Replies to post #107327 on Biotech Values

[genisi]

Tysabri/JCV test

The Leerink Swann analyst asked about the false negative rate (test's sensitivity), which was 2.5% in the STRATA study and Scangos replied that so far they get similar rate from STRATIFY 1 study. It will take few more years to know the predictive value and PML risk of the assay.

[zipjet]

Before we can make even loose assertions about the market impact of a JC test, we need to have some idea of the sensitivity and specificity of the test.

My statement was predicated upon there being an approved test* and that ~50% of them test positive.

My conclusion was that a lot of those who test positive will drop Tysabri.

So for now, I will stick to my loose assertion.

:-)

No doubt, I have more at stake here than logic.

ij



* Perhaps this is where you think I err, but I would expect the test have high sensitivity and specificity, say over 90%.