Pharmacogenetics of Warfarin in Puerto Ricans.
Warfarin (Coumadin) is a prescribed "blood thinner" medication used to make the blood less thick in people with high risk of forming blood clots. Despite the various methods to monitor this drug, life-threatening bleeding is a common undesired effect and might result in patient death. Patients starting warfarin therapy may require several weeks or even months to reach the appropriate blood level of warfarin. This blind practice could place the patient at high risk. There are several demographic and clinical factors that significantly influence how much warfarin the patient needs to attain the desired response. Genes, which control hereditary traits, are also important. Now, the investigators know that by using the information encoded in patient's genes the investigators are able to individualize the therapy. Two genes are considered to be involved in warfarin response (CYP2C9 and VKORC1). This study proposes to ascertain what CYP2C9 and VKORC1 variants are present in warfarin-treated Puerto Rican patients. To this purpose, a novel physiogenomic array comprising 384 variants in 222 genes of cardio-metabolic relevance will be used so the investigators are able to determine the structure of the Puerto Rican population in terms of ancestral contributions and how the admixture may impact the prevalence of CYP2C9 and VKORC1 variants. Secondly, the investigators will assess the association of these variants to clinical responses in order to develop a better method of dose estimation. The expected result is the improvement of warfarin therapy in Puerto Ricans. The proposed study will fill a gap in the knowledge of warfarin pharmacogenetics, providing new information on the prevalence of CYP2C9 (metabolism) and VKORC1 (sensitivity) polymorphisms in Puerto Ricans as well as their role in the warfarin response variability observed in this admixed population.
Deep Vein Thrombosis
Cardiac Valvular Insufficiency
|Study Design:||Observational Model: Cohort
Time Perspective: Retrospective
|Official Title:||Pharmacogenetics of Warfarin in Puerto Rican Patients Using a Physiogenomics Approach.|
- time to achieve stable warfarin dose [ Time Frame: 6 months ] [ Designated as safety issue: No ]time to get a stable warfarin dose is defined by the time span (days) from the initial dose until achieving three consecutive INR measurements within therapeutic range (2-3 or 2.5-3.5, according to indication.
- time to first bleeding [ Time Frame: 6 months ] [ Designated as safety issue: Yes ]time to first bleeding is defined as the time span (days) from the initiation of therapy until the first report of serious or life-threatening bleeding episode.
- time to first INR>4 [ Time Frame: 6 months ] [ Designated as safety issue: Yes ]time to first INR above 4 is an indicator of overanticoagulation that is defined as the time span (days) from the initiation of therapy until the first measurement of INR above 4.
Biospecimen Retention: Samples With DNA
Whole fresh blood and Genomic DNA samples fom enrolled patients
|Study Start Date:||February 2011|
|Study Completion Date:||July 2014|
|Primary Completion Date:||July 2014 (Final data collection date for primary outcome measure)|
Wild-Type are those individuals who were non-carriers of any functional (loss-of-function)variant in CYP2C9 and/or VKORC1 genes
Those patients who were identified as having any functional CYP2C9 and/or VKORC1 polymorphism
Warfarin is a frequently prescribed drug for both the treatment and prevention of thromboembolic complications. Although many reports have been published over the past years in different populations worldwide, there is a fundamental gap in understanding whether variations in CYP2C9 and VKORC1 genes account for the inter-individual variability in response to warfarin that is observed in Puerto Rican patients. This study is a first step toward the development of DNA-driven personalized guidelines for warfarin dose optimization in Puerto Rican patients with thromboembolic complications. Guided by strong preliminary data, this application will pursuit two specific aims: 1) Develop a physiogenomic (PG)-driven admixture analysis of 350 samples from a population of warfarin-treated Puerto Rican patients using the PG array in order to study the pharmacogenetics of warfarin in Puerto Ricans and 2) Determine whether combinatorial CYP2C9 and VKORC1 genotypes are associated with clinical phenotypes during warfarin therapy in Puerto Rican patients. Under the first aim, 350 DNA specimens from warfarin-treated Puerto Rican patients who consent to participate in this study will be genotyped at large-scale using a novel Illumina-based PG-array of 222 candidate genes from relevant cardio-metabolic and neuro-endocrine pathways in order to examine the population structure of Puerto Ricans and create a reference database of individual admixture, allele frequencies, linkage disequilibrium (LD) and haplotypes for pharmacogenetics studies. Noteworthy, this information remains to be determined in Puerto Ricans. Under the second aim, demographic and clinically relevant non-genetic data will be retrospectively collected from medical records of these patients in order to perform an association analysis between their previously obtained CYP2C9 and VKORC1 genotypes and the corresponding time to achieve stable warfarin dosing following survival analysis techniques and Cox proportional hazards model. Accomplishment of this specific aim will also give the basis for developing a DNA-guided warfarin dosing algorithm in Puerto Rican by using these patients as a learning sample. The long-term goal is to generate valuable information from the genetic background of Puerto Ricans in order to further validate the pharmacogenetic-driven warfarin dosing algorithm for this admixed population. The proposed research is significant because it is expected to advance and expand understanding of how these clinically relevant variants affect the way people from an admixed, under-served population respond to warfarin. This is an important and under-investigated area of pharmacogenetics in minority populations that will have potential applicability to personalize warfarin therapy.
Please refer to this study by its ClinicalTrials.gov identifier: NCT01318057
|Veteran Affair Caribbean Healthcare System|
|San Juan, Puerto Rico, 00921|
|Principal Investigator:||Giselle T Rivera-Miranda, PharmD||VACHS at San Juan|
|Principal Investigator:||Jorge Duconge, PhD||University of Puerto Rico|