All participants in the experimental and comparator groups underwent standard clinical investigations by current guideline recommendations for:

* the initial assessment,
* follow-up and detection of major adverse cardiovascular events. All patients received the conventional drug treatment by current guideline recommendations for chronic coronary artery disease and comorbid condition management and adverse cardiovascular events prevention.

The main research outcome measures include:

* evaluating clinical outcomes of CYP2C19 genotype-guided antiplatelet treatment application,
* describing models for application of CYP2C19 genotype-guided antiplatelet treatment,
* learning about potential access points to the real practice process pipeline for implementation of genotype-guided medication treatment.

The concept of the study is based on current evidence from multiple genetic and clinical studies. At this stage of development preventive treatment of chronic coronary artery disease after ePCI is challenged by risks related to multi-morbidity, recurrent MACCEs and bleeding. Scientific evidence broadly supports pharmacogenetic approaches for routine use of P2Y12 inhibitors (clopidogrel or alternative). Clopidogrel remains the most commonly used P2Y12 inhibitor in the post-ePCI settings. Along with disease-related and co-morbid factors treatment effects are influenced by the variability of the CYP2C19 genotype in the population, which significantly increases the risk of MACCE in loss of function allele (LoF) carriers even with conventional clopidogrel treatment. To improve treatment, a pharmacogenetic expediency model for drug selection is introduced. CYP2C19 allele genotype-guided clopidogrel or an alternative P2Y12 inhibitor treatment is based on robust evidence.

The study aimed to learn the comparative benefits of CYP2C19 genotype-guided versus conventional clopidogrel treatment selection applied in real clinical practice for preventing adverse cardiovascular events after ePCI in chronic coronary artery disease.

For this purpose, the randomized parallel-group controlled study for CYP2C19 genotype-guided clopidogrel treatment outcomes evaluation for chronic coronary artery disease after the ePCI in real-world practice was conducted.

The study addressed research-specific objectives:

* forming and random allocating of participants into study arms for CYP2C19 allele genotype-guided versus conventional clopidogrel treatment,
* ensuring RT-PCR based assay for CYP2C19 \*2, \*3 LoF alleles detection in randomly selected study participants and forming the experimental study groups,
* characterizing clinical traits of study participants and observing adverse clinical events during the 12-month course of study intervention treatment;
* evaluating the clinical and non-clinical study outcomes. Following the completion of the informed consent, 283 patients eligible for inclusion and exclusion criteria have been enrolled in the study and randomly allocated into two groups.

  83 participants created the control group. They did not undergo CYP2C19 genotyping and received conventional antiplatelet treatment based on clopidogrel.

  200 participants were tested for CYP2C19 \*2, \*3 allele genotype. 157 of those who revealed normal CYP2C19 \*2, \*3 allele genotype received conventional preventive antiplatelet treatment based on clopidogrel and created a separate experimental arm.

  43 participants who revealed CYP2C19 \*2, \*3 LoF allele genotype required preventive antiplatelet treatment alternative to clopidogrel - based on ticagrelor or prasugrel were allocated into another separate experimental arm and withal assigned as the perspective arm for further study.

Before inclusion, informed consent was obtained from all study participants (or their legal representatives).

The randomization and study arm allocation processes were blinded for participants, healthcare teams providing medical care and study outcomes assessors. Nevertheless, after randomization and genetic testing, CYP2C19 allele genotyping results were disclosed to the medical care team and study participants to make ongoing clinical management safe and transparent but remained blinded for study outcomes assessors.

RT-PCR-based laboratory assay for CYP2C19 \*2, \*3 alleles genotyping was carried out only once after randomization for each study participant allocated into the experimental group. Tests were performed in the diagnostic laboratory of Vistamedi Ltd served as the central study laboratory.

The laboratory test report was provided to the authenticated investigator and as well as participant and entered in the study data report form.

