According to the Warning Letter, Pathway never registered with the FDA, never received clearance, and never performed any (reported) clinical trials.  The key sentence from the letter is:<p>&quot;We have conducted a review of our files and have been unable to identify any Food and Drug Administration (FDA) records reflecting the approval, clearance, or listing of these devices.&quot;<p>They were seeking to fly under the radar as a &quot;lab-derived test&quot; or LDT, using an FDA loophole that the FDA is increasingly seeking to close (also see Theranos).  The &quot;we&#x27;ve reviewed the literature&quot; part is just the FDA&#x27;s attempt to dig into what&#x27;s been published to see if they can find ANY support for their marketing claims — even if there were volumes of papers on their method, they still would have been sent the warning letter (which is a Very Serious thing to get from the FDA).<p>The issue wasn&#x27;t that &quot;this test is too risky for us&quot; it&#x27;s that they were 100% out of compliance.  If you sell a medical device, it must be classified for risk and at the very least registered with the FDA.  In the case of a cancer diagnostic, there is zero chance it would be a Class I (lowest) device, so they (at least) would have needed &quot;clearance&quot; requiring a submission of something called a 510(k) documenting tests they&#x27;ve done on their product, audits of suppliers, etc. etc. In addition to the 510(k) submission itself, they would need documented evidence of having put in place a &quot;quality management system&quot; that puts standard operating procedures around 100% of product development from cradle to grave.  This is why health tech&#x2F;biotech companies need to raise so much money, as this is a lot of overhead.<p>If their test were classified as Class III (highest risk), they would need &quot;approval&quot; rather than &quot;clearance,&quot; the bar for which is even higher (although this is primarily limited to ingestibles&#x2F;implantables).  Just the FDA submission itself costs something like a quarter million dollars.<p>GRAIL, on the other hand, is raising a huge amount of money partially because they know how much it costs to run proper trials and earn a clearance or approval.  It&#x27;s apples and oranges to compare the two.