Not exactly. As a first step have a read through the FDA...

Not exactly. As a first step have a read through the FDA guidance for acne trials to understand the issues.

https://www.fda.gov/media/71152/download

The key design issue is that methodologically from the analysis of absolute lesion number change or percent lesion change clinical significance just doesn’t magically pop out.

So the FDA turns the question upside down.

Success or failure is defined by IGA change (2 points) which represents clinically significant improvement. With the quantitative lesion count providing the magnitude of change.

But clinical significance is the first key … because the FDA believe drugs shouldn’t be approved just because they help things … but rather that help needs to be clinically significant.

There is a big long complicated history to why the FDA thinks the way they do about this. .

But in brief the IGA operates like the Clinical Global Impressions (CGI) scale that is commonly used in neuroscience.

Here for example you might improve 3 points on a memory test. But what that means in the real world is highly unclear.

So the FDA promotes the CGI scale as a co-primary to the memory test .… where it wants a clinician to actually qualitatively make a judgment that this change in memory score has made a real world difference …the person can get to the shops and home again now where as before they couldn’t and this has led to a major improvement in quality of life.

All very complicated.

Keeping it simple … would you sign up to a treatment that produces clinical significant improvement in less than 10% of people.

If you had a daughter with Retts disease quite possibly … because there are no other treatments and we are talking about life and death. But not for acne treatment where there are more effective options; defined as higher percentages of people showing two or more point improvement on the IGA.

But that’s it for me for a while … back to trying make difference in the real world myself.