Innovation Pharmaceuticals Inc (IPIX)

[KMBJN]

Agree with general PASI rule of thumb conversion to IGA final score, but it's good to remember that PASI percent reduction depends on the starting PASI score.

https://en.wikipedia.org/wiki/Psoriasis_Area_and_Severity_Index

If starting with IGA4~=PASI 25 (severe), then going down to IGA2~=PASI 5 would be PASI-80 (80% reduction). However, starting with moderate disease, IGA3~=PASI 15, then going down to IGA2~=PASI 5 would be PASI-67 (67% reduction). Or starting with more severe disease, PASI 48, going to IGA2~=PASI 4/5 would be PASI-90 (90% reduction).

PASI scoring will allow for much finer gradation of scoring versus IGA scores.

Another thing to keep in mind is that I believe the final analysis will be from the ITT group (with last observation carried forward), so for us the 200 mg group had 26% (mild-to moderate combined, 7/27) or perhaps 33% (6/18 in moderate group) drop of >=2 points on IGA. Not bad compared to Otezla ~21% sPGA drop of >=2 points (in moderate to severe disease, PASI>=12, >10% BSA involvement, and sPGA>=3). Complicating things further is that Otezla used the sPGA 6 point scale, and we used the IGA 5 point scale.

It's in our favor that our placebo response rate was pretty high, and should be much lower in the larger Phase IIb trial (was ~4-5% in Otezla studies).

Some color from a previous post (just so I don't have to look it up all over again):

http://investorshub.advfn.com/boards/read_msg.aspx?message_id=127466210

Prurisol had promising results in Phase IIa in the 200 mg arm, but it's helpful to keep in mind these results were in very small numbers - just 7/27 (26%) subjects in the ITT population, and 7/20 (35%) in the per-protocol group. I believe the 46% you quote is eliminating even more non-responders due to possible site non-compliance, to get 6/13 subjects.

100 mg arm no effect vs. placebo (which was high "response" to start), 200 mg pretty good in small numbers, and hoping/expecting 300 and 400 mg to match or improve on the 26% in a larger population. It will be nice to see a decent dose-response curve, comparing placebo to 100, 200, 300, and 400 mg doses.

We may also do better in more severe psoriasis, as the 200 mg arm had 18 subjects with IGA=3 (moderate), and presumably a good number of these had a decent response.

Regarding the correlation/conversion between IGA (modified, meaning 5 point scale vs. original 6 point scale, which most other trials had used) and PASI score, take a look at this poster:

https://www.ispor.org/research_pdfs/52/pdffiles/PSS1.pdf

Just by eye-balling the graph, can say that IGA0~=PASI 0-1; IGA1~=PASI 3 (range 1-15), IGA2~= PASI 5 (range 3-14), IGA3~= PASI 15? (range 4-38), and IGA4~= PASI 25 (range 20-38). So, on average a decrease from IGA3 to 0 or 1 is a reduction of 12/15 (PASI-80). Of course these are averages and rough guesses.

Here's another study comparing IGA (original) and PASI rating scales:

www.tandfonline.com/doi/full/10.3109/09546634.2013.865009

It's interesting that FDA guides to use IGA (modified, 5 point scale) but most previous trials used PASI scoring (with many also collecting the older 6 point IGA scale).

Looking forward to good results from Prurisol PhaseIIb. Would still like to hear some more from the company about how they think the drug works.