Regular healthcare teams conducted clinical management of study participants in a real practice environment including medication treatment under conventional guideline recommendations were detected and initially reported major adverse cardiovascular outcomes, other adverse events, or additional clinical conditions diagnosed or study-related circumstances emerged through the study follow-up period up to the end of the study. Study participants (or their legal representatives) were also allowed to report adverse clinical outcomes, events or emerging circumstances.

For a study participant, the expected end of the study is defined as the end date of the 12-month follow-up from the date of the index ePCI. However, in the case of the clinical endpoint which corresponded to and defined the study outcome measure, the date of such endpoint event was determined as the end of the study, even if earlier than 12 months from the index ePCI.

The study participant could terminate participation by his or her independent decision, from any time of the research and for any reason, which could or could not be established.

Early withdrawal of a participant from the study was considered reasonable if there was repeated non-adherence to the treatment of study interest, rather than sporadic, or when there was preferred to terminate treatment based on the justified best interests of the participant.

Clinical outcomes conventionally defined by the Standardized Data Collection for Cardiovascular Trials Initiative (SCTI), the US Food and Drug Administration (FDA), the Academic Research Consortium for High Bleeding Risk (ARC-HBR) and WHO have been measured by clinical endpoints developed over the course of clinical cases.

Certain elements of the Coronary Revascularization Outcome Questionnaire (CROQ) and Patient-Reported Outcomes Measurement Information System®-Plus-Heart Failure profile were used for measuring of Patient-Reported Outcomes (PROs).

Study results were also analyzed using other non-clinical outcome measures that characterized the effectiveness of СYP2C19 genotype-guided P2Y12 inhibitor treatment utilization in real practice.

Data from each study participant were entered into a CRF, the form of which was the same for all participants and study centers.

Study data are collected, stored, and processed into a custom-designed electronic database. Identifiers, study variables and record data are validated with codes to ensure personal data protection.

Personal data, code keys and definitions, and research data are warehoused in separate databases. Only authenticated researchers have access to them. Research data collection centers do not have an internet connection or any other access to the database files.

Study data processing is only allowed by the study procedures given in the study protocol.

After the data collection, the database containing the personal data of the study participants will be deleted.

The de-identified electronic database will be stored after the end of the study for further research purposes for an indefinite period.

Eligibility Criteria:
Inclusion Criteria:

* Diagnosed with chronic coronary artery disease;
* Undergone elective PCI within the last 12 weeks without procedure-related complications;
* LVEF≥38% after index PCI;
* Completed informed consent form for participation in the study;

Exclusion Criteria:

* Concomitant using of potent CYP3A4 or CYP2C19 inhibitors;
* Morbid obesity, BMI 40 kg/sq.m or more;
* Type 1 diabetes mellitus;
* Poorly controlled type 2 diabetes mellitus, HbA1c - 9% or more;
* Acute Myocardium Infarction;
* Coronary artery bypass grafting performed within the last 12 weeks;
* Valvular heart disease due to dysplasia, connective tissue disorders or inflammatory disorders, or valvular disorders requiring cardiac surgery;
* History of severe hepatic impairment;
* Severe chronic kidney disease;
* Clinically important leucopenia, lymphopenia, thrombocytopenia or thrombocytosis;
* History of hemorrhagic diathesis or coagulopathy;
* An active or an obvious threat of bleeding (including GI bleeding):
* Bleeding within the past 6 months that required hospitalization;
* Blood transfusion during the past 6 months or its refusal;
* History of intracranial hemorrhage;
* Cardiac or non-cardiac degenerative disease, including: cardiomyopathy, restrictive lung disease, or Neurodegenerative diseases;
* Malignant tumor (cancer) that limits life expectancy to less than one year;
* Current chemotherapy or immunosuppressive therapy;
* Ongoing immunosuppression or immunosuppressive conditions;
* Pregnancy or lactation period;
* Any disease/condition control of which is not achieved;
* Personal (patient/physician dependent) or health care system-related circumstances that can restrict or limit any study procedures or operations.