A Genomic Approach to Warfarin Dose Prescription in Admixed Caribbean Hispanics

Overview

Caribbean Hispanics are a population with a disproportionately high prevalence of cardio-metabolic disorders but with a limited expectation of benefits from current pharmacogenetic algorithms derived mainly in subjects of relatively pure ancestry. The investigators focus on warfarin responses to develop urgently-needed DNA-driven prescription guidelines for this population, who have arisen from European, West African and Amerindian genomic origins to produce a highly heterogeneous population. Our project combines admixture analysis and DNA-sequencing with development of more accurate rules for better predictability of warfarin dosing to immediately serve this medically underserved population.

Despite the substantial number of work published over the past years in different populations around the world, a fundamental gap remains in understanding whether and how genomic admixture and polymorphisms in warfarin-related pharmacogenes account for the high inter-individual dose variability observed in Caribbean Hispanic patients. In addition to being a medically underserved population, often marginally represented in clinical studies, Caribbean Hispanics are also a genomically heterogeneous population whose high level of admixture has produced a rich repertoire of combinatorial genotypes (e.g., CYP2C9\*2/\*5 + VKORC1-1639 A/A) that appear to challenge current pharmacogenetic-driven prescribing models. Our project takes a novel approach to definitively assess this admixture component and is also highly practical for its incorporation into a customized pharmacogenetic algorithm that will be implemented in "real-world" clinical settings through a web-based portal. Moreover, the project is also aimed at performing DNA-sequencing to identify those unknown variants on candidate pharmacogenes (i.e., CYP2C9 and VKORC1) that may contribute further to explain dose variability in Caribbean Hispanics. Shaped by strong preliminary data from a SC2 pilot project, the investigators will assess clinical validity and utility of an admixture-adjusted, pharmacogenetic-guided prescribing model for personalized prediction of effective warfarin dosing in Caribbean Hispanics, which also encompasses genetic (common and novel variants) and non-genetic clinical and demographic factors. The study will be conducted over 4 years in 300 patients with thromboembolic disorders receiving warfarin. Four collaborating/recruiting sites will be further connected through precise delivery of genotyping results and prescribing advice to clinicians via a web-based portal. Our novel assessment of genetic admixture will quantify the contribution of European, African and Amerindian ancestry, and the investigators will test whether this admixture component can explain the heritability that is currently missing in the response variability to this drug among Caribbean Hispanics. If successful in our target population, the same approach can ultimately render current pharmacogenomic models for clinical management of related thromboembolic conditions more accurate and predictive for other populations. The proposed research will advance and expand our understanding of how these clinically relevant variants affect the response to warfarin in an admixed population. Advancing knowledge in the important and under-investigated area of pharmacogenetics in minority populations will generate results that apply to personalize oral anticoagulation therapy in the wider population as it moves, inevitably, toward increasing heterogeneity through admixed genomes.