Replies to post #160042 on Biotech Values

[iwfal]

EXAS—

Low sensitivity can be conquered by repeating the test frequently, which is not a major imposition given that the test is non-invasive. I.e., the cumulative sensitivity of a series of tests over a multi-year period can be made to be acceptably high.

As per usual in biotech, if the company hasn't provided data it is reasonable to speculate that the data isn't particularly good. And so far I haven't seen any data that says that says the tests are significantly independent - e.g. for instance, data about two tests given, say, 3 months apart. Or even detailed data about how the signature for polyps varies over time.

For completely independent tests where 15% (WAG) of the population has polyps detectable via colonoscopy and they miss 58% of them then they should become positive on 3.7% (0.42*0.58*0.15) - plus false positive rate of 13% of the retested population. But I'd bet a good deal of money that they find nowhere near 3.7% rate of real polyps in retested patients who were negative the first time just a short time earlier. For instance I suspect that some significant fraction of undetected polyps are just "low shedding". And others just shed "benign signature" or "signature not caught by test".