Color Genomics, a genetic test company, plans to sell DNA tests to determine which antidepressants are most effective for specific patients—but experts aren't sold on the science behind it, Rebecca Robbins reports for STAT News.
About the test
When Color Genomics launched in 2015, the company focused on a method of analyzing 19 genes to determine an individual's cancer risk, Robbins writes. Over time, the company has also started selling tests that measure one's risk for cardiovascular issues, including high cholesterol and certain heart conditions.
Now, the company wants to sell a new test that it claims will determine which antidepressants are likely to be effective for a given patient.
The test, which requires customers to mail in a saliva sample, will look at two genes—CYP2D6 and CYP2C19. These two genes, the company claims, impact the metabolism of 13 psychiatric medications, including Zoloft, Paxil, and Lexapro.
Unlike other mail-in genetic tests like 23andMe, the test can only be prescribed by a physician.
The science behind pharmacogenetics
While Color Genomics claims the science behind using pharmacogenetics for psychiatry "is sound and based on clear evidence and consensus statements," not all experts are convinced. In a review published in April, the American Psychiatric Association's research council said there is "insufficient evidence to support widespread use of combinatorial pharmacogenetic decision support tools at this point in time."
Similarly, Bruce Cohen, a psychiatrist at Harvard Medical School who used to run McLean Hospital, said he wouldn't order a test from Color Genomics or any test like it for his patients. "They cost a lot of money, and they have absolutely no proven value," he said.
Cohen added that there's a difference between using pharmacogenetics for cancer and for psychiatry. Certain genes have been identified by oncology researchers as significant determinants in getting cancer and responding to treatment. "In psychiatry, we don't have that," he said.
A 2013 meta-analysis that analyzed genetic data on over 2,200 patients and their responses to psychiatric medicine reached a similar conclusion. The authors found "no reliable predictors of antidepressant treatment outcome." However, it did find that factors like age, diet, and hormonal status could influence how well antidepressants work.
Even the research that does support pharmacogenetics appears questionable, Robbins writes. She notes that Cohen co-authored a JAMA Psychiatry opinion article in which the researchers examined and discussed 10 previously published studies on the topic. They found that none of the studies "were adequately blinded and properly controlled."
Cohen said he understands that doctors and patients want answers on which drug to use, but asking questions about a patient's diet or other symptoms are much more effective than pharmacogenetics. "Why spend money on this when there's a better way?" he said. "Why not spend more time with the patient? Why not use the guidelines that are there? Why not get a consultation if you're uncertain how to proceed?" (Robbins, STAT News, 9/28).
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