TBG Diagnostics Ltd fka TDLAF

[busker]

With permission from the author posted to Ihub in order to keep the forum informed.



QUOTE
Not to keep going back to the HCC data, but I don't want to understate the validity and utility of what Progen did with the data in the AASLD presentation.

This is a reformulation of my thinking and may help those concerned with the "data-mining" aspect of post-hoc analysis.

In many cases, a post-hoc sub-group analysis involves looking at sick patients and finding "reasons" why some got better and some were not helped by the therapy. Often this involves looking at numerous markers and perhaps trying to determine which patients should recieve the drug in the future. This is sometimes a desperate attempt to show that the drug DOES work in some patients, by excluding sick patients that did not benefit. What was done with the HCC data is quite different. The subgroup identified as high-risk is comprised of patients that are likely still "cancerous". The excluded patients (low-risk) were likely to be disease free for quite some time, and hence not "sick". This is hardly the same situation as the "desperate" case above.

What needs to be understood is that the high-risk group is defined largely by the aggressiveness of the cancer. Aggressiveness comes from genetic instability and variation (the source of the "histopathology" referred to in the poster) and signs of recruitment of blood vessels (and possibly immune suppression, although this is harder to "see"). This aggressive cancer is more likely to leave residual disease (and more aggressive disease) after resection, therefore this patient is more likely to be "sick". If a patient is low risk (having a less aggressive cancer), the tumor was more likely completely removed, and that patient may even be considered "cured". There is good reason to remove the low risk patients from the data.

Rather than being a post-hoc analysis that excludes sick non-responding patients (typical data-mining), this is more akin to removing healthy volunteers from data in order to produce a more appropriate data-set.

They did the right thing for the right reasons. I am even more impressed now than after my first look at the presentation.
End of quote

Posted in connection with this PGLA announcement.

http://www.progen-pharma.com/prs/AASLD%202007a.pdf