@HHSGov recently added an #LDT FAQ to the statement on its website that @US_FDA cannot require premarket review of LDTs w/out notice-and-comment rulemaking. Here's the FAQ: hhs.gov/sites/default/… 
In the FAQ, @HHSGov states that "although FDA has asserted the authority to [mandate premarket review of LDTs], this requirement has in fact almost never been enforced. It was only being enforced during public health emergencies." This, in fact, is false and misleading.
As I recently wrote in @GenomeWeb, FDA under multiple presidents — George W. Bush, Barack Obama, & Donald Trump — has maintained that it has legal authority to regulate all diagnostics: IVDs performed at many labs and LDTs developed & performed in 1 lab. genomeweb.com/molecular-diag…
There's a lot of nuance missing in the HHS FAQ. To understand this issue, it's important to start off with a definition of LDTs. The FDA has defined LDTs as tests developed, validated, and performed in a single lab.
However, the industry's definition of an LDT has not always aligned with the agency's definition. And this tension has resulted in a lot of FDA regulatory activity.
In Oct. 2008 (under George W. Bush admin) FDA sent a warning letter to LabCorp for marketing an ovarian cancer test developed at Yale. That, the agency said wasn't an LDT, b/c not developed and performed in the same lab; many in the lab industry disagreed genomeweb.com/archive/fda-wa…
In 2010 (Obama admin), FDA started regulating direct-to-consumer genetic testing companies saying these aren't LDTs. But, companies had launched these tests w/out seeking FDA premarket review precisely b/c they assumed what they were providing were LDTs genomeweb.com/diagnostics/fd…
HHS states in the FAQ that DTC tests aren't LDTs. Those in the lab and pathology community historically against FDA regulation of LDTs tend to agree that DTC genetic tests aren't LDTs.
But then again, new consumer facing labs have tried to distance themselves from DTC label by employing 3rd party physician networks to approve customer test orders. Many feel there's not much practical difference btw a person ordering online & a doc they never met ordering
Are LDTs sold to consumers online not "distributed" tests simply b/c test orders are cleared through 3rd party doc networks a/c to HHS? (Common argument: when a doc orders a test, even if not pts own doc, its out of FDA jurisdiction b/c FDA can't regulate practice of medicine)
The FDA has, since at least 2011 (under Obama), consistently regulated companion diagnostics (LDTs & IVDs) which are tests used to determine whether a patient should or should not receive a specific drug. Final guidance: 2014 fda.gov/media/81309/do…
Finally, the agency spent much of 2019 (under Trump admin), going after labs performing pharmacogenetic LDTs without the agency's approval/clearance. genomeweb.com/regulatory-new…
HHS action limiting FDA authority on LDTs has raised a lot of questions about what precisely is an LDT. Worth noting that FDA & industry have clashed over the line defining LDTs in the past, and HHS hasn't clearly delineated the line now. This FAQ raises even more questions.
