Commercial Imperatives: Labels, Tests, and “Ethnic” Product Differentiation

By August, 2007, enough data on the genetics of warfarin response had been published to convince the FDA to authorize a labeling change to Coumadin to explain how people's genetics may affect their response to the drug. In a conference call announcing the change, the FDA's Lawrence Lesko noted that “this marks the first time that such pharmacogenomic information has been included in a widely used drug .... This means that personalized medicine is no longer an abstract concept, but has moved into the mainstream, where it is recognized as a factor in a product used by millions of Americans.” An article in the journal Medical Marketing & Media enthused, “The FDA rang in the era of personalized medicine with a labeling change on blood thinner warfarin cautioning that patients with either of two genetic variations might respond differently to the drug.”

News reports of the FDA mandated label change also noted some of its regulatory, legal, and commercial implications. First, Jane Woodcock, deputy commissioner and chief medical officer of the FDA, emphasized that the labeling update was “not a directive to doctors” to use genetic tests for warfarin therapy since current clinical studies do not definitively support such a recommendation. This caution was warranted given fact that no prospective clinical trials had yet been conducted comparing the outcomes of using genetic tests to guide warfarin dosing as compared to existing practices. It reflected well-established understandings of the FDA's role as regulating drugs, not medical practice, but indicated as well a second concern involving potential legal claims of malpractice liability. A report in the Wall Street Journal noted that prior to the labeling change, a medical group called the Anticoagulation Forum wrote a letter to Dr. Lesko warning that doctors might rely too heavily on the genetic tests and fail to monitor patients closely enough. Some doctors might even hold off in starting a patient on warfarin until they had the results of a test in hand. The group asked that any new label “reflect the uncertainty” so that doctors “wouldn't be held liable in court for failing to do the tests.” Third, even without a directive to test, large insurers like Aetna take account of such labeling changes when deciding whether to reimburse for a genetic test. The labeling change thus had significant implications for the growing industry of pharmacogdiagnostics. Following the labeling change, a number of companies petitioned the FDA for approval of diagnostic kits that tested for a variety of CYP2C9 and VKORC1 polymorphisms related to warfarin response.