“The FDA considers both unwanted harmful effects and lack of efficacy to be adverse events. When considering candidates for pharmacogenomic relabeling, the FDA evaluates the severity of the adverse reaction, the degree to which genetics predicts the reaction, and the total number of individuals likely to be affected. These factors are important in assessing the potential public health impact of a recommendation to consider genetics when using the drug.” (see http://www.fda.gov/Drugs/ScienceResearch/ResearchAreas/Pharmacogenetics/ucm083367.htm).
So, what are the implications for the hospital physician? To date, FDA labeling has required, recommended, or mentioned gene testing prior to prescription in about ten percent of the labels for drugs approved by the FDA. At the recent Personalized Medicine World Conference held at Stanford, an FDA official said “things are changing hugely” at the agency in this domain. Many hospital and private practice physicians are not familiar with the myriad of gene tests that are commercially available, how the consequences of an individual’s patient’s genetic variation impacts dosing, and may not be familiar with the terminology of personal genomic variation. Pharmacogenomic Clinical Decision Support systems, combining clinical and pharmacogenomic data, have the potential to support the clinician per FDA gene testing requirements. This presumes that such software applications have been developed, and are integrated with the Electronic Health Record or as stand-alone software – but that is certainly not the case as of early 2010. In addition, approved hardware platforms and certified laboratories are required for testing a patient’s genetic markers that are associated with variability in drug response, and this is another area in which hospitals need to develop or expand their own laboratories or outsource to companies like LabCorp and Quest Diagnostics – but time is often key in drug prescription. The only sure bet is that a surge of new FDA gene testing requirements will eventually impact clinical practice
Some definitions from the FDA: Pharmacogenomics (PGx) is defined as the study of variations of DNA and RNA characteristics as related to drug response. Pharmacogenetics (PGt) is a subset of pharmacogenomics (PGx) and is defined as the study of variations in DNA sequence as related to drug response.