The implementation of a pharmacogenomics-based algorithm for warfarin dosing

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Dr. Perera's long-term career goal is to implement clinical pharmacogenetic testing as an indispensable part of clinical care. With the explosion of pharmacogenetic research, the opportunity to advance the use of pharmacogenetics into clinical care has become apparent. Warfarin has been a long-standing target of research because of its narrow therapeutic index and serious side effect profile. Currently, algorithms using genetic variants in CYP2C9 and VKORC1 have been developed to predict maintenance dose of warfarin in Caucasians and Asians. However, the extent of variation that affects dose in African Americans and an algorithm to guide dosing have yet to be investigated. In pursuit of this goal, Dr. Perera will first determine the genetic haplotype structure of CYP2C9 and VKORC1 in African Americans. By using comparative genomics and software that identifies putative functional regions, resequencing can be narrowed to areas most likely to yield informative SNPs. Next, haplotype-tagging SNPs along with non-genetic factors will be used to develop a predictive algorithm for maintenance dose in this population. Dr. Perera, along with collaborating physicians, will recruit African American anticoagulation patients and collect genotype data and non-genetic information. Regression analysis will be used to derive a dosing algorithm to predict maintenance dose. A second cohort of patients will be recruited to test the predictive power of this algorithm. Patient will be dosed empirically, as is standard of care; however, the correlation between predicted and observed maintenance dose will be determined. Lastly, she will evaluate the clinical outcomes through a pilot study in African American orthopedic patients. This study will be conducted to determine aspects of feasibility. Outcomes such as time to therapeutic INR and adverse events will be determined to assist in the development of a well-power clinical trial. Additional cost-effective analysis will be conducted to determine the utility of this algorithm in clinical care. The proposed research is both timely and necessary to fill gaps in the current knowledge and to affect real translation of pharmacogenetics into clinical practice. Such studies have the potential to change the way medicine is practiced. RELEVANCE (See instructions): The accurate dosing of warfarin is critical to both clinicians and institutions. Therefore the development of an algorithm that would predict warfarin dose in African Americans, a currently under-studied population, would greatly improve clinical practice in numerous medical fields. Such research will help lead the way to the translation of pharmacogenetic findings into clinical practice.