Innovation Pharmaceuticals Inc (IPIX)

[PlentyParanoid]

Ponderings at compost pile

I like (read: wife makes me) to compost our tree leaves and bush trimmings. That activity does not require much brain power, so, while loitering around my pile it occurred in my idle head to check what would be success limits for brilacidin trial based on interim data. So, in case somebody else is interested.

Interim results, who grade > 3:
Brilacidin: 7 out of 10, 70 %
Placebo: 2 out of 9, 22.2 %
2-sided p value by Fisher’s exact method: 0.07

A. Assume 31 subjects in placebo arm (enrollment is 61 subjects, 1: 1 ratio) with the same success ratio as at interim analysis. Question: how low can brilacidin success rate go while the trial still remains successful?
Placebo: 7 out of 31 (rounded up)
The trial is within p < 0.05 limits if success rate for brilacidin is more than 14 out of 30 or better than 47%.

B. Assume that brilacidin success rate is the same as at interim analysis. Question: how high can placebo success rate go while trial is still success?
Brilacidin 21 out of 30
The trial is within 0.05 limits if placebo success rate stays below 14 out of 31, or lower that 45 %.

One could make a x-y ( brilacidin vs placebo) curve for success/failure boundary. I am too lazy. However, lets check one point in between.

Assume that success rate with placebo is 50 % higher than at interim analysis.
Placebo: 10 out of 31
Brilacidin success rate can drop to 18 out 30 or to 60 % and the trial is still successful.

Looks quite good to me.