In September, The New York Times reported that the Food and Drug Administration was taking steps to regulate a new category of complex diagnostic tests expected to play a growing role in tailoring medical treatments to specific patients. The new policy was published only as draft guidelines open for public comment, so the regulation has not yet become law and there is still time to voice any concerns you or your lab may have.

The FDA already requires approval of diagnostic test kits that are sold widely to labs, hospitals, and doctors. But it has yet to regulate “home-brew” tests developed and performed by a single laboratory. The FDA’s September announcement specifically targets one category of home-brew tests, which it refers to as “multivariate index assays.” These tests measure multiple genes, proteins, or other pieces of clinical information taken from a patient and then use an algorithm or software program to analyze the data. Perhaps the most well-known of these tests is the Oncotype DX, offered by Genomic Health, which analyzes the activities of 21 genes in a sample of a breast tumor and then computes a score that is said to be predictive of whether a patient’s cancer will recur and whether she would benefit from chemotherapy.

The FDA says that its primary concern with multivariate index assays is based on the fact that these assays use algorithms in analysis of the test results. Because these algorithms are usually proprietary, it is difficult for doctors to interpret the test results.

The FDA regulation of multivariate index assays will have significant effects on laboratories that create and offer these tests. First, FDA restrictions may serve to inhibit labs from creating such tests because the amount of time that the lab must wait to get approval for the test could make the amount of time it takes to recoup the investment costs from test development exponentially longer. Furthermore, the requirement might inhibit the gradual improvement of new or existing tests because each change in the test might require an additional regulatory submission.

Second, the FDA regulation of multivariate index assays may affect certain tests, such as the Oncotype DX, that are already on the market and gaining in clinical acceptance. Laboratories currently offering multivariate index assays may find themselves unable to continue offering such test until FDA approval has been obtained.

FDA regulation of genetic tests is a hot topic, widely discussed by both those that are pro-and anti-regulation of such tests. Public notice and public debate about the development and use of genetic tests is expanding outside the medical community and the clinical diagnostics industry. Over-regulation by the FDA of diagnostic tests that incorporate genetic technologies would inhibit the development of useful new assays. It would also lengthen the time and increase the costs of developing such tests and introducing them into clinical use. Lab managers and pathologists should stay alert to ongoing developments in this story. The outcome is likely to be more regulation, not less.