LDTs: FDA Cracks Down on Marketing of Non-Approved PGx Medication Response Tests

Laboratory Developed Tests (LDTs) are back in the FDA’s enforcement crosshairs. This time the target is marketing claims related to the medication predictive qualities of pharmacogenetics (PGx) tests that have not received premarket clearance or approval.

The FDA’s PGx Concerns

PGx tests can be used to detect genetic variants associated with responses to specific medications, e.g., genes that code for drug-metabolizing enzymes or drug targets, explains Steven Tjoe, an attorney with Goodwin Procter LLP in Washington, D.C., and former regulatory counsel in FDA’s Center for Devices and Radiological Health. PGx test results can inform medication decisions such as drug effectiveness and dosage amounts.

The FDA’s beef, Tjoe explains, is with claims about the capabilities of unreviewed PGx tests to predict response to specific medications. Thus, on Nov. 1, 2018, the FDA issued a Safety Communication to alert patients and physicians that such claims may not be supported by sufficient scientific or clinical evidence. The FDA cites genetic tests purporting to be capable of predicting whether certain medications used to treat depression may be less effective or have an increased chance of side effects. The relationship between variations and the effectiveness of antidepressant medication has never been established, the Safety Communication states. So, changing drug treatment based on the results from such tests could result in inappropriate and harmful treatment decisions.

The Follow-Up Enforcement

As the Safety Communication warns, the FDA has backed up its clinical warning with enforcement scrutiny. Thus, in April 2019, the FDA issued a warning letter to Inova Genomics Laboratory for marketing genetic tests that claim to predict patients’ responses to specific medications without FDA clearance or approval (See Lab Industry Report, (LIR), April 29, 2019). In response, Inova reportedly stopped offering its PGx tests. And Inova is not alone. Tjoe says the agency has also contacted several other laboratories making similar marketing claims about their own PGx tests.

Impact on Laboratories

This new FDA enforcement focus has had a chilling effect on just about all laboratories that provide PGx tests for medication response, including those that have not received a warning letter. According to Tjoe, some laboratories have stopped reporting drug information and no longer mention specific drugs on their websites and marketing materials. Others are reviewing their LDT marketing materials, test menus, test reports and other labeling in response to the FDA actions.

Perspective: Recognize that the FDA’s current enforcement activities against clinical laboratories offering PGx tests as LDTs are part of the larger discussion among the agency, Congress, regulators and laboratories about whether and how to regulate LDTs. Laboratories need to pay close attention to these conversations, not only for clues as to FDA’s enforcement priorities but also to see what the FDA, Congress and other regulators will actually do about LDTs regulation.


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