KMBJN, You have no idea how confused I occasionally am about censoring. As far I know there does not exist a good, comprehensive treatment of censoring. A lot of stuff covering some parts, yes.
I am not certain that I have answers to your questions, but the lack of knowledge has seldom stopped me from opening my mouth (ask my wife) - here goes.
Intent to Treat (ITT) population:
all subject that were randomized for the trial. Any reduction to it is considered per protocol - even excluding subjects randomized but not treated. In OM trial case: 61
When you talk to FDA you need to have data at least and always for this group, which means IPIX will present that analysis to FDA at some point of time.
Per Protocol (PP) population:
Treatment for OM and radiation for head and neck cancer are concurrent. Hence you can't put minimum cumulative radiation dose in inclusion criteria for ITT, which is always before any treatment. Solution:
Employ per protocol group: cumulative radiation at least 55 Gy.
1. That way you have analysis that definitely addresses also radiation effects, not only chemo effects.
2. Number 55 Gy specifically is probably to make result comparable with Dusquetide, which had the same per protocol group in phase 2.
3. I suspect that FDA had its finger on points 1 and 2.
In OM case per protocol analysis is probably more important to clinical practitioners (and hence to pharma cos) than ITT analysis because it is THE ANALYSIS for high radiation group.
Good Luck.