The Trouble with Targeting Treatments
Researchers are working to develop diagnostic tests to determine who is eligible for targeted therapies, but red tape and limited expertise stand in the way.
The future of personalized medicine depends in large measure on the development of companion diagnostics intended to identify patients with gene mutations and other biomarkers that make them candidates for targeted therapies. Companion diagnostics also include tests designed to detect gene variations that can cause some patients to experience severe side effects from certain medications, allowing doctors to adjust dosages or prescribe other drugs.
Yet while testing patients to tailor therapies seems logical, not all physicians and health insurers have embraced the idea. For starters, a 2012 survey of nearly 700 physicians in the United States and Europe, conducted by the health care communications agency CAHG and the consulting firms Diaceutics and Adelphi Group, found that the most common barrier to using molecular diagnostic tests was lack of knowledge among physicians about the tests and the kinds of genetic information they might provide in general.
Moreover, when physicians do use companion diagnostics, insurers deny coverage for the tests roughly half the time (though patients can appeal such decisions), says Tufts University health economist Joshua Cohen. The major reason, Cohen explains, is lack of evidence that a particular test actually helps patients. An oft-cited example: A blood test can determine whether a patient carries mutations that increase the risk of bleeding if treated with the anticoagulant warfarin. Yet two recent studies found that using a patient’s genetic makeup to guide warfarin dosing was no safer or more effective than using standard clinical guidelines.
However, other studies have found that warfarin-sensitivity testing can prevent hospitalizations, notes Felix Frueh, former associate director of genomics at the FDA and now chief scientific officer at Human Longevity, Inc., a genomics research firm. Makers of companion diagnostics face other challenges, such as low profit margins; while a targeted therapy might cost $10,000 a month, notes Frueh, insurers only reimburse $200 to $300 for a typical diagnostic test. And unlike prescription drugs, which have patent protection for at least a few years, diagnostic tests are more easily copied by competitors, further cutting into profitability. Despite the challenges, though, Frueh believes there’s a role for effective companion diagnostics in medicine: “There will always be a market for innovative products.”