Innovation Pharmaceuticals Inc (IPIX)

[PlentyParanoid]

Hi Sox thanks for the insights. And, of course, I am going to pipe in.

Some time ago I tried to find out if there is a way to map IGA scores to PASI scores. Turns out that there is until there isn't. Based on 'vast' sampling (is not like this is a hot topic is psoriasis research) of two studies covering some 1700 subject very lopsided, one had about 1550 subjects, the other had about 150. The bigger study included subjects being various lengths of time in treatment - useless for my purposes.The smaller study (typical, aargh!) had a scatter plot IGA vs PASI. Using that it turns out that at the extremes mapping IGA to PASI works - elsewhere not so much.

A rough mapping of IGA to PASI
IGA clear and almost clear (0/1) was always PASI 3 or less.
IGA mild (2) is between PASI 3 and 12
IGA moderate (3) varies from PASI 3 to 20
IGA severe (4) almost exclusively PASI > 20

Looks neat and clean except, of course IGA 3, which looks problematic.

From the scatter plot I could figure out that about 50 to 60 % IGA 3 values where in the region PASI > 12, which is the inclusion limit for the new IPIX study. PASI 12 is interesting number. If a subject has IGA 3 with PASI > 12 then a 75 % drop in PASI does not necessarily require 2 category drop in IGA (from 3 to 1 or 0), but 2 category drop in IGA will be at least PASI 75 drop! The opposite is true for IGA 3, PASI < 12, two category drop in IGA does not necessarily translate to PASI 75 or better.

What is all this weird IGA PASI, PASI IGA gibberish? Well, we can infer some pseudo-probabilities:
In my reference trial about 50 to 60 % IGA 3 values where in the region PASI > 12. Also, in the completed psoriasis trial IPIX observed that 46.2 % of IGA 3 subjects had 2 category drop. Assume that the PASI value distribution in the reference trial is typical. Then, based on the distribution of IGA 3 in terms of PASI it is slightly more probable than not ( 50 to 60 % vs 40 to 50 %) that in IPIX trial the percentage of IGA 3 subjects experiencing PASI 75 drop was at least the same as the number of subjects experiencing 2 point IGA drop.

Minor good news.

Beware!: All my reasoning is based on ONE small study